Luteolin ameliorates experimental lung fibrosis both in vivo and in vitro: implications for therapy of lung fibrosis

Therapeutic effects of flavonoids on pulmonary fibrosis: A preclinical meta-analysis

BACKGROUND

The efficacy of flavonoid supplementation in animal models of pulmonary fibrosis has been demonstrated.

PURPOSE

We conducted a systematic review and meta-analysis to evaluate the efficacy and underlying mechanisms of flavonoids in animal models of bleomycin-induced pulmonary fibrosis.

STUDY DESIGN

Relevant studies (n = 45) were identified from English- and Chinese-language databases from the inception of the database until October 2023.

METHODS

Methodological quality was evaluated using the SYRCLE risk of bias tool. Statistical analyses were conducted using RevMan 5.3 and Stata 17.0. Lung inflammation and fibrosis score were the primary outcome indicators.

RESULTS

Flavonoids can alleviate pathological changes in the lungs. The beneficial effects of flavonoids on pulmonary fibrosis likely relate to their inhibition of inflammatory responses, restoration of oxidative and antioxidant homeostasis, and regulation of fibroblast proliferation, migration, and activation by transforming growth factor β1/mothers against the decapentaplegic homologue/AMP-activated protein kinase (TGF-β1/Smad3/AMPK), inhibitor kappa B alpha/nuclear factor-kappa B (IκBα/NF-κB), phosphatidylinositol 3-kinase (PI3K)/AKT, interleukin 6/signal transducer/activator of transcription 3 (IL6/STAT3), and nuclear factor erythroid 2-related factor 2/Kelch-like ECH-associated protein 1 (Nrf2-Keap1) pathways.

CONCLUSION

Flavonoids are potential candidate compounds for the prevention and treatment of pulmonary fibrosis. However, extensive preclinical research is necessary to confirm the antifibrotic properties of natural flavonoids.

Exploring the efficacy and molecular mechanism of Danhong injection comprehensively in the treatment of idiopathic pulmonary fibrosis by combining meta-analysis, network pharmacology, and molecular docking methods

BACKGROUND

Danhong injection, a compound injection of Chinese herbal medicine, has been widely used in idiopathic pulmonary fibrosis (IPF) at present as an adjuvant treatment. However, the clinical efficacy and molecular mechanism of IPF are still unclear. This study will evaluate and explore the clinical efficacy and molecular mechanism of Danhong injection in the treatment of IPF.

METHODS

In meta-analysis, the computer was used to search 8 databases (PubMed, EMbase, CENTRAL, MEDLINE, CBM, CNKI, WanFang, and VIP) to collect the RCTs, and RevMan 5.3 and Stata 14.0 were used for statistical analysis. It has been registered on PROSPERO: CRD42020221096. In network pharmacology, the main chemical components and targets of the chemical components of Danhong injection were obtained in TCMSP and Swiss Target Prediction databases. The main targets of IPF were obtained through Gencards, Disgenet, OMIM, TTD, and DRUGBANK databases. The String platform was used to construct PPI networks. Cytoscape 3.8.2 was used to construct the "Danhong components - IPF targets-pathways" network. The molecular docking verification was conducted by Auto Dock.

RESULTS

Twelve RCTs were finally included with a total of 896 patients. The meta-analysis showed that Danhong injection could improve the clinical efficiency ([OR] = 0.25, 95% CI [0.15, 0.41]), lung function, arterial blood gas analysis, inflammatory cytokines, and serum cytokines associated with pulmonary fibrosis of IPF patients, respectively (P < .05). The core active components of Danhong injection on IPF were Luteolin, Quercetin, and Kaempferol, and the core targets were PTGS2, AR, ESR1, PPARG, and RELA. Danhong injection mainly improved IPF through PD-L1 expression and PD-1 checkpoint path in cancer, pathways in cancer, PI3K-Akt signaling pathway, etc.

CONCLUSION

These results provided scientific basis for the clinical use of Danhong injection for the treatment of IPF, and provided a new direction to explore the potential mechanism of action of Danhong injection.

Antifibrotic effect of silymarin on arecoline-induced fibrosis in primary human buccal fibroblasts: an in silico and in vitro analysis

BACKGROUND

This study aimed to assess silymarin's anticancer and antifibrotic potential through in silico analysis and investigate its impact on in vitro arecoline-induced fibrosis in primary human buccal fibroblasts (HBF).

METHODS & RESULTS

The study utilized iGEMDOCK for molecular docking, evaluating nine bioflavonoids, and identified silymarin and baicalein as the top two compounds with the highest target affinity, followed by subsequent validation through a 100ns Molecular Dynamic Simulation demonstrating silymarin's stable behavior with Transforming Growth Factor Beta. HBF cell lines were developed from tissue samples obtained from patients undergoing third molar extraction. Arecoline, a known etiological factor in oral submucous fibrosis (OSMF), was employed to induce fibrogenesis in these HBFs. The inhibitory concentration (IC50) of arecoline was determined using the MTT assay, revealing dose-dependent cytotoxicity of HBFs to arecoline, with notable cytotoxicity observed at concentrations exceeding 50µM. Subsequently, the cytotoxicity of silymarin was assessed at 24 and 72 h, spanning concentrations from 5µM to 200µM, and an IC50 value of 143µM was determined. Real-time polymerase chain reaction (qPCR) was used to analyze the significant downregulation of key markers including collagen, epithelial-mesenchymal transition (EMT), stem cell, hypoxia, angiogenesis and stress markers in silymarin-treated arecoline-induced primary buccal fibroblast cells.

CONCLUSION

Silymarin effectively inhibited fibroblast proliferation and downregulated genes associated with cancer progression and EMT pathway, both of which are implicated in malignant transformation. To our knowledge, this study represents the first exploration of silymarin's potential as a novel therapeutic agent in an in vitro model of OSMF.

Buyang Huanwu Decoction alleviates blood stasis, platelet activation, and inflammation and regulates the HMGB1/NF-κB pathway in rats with pulmonary fibrosis

ETHNOPHARMACOLOGICAL RELEVANCE

Qi deficiency and blood stasis are identified to be pathological factors of pulmonary fibrosis (PF) in traditional Chinese medicine (TCM) theory. Buyang Huanwu Decoction (BYHWD) is a traditional Chinese prescription ameliorating Qi deficiency and blood stasis.

AIM OF THE STUDY

The objective of this study was to investigate the anti-fibrosis effect of BYHWD and the potential molecular mechanism in rats.

MATERIALS AND METHODS

Bleomycin was used to construct PF rat models. 27 PF rats were randomly divided into three groups based on treatments: model group (saline solution, n = 9), low-dose BYHWD group (3.5 g/kg, n = 9), and high-dose BYHWD group (14.0 g/kg, n = 9). Moreover, 9 normal rats were used as the blank group. The blood viscosity, coagulation indexes (APTT, TT, PT, and FIB), platelet-related parameters (PLT, PDW, MPV, PCT, and PLCR), platelet microparticles (PMPs), and inflammatory factors (IL-2, IL-10, IL-1β, IL-6, IL-8, IL-17, IFN-γ, TNF-α, PAC-1, HMGB1, NF-κB, and TF) were determined. The lung tissue samples of rats were observed after hematoxylin-eosin (HE) staining. The full component analysis of the BYHWD extract was performed using the ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method. The signaling pathway included into the study was selected on the basis of bioinformatics analysis and the results of the phytochemical analysis. The expression levels of genes and proteins involved in the selected signaling pathway were detected.

RESULTS

Compared to the blank group, the whole blood viscosity, PLR, PDW, MPV, PCT, PLCR, PMPs, and the levels of IL-1β, IL-6, IL-8, IL-17, TNF-α, PAC-1, HMGB1, NF-κB, and TF were increased, while the levels of IL-2 and IL-10 were decreased in the model group. Both low-dose BYHWD and high-dose BYHWD reversed these PF-induced effects in spite of the fact that low-dose BYHWD had no significant effect on the level of NF-κB. In addition, BYHWD ameliorated PF-induced inflammation in the rat lung tissue. The phytochemical analysis of the BYHWD extract combined with the bioinformatics analysis suggested that the therapeutical effect of BYHWD on PF was related to the HMGB1/NF-κB pathway, which consisted of NF-κB, IKBKB, ICAM1, VCAM1, HMGB1, and TLR4. Both RT-qPCR and western blot analyses showed that PF induced increases in the expression levels of NF-κB, ICAM1, VCAM1, HMGB1, and TLR4, but a decrease in the expression level of IKBKB. Moreover, both low-dose BYHWD and high-dose BYHWD exerted the opposite effects, and recovered the expression levels of NF-κB, ICAM1, VCAM1, HMGB1, TLR4, and IKBKB, despite the fact that low-dose BYHWD had no effects on the mRNA expression levels of NF-κB or TLR4.

CONCLUSIONS

In summary, BYHWD alleviated PF-induced blood stasis, platelet activation, and inflammation in the rats. Our study suggested BYHWD had a therapeutic effect on PF and was a good alternative for the complementary therapy of PF, and the potential molecular mechanism was modulation of HMGB1/NF-κB signaling pathway, and it needs further study.

Chinese medicine as a therapeutic option for pulmonary fibrosis: Clinical efficacies and underlying mechanisms

ETHNIC PHARMACOLOGICAL RELEVANCE

Pulmonary fibrosis (PF) is a fibrotic interstitial lung disease caused by continuous damage and excessive repair of alveolar epithelial cells, the pathogenesis of which is not fully understood. At present, the incidence of PF has increased significantly around the world. The therapeutic arsenals against PF are relatively limited, with often poor efficacy and many adverse effects. As a conventional and effective therapeutic strategy, traditional Chinese medicine (TCM) has been widely applied in treating lung fibrosis for thousands of years in China. Due to the multi-ingredient, multi-target characteristics, Chinese medicines possess promising clinical benefits for PF treatment.

AIM OF THIS REVIEW

This review aims to systematically analyze the clinical efficacy of Chinese medicine on PF, and further summarize the relevant mechanisms of Chinese medicine treating PF in preclinical studies, in order to provide a comprehensive insight into the beneficial effects of Chinese medicines on PF.

METHODS

Eight major Chinese and English databases were searched from database inception up to October 2022, and all randomized clinical trials (RCTs) investigating the effects of Chinese medicine intervention on effectiveness and safety in the treatment of PF patients were included. Subsequently, preclinical studies related to the treatment of PF in Chinese medicine, including Chinese medicine compounds, Chinese herbal materials and extracts, and Chinese herbal formulas (CHFs) were searched through PubMed and Web of science to summarize the related mechanisms of Chinese medicine against PF.

RESULTS

A total of 56 studies with 4019 patients were included by searching the relevant databases. Total clinical efficacy, pulmonary function, blood gas analysis, lung high resolution CT (HRCT), 6 min walk test (6-MWT), St George's Respiratory Questionnaire (SGRQ) scores, clinical symptom scores, TCM syndrome scores and other outcome indicators related to PF were analyzed. Besides, numerous preclinical studies have shown that many Chinese medicine compounds, Chinese herbal materials and extracts, and CHFs play a preventive and therapeutic role in PF by reducing oxidative stress, ameliorating inflammation, inhibiting epithelial-mesenchymal transition and myofibroblasts activation, and regulating autophagy and apoptosis.

CONCLUSION

Chinese medicines show potential as supplements or substitutes for treating PF. And studies on Chinese medicines will provide a new approach to better management of PF.

Lonicera japonica Thunb extract ameliorates lipopolysaccharide-induced acute lung injury associated with luteolin-mediated suppression of NF-κB signaling pathway

OBJECTIVE

Lonicera japonica Thunb (LJT) is a commonly used herbal soup to treat inflammation-related diseases. However, the effect of LJT on ALI is unknown. The present study was aimed at investigating the protective effects of LJT extract (LTE) and its active ingredient luteolin (Lut) on lipopolysaccharide (LPS)-stimulated ALI and investigate its potential mechanism.

MATERIALS AND METHODS

The effects of LTE and Lut were explored in an ALI mouse model induced by intraperitoneal injection of lipopolysaccharide (LPS). Besides, the LPS-induced inflammation model in BEAS-2B cells was used to clarify the underlying mechanisms. The ALI pathological changes in lung tissues were tested through Haematoxylin and eosin (HE) staining. The apoptosis of cells in lung tissue and the cell model in vitro was evaluated by TUNEL assays, respectively. Meanwhile, the viability of cells in vitro was evaluated by Cell Counting Kit-8 (CCK-8) assay. The levels/concentrations of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), IL-1β and IL-10 in BALF were detected by enzyme-linked immunosorbent assay (ELISA). Besides, through quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting, the expression of the above-mentioned inflammatory factors and key factors in the NF-κB signaling pathway was examined. The distribution of inflammatory factors in tissue was observed through immunohistochemistry (IHC) assays .

RESULTS

In relative to LPS-stimulated group, the in vivo study showed that LTE and different concentrations of Lut dramatically alleviated LPS-evoked lung pathological injury and lung edema based on the changes in total protein levels and lung wet/dry (W/D) ratio in the bronchoalveolar lavage fluid (BALF) from ALI mice. LTE and different concentrations of Lut also suppressed the inflammatory response, as reflected by the variations of neutrophil accumulation and the production of proinflammatory and anti-inflammatory cytokines in the lung tissues and BALF of ALI mice. The in vitro research also demonstrated that LTE and Lut visibly facilitated cell viability and restrained the apoptosis of BEAS-2B cells stimulated by LPS. Lut hindered LPS-inducible activation of NF-κB pathway in BEAS-2B cells.

CONCLUSION

The present study proved that LTE might suppress LPS-induced acute injury and inflammation in mice and BEAS-2B cells through the Lut-caused suppression of NF-κB signal path (Figure 1).

Luteolin alleviated neutrophilic asthma by inhibiting IL-36γ secretion-mediated MAPK pathways

CONTEXT

Luteolin can affect multiple biological functions, such as anti-inflammatory, antioxidant and immune enhancement processes. Luteolin can inhibit inflammation of T2-high asthma, but its role in neutrophilic asthma has been insufficently studied.

OBJECTIVE

This study determines the effect of luteolin on IL-36γ secretion-mediated MAPK pathway signalling in neutrophilic asthma.

MATERIALS AND METHODS

The asthma model was established by using ovalbumin/lipopolysaccharide (OVA/LPS). Female 6-8-week-old C57BL/6 mice were divided into control, asthma, luteolin (20 mg/kg) and asthma + luteolin (20 mg/kg) groups. To explore the mechanism of anti-inflammatory effects of luteolin in neutrophilic asthma, Beas-2B cells were treated with luteolin (20 µmol/L), LPS (100 ng/mL), recombinant human IL-36γ protein (rhIL-36γ; 100 ng/mL) or IL-36γ siRNA.

RESULTS

IL-36γ secretion and MAPK/IL-1β signalling were significantly increased in the asthma mouse model compared with the control (p < 0.05). However, the levels of IL-36γ secretion and MAPK/IL-1β signalling were reduced by luteolin (p < 0.05). In addition, luteolin inhibited IL-36γ and MAPK/IL-1β levels after LPS (100 ng/mL) stimulation of Beas-2B cells (p < 0.05). We found that in Beas-2B cells, luteolin inhibited activation of the MAPK pathway and IL-1β secretion following stimulation with rhIL-36γ (100 ng/mL; p < 0.05). Finally, IL-1β and phosphorylated MAPK levels were found to be lower in the IL-36γ siRNA + LPS (100 ng/mL) group than in the nonspecific control (NC) siRNA + LPS group (p < 0.05).

DISCUSSION AND CONCLUSIONS

Luteolin alleviated neutrophilic asthma by inhibiting IL-36γ secretion-mediated MAPK pathways. These findings provided a theoretical basis for the application of luteolin in the treatment of neutrophilic asthma.

Tangeretin attenuates bleomycin-induced pulmonary fibrosis by inhibiting epithelial-mesenchymal transition via the PI3K/Akt pathway

Background: Pulmonary fibrosis (PF) is a terminal pathological change in a variety of lung diseases characterized by excessive deposition of extracellular matrix, for which effective treatment is lacking. Tangeretin (Tan), a flavonoid derived from citrus, has been shown to have a wide range of pharmacological effects. This study aimed to investigate the role and potential mechanisms of Tan on pulmonary fibrosis. Methods: A model of pulmonary fibrosis was established by administering bleomycin through tracheal drip, followed by administering Tan or pirfenidone through gavage. HE and Masson staining were employed to assess the extent of pulmonary fibrosis. Subsequently, Western blot, enzyme-linked immunosorbent assay (ELISA), RNA sequencing, and immunohistochemistry techniques were employed to uncover the protective mechanism of Tan in PF mice. Furthermore, A549 cells were stimulated with TGF-β1 to induce epithelial-mesenchymal transition (EMT) and demonstrate the effectiveness of Tan in mitigating PF. Results: Tan significantly ameliorated bleomycin-induced pulmonary fibrosis, improved fibrotic pathological changes, and collagen deposition in the lungs, and reduced lung inflammation and oxidative stress. The KEGG pathway enrichment analysis revealed a higher number of enriched genes in the PI3K/Akt pathway. Additionally, Tan can inhibit the EMT process related to pulmonary fibrosis. Conclusion: Taken together, the above research results indicate that Tan suppresses inflammation, oxidative stress, and EMT in BLM-induced pulmonary fibrosis via the PI3K/Akt pathway and is a potential agent for the treatment of pulmonary fibrosis.

Unraveling the mechanism of tetrandrine combined with Buyang Huanwu Decoction against silicosis using network pharmacology and molecular docking analyses

Silicosis is an incurable chronic disease characterized by lung fibrosis and inflammation. The combination of tetrandrine and Buyang Huanwu Decoction (BYHWD) has a curative effect on silicosis. However, the mechanism of action and the key active constituent in BYHWD are still unclear. The present study employed network pharmacology and molecular docking to determine the mechanism of action and the key active components of BYHWD of Tetrandrine in combination with BYHWD for silicosis. The primary elements and targets of BYHWD were obtained from the Traditional Chinese Medicine Systems Pharmacology and analysis platform. The targets associated with tetrandrine and silicosis were identified and extracted from the Comparative Toxicogenomics Database and GeneCards database. The potential targets for the treatment of silicosis using a combination of Tetrandrine and BYHWD were identified by considering the overlapping targets between compound drugs and silicosis. These targets were then utilized to construct protein-protein interaction networks, compound drug-ingredient-target networks, and perform enrichment analyses. The top 5 active ingredients present in the compound drug-ingredient-target network are tetrandrine, quercetin, luteolin, kaempferol, and beta-carotene. Similarly, the top 6 hub genes in the protein-protein interaction network are FGF2, MMP-9, MMP-1, IL-10, IL-17A, and IL-6. The molecular docking suggested that the active components may easily access the active pocket of the hub gene. The in-silico investigation suggested that quercetin might be the active component in BYHWD responsible for therapeutic effectiveness against silicosis. This study identified the active compound and potential molecular mechanism underlying the therapeutic effects of BYHWD in combination with tetrandrine for treating silicosis. Notably, we found that quercetin may serve as the key compound in BYHWD for the treatment of silicosis.

Natural plant resource flavonoids as potential therapeutic drugs for pulmonary fibrosis

Pulmonary fibrosis is an enduring and advancing pulmonary interstitial disease caused by multiple factors that ultimately lead to structural changes in normal lung tissue. Currently, pulmonary fibrosis is a global disease with a high degree of heterogeneity and mortality rate. Nitidine and pirfenidone have been approved for treating pulmonary fibrosis, and the quest for effective therapeutic drugs remains unabated. In recent years, the anti-pulmonary fibrosis properties of natural flavonoids have garnered heightened attention, although further research is needed. In this paper, the resources, structural characteristics, anti-pulmonary fibrosis properties and mechanisms of natural flavonoids were reviewed. We hope to provide potential opportunities for the application of flavonoids in the fight against pulmonary fibrosis.

Luteolin Alleviates Liver Fibrosis in Rat Hepatic Stellate Cell HSC-T6: A Proteomic Analysis

BACKGROUND

Traditional Chinese medicine (TCM) with single or compound materials is an effective cure for liver fibrosis. Hepatic stellate cells (HSCs) play a key role in liver fibrosis pathology and have become a novel drug target for this condition.

METHODS

CCK-8 assay was used to determine the cytotoxicity of four components, SYPA, HSYPA, Apigenin, and Luteolin, from Deduhonghua-7 powder on HSC-T6 cells. Transforming Growth Factor β 1 (TGFβ1)-induced fibrotic cell model and CCI4-induced fibrotic rat model were constructed, the expression of fibrosis-related genes, the pathological changes and serum biochemical markers were evaluated. Proteomic analysis was performed to determine the mechanism by which luteolin attenuated liver fibrosis, which were further confirmed by Western blot.

RESULTS

Luteolin attenuates liver fibrosis in HSC-T6 cells and luteolin decreases the liver fibrosis index level in vivo. A total of 5000 differentially expressed proteins (DEPs) were obtained using proteomic analysis. KEGG analysis found that DEPs were concentrated in various metabolic pathways, including DNA replication and repair and lysosomal signaling. GO analysis showed that molecular functions included the activity and binding of various enzymes, related cellular components included the extracellular space, lysosomal lumen, mitochondrial matrix, and nucleus, and biological processes included collagen organization and biosynthesis and the positive regulation of cell migration. Western blot results showed that CCR1, CD59, and NAGA were downregulated in TGFβ1 treatment, while upregulated both in Lut2 and Lut10 treatment. Meanwhile, eight proteins, ITIH3, MKI67, KIF23, DNMT1, P4HA3, CCDC80, APOB, FBLN2, that were upregulated in TGFβ1 treatment, while downregulated both in Lut2 and Lut10 treatment.

CONCLUSION

Luteolin was shown to have a strong protective effect on liver fibrosis. CCR1, CD59, and NAGA may promote liver fibrosis while ITIH3, MKI67, KIF23, DNMT1, P4HA3, CCDC80, APOB, and FBLN2 may facilitate protection against fibrosis.

Luteolin reduces cardiac damage caused by hyperlipidemia in Sprague-Dawley rats

Objective

Hyperlipidemia is a risk factor for cardiac damage that can lead to many cardiovascular diseases. A recent study reported the cardioprotective effects of luteolin in vitro and in vivo. In this study, we aimed to investigate the possible protective effects of luteolin against hyperlipidemia-induced cardiac damage in Sprague-Dawley (SD) rats.

Methods

Six-week-old male SD rats were randomly divided into five groups: a normal diet (ND) group; a high-fat diet (HFD) group; and three high-fat diet mixed with luteolin (HFD + LUT) groups, where in a luteolin dosage 50, 100, or 200 mg/kg/day was administered. All groups were fed their respective diets for 12 weeks.

Results

Left ventricular ejection fraction and fractional shortening (parameters of cardiac function) were lower in the HFD + LUT (100 mg/kg/day) group than in the HFD group. Metabolic parameters were lower in the HFD + LUT (100 mg/kg/day) group than in the HFD group. Collagen I, collagen III, and TGF-β expression levels were lower in the cardiac tissues of the HFD + LUT (100 mg/kg/day) group, compared to those of the HFD group. Expression of the profibrotic genes MMP2 and MMP9 was suppressed in the cardiac tissues of the HFD + LUT (100 mg/kg/day) group, compared to those of the HFD group. Furthermore, CD36 and lectin-like oxidized low-density lipoprotein receptor-1 protein levels were lower in the cardiac tissues of the HFD + LUT (100 mg/kg/day) group, compared to those of the HFD group.

Conclusion

These findings would provide new insights into the role of luteolin in hyperlipidemia-induced cardiac damage and contribute to the development of novel therapeutic interventions to treat cardiovascular disease progression.

Luteolin inhibits subretinal fibrosis and epithelial-mesenchymal transition in laser-induced mouse model via suppression of Smad2/3 and YAP signaling

BACKGROUND

Subretinal fibrosis (SF) accounts for vision loss in patients with neovascular age-related macular degeneration (nAMD) even treated with adequate intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF) drugs. Currently, there is no treatment available to prevent or treat SF caused by nAMD.

PURPOSE

This study aims to investigate the potential effects of luteolin on SF and epithelial-mesenchymal transition (EMT) as well as the underlying molecular pathways both in vivo and in vitro.

METHODS

Seven-week-old male C57BL/6J mice were employed to establish laser-induced choroidal neovascularization (CNV) and SF. One day after the laser induction, luteolin was administered intravitreally. SF and CNV were assessed with the immunolabeling of collagen type I (collagen I) and isolectin B4 (IB4), respectively. RPE65 and α-SMA colocalization in the lesions was used to evaluate the extent of EMT in retinal pigment epithelial (RPE) cells by using immunofluorescence. In vitro, luteolin was administered to TGFβ1-treated primary human RPE (phRPE) cells. RT-qPCR, Western blot and immunofluorescence were employed to evaluate the change of EMT-related molecules, epithelial markers, and relevant signaling pathways. The functional changes associated with EMT were investigated using the scratch assay, Transwell migration assay, and collagen gel contraction assay. CCK-8 was used to determine the cell viability of phRPE cells.

RESULTS

On day 7 and 14 after laser induction in mice, intravitreal injection of luteolin dramatically decreased the immunolabeled sizes of both collagen I and IB4, as well as the amount of colocalized double immunostaining of α-SMA and RPE65 in laser-induced SF lesions. In vitro, TGFβ1-treated phRPE cells demonstrated increased cell migration and contraction capacity, accompanied with considerable overexpression of fibronectin, α-SMA, N-cadherin and vimentin, as well as downregulation of E-cadherin and ZO-1. The above changes were largely inhibited by luteolin co-incubation. Mechanistically, luteolin could evidently decrease the phosphorylation of Smad2/3, whereas increase the phosphorylation of YAP in TGFβ1-treated phRPE cells.

CONCLUSION

This study demonstrates that luteolin exhibits the anti-fibrotic effect in a laser-induced mouse model by inhibiting EMT of RPE cells via deactivating Smad2/3 and YAP signaling, which provides a potential natural compound for the prevention and treatment of SF and fibrosis-related diseases.

Tanreqing injection protects against bleomycin-induced pulmonary fibrosis via inhibiting STING-mediated endoplasmic reticulum stress signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Idiopathic pulmonary fibrosis (IPF), characterized by excessive collagen deposition, is a progressive and typically fatal lung disease without effective therapeutic methods. Tanreqing injection (TRQ), a Traditional Chinese Patent Medicine, has been widely used to treat inflammatory respiratory diseases clinically.

AIM OF THE STUDY

The present work aims to elucidate the therapeutic effects and the possible mechanism of TRQ against pulmonary fibrosis.

METHODS

The pulmonary fibrosis murine model were constructed by the intratracheal injection of bleomycin (BLM). 7 days later, TRQ-L (2.6 ml/kg) and TRQ-H (5.2 ml/kg) were administered via intraperitoneal injection respectively for 21 days. The efficacy and underlying molecular mechanism of TRQ were investigated.

RESULTS

Here, we showed that TRQ significantly inhibited BLM-induced lung edema and pulmonary function. TRQ markedly reduced BLM-promoted inflammatory cell infiltration in BALF and inflammatory cytokines release (TNF-α, IL-6, and IL-1β) in serum and lung tissues. Meanwhile, TRQ also alleviated BLM-induced collagen synthesis and deposition. Simultaneously, TRQ attenuated BLM-induced pulmonary fibrosis through regulating the expression of fibrotic hallmarks, manifested by down-regulated α-SMA and up-regulated E-cadherin. Moreover, we found that TRQ significantly prevented STING, p-P65, BIP, p-PERK, p-eIF2α, and ATF4 expression in lung fibrosis mice.

CONCLUSIONS

Taken together, our results indicated that TRQ positively affects inflammatory responses and lung fibrosis by regulating STING-mediated endoplasmic reticulum stress (ERS) signal pathway.

Application Potential of Luteolin in the Treatment of Viral Pneumonia

Aim of the Review. This study aims to summarize the therapeutic effect of luteolin on the pathogenesis of viral pneumonia, explore its absorption and metabolism in the human body, evaluate the possibility of luteolin as a drug to treat viral pneumonia, and provide a reference for future research. Materials and Methods. We searched MEDLINE/PubMed, Web of Science, China National Knowledge Infrastructure, and Google Scholar and collected research on luteolin in the treatment of viral pneumonia and related diseases since 2003. Then, we summarized the efficacy and potential of luteolin in directly inhibiting viral activity, limiting inflammatory storms, reducing pulmonary inflammation, and treating pneumonia complications. Results and Conclusion. Luteolin has the potential to treat viral pneumonia in multiple ways. Luteolin has a direct inhibitory effect on coronavirus, influenza virus, and respiratory syncytial virus. Luteolin can alleviate the inflammatory factor storm induced by multiple factors by inhibiting the function of macrophages or mast cells. Luteolin can reduce pulmonary inflammation, pulmonary edema, or pulmonary fibrosis induced by multiple factors. In addition, viral pneumonia may cause multisystem complications, while luteolin has extensive protective effects on the gastrointestinal system, cardiovascular system, and nervous system. However, due to the first-pass metabolism mediated by phase II enzymes, the bioavailability of oral luteolin is low. The bioavailability of luteolin can be improved, and its potential value can be further developed by changing the dosage form or route of administration.

Dinebra retroflexa Herbal Phytotherapy: A Simulation Study Based on Bleomycin-Induced Pulmonary Fibrosis Retraction Potential in Swiss Albino Rats

Background and Objectives: Fibrotic lung disease is one of the main complications of many medical conditions. Therefore, the use of anti-fibrotic agents may provide a chance to prevent, or at least modify, such complication. The aim of this study was to evaluate the protective pulmonary anti-fibrotic and anti-inflammatory effects of Dinebra retroflexa. Materials and methods: Dinebra retroflexa methanolic extract and its synthesized silver nanoparticles were tested on bleomycin-induced pulmonary fibrosis. Pulmonary fibrosis was induced by intratracheal instillation of bleomycin (5 mg/5 mL/kg-Saline) as a supposed model for induced lung fibrosis. The weed evaluation was performed by intratracheal instillation of Dinebra retroflexa methanolic extract and its silver nanoparticles (35 mg/100 mL/kg-DMSO, single dose). Results: The results showed that both Dinebra retroflexa methanolic extract and its silver nanoparticles had a significant pulmonary fibrosis retraction potential, with Ashcroft scores of three and one, respectively, and degrees of collagen deposition reduction of 33.8 and 46.1%, respectively. High-resolution UHPLC/Q-TOF-MS/MS metabolic profiling and colorimetrically polyphenolic quantification were performed for further confirmation and explanation of the represented effects. Such activity was believed to be due to the tentative identification of twenty-seven flavonoids and one phenolic acid along with a phenolic content of 57.8 mg/gm (gallic acid equivalent) and flavonoid content of 22.5 mg/gm (quercetin equivalent). Conclusion: Dinebra retroflexa may be considered as a promising anti-fibrotic agent for people at high risk of complicated lung fibrosis. The results proved that further clinical trials would be recommended to confirm the proposed findings.

Luteolin-Induced Activation of Mitochondrial BKCa Channels: Undisclosed Mechanism of Cytoprotection

Luteolin (LUT) is a well-known flavonoid that exhibits a number of beneficial properties. Among these, it shows cardioprotective effects, as confirmed by numerous studies. However, its effect on mitochondrial potassium channels, the activation of which is related to cytoprotection, as well as on heart ischemia/reperfusion (I/R) damage prevention, has not yet been investigated. The large conductance calcium-regulated potassium channel (mitoBKCa) has been identified in both the mitochondria of the vascular endothelial cells, which plays a significant role in the functioning of the cardiovascular system under oxidative stress-related conditions, and in the mitochondria of cardiomyocytes, where it is deeply involved in cardiac protection against I/R injury. Therefore, the aim of this study was to explore the role of the mitoBKCa channel in luteolin-induced cytoprotection. A number of in vitro, in vivo, ex vivo and in silico studies have confirmed that luteolin activates this channel in the mitochondria of cardiomyocytes and endothelial cells, which in turn leads to the protection of the endothelium and a significant reduction in the extent of damage resulting from myocardial infarction, where this effect was partially abolished by the mitoBKCa channel blocker paxilline. In conclusion, these results suggest that luteolin has cardioprotective effects, at least in part, through the activation of the mitoBKCa channel, shedding light on a new putative mechanism of action.

Flavonols and Flavones as Potential anti-Inflammatory, Antioxidant, and Antibacterial Compounds

Plant preparations have been used to treat various diseases and discussed for centuries. Research has advanced to discover and identify the plant components with beneficial effects and reveal their underlying mechanisms. Flavonoids are phytoconstituents with anti-inflammatory, antimutagenic, anticarcinogenic, and antimicrobial properties. Herein, we listed and contextualized various aspects of the protective effects of the flavonols quercetin, isoquercetin, kaempferol, and myricetin and the flavones luteolin, apigenin, 3 $\prime$ ,4 $\prime$ -dihydroxyflavone, baicalein, scutellarein, lucenin-2, vicenin-2, diosmetin, nobiletin, tangeretin, and 5-O-methyl-scutellarein. We presented their structural characteristics and subclasses, importance, occurrence, and food sources. The bioactive compounds present in our diet, such as fruits and vegetables, may affect the health and disease state. Therefore, we discussed the role of these compounds in inflammation, oxidative mechanisms, and bacterial metabolism; moreover, we discussed their synergism with antibiotics for better disease outcomes. Indiscriminate use of antibiotics allows the emergence of multidrug-resistant bacterial strains; thus, bioactive compounds may be used for adjuvant treatment of infectious diseases caused by resistant and opportunistic bacteria via direct and indirect mechanisms. We also focused on the reported mechanisms and intracellular targets of flavonols and flavones, which support their therapeutic role in inflammatory and infectious diseases.

Therapeutic and prophylactic effect of flavonoids in post-COVID-19 therapy

The high incidence of post-covid symptoms in humans confirms the need for effective treatment. Due to long-term complications across several disciplines, special treatment programs emerge for affected patients, emphasizing multidisciplinary care. For these reasons, we decided to look at current knowledge about possible long-term complications of COVID-19 disease and then present the effect of flavonoids, which could help alleviate or eliminate complications in humans after overcoming the COVID-19 infection. Based on articles published from 2003 to 2021, we summarize the flavonoids-based molecular mechanisms associated with the post-COVID-19 syndrome and simultaneously provide a complex view regarding their prophylactic and therapeutic potential. Review clearly sorts out the outcome of post-COVID-19 syndrome according particular body systems. The conclusion is that flavonoids play an important role in prevention of many diseases. We suggest that flavonoids as critical nutritional supplements, are suitable for the alleviation and shortening of the period associated with the post-COVID-19 syndrome. The most promising flavonoid with noteworthy therapeutic and prophylactic effect appears to be quercetin.

Mechanistic Insights of Qingre Jiedu Recipe Based on Network Pharmacology Approach against Heart Failure

Qingre Jiedu (QJ) recipe exerted significant cardioprotective efficacy against heart failure (HF), which is a growing health concern that continues to endanger patients' lives. To investigate the protective properties and mechanism of the QJ recipe, we established hydrogen peroxide (H2O2)-induced H9C2 cells and HF rats. The predicted targets and significant pathways of QJ against HF were collected and screened based on network pharmacology from key ingredients and validated by in vivo and in vitro experiments. The decoction of QJ (0.823 g/kg/day) was intragastrically administered for four weeks. QJ (400 μg/mL) was cultured with H2O2 stimulated in the H9C2 cells. A total of 31 effective active compounds were screened in QJ and covered 277 targets, of which 85 were shared with HF-related targets. In vivo, the QJ recipe remarkably protected heart function and reduced serum IL-1, IL-6, PIIINP, and CIV levels. Furthermore, QJ downregulated the key proteins mediating inflammatory responses (p-IKKα/β, p-NFκB, and IL-6) and cardiac fibrosis (STAT3 and MMP-9). In vitro, QJ protected the cardiomyocytes against H2O2-stimulated reactive oxygen species (ROS) production and upregulated PI3K and AKT expressions. Further experiments demonstrate that PI3K inhibitor LY294002 remarkably compromised the effects of QJ. In conclusion, our findings indicate that QJ could exert a cardioprotective effect and inhibit fibrosis and inflammation in HF rats via the PI3K-AKT signaling pathway.

Feibi decoction-medicated serum inhibits lipopolysaccharide-induced inflammation in RAW264.7 cells and BMDMs

Feibi decoction (FBD) is a traditional Chinese herbal medicine and has been clinically used in the treatment of pulmonary fibrosis (PF), which is characterized by diffuse interstitial inflammation and exaggerated collagen accumulation. However, the potential mechanisms remain to be elucidated. The present study aimed to investigate the effect of FBD-medicated serum (FBDS) on lipopolysaccharide (LPS)-induced inflammation in macrophages. In RAW264.7 macrophages and bone marrow-derived macrophages (BMDMs), FBDS treatment significantly inhibited the production of pro-inflammatory cytokines induced by LPS. In addition, it was indicated that FBDS treatment suppressed the activation of NF-κB and Smad2/Smad3 following LPS treatment. Furthermore, FBDS treatment decreased the expression of transforming growth factor-β1 and chitinase-3-like protein 1. In conclusion, the results demonstrated that treatment with FBDS inhibited LPS-induced inflammation in RAW264.7 and BMDM cells. These data may improve understanding of the effect of FBD on anti-inflammation and help determine the mechanisms underlying the alleviation of PF via FBD.

Luteolin Attenuates Diabetic Nephropathy through Suppressing Inflammatory Response and Oxidative Stress by Inhibiting STAT3 Pathway

BACKGROUND

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease (ESRD). DN has many pathological changes, but tubular injury is considered to be a crucial pathological feature and plays a key role in the progression of DN. Accumulating studies have confirmed that Luteolin (3,4,5,7-tetrahydroxyflavone, Lut) possesses anti-inflammatory and antioxidant activities, which may play a role in kidney protection in DN.

OBJECTIVES

This paper described the effects of Lut on appropriated tubular injury in the kidneys of db/db mice and searched the possible mechanisms underlying the kidney protection effect in DN.

METHODS

Twelve-week-old male C57BL/6 J db/db and C57BL/6 J db/m mice were used for the animal experiments. They were organized into the following five groups for the animal experiments: a db/m group (control, n=6); a db/db group(n=8) ; a db/db group receiving Lut (10 mg/kg/day, n=8)treatment by oral gavage; a db/db group receiving stattic (a selective STAT3 inhibitor,50 mg/Kg/day, n=8) treatment by oral gavage and a db/db group receiving both stattic and Lut treatment by oral gavage.

RESULTS

In this study, we found that Lut might ameliorate glomerular sclerosis and interstitial fibrosis in DN mouse models through inhibiting the inflammatory response and oxidative stress. And it might play its biological function mainly through repressing the STAT3 activation.

CONCLUSIONS

Lut attenuates DN mainly via suppression of inflammatory response and oxidative response. STAT3 pathway is the potential target, which ultimately reduces renal fibrosis and delays the progress of DN.

Key points for the development of antioxidant cocktails to prevent cellular stress and damage caused by reactive oxygen species (ROS) during manned space missions

Exposure to microgravity and ionizing radiation during spaceflight missions causes excessive reactive oxygen species (ROS) production that contributes to cellular stress and damage in astronauts. Average spaceflight mission time is expected to lengthen as humanity aims to visit other planets. However, longer missions or spaceflights will undoubtedly lead to an increment in microgravity, ionizing radiation and ROS production. Strategies to minimize ROS damage are necessary to maintain the health of astronauts, future space colonists, and tourists during and after spaceflight missions. An antioxidant cocktail formulated to prevent or mitigate ROS damage during space exploration could help maintain the health of space explorers. We propose key points to consider when developing an antioxidant cocktail. We discuss how ROS damages our body and organs, the genetic predisposition of astronauts to its damage, characteristics and evidence of the effectiveness of antioxidants to combat excess ROS, differences in drug metabolism when on Earth and in space that could modify antioxidant effects, and the characteristics and efficacy of common antioxidants. Based on this information we propose a workflow for assessing astronaut resistance to ROS damage, infight monitoring of ROS production, and an antioxidant cocktail. Developing an antioxidant cocktail represents a big challenge to translate current medical practices from an Earth setting to space. The key points presented in this review could promote the development of different antioxidant formulations to maintain space explorers' health in the future.

Experimental and clinical studies on the effects of Portulaca oleracea L. and its constituents on respiratory, allergic, and immunologic disorders, a review

Various pharmacological effects for Portulaca oleracea were shown in previous studies. Therefore, the effects of P. oleracea and its derivatives on respiratory, allergic, and immunologic diseases according to update experimental and clinical studies are provided in this review article. PubMed/Medline, Scopus, and Google Scholar were searched using appropriate keywords until the end of December 2020. The effects of P. oleracea and its constituents such as quercetin and kaempferol on an animal model of asthma were shown. Portulaca oleracea and its constituents also showed therapeutic effects on chronic obstructive pulmonary disease and chronic bronchitis in both experimental and clinical studies. The possible bronchodilatory effect of P. oleracea and its ingredients was also reported. Portulaca oleracea and its constituents showed the preventive effect on lung cancer and a clinical study showed the effect of P. oleracea on patients with lung adenocarcinoma. In addition, a various constituents of P. oleracea including, quercetin and kaempferol showed therapeutic effects on lung infections. This review indicates the therapeutic effect of P. oleracea and its constituents on various lung and allergic disorders but more clinical studies are required to establish the clinical efficacy of this plant and its constituents on lung and allergic disorders.

Effects of Eugenol and Dehydrodieugenol B from Nectandra leucantha against Lipopolysaccharide (LPS)-Induced Experimental Acute Lung Inflammation

Acute lung injury (ALI) is an important public health problem. The present work investigated whether dehydrodieugenol B treatment, a compound isolated from Brazilian plant Nectandra leucantha (Lauraceae), modulates experimental ALI and compared the observed effects to eugenol. Effects of dehydrodieugenol B in vitro in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells were evaluated. The lung and systemic inflammatory profile, lung function, and possible mechanisms involved in BALB/C male mice (6-8 weeks) with ALI induced by LPS instillation (5 mg/kg) was assayed. Dehydrodieugenol B did not affect the cell viability and inhibited the increase in NO release and IL-1β and IL-6 gene expression induced by LPS. In vivo, both compounds reduced lung edema, inflammatory cells, and the IL-6 and IL-1 β levels in bronchoalveolar lavage fluid, as well as reduced inflammatory cell infiltration and those positive to iNOS, MMP-9, and TIMP-1, and reduced the collagen content and the 8-isoprostane expression in lung tissue. Eugenol and dehydrodieugenol B also inhibited the phosphorylation of Jc-Jun-NH2 terminal Kinase (JNK), a signaling protein involved in the MAPKinase pathway. There was no effect of these compounds in lung function. Therefore, eugenol and dehydrodieugenol B ameliorates several features of experimental ALI and could be considered as a pharmacological tool to ameliorate acute lung inflammation.

Flavonoids as potential phytotherapeutics to combat cytokine storm in SARS-CoV-2

Emergence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection, COVID-19, has become the global panic since December 2019, which urges the global healthcare professionals to identify novel therapeutics to counteract this pandemic. So far, there is no approved treatment available to control this public health issue; however, a few antiviral agents and repurposed drugs support the patients under medical supervision by compromising their adverse effects, especially in emergency conditions. Only a few vaccines have been approved to date. In this context, several plant natural products-based research studies are evidenced to play a crucial role in immunomodulation that can prevent the chances of infection as well as combat the cytokine release storm (CRS) generated during COVID-19 infection. In this present review, we have focused on flavonoids, especially epicatechin, epigallocatechin gallate, hesperidin, naringenin, quercetin, rutin, luteolin, baicalin, diosmin, ge nistein, biochanin A, and silymarin, which can counteract the virus-mediated elevated levels of inflammatory cytokines leading to multiple organ failure. In addition, a comprehensive discussion on available in silico, in vitro, and in vivo findings with critical analysis has also been evaluated, which might pave the way for further development of phytotherapeutics to identify the potential lead candidatetoward effective and safe management of the SARS-CoV-2 disease.

Exploring the Pharmacological Mechanism of Radix Salvia Miltiorrhizae in the Treatment of Radiation Pneumonia by Using Network Pharmacology

Background

Radiation pneumonia (RP) is the most common complication of radiotherapy to the thorax and seriously affects the survival rate and quality of life of patients. Radix Salviae Miltiorrhizae (RSM) is an ancient Chinese medicine, whose main pharmacological effect is to promote blood circulation and remove stasis. A growing number of studies have proved that RSM has a good effect on RP. However, the underlying mechanism is still unclear and needs to be fully elucidated.

Methods

The effective components and predictive targets of RSM were analyzed by Traditional Chinese Medicine Systems Pharmacology (TCMSP) database, and the related targets of RP were predicted by GeneCards database. The common targets of the two targets mentioned above were analyzed by protein-protein interaction on the STRING website, GO and KEGG analysis on the DAVID website, visualization by CytoScape3.7.0, and screening for Hubber gene by cytoHubber plug-in.

Results

A search of the TCMSP database revealed that RSM contains 65 chemical constituents and 165 potential protein targets. A total of 2,162 protein targets were found to be associated with RP. The top 10 hub genes were obtained by MCC algorithm for 70 common genes, including TP53, CASP3, MAPK1, JUN, VEGFA, STAT3, PTGS2, IL6, AKT1, and FOS. By analyzing the Gene Ontology, The anti-radiation pneumonia effect of RSM is that it performs molecular functions (protein homodimerization activity) in the nucleus through three biological processes (positive regulation of transcription from RNA polymerase II promoter,Extrinsic apoptotic signaling pathway in absence of ligand and lipopolysaccharide-mediated signaling pathway). Through KEGG analysis, the mechanism of RSM treatment of radiation pneumonia may be through PI3K-Akt, HIF-1, TNF signaling pathways.

Conclusions

Through network pharmacology analysis, we found the possible target genes of RSM on RP and revealed the most likely signaling pathway, providing theoretical basis for further elucidating the potential mechanism of RSM on RP.

The role of natural products in the prevention and treatment of pulmonary fibrosis: a review

Pulmonary fibrosis is an incurable end-stage lung disease and remains a global public health problem. Although there have been some breakthroughs in understanding the pathogenesis of pulmonary fibrosis, effective intervention methods are still limited. Natural products have the advantages of multiple biological activities and high levels of safety, which are important factors for preventing and treating pulmonary fibrosis. In this review, we summarized the mechanisms and health benefits of natural products against pulmonary fibrosis. These natural products target oxidative stress, inflammatory injury, epithelial-mesenchymal transition (EMT), fibroblast activation, extracellular matrix accumulation and metabolic regulation, and the mechanisms involve the NF-κB, TGF-β1/Smad, PI3K/Akt, p38 MAPK, Nrf2-Nox4, and AMPK signaling pathways. We hope to provide new ideas for pulmonary fibrosis prevention and treatment strategies.

Chinese Herbs and Repurposing Old Drugs as Therapeutic Agents in the Regulation of Oxidative Stress and Inflammation in Pulmonary Diseases

Several pro-inflammatory factors and proteins have been characterized that are involved in the pathogenesis of inflammatory diseases, including acute respiratory distress syndrome, chronic obstructive pulmonary disease, and asthma, induced by oxidative stress, cytokines, bacterial toxins, and viruses. Reactive oxygen species (ROS) act as secondary messengers and are products of normal cellular metabolism. Under physiological conditions, ROS protect cells against oxidative stress through the maintenance of cellular redox homeostasis, which is important for proliferation, viability, cell activation, and organ function. However, overproduction of ROS is most frequently due to excessive stimulation of either the mitochondrial electron transport chain and xanthine oxidase or reduced nicotinamide adenine dinucleotide phosphate (NADPH) by pro-inflammatory cytokines, such as interleukin-1β and tumor necrosis factor α. NADPH oxidase activation and ROS overproduction could further induce numerous inflammatory target proteins that are potentially mediated via Nox/ROS-related transcription factors triggered by various intracellular signaling pathways. Thus, oxidative stress is considered important in pulmonary inflammatory processes. Previous studies have demonstrated that redox signals can induce pulmonary inflammatory diseases. Thus, therapeutic strategies directly targeting oxidative stress may be effective for pulmonary inflammatory diseases. Therefore, drugs with anti-inflammatory and anti-oxidative properties may be beneficial to these diseases. Recent studies have suggested that traditional Chinese medicines, statins, and peroxisome proliferation-activated receptor agonists could modulate inflammation-related signaling processes and may be beneficial for pulmonary inflammatory diseases. In particular, several herbal medicines have attracted attention for the management of pulmonary inflammatory diseases. Therefore, we reviewed the pharmacological effects of these drugs to dissect how they induce host defense mechanisms against oxidative injury to combat pulmonary inflammation. Moreover, the cytotoxicity of oxidative stress and apoptotic cell death can be protected via the induction of HO-1 by these drugs. The main objective of this review is to focus on Chinese herbs and old drugs to develop anti-inflammatory drugs able to induce HO-1 expression for the management of pulmonary inflammatory diseases.

Systematic elucidation of the mechanism of Jingyin granule in the treatment of Novel Coronavirus (COVID-19) Pneumonia via Network Pharmacology

Background: Jingyin granule is one of the widely used traditional Chinese medicine mixture composed of multiple herbs in the treatment of respiratory system diseases. The mechanism of its therapeutic effects has still been obscure. The aim of this study is to use the network pharmacology approach for identification of the main active ingredients of Jingyin granule against COVID-19 targets and to explore their therapeutic mechanism. Material and Method: In this study, the ingredients of Jingyin granule were evaluated by the usage of Traditional Chinese Medicine Systems Pharmacology Database and Traditional Chinese Medicine Integrated Database, and the interactions between potential gene targets and ingredients were identified using the SwissTargetPrediction database. Meanwhile the possible efficient targets COVID-19 acts on were identified via Online Mendelian Inheritance in Man database, DisGeNET database and GeneCards database. In addition, functions, components and pathways were identified by Gene Ontology enrichment analysis and Kyoto Encyclopedia of Genes and Genomes pathway analysis. Protein interaction, ingredients-targets network was established. Results: Our findings showed that numerous ingredients of Jingyin granule could act on COVID-19 with 88 target genes. GO enrichment analysis, KEGG pathway analysis, and protein-protein interaction network revealed that these targets were interrelated with regulation of immune function, directly targeting disease genes. Conclusions: Jingyin granule could be utilized to exert systematic pharmacological effects. Jingyin granule could directly target the major genes, and also regulate the immune system, acting as oblique disease treatment.

Effect of hydroalcoholic and aqueous extracts of Dracocephalum kotschyi on bleomycin induced pulmonary fibrosis

Introduction: Dracocephalum kotschyi is an Iranian traditional medicine with anti-inflammatory and bronchodilatory properties. The objective of this research was to investigate the preventive effect of D. kotschyi extract in bleomycin induced fibrosis. Methods: Fibrosis was induced by intratracheal administration of a single dose of bleomycin (5 mg/kg) in rat. One group received daily administration of normal saline. Other groups were treated daily with oral administration of either hydroalcoholic or aqueous extract of D. kotschyi (20, 40, & 80 mg/kg). Another group was treated with pirfenidone (100 mg/kg). After 4 weeks daily treatments, the animals were sacrificed and the whole lungs were dissected out for biochemical and histopathological examinations. The biochemical examination included assessment of hydroxyproline and malondialdehyde levels. Results: The lung tissues in bleomycin treated groups showed severe tissue injuries. However, lung tissues in the groups that received hydroalcoholic or aqueous extracts of D. kotschyi showed mild to moderate tissue injuries. Intratracheal instillation of bleomycin significantly increased hydroxyproline and malondialdehyde biomarker levels compared with the sham group. In the positive control group treated with pirfenidone, there was a marked reduction in both hydroxyproline and malondialdehyde levels. Both hydroalcoholic and aqueous extracts of D. kotschyi significantly prevented the elevation of hydroxyproline and malondialdehyde levels at the above oral doses in comparison to the vehicle treated control group. Conclusion: Prevention of hydroxyproline and malondialdehyde elevation levels in this experiment indicates that D. kotschyi extract might be a suitable remedy for the treatment of respiratory fibrosis induced by drugs such as bleomycin.

Mushroom Inonotus sanghuang alleviates experimental pulmonary fibrosis: Implications for therapy of pulmonary fibrosis

Mushroom Inonotus sanghuang has been characterized as a traditional medicine in China and has pharmacological activities to treat inflammation, gastroenteric dysfunction, and cancer. Recently, we reported the impact of Inonotus sanghuang extract (ISE) from ethyl acetate fraction on bleomycin (BLM)-induced acute lung injury in mice. Here, we aimed to investigate ISE's impact on pulmonary fibrosis using in vivo and in vitro models and the underlying mechanisms. To evaluate pulmonary fibrosis, female C57BL/6 mice fed ISE (0% or 0.6% in diet) for 4 weeks were instilled intratracheally with BLM and then continued the same diet before the end of the experiment. A549 cells were used to evaluate the epithelial-mesenchymal transition (EMT). Feeding ISE improved BLM-treated mice's survival via decreasing lung infiltrating cells and fibrosis, followed by reducing hydroxyproline content, collagen deposition, and mesenchymal markers (α-SMA and vimentin) while increasing epithelial marker E-cadherin. ISE also suppressed the TGF-β expression, Smad2/3 phosphorylation, and EMT-related transcription factor Snail upon BLM instillation. Iin vitro study demonstrated that ISE inhibited TGF-β-induced EMT-like phenotype and cell behaviors, the expression of α-SMA and vimentin, and prevented E-cadherin reduction of A549 cells. Consistent with in vivo study, ISE abrogated p-Smad2/3, and Snail expression. Finally, the influence of ISE on EMT was not due to ISE toxicity. Our findings indicated that ISE effectively attenuated BLM-induced lung fibrosis. These ISE properties were thought to be involved in interfering TGF-β, Smad2/3 phosphorylation, and EMT process, suggesting that the material has the potential health benefits to improve lung fibrosis.

Inhibiting TGF-[Formula: see text] 1-Mediated Cellular Processes as an Effective Strategy for the Treatment of Pulmonary Fibrosis with Chinese Herbal Medicines

Pulmonary fibrosis (PF) is a chronic and irreversible interstitial lung disease that even threatens the lives of some patients infected with COVID-19. PF is a multicellular pathological process, including the initial injuries of epithelial cells, recruitment of inflammatory cells, epithelial-mesenchymal transition, activation and differentiation of fibroblasts, etc. TGF-[Formula: see text]1 acts as a key effect factor that participates in these cellular processes of PF. Recently, much attention was paid to inhibiting TGF-[Formula: see text]1 mediated cell processes in the treatment of PF with Chinese herbal medicines (CHM), an important part of traditional Chinese medicine. Here, this review first summarized the effects of TGF-[Formula: see text]1 in different cellular processes of PF. Then, this review summarized the recent research on CHM (compounds, multi-components, single medicines and prescriptions) to directly and/or indirectly inhibit TGF-[Formula: see text]1 signaling (TLRs, PPARs, micrRNA, etc.) in PF. Most of the research focused on CHM natural compounds, including but not limited to alkaloids, flavonoids, phenols and terpenes. After review, the research perspectives of CHM on TGF-[Formula: see text]1 inhibition in PF were further discussed. This review hopes that revealing the inhibiting effects of CHM on TGF-[Formula: see text]1-mediated cellular processes of PF can promote CHM to be better understood and utilized, thus transforming the therapeutic activities of CHM into practice.

Natural product derived phytochemicals in managing acute lung injury by multiple mechanisms

Acute lung injury (ALI) and its more severe form, acute respiratory distress syndrome (ARDS) as common life-threatening lung diseases with high mortality rates are mostly associated with acute and severe inflammation in lungs. With increasing in-depth studies of ALI/ARDS, significant breakthroughs have been made, however, there are still no effective pharmacological therapies for treatment of ALI/ARDS. Especially, the novel coronavirus pneumonia (COVID-19) is ravaging the globe, and causes severe respiratory distress syndrome. Therefore, developing new drugs for therapy of ALI/ARDS is in great demand, which might also be helpful for treatment of COVID-19. Natural compounds have always inspired drug development, and numerous natural products have shown potential therapeutic effects on ALI/ARDS. Therefore, this review focuses on the potential therapeutic effects of natural compounds on ALI and the underlying mechanisms. Overall, the review discusses 159 compounds and summarizes more than 400 references to present the protective effects of natural compounds against ALI and the underlying mechanism.

Luteolin attenuates angiotensin II‑induced renal damage in apolipoprotein E‑deficient mice

Renal damage is a common and severe condition encountered in the clinic. Luteolin (Lut) exhibits anti-inflammatory, anti-fibrotic and anti-apoptotic effects. Thus, the present study aimed to investigate the pharmacological effects of Lut on angiotensin II (AngII)-induced renal damage in apolipoprotein E-deficient (ApoE^−/−) mice. Male ApoE^−/− mice (age, 8 weeks) were randomly divided into the following three groups: i) Control group (n=6); ii) AngII group (n=6); and iii) AngII + Lut group (n=6). Lut was administered by gavage (100 mg/kg/d). ApoE^−/− mice were implanted with Alzet osmotic minipumps, filled with either saline vehicle or AngII solution for a maximum period of 4 weeks. After 4 weeks, metabolic characteristics were measured and the histopathological alterations in the kidney tissue were observed. The metabolic characteristics of blood creatinine (CRE) levels were lower in the AngII + Lut group compared with in the AngII group. The expression levels of collagen I and III were lower in the kidney tissues of the AngII + Lut group compared with the corresponding tissues of the AngII group. The gene expression levels of IL-1β, IL-6, TNF-α and IL-10 were also suppressed in the kidney tissues of the AngII + Lut group compared with those in the corresponding tissues of the AngII group. Furthermore, the AngII + Lut group exhibited markedly increased LC3 protein expression and notably decreased p62 protein expression in the kidney tissues compared with the expression levels in the AngII group. The data demonstrated that Lut attenuated AngII-induced collagen deposition and inflammation, while inducing autophagy. Collectively, the results suggested that Lut treatment exhibited a exerted effect on AngII-induced renal injury in ApoE^−/− mice.

The upshot of Polyphenolic compounds on immunity amid COVID-19 pandemic and other emerging communicable diseases: An appraisal

Polyphenols are a large family of more than 10,000 naturally occurring compounds, which exert countless pharmacological, biological and physiological benefits for human health including several chronic diseases such as cancer, diabetes, cardiovascular, and neurological diseases. Their role in traditional medicine, such as the use of a wide range of remedial herbs (thyme, oregano, rosemary, sage, mint, basil), has been well and long known for treating common respiratory problems and cold infections. This review reports on the most highlighted polyphenolic compounds present in up to date literature and their specific antiviral perceptive properties that might enhance the body immunity facing COVID-19, and other viral infectious diseases. In fact, several studies and clinical trials increasingly proved the role of polyphenols in controlling numerous human pathogens including SARS and MERS, which are quite similar to COVID-19 through the enhancement of host immune response against viral infections by different biological mechanisms. Thus, polyphenols ought to be considered as a potential and valuable source for designing new drugs that could be used effectively in the combat against COVID-19 and other rigorous diseases.

In silico screening of potential anti-COVID-19 bioactive natural constituents from food sources by molecular docking

OBJECTIVES

The aim of this study was to seek potential natural compounds that can resist COVID-19 using computer virtual screening technology through molecular docking of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) 3CL hydrolytic enzyme (3CL^pro) and angiotensin-converting enzyme 2 (ACE2).

METHODS

Molecular docking was achieved by using the Autodock Vina software. The natural phytocompounds acting on 3CL^pro and ACE2 were then selected from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform. This was followed by speculation on the mechanism of action of phytocompounds.

RESULTS

Six potential natural anti-COVID-19 phytocompounds were selected and were evaluated for absorption, distribution, metabolism and excretion (ADME) and Lipinski rules. The content of the six phytocompounds in various fruits and vegetables was determined via a literature search. Red wine, Chinese hawthorn, and blackberry were recommended as supplements because they contained antiviral phytocompounds.

CONCLUSION

Red wine, Chinese hawthorn, and blackberry show promise for resisting COVID-19 and are thus recommended as supplements to prevent the infection of COVID-19 during its outbreak period.

A long-acting isomer of Ac-SDKP attenuates pulmonary fibrosis through SRPK1-mediated PI3K/AKT and Smad2 pathway inhibition

Idiopathic pulmonary fibrosis (IPF) is a progressive, life-threatening lung disease with a poor prognosis. N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) is a critical negative regulator of fibrosis development. However, it's extremely short half-life greatly limits its applications. Previously, we reported an Ac-SDKP analog peptide in which Asp and Lys residues were replaced with D-amino acids (Ac-SD_D K_D P). Ac-SD_D K_D P exhibits better resistance to angiotensin-1-converting enzyme (ACE)-mediated degradation and a longer half-life than Ac-SDKP in rat and human sera. The objective of this study was to explore the potential application of Ac-SD_D K_D P for the treatment of IPF and to clarify the underlying mechanisms. We found that Ac-SD_D K_D P exerted similar antifibrotic effects as Ac-SDKP on human fetal lung fibroblast-1 (HFL-1) proliferation, α-smooth muscle actin (α-SMA), collagen I and collagen III expression, and Smad-2 phosphorylation in vitro. In vivo, Ac-SD_D K_D P exhibited significantly greater protective effects against bleomycin-induced pulmonary fibrosis than Ac-SDKP in mice. α-SMA, CD45, collagen I and collagen III expression, and Smad-2 phosphorylation were significantly decreased in the lungs of Ac-SD_D K_D P-treated but not Ac-SDKP-treated mice. Furthermore, a pull-down experiment was used to screen for molecules that interact with Ac-SDKP. Co-immunoprecipitation (Co-IP) and computer-based molecular docking experiments demonstrated an interaction between Ac-SDKP or Ac-SD_D K_D P (Ac-SDKP/Ac-SD_D K_D P) and serine/arginine-rich protein-specific kinase 1 (SRPK1) that caused inhibition SRPK1-mediated phosphatidylinositol-3 kinase/ serine/threonine kinase (PIK3/AKT) signaling pathway activation and Smad2 phosphorylation and thereby attenuated lung fibrosis. Our data suggest that long-acting Ac-SD_D K_D P may potentially be an effective drug for the treatment of pulmonary fibrosis. The interacting molecule and antifibrotic mechanism of Ac-SDKP/Ac-SD_D K_D P were also identified, providing an experimental and theoretical foundation for the clinical application of the drug.

Lonicerae japonicae flos and Lonicerae flos: a systematic review of ethnopharmacology, phytochemistry and pharmacology

Lonicerae japonicae flos (called Jinyinhua, JYH in Chinese), flowers or flower buds of Lonicera japonica Thunberg, is an extremely used traditional edible-medicinal herb. Pharmacological studies have already proved JYH ideal clinical therapeutic effects on inflammation and infectious diseases and prominent effects on multiple targets in vitro and in vivo, such as pro-inflammatory protein inducible nitric oxide synthase, toll-like receptor 4, interleukin-1 receptor. JYH and Lonicerae flos [called Shanyinhua, SYH in Chinese, flowers or flower buds of Lonicera hypoglauca Miquel, Lonicera confusa De Candolle or Lonicera macrantha (D.Don) Spreng] which belongs to the same family of JYH were once recorded as same herb in multiple versions of Chinese Pharmacopoeia (ChP). However, they were listed as two different herbs in 2005 Edition ChP, leading to endless controversy since they have close proximity on plant species, appearances and functions, together with traditional applications. In the past decades, there has no literature regarding to systematical comparison on the similarity concerning research achievements of the two herbs. This review comprehensively presents similarities and differences between JYH and SYH retrospectively, particularly proposing them the marked differences in botanies, phytochemistry and pharmacological activities which can be used as evidence of separate list of JYH and SYH. Furthermore, deficiencies on present studies have also been discussed so as to further research could use for reference.

A natural AKT inhibitor swertiamarin targets AKT-PH domain, inhibits downstream signaling, and alleviates inflammation

Swertiamarin (SW), a representative component in Flos Lonicerae Japonicae, has been reported to exert significant activity in preventing infections. In this research, we aim to clarify the details of SW and its target to explore SW's underlying anti-inflammatory mechanisms. An azide labeled SW probe was synthesized for protein target fishing, and the results demonstrated that AKT could be captured specifically. Immunofluorescence colocalization with AKT was implemented by a click reaction of the SW probe and alkynyl CY5. The result showed that AKT was one of the targets of SW. Then, a competitive combination experiment using a set of AKT inhibitors and a membrane translocation experiment confirmed that SW might target the pleckstrin homology (PH) domain of AKT. This specific binding directly deactivated the phosphorylation of AKT on both Ser473 and Thr308, which induced the dephosphorylation of IKK and NF-κB. Finally, proinflammatory cytokines (TNF-α, IL-6, and IL-8) were suppressed both in cells and in acute lung injury animal model by targeting AKT-PH domain. This study demonstrated that SW functions as a natural AKT inhibitor and presents significant anti-inflammatory activity by directly regulating the AKT-PH domain and inhibiting downstream inflammatory molecules.

Anti-Inflammatory Properties of Plant Derived Natural Products - A Systematic Review

Traditionally, natural medicines have been administered as plant extracts, which are composed of a mixture of molecules. The individual molecular species in this mixture may or may not contribute to the overall medicinal effects and some may even oppose the beneficial activity of others. To better control therapeutic effects, studies that characterized specific molecules and describe their individual activity that have been performed over the past decades. These studies appear to underline that natural products are particularly effective as antioxidants and anti-inflammatory agents. In this systematic review we aimed to identify potent anti-inflammatory natural products and relate their efficacy to their chemical structure and physicochemical properties. To identify these compounds, we performed a comprehensive literature search to find those studies, in which a dose-response description and a positive control reference compound was used to benchmark the observed activity. Of the analyzed papers, 7% of initially selected studies met these requirements and were subjected to further analysis. This analysis revealed that most selected natural products indeed appeared to possess anti-inflammatory activities, in particular anti-oxidative properties. In addition, 14% of the natural products outperformed the remaining natural products in all tested assays and are attractive candidates as new anti-inflammatory agents.

Use of Chou's 5-Steps Rule to Reveal Active Compound and Mechanism of Shuangshen Pingfei San on Idiopathic Pulmonary Fibrosis

BACKGROUND

Shuangshen Pingfei San (SPS) is the derivative from the classic formula Renshen Pingfei San in treating idiopathic pulmonary fibrosis (IPF).

METHODS

In this study, Chou's 5-steps rule was performed to explore the potential active compound and mechanism of SPS on IPF. Compound-target network, target- pathway network, herb-target network and the core gene target interaction network were established and analyzed. A total of 296 compounds and 69 candidate therapeutic targets of SPS in treating IPF were obtained. Network analysis revealed that the main active compounds were flavonoids (such as apigenin, quercetin, naringenin, luteolin), other clusters (such as ginsenoside Rh2, diosgenin, tanshinone IIa), which might also play significant roles. SPS regulated multiple IPF relative genes, which affect fibrosis (PTGS2, KDR, FGFR1, TGFB, VEGFA, MMP2/9) and inflammation (PPARG, TNF, IL13, IL4, IL1B, etc.).

CONCLUSION

In conclusion, anti-pulmonary fibrosis effect of SPS might be related to the regulation of inflammation and pro-fibrotic signaling pathways. These findings revealed that the potential active compounds and mechanisms of SPS on IPF were a benefit to further study.

Bronchodilator effect of apigenin and luteolin, two components of Dracocephalum kotschyi on isolated rabbit trachea

Introduction: Dracocephalum kotschyi is a native Iranian plant with antispasmodic activities on smooth muscles such as ileum and uterus. However, so far antispasmodic effect of D. kotschyi on tracheal smooth muscle has not been reported. Therefore, the objective of this research was to investigate antispasmodic activity of D. kotschyi extract and two of its components luteolin and apigenin on rabbit tracheal contraction in vitro. Methods: Rabbits were euthanized by carbon dioxide and the trachea was dissected and immersed in a Tyrode’s solution. Tracheal rings were prepared and mounted vertically in an organ bath at 37°C and gassed continuously with O2. The tracheal ring preparations were contracted with acetylcholine (ACh) and KCl. The isotonic tension was recorded before and after addition of aminophylline, apigenin, luteolin or flavonoids rich extract of D. kotschyi. Flavonoids rich extract were prepared from D. kotschyi using solvent-solvent fractionation technique. Results: Standard drug aminophylline, prevented tracheal ring preparation contracted with ACh. Cumulative addition of aminophylline also attenuated tonic contraction induced by KCl on tracheal smooth muscle. D. kotschyi extract at concentration ranges of 32-512 μg/mL in a concentration dependent manner inhibited KCl and ACh induced tracheal contraction. Apigenin and luteolin (range 16–512 μg/mL) relaxed KCl and ACh-induced contraction of tracheal smooth muscle in vitro in a concentration-dependent manner. Conclusion: This study demonstrated that D. kotschyi extract is a relaxant of tracheal smooth muscle. The relaxant effect of D. kotschyi extract could be due to its flavonoids component such as apigenin and luteolin.

Luteolin protects against diabetic cardiomyopathy by inhibiting NF-κB-mediated inflammation and activating the Nrf2-mediated antioxidant responses

BACKGROUND

Diabetes mellitus is a well-known risk factor for the development of heart failure. Inflammation and oxidative stress play a key role in the development of diabetic cardiomyopathy (DCM), and this nexus represents an attractive target to combat this disease. Naturally occurring flavonoid luteolin exhibits both anti-inflammatory and antioxidant activities in various systems.

HYPOTHESIS/PURPOSE

In this study, we aimed to investigate potential cardioprotective effects of luteolin in cultured cardiomyocytes and in mice with type 1 diabetes.

METHODS

C57BL/6 mice were intraperitoneal injection of streptozotocin (STZ) to induce DCM. High glucose (HG) was used to induce H9C2 cells injury in vitro. Cardiac fibrosis, hypertrophy, inflammation and oxidative stress were studied both in vitro and in vivo.

RESULTS

Our studies show that luteolin significantly reduces HG-induced inflammatory phenotype and oxidative stress in H9C2 cardiomyocytes. We found that the mechanisms involved inhibition of nuclear factor-kappa B (NF-κB) pathway and the activation of antioxidant nuclear factor-erythroid 2 related factor 2 (Nrf2) signaling pathway. Modulation of these pathways resulted in reduced expression of matrix proteins and cellular hypertrophy. Luteolin also prevented cardiac fibrosis, hypertrophy, and dysfunction in STZ-induced diabetic mice. These readouts were also associated with reduced levels of inflammatory cytokines and oxidative stress biomarkers.

CONCLUSION

Our results indicate that luteolin protects heart tissues in STZ-induced diabetic mice through modulating Nrf2-mediated oxidative stress and NF-κB-mediated inflammatory responses. These findings suggest that luteolin may be a potential therapeutic agent for DCM.

Effects of Ginkgo biloba leaf extract, shenmai and matrine on a human embryonic lung fibroblast fibrosis model

The aim of the present study was to investigate the effects of Ginkgo biloba leaf extract (GBLE), shenmai (S), and matrine (M) on human embryonic lung fibroblasts (HELFs). HELFs were allocated into the following groups: Group A (control group), group B [transforming growth factor β1 (TGF-β1) model group], groups C1-3 (TGF-β1 + low-, moderate- and high-dose GBLE), groups D1-3 (TGF-β1 + low-, moderate- and high-dose S) and groups E1-3 (TGF-β1 + low-, moderate- and high-dose oM). Cell proliferation was assessed with an MTT assay and apoptosis was measured by annexin V/propidium iodide double staining and flow cytometry analysis. Collagen type I (COL-I), collagen type III (COL-III), α-smooth muscle actin (α-SMA) and extracellular superoxide dismutase (ECSOD) mRNA expression levels were measured using semi-quantitative reverse transcription-polymerase chain reaction, and protein content was measured using ELISA. The cell growth inhibition rates of the S groups were significantly higher than those of the other treatment groups (P<0.05). The rate of apoptosis was significantly increased in the treatment groups compared with the model group (P<0.05), and S induced a significant increase in HELF apoptosis compared with the other treatment groups (P<0.05). The mRNA and protein expressions of COL-III, COL-I and α-SMA in the GBLE, S and M groups were significantly decreased, while the expression of ECSOD was significantly increased when compared with the model group (P<0.05). In conclusion, GBLE, S and M inhibited the pro-fibrotic role of TGF-β1 by targeting different steps in TGF-β1-mediated fibrosis.

Natural Products as a Source for Antifibrosis Therapy

Although fibrosis is a final pathological feature of many chronic diseases, few interventions are available that specifically target the pathogenesis of fibrosis. Natural products are becoming increasingly recognized as effective therapies for fibrosis. The highlights of common cellular and molecular mechanisms of fibrosis facilitate the discovery of effective antifibrotic drugs. We describe some new profibrotic mechanisms and corresponding therapeutic targets using natural products. Interleukin, ephrin-B2, Gas6/TAM, Wnt/β-catenin, hedgehog pathway, PPARγ, lysophosphatidic acid, and CTGF are promising therapeutic targets. Natural products can target these mediators and inhibit chronic inflammation, myofibroblast activation, epithelial-mesenchymal transition, and extracellular matrix accumulation to alleviate fibrosis. Of note, natural products have the potential to inhibit fibrosis in one organ, simultaneously targeting fibrosis in multiple other organs, which provides us new strategies to find antifibrotic drugs.

Luteolin: A Flavonoid that Has Multiple Cardio-Protective Effects and Its Molecular Mechanisms

Cardiovascular disease (CVD) has become the leading cause of morbidity and mortality worldwide. A well-monitored diet with a sufficient intake of fruits and vegetables has been confirmed as a primary prevention of CVD. Plant constituents such as flavonoids have been shown to confer healthy benefits. Luteolin (Lut), a kind of flavonoid, possesses anti-oxidative, anti-tumor, and anti-inflammatory properties. Recent scientific literature has reported the cardiac protective effects of Lut in vitro and in vivo. Therefore, the aim of this review is to provide an update and detailed overview with cardio-protective molecular mechanisms of Lut with a focus on multiple intrinsic and extrinsic effectors. We further explore how these mechanisms participate in ischemia/reperfusion (I/R) injury, heart failure (HF) and atherosclerosis (AS). A proper understanding of the cardiovascular protective effects and the relative mechanisms of Lut may provide the possibility of new drug design and development for CVD. With the previous studies mainly focused on basic research, we need to advance the prospects of its further clinical utilization against CVD, large prospective clinical trials of Lut are needed to observe its therapeutic effects on patients with I/R injury, HF and AS, especially on the effective therapeutic dosage, and safety of long-term administration.