Synthesis and antimicrobial activity evaluation of pyrazole derivatives containing imidazothiadiazole moiety

AIM

The purpose of this work was to investigate the antimicrobial activity of pyrazole derivatives (21a - i and 23a - o) synthesized.

MATERIALS & METHODS

The pyrazole derivatives were synthesized, molecular docked and tested for their antimicrobial activity, cytotoxicity, and hemolysis rate.

RESULTS

Most of the target compounds showed high selective inhibitory activity against multi-drug resistance compared with other strains. Of these, compounds 21c (MIC = 0.25 µg/mL) and 23 h (MIC = 0.25 µg/mL) showed the strongest antibacterial activity, which was 4-flods than that of the positive control compound gatifloxacin (MIC = 1 µg/mL). Furthermore, compound 23 h showed no cytotoxicity to human LO2 cells, and did not show hemolysis even at ultra-high concentration.

CONCLUSION

These results prompted that these compounds are valuable for further development as antimicrobial agents.

Application of Compounds with Anti-Cardiac Fibrosis Activity: A Review

Coronary heart disease, hypertension, myocarditis, and valvular disease cause myocardial fibrosis, leading to heart enlargement, heart failure, heart rate failure, arrhythmia, and premature ventricular beat, even defibrillation can increase the risk of sudden death. Although cardiac fibrosis is common and widespread, there are still no effective drugs to provide adequate clinical intervention for cardiac fibrosis. In this review article, we classify the compounds for treating cardiac fibrosis into natural products, synthetic compounds, and patent drugs according to their sources. Additionally, the structures, activities and signaling pathways of these compounds are discussed. This review provides insight and could provide a reference for the design of new anti-cardiac fibrosis compounds and the new use of older drugs.

Alkaloids in Chelidonium majus L: a review of its phytochemistry, pharmacology and toxicology

Chelidonium majus L. (C. majus), commonly known as "Bai Qu Cai" in China, belongs to the genus Chelidonium of the Papaveraceae family. It has rich medicinal value, such as alleviating coughs, asthma, spasms and pain. Recent studies have demonstrated that C. majus is abundant in various alkaloids, which are the primary components of C. majus and have a range of pharmacological effects, including anti-microbial, anti-inflammatory, anti-viral, and anti-tumor effects. So far, 94 alkaloids have been isolated from C. majus, including benzophenanthridine, protoberberine, aporphine, protopine and other types of alkaloids. This paper aims to review the research progress in phytochemistry, pharmacology and toxicology of C. majus alkaloids, in order to provide a theoretical basis for the application of C. majus in the field of medicinal chemistry and to afford reference for further research and development efforts.

ZNF70 regulates IL-1β secretion of macrophages to promote the proliferation of HCT116 cells via activation of NLRP3 inflammasome and STAT3 pathway in colitis-associated colorectal cancer

Chronic inflammation is a key driver for colitis-associated colorectal cancer (CAC). It has been reported that inflammatory cytokines, such as IL-1β, could promote CAC. Zinc finger protein 70 (ZNF70) is involved in multiple biological processes. Here, we identified a previously unknown role for ZNF70 regulates macrophages IL-1β secretion to promote HCT116 proliferation in CAC, and investigated its underlying mechanism. We showed ZNF70 is much higher expressed in CAC tumor tissues compared with adjacent normal tissues in clinical CAC samples. Further experiments showed ZNF70 promoted macrophages IL-1β secretion and HCT116 proliferation. In LPS/ATP-stimulated THP-1 cells, we found ZNF70 activated NLRP3 inflammasome, resulting in robust IL-1β secretion. Interestingly, we discovered the ZnF domain of ZNF70 could interact with NLRP3 and decrease the K48-linked ubiquitination of NLRP3. Moreover, ZNF70 could activate STAT3, thereby promoting IL-1β synthesis. Noteworthy, ZNF70 enhanced proliferation by upregulating STAT3 activation in HCT116 cells cultured in the conditioned medium of THP-1 macrophages treated with LPS/ATP. Finally, the vivo observations were confirmed using AAV-mediated ZNF70 knockdown, which improved colitis-associated colorectal cancer in the AOM/DSS model. The correlation between ZNF70 expression and overall survival/IL-1β expression in colorectal cancer was verified by TCGA database. Taken together, ZNF70 regulates macrophages IL-1β secretion to promote the HCT116 cells proliferation via activation of NLRP3 inflammasome and STAT3 pathway, suggesting that ZNF70 may be a promising preventive target for treating in CAC.

Pseudoginsenoside GQ mitigates chronic intermittent hypoxia-induced cognitive damage by modulating microglia polarization

Obstructive sleep apnea (OSA), a state of sleep disruption, is characterized by recurrent apnea, chronic intermittent hypoxia (CIH) and hypercapnia. Previous studies have showed that CIH-induced neuroinflammatory plays a crucial role in cognitive deficits. Pseudoginsenoside GQ (PGQ) is a new oxytetracycline-type saponin formed by the oxidation and cyclization of the 20(S) Rg3 side chain. Rg3 has been found to afford anti-inflammatory effects, while whether PGQ plays a role of anti-neuroinflammatory remains unclear. The purpose of this study was to investigate whether PGQ attenuates CIH-induced neuroinflammatory and cognitive impairment and the possible mechanism it involves. We found that PGQ significantly ameliorated CIH-induced spatial learning deficits, and inhibited microglial activation, pro-inflammatory cytokine release, and neuronal apoptosis in the hippocampus of CIH mice. In addition, PGQ pretreatment promoted microglial M1 to M2 phenotypic transition in IH-induced BV-2 microglial, as well as indirectly inhibited IH-induced neuronal injury via modulation of microglia polarization. Furthermore, we noted that activation of HMGB1/TLR4/NF-κB signaling pathway induced by IH was inhibited by PGQ. Molecular docking results revealed that PGQ could bind to the active sites of HMGB1 and TLR4. Taken together, this work supports that PGQ inhibits M1 microglial polarization via the HMGB1/TLR4/NF-κB signaling pathway, and indirectly exerts neuroprotective effects, suggesting that PGQ may be a potential therapeutic strategy for cognitive impairment accompanied OSA.

Protective effect of arctiin against Toxoplasma gondii HSP70-induced allergic acute liver injury by disrupting the TLR4-mediated activation of cytosolic phospholipase A2 and platelet-activating factor

Toxoplasma gondii (T. gondii)-derived heat shock protein 70 (T.g.HSP70) is a toxic protein that downregulates host defense responses against T. gondii infection. T.g.HSP70 was proven to induce fatal anaphylaxis in T. gondii infected mice through cytosolic phospholipase A2 (cPLA2) activated-platelet-activating factor (PAF) production via Toll-like receptor 4 (TLR4)-mediated signaling. In this study, we investigated the effect of arctiin (ARC; a major lignan compound of Fructus arctii) on allergic liver injury using T.g.HSP70-stimulated murine liver cell line (NCTC 1469) and a mouse model of T. gondii infection. Localized surface plasmon resonance, ELISA, western blotting, co-immunoprecipitation, and immunofluorescence were used to investigate the underlying mechanisms of action of ARC on T. gondii-induced allergic acute liver injury. The results showed that ARC suppressed the T.g.HSP70-induced allergic liver injury in a dose-dependent manner. ARC could directly bind to T.g.HSP70 or TLR4, interfering with the interaction between these two factors, and inhibiting activation of the TLR4/mitogen-activated protein kinase/nuclear factor-kappa B signaling, thereby inhibiting the overproduction of cPLA2, PAF, and interferon-γ. This result suggested that ARC ameliorates T.g.HSP70-induced allergic acute liver injury by disrupting the TLR4-mediated activation of inflammatory mediators, providing a theoretical basis for ARC therapy to improve T.g.HSP70-induced allergic liver injury.

Synthesis and Evaluation of Imidazole Derivatives Bearing Imidazo[2,1-b] [1,3,4]thiadiazole Moiety as Antibacterial Agents

BACKGROUND

Drug-resistant infections kill hundreds of thousands of people globally every year. In previous work, we found that tri-methoxy- and pyridine-substituted imidazoles show strong antibacterial activities.

OBJECTIVE

The aim of this work was to investigate the antibacterial activities and bacterial resistances of imidazoles bearing an aromatic heterocyclic, alkoxy, or polycyclic moiety on the central ring.

METHODS

Three series of 2-cyclopropyl-5-(5-(6-methylpyridin-2-yl)-2-substituted-1H-imidazol-4- yl)-6-phenylimidazo[2,1-b][1,3,4]thiadiazoles (13a-e, 14a-d, and 15a-f) were synthesized and their antibacterial activity was evaluated. The structures were confirmed by their 1H NMR, 13C NMR, and HRMS spectra. All the synthesized compounds were screened against Gram-positive, Gramnegative, and multidrug-resistant bacterial strains.

RESULTS

More than half of the compounds showed moderate or strong antibacterial activity. Among them, compound 13e (MICs = 1-4 μg/mL) showed the strongest activity against Gram-positive and drug-resistant bacteria as well as high selectivity against Gram-negative bacteria. Furthermore, it showed no cytotoxicity against HepG2 cells, even at 100 μM, and no hemolysis at 20 μM.

CONCLUSION

These results indicate that compound 13e is excellent candicate for further study as a potential antibacterial agent.

Recent Advances in Research on Active Compounds Against Hepatic Fibrosis

BACKGROUND

Almost all chronic liver diseases cause fibrosis, which can lead to cirrhosis and eventually liver cancer. Liver fibrosis is now considered to be a reversible pathophysiological process and suppression of fibrosis is necessary to prevent liver cancer. At present, no specific drugs have been found that have hepatic anti-fibrotic activity.

OBJECTIVE

The research progress of anti-hepatic fibrosis compounds in recent ten years was reviewed to provide a reference for the design and development of anti-hepatic fibrosis drugs.

METHODS

According to the structure of the compounds, they are divided into monocyclic compounds, fused-heterocyclic compounds, and acyclic compounds.

RESULTS

In this article, the natural products and synthetic compounds with anti-fibrotic activity in recent ten years were reviewed, with emphasis on their pharmacological activity and structure-activity relationship (SAR).

CONCLUSION

Most of these compounds are natural active products and their derivatives, and there are few researches on synthetic compounds and SAR studies on natural product.

Chelidonine reduces IL-1β-induced inflammation and matrix catabolism in chondrocytes and attenuates cartilage degeneration and synovial inflammation in rats

Chondrocyte inflammation and catabolism are two major features in the progression of osteoarthritis (OA). Chelidonine, a principal alkaloid extracted from Chelidonium majus, is suggested to show anti-inflammation, anti-apoptosis, and anti-oxidation activities in various diseases. However, its potential effects on OA cartilage degeneration remains unclear. To evaluate the effect of chelidonine on OA and its underlying mechanism, we incubated chondrocytes with interleukin (IL)-1β and chelidonine at varying concentrations. Then, we performed the CCK-8 assay, fluorescence immunostaining, reverse transcription PCR, ELISA, and western blotting to evaluate cell viability, catabolic/inflammatory factors, levels of extracellular matrix (ECM)-related proteins, and the involved pathways. H&E and Safranin-O staining and ELISA were performed to measure cartilage degradation and synovial inflammation. Chelidonine suppressed the IL-1β-mediated catabolism and inflammation of chondrocytes. Chelidonine suppressed the NF-κB pathway activation. Similarly, our in vivo experiment showed that chelidonine partially attenuated cartilage degradation while inhibiting synovial inflammation. Chelidonine inhibited inflammation and catabolism through modulation of NF-κB pathways in vitro, thereby avoiding rat cartilage degeneration and synovial inflammation within OA.

Synthesis and antimicrobial activity evaluation of pyrazole derivatives containing the imidazo[2,1-b][1,3,4]thiadiazole moiety

Four series of novel pyrazole derivatives (compounds 17a-m, 18a-m, 19a-g, and 20a-g) were synthesized, and their antibacterial and antifungal activities were evaluated. Most of the target compounds (17a-m, 18k-m, and 19b-g) showed strong antifungal activity and high selectivity relative to both Gram-positive and Gram-negative bacteria. Among them, compounds 17l (minimum inhibitory concentration [MIC] = 0.25 µg/mL) and 17m (MIC = 0.25 µg/mL) showed the strongest antifungal activity, being 2- and 4-fold more active than the positive controls gatifloxacin and fluconazole, respectively. In particular, compound 17l showed little cytotoxicity against human LO2 cells and did not exhibit hemolysis at ultrahigh concentrations, as did the positive control compounds gatifloxacin and fluconazole. These results indicate that these compounds are valuable for further development as antifungal agents.

Determination of Selected Isoquinoline Alkaloids from Chelidonium majus, Mahonia aquifolium and Sanguinaria canadensis Extracts by Liquid Chromatography and Their In Vitro and In Vivo Cytotoxic Activity against Human Cancer Cells

The search for new substances with cytotoxic activity against various cancer cells, especially cells that are very resistant to currently used chemotherapeutic agents, such as melanoma cells, is a very important scientific aspect. We investigated the cytotoxic effect of Chelidonium majus, Mahonia aquifolium and Sanguinaria canadensis extracts obtained from different parts of these plants collected at various vegetation stages on FaDu, SCC-25, MCF-7, and MDA-MB-231 cancer cells. Almost all the tested extracts showed higher cytotoxicity against these cancer cells than the anticancer drug etoposide. The highest cytotoxicity against the FaDu, SCC-25, MCF-7 and MDA-MB-231 cancer cell lines was obtained for the Sanguinaria candensis extract collected before flowering. The cytotoxicity of extracts obtained from different parts of Chelidonium majus collected at various vegetation stages was also evaluated on melanoma cells (A375, G361 and SK-MEL-3). The highest cytotoxic activity against melanoma A375 cells was observed for the Chelidonium majus root extract, with an IC50 of 12.65 μg/mL. The same extract was the most cytotoxic against SK-MEL-3 cells (IC50 = 1.93 μg/mL), while the highest cytotoxic activity against G361 cells was observed after exposure to the extract obtained from the herb of the plant. The cytotoxic activity of Chelidonium majus extracts against melanoma cells was compared with the cytotoxicity of the following anticancer drugs: etoposide, cisplatin and hydroxyurea. In most cases, the IC50 values obtained for the anticancer drugs were higher than those obtained for the Chelidonium majus extracts. The most cytotoxic extract obtained from the root of Chelidonium majus was selected for in vivo cytotoxic activity investigations using a Danio rerio larvae xenograft model. The model was applied for the first time in the in vivo investigations of the extract’s anticancer potential. The application of Danio rerio larvae xenografts in cancer research is advantageous because of the transparency and ease of compound administration, the small size and the short duration and low cost of the experiments. The results obtained in the xenograft model confirmed the great effect of the investigated extract on the number of cancer cells in a living organism. Our investigations show that the investigated plant extracts exhibit very high cytotoxic activity and can be recommended for further experiments in order to additionally confirm their potential use in the treatment of various human cancers.

Coixol ameliorates Toxoplasma gondii infection-induced lung injury by interfering with T. gondii HSP70/TLR4/NF-κB signaling pathway

Toxoplasma gondii (T. gondii) is an obligate intracellular protozoan parasite that causes pulmonary toxoplasmosis, although its pathogenesis is incompletely understood. There is no cure for toxoplasmosis. Coixol, a plant polyphenol extracted from coix seeds, has a variety of biological activities. However, the effects of coixol on T. gondii infection have not been clarified. In this study, we infected a mouse macrophage cell line (RAW 264.7) and BALB/c mice with the T. gondii RH strain to establish infection models in vitro and in vivo, respectively, to explore protective effects and potential mechanisms of coixol on lung injury caused by T. gondii infection. Anti-T. gondii effects and underlying anti-inflammatory mechanisms of coixol were investigated by real-time quantitative PCR, molecular docking, localized surface plasmon resonance, co-immunoprecipitation, enzyme-linked immunosorbent assay, western blotting, and immunofluorescence microscopy. The results show that coixol inhibits T. gondii loads and T. gondii-derived heat shock protein 70 (T.g.HSP70) expression. Moreover, coixol reduced inflammatory cell recruitment and infiltration, and ameliorated pathological lung injury induced by T. gondii infection. Coixol can directly bind T.g.HSP70 or Toll-like receptor 4 (TLR4) to disrupt their interaction. Coixol prevented overexpression of inducible nitric oxide synthase, tumor necrosis factor-α, and high mobility group box 1 by inhibiting activation of the TLR4/nuclear factor (NF)-κB signaling pathway, consistent with effects of the TLR4 inhibitor CLI-095. These results indicate that coixol improves T. gondii infection-induced lung injury by interfering with T.g.HSP70-mediated TLR4/NF-κB signaling. Altogether, these findings suggest that coixol is a promising effective lead compound for the treatment of toxoplasmosis.

Blocking Two-Pore Domain Potassium Channel TREK-1 Inhibits the Activation of A1-Like Reactive Astrocyte Through the NF-κB Signaling Pathway in a Rat Model of Major Depressive Disorder

Major depressive disorder (MDD) refers to a widespread psychiatric disorder. Astrocytes play a pivotal role in regulating inflammation which is a well-acknowledged key component in depression pathogenesis. However, the effects of the neuroinflammation-inducing A1-like astrocytes on MDD are still unknown. TWIK-related K⁺ channel 1 (TREK-1) has been demonstrated to regulate the action of antidepressants. Nevertheless, its mechanisms and effects on A1-like astrocyte stimulation in MDD are not clear. Therefore, we conducted in vivo and in vitro experiments using TREK-1 specific inhibitor spadin. In vivo, rats were subjected to a 6-week chronic unpredictable mild stress (CUMS) followed by spadin treatment. Behavioral tests were employed to surveil depressive-like behaviors. Hippocampal proteomic analysis was carried out with the purpose of identifying differentially expressed proteins after CUMS and spadin treatments. In vitro, astrocyte-conditioned medium and spadin were used to treat rat astrocyte cell line. The activated microglia, inflammatory factors, A1 astrocyte markers, and activated nuclear factor kappa B (NF-κB) pathway were later analyzed using immunofluorescence, western blot, and RT-qPCR. Our findings indicated that blockage of TREK-1 reduced CUMS-induced depressive-like behavior in rats, inhibited the microglial stimulation, reduced inflammatory factor levels, and suppressed the activation of A1-like reactive astrocytes in the hippocampus. We also verified that the suppression of A1-like astrocytes by spadin necessitated the NF-κB pathway. According to the findings, blocking TREK-1 inhibited the activation of A1-like reactive astrocytes via the NF-κB signaling pathway in MDD. Our study preliminarily identifies a novel antidepressant mechanism of TREK-1 action and provides a therapeutic path for MDD.

Resveratrol inhibits Toxoplasma gondii-induced lung injury, inflammatory cascade and evidences of its mechanism of action

BACKGROUND

Toxoplasma gondii is an opportunistic protozoan that can infect host to cause toxoplasmosis. We have previously reported that resveratrol (RSV) has protective effects against liver damage in T. gondii infected mice. However, the effect of RSV on lung injury caused by T. gondii infection and its mechanism of action remain unclear.

PURPOSE

In this work, we studied the protective effects of RSV on lung injury caused by T. gondii infection and explored the underlying mechanism.

METHODS

Molecular docking and localized surface plasmon resonance assay were used to detect the molecular interactions between RSV and target proteins. In vitro, the anti-T. gondii effects and potential anti-inflammatory mechanisms of RSV were investigated by quantitative competitive-PCR, RT-PCR, ELISA, Western blotting and immunofluorescence using RAW 264.7 cells infected with tachyzoites of T. gondii RH strain. In vivo, the effects of RSV on lung injury caused by T. gondii infection were assessed by observing pathological changes and the expression of inflammatory factors of lung.

RESULTS

RSV inhibited T. gondii loads and T. gondii-derived heat shock protein 70 (T.g.HSP70) expression in RAW 264.7 cells and lung tissues. Moreover, RSV interacts with T.g.HSP70 and toll-like receptor 4 (TLR4), respectively, and interferes with the interaction between T.g.HSP70 and TLR4. It also inhibited the overproduction of inducible nitric oxide synthase, TNF-α and high mobility group protein 1 (HMGB1) by down-regulating TLR4/nuclear factor kappa B (NF-κB) signaling pathway, which is consistent with the effect of TLR4 inhibitor CLI-095. In vivo, RSV improved the pathological lung damage produced by T. gondii infection, as well as decreased the number of inflammatory cells in bronchoalveolar lavage fluid and the release of HMGB1 and TNF-α.

CONCLUSION

These findings indicate that RSV can inhibit the proliferation of T. gondii and T.g.HSP70 expression both in vitro and in vivo. RSV can inhibit excessive inflammatory response by intervening T.g.HSP70 and HMGB1 mediated TLR4/NF-κB signaling pathway activation, thereby ameliorating lung injury caused by T. gondii infection. The present study provides new data that may be useful for the development of RSV as a new agent for the treatment of lung damage caused by T. gondii infection.

Isoquinoline alkaloids from Hylomecon japonica and their potential anti-breast cancer activities

Four pairs of undescribed enantiomeric isoquinoline alkaloids (6S/R-(N,N-diethylacetamido)yl-dihydrochelerythrine, 6R/S-acetonyl-9-hydroxy-dihydrochelerythrine, 6S/R-acroleinyl-dihydrochelerythrine, 6S/R-acetatemethyl-dihydrochelerythrine), five undescribed isoquinoline alkaloids (6,10-dimethoxydihydrochelerythrine, 6-ethoxy-ethaniminyl-dihydrochelandine, 9-hydroxy-dihydrochelerythrine, 9-methoxy-10-hydroxy-norchelerythrine, chelidoniumine A), together with 13 known isoquinoline alkaloids were isolated from an extract of the roots and rhizomes of Hylomecon japonica. The structures of the undescribed compounds were identified by NMR, HRESIMS, UV, IR, and their absolute configurations were defined via electronic circular dichroism data and optical rotation. All of the isolated compounds were tested for their anti-breast cancer activities in MCF-7 cells. Among them, the undescribed alkaloids 6S/R-acroleinyl-dihydrochelerythrine, 6,10-dimethoxydihydrochelerythrine, 6-ethoxy-ethaniminyl-dihydrochelandine, 9-methoxy-10-hydroxy-norchelerythrine and other known alkaloids 6-methoxydihydrosanguinarine, 6-acetaldehyde-dihyrochelerythrine, dihydrosanguinaline and 10-methoxy boconoline had good inhibitory effects on MCF-7 cells of breast cancer with an IC₅₀ lower than 20 μM.

Synergistic anti-inflammatory effects of peimine, peiminine, and forsythoside a combination on LPS-induced acute lung injury by inhibition of the IL-17-NF-κB/MAPK pathway activation

ETHNOPHARMACOLOGICAL RELEVANCE

Forsythia suspensa (Thunb.) Vahl and Fritillaria thunbergii Miq are traditional Chinese medicines that exhibit the ability to clear heat and toxic material effects. In China, the combination of these two medicines is widely used to treat mucopurulent sputum and bloody phlegm, arising due to phlegm-heat obstruction in respiratory diseases. However, very limited information is available regarding the combined anti-inflammatory effect of important effective components of Forsythia suspensa (Thunb.) Vahl and Fritillaria thunbergii Miq, namely peimine, peiminine, and forsythoside A.

AIM OF THIS STUDY

To investigate synergistic anti-inflammatory effects of combined administration of peimine, peiminine, and forsythoside A on LPS-induced acute lung injury compared to combined administration of two compounds or individual administration, and unravel the underlying mechanism.

MATERIAL AND METHODS

In the present study, male BALB/c mice received an oral dosage of sodium carboxymethylcellulose (CMC-Na) (0.5%, 1 mL/100 g), peimine, peiminine, forsythoside A, peimine + forsythoside A, peiminine + forsythoside A, and peimine + peiminine + forsythoside A (suspended in CMC-Na; 0.5%), once daily for 7 days. Subsequently, intratracheal instillation of LPS was applied to establish acute lung injury model. After 6 h of administration, the mice were sacrificed, and bronchoalveolar lavage fluid (BALF) and lung tissues were collected. These samples were further used to determine lung W/D (wet/dry) weight ratio, total protein (TP) levels, inflammatory cytokines (IL-6, TNF-α, IL-1β, and IL-17), and expression of proteins involved in TLR4/MAPK/NF-κB pathway and IL-17 pathway. Further, tissue sections were subjected to H&E staining to assess the pathological alterations induced by LPS. The expression of IL-6 and TNF-α proteins in lung tissues was also analyzed using immunohistochemical staining.

RESULTS

A synergistic anti-inflammatory effect of peimine, peiminine, and forsythoside A was observed when administered in combination to LPS-induced acute lung injury. The combined administration of peimine, peiminine, and forsythoside A had a strongly inhibitory effects on the W/D weight ratio, total protein (TP) level and the inflammatory cytokines (TNF-α, IL-6, IL-1β, and IL-17) level in acute lung injury mice, compared to combined administration of two compounds or individual administration. The infiltration of inflammatory cells and thickened bronchoalveolar walls induced by LPS were also ameliorated through the combined administration of peimine, peiminine, and forsythoside A. More importantly, the upregulation of protein related to TLR4/MAPK/NF-κB signaling pathway and the activation of IL-17 were significantly suppressed by pretreatment with each of the three compounds alone, while the effects of individual compounds were synergistically augmented by the combined pretreatment of these three compounds.

CONCLUSION

The combined administration of peimine, peiminine, and forsythoside A ameliorated inflammatory response in acute lung injury mice induced by LPS in a synergistic manner, the mechanism may be related to the dampening of the TLR4/MAPK/NF-κB signaling pathway and IL-17 activation.

SAR analysis of heterocyclic compounds with monocyclic and bicyclic structures as antifungal agents

Infections caused by eukaryotic organisms, such as fungi, are generally more difficult to treat than bacterial infections. With the widespread use of antifungal drugs in humans and plants, resistance and toxicity have emerged. Therefore, it is desirable to develop new antifungal drugs with low toxicity that are not susceptible to the development of resistance. This review presents a summary of the past 2017 to 2021 years of research on heterocyclic compounds as antifungal agents for use in humans and plants, focusing on the structure-activity relationships (SAR) of these compounds. This review may provide ideas and data for designing and developing new antifungal drugs with fewer side effects compared with currently available drugs.

Ginsenoside Rh2 reduces depression in offspring of mice with maternal toxoplasma infection during pregnancy by inhibiting microglial activation via the HMGB1/TLR4/NF-κB signaling pathway

Background

Maternal Toxoplasma gondii (T. gondii) infection during pregnancy has been associated with various mental illnesses in the offspring. Ginsenoside Rh2 (GRh2) is a major bioactive compound obtained from ginseng that has an anti-T. gondii effect and attenuates microglial activation through toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signaling pathway. GRh2 also alleviated tumor-associated or lipopolysaccharide-induced depression. However, the effects and potential mechanisms of GRh2 on depression-like behavior in mouse offspring caused by maternal T. gondii infection during pregnancy have not been investigated.

Methods

We examined GRh2 effects on the depression-like behavior in mouse offspring, caused by maternal T. gondii infection during pregnancy, by measuring depression-like behaviors and assaying parameters at the neuronal and molecular level.

Results

We showed that GRh2 significantly improved behavioral measures: sucrose consumption, forced swim time and tail suspended immobility time of their offspring. These corresponded with increased tissue concentrations of 5-hydroxytryptamine and dopamine, and attenuated indoleamine 2,3-dioxygenase or enhanced tyrosine hydroxylase expression in the prefrontal cortex. GRh2 ameliorated neuronal damage in the prefrontal cortex. Molecular docking results revealed that GRh2 binds strongly to both TLR4 and high mobility group box 1 (HMGB1).

Conclusion

This study demonstrated that GRh2 ameliorated the depression-like behavior in mouse offspring of maternal T. gondii infection during pregnancy by attenuating the excessive activation of microglia and neuroinflammation through the HMGB1/TLR4/NF-κB signaling pathway. It suggests that GRh2 could be considered a potential therapy in preventing and treating psychiatric disorders in the offspring mice of mothers with prenatal exposure to T. gondii infection.

Inhibitory Effects of Inonotus obliquus Polysaccharide on Inflammatory Response in Toxoplasma gondii-Infected RAW264.7 Macrophages

Our previous reports have shown that Inonotus obliquus polysaccharide (IOP) has protective effects against Toxoplasma gondii (T. gondii) infection in vivo. The aim of the present research is to explore the in vitro anti-inflammatory effects of IOP and its mechanism in RAW264.7 macrophages infected by T. gondii. In this study, it is indicated that IOP decreased the excessive secretion of inflammatory cytokines tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-1β (IL-1β), IL-4, and IL-6 in T. gondii-infected RAW264.7 macrophages. IOP effectively suppressed the mRNA expression of these cytokines and chemokines monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1α (MIP-1α). Moreover, IOP inhibited the phosphorylation of inhibitor kappa B kinase α/β (IKKα/β), inhibitor κBα (IκBα), p65 in nuclear factor-kappa B (NF-κB) signaling pathway and p38, c-Jun N-terminal kinase (JNK), and extracellular signal-regulated kinase 1/2 (ERK1/2) in mitogen-activated protein kinases (MAPKs) signaling pathway. Meantime, IOP prevented NF-κB p65 and c-Jun translocation from the cytoplasm to the nucleus. Further, IOP downregulated the protein expression of toll-like receptor 2 (TLR2) and TLR4 in T. gondii-infected RAW264.7 macrophages. The above results suggest that IOP can inhibit the inflammatory response infected with T. gondii via regulating TLR2/TLR4-NF-κB/MAPKs pathways and exerting its anti-T. gondii role in vitro.

Zinc finger protein 91 mediates necroptosis by initiating RIPK1-RIPK3-MLKL signal transduction in response to TNF receptor 1 ligation

Necroptosis is a form of regulated programmed cell death that is mediated by receptor-interacting protein kinase 1 (RIPK1), receptor-interacting serine/threonine protein kinase-3 (RIPK3), and mixed lineage kinase domain-like protein (MLKL); however, it is not known whether zinc finger protein 91 (ZFP91) is involved in this process. Here, we investigated ZFP91 as a potential mediator of necroptosis. Our mechanistic study demonstrates that ZFP91 promotes RIPK1-RIPK3 interaction, thereby stabilizing the RIPK1 and RIPK3 proteins and facilitating necroptosis. ZFP91 stabilized RIPK1 to promote cell death by inducing RIPK1 de-ubiquitination. ZFP91 also significantly increased production of mitochondrial reactive oxygen species (ROS). Accumulation of ROS promoted RIPK3-independent necroptosis triggered by tumor necrosis factor (TNF). in vivo, ZFP91 knockdown alleviated TNFα-induced systemic inflammatory response syndrome (SIRS). These results provide direct evidence that ZFP91 plays an important role in the initiation of RIPK1/RIPK3-dependent necroptosis in vitro and in vivo. We discussed the potential of ZFP91 as a novel therapeutic target for necroptosis-associated diseases.

Development of natural products for anti-PD-1/PD-L1 immunotherapy against cancer

ETHNOPHARMACOLOGICAL RELEVANCE

The programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) immune checkpoint is one of the most promising therapeutic targets for cancer immunotherapy, but several challenges remain in current anti-PD-1/PD-L1 therapy. Natural products, mainly derived from traditional medicine, could improve and expand anti-PD-1/PD-L1 therapy because of their advantages such as large diversity and multi-target effects.

AIM OF THE STUDY

This review summarize natural products, raw extracts, and traditional medicines with pharmacological effects associated with the PD-1/PD-L1 axis, particularly PD-L1.

MATERIALS AND METHODS

Electronic literature databases, including Web of Science, PubMed, and ScienceDirect, and online drugs and chemicals databases, including DrugBank, ZINC, PubChem, STITCH, and CTD, were searched without date limitation by February 2021. 'Natural product or herb or herbal plant or traditional medicine' and 'PD-L1' and 'Cancer immunotherapy' were used as the search keywords. Among 112 articles identified in database searching, 54 articles are full text articles, reporting in silico, in vitro, in vivo and clinical trials. 68 articles included are review articles and grey literature such as thesis and congress abstracts.

RESULTS

Several natural products and traditional medicines have exhibited diverse and multi-functional effects including direct blockade of PD-1/PD-L1 interactions, modulation of PD-L1 expression, and cooperation with PD-1/PD-L1 inhibitors.

CONCLUSION

Natural products and traditional medicines can facilitate the development of more effective and acceptable diverse strategies for anti-PD-1/PD-L1 therapy, but further exploration of natural products and pharmaceutical techniques is required.

Formononetin represses cervical tumorigenesis by interfering with the activation of PD-L1 through MYC and STAT3 downregulation

Astragalus membranaceus is a traditional Chinese medicine that regulates blood sugar levels, suppresses inflammation, protects the liver, and enhances immunity. In addition, A. membranaceus is also widely used in diet therapy and is a well-known health tonic. Formononetin is a natural product isolated from A. membranaceus that has multiple biological functions, including anti-cancer activity. However, the mechanism by which formononetin inhibits tumor growth is not fully understood. In this present study, we demonstrated that formononetin suppresses PD-L1 protein synthesis via reduction of MYC and STAT3 protein expression. Furthermore, formononetin markedly reduced the expression of MYC protein via the RAS/ERK signaling pathway and inhibited STAT3 activation through JAK1/STAT3 pathway. Co-immunoprecipitation experiments illustrated that formononetin suppresses protein expression of PD-L1 by interfering with the interaction between MYC and STAT3. Meanwhile, formononetin promoted PD-L1 protein degradation via TFEB and TFE3-mediated lysosome biogenesis. T cell killing assay revealed that formononetin could enhance the activity of cytotoxic T lymphocytes (CTLs) and restore ability to kill tumor cells in a co-culture system of T cells and tumor cells. In addition, formononetin inhibited cell proliferation, tube formation, cell migration, and promoted tumor cell apoptosis by suppressing PD-L1. Finally, the inhibitory effect of formononetin on tumor growth was confirmed in a murine xenograft model. The present study revealed the anti-tumor potential of formononetin, and the findings should support further research and development of anti-cancer drugs for cervical cancer.

Resveratrol modulates Toxoplasma gondii infection induced liver injury by intervening in the HMGB1/TLR4/NF-κB signaling pathway

Toxoplasma gondii (T. gondii) is an obligate intracellular parasite that can cause liver diseases in the host, including hepatitis and hepatomegaly. High mobility group box 1 (HMGB1) is the main inflammatory mediator causing cell injury or necrosis. HMGB1 binds to toll like receptor 4 (TLR4), then activates the nuclear factor-κB (NF-κB) signaling pathway, which promotes the release of inflammatory factors. Our previous studies showed that HMGB1 mediated TLR4/NF-κB signaling pathway plays an important role in liver injury induced by T. gondii infection. Resveratrol (RSV) is a small polyphenol, which has anti-inflammatory, anti-cancer, anti-T. gondii effect. However, the effect of RSV on liver injury caused by T. gondii infection is unclear. This study used the RH strain tachyzoites of T. gondii to infect murine liver line, NCTC-1469 cells to establish an in vitro model and acute infection of mice for the in vivo model to explore the protective effect of RSV on liver injury induced by T. gondii infection. The results showed that RSV inhibited the proliferation of T. gondii in the liver, reduced the alanine aminotransferase/aspartate aminotransferase levels and pathological liver damage. Additionally, RSV inhibited the production of tumor necrosis factor-α, inducible nitric oxide synthase and HMGB1 by interfering with the TLR4/NF-κB signaling pathway. These results indicate that RSV can protect liver injury caused by T. gondii infection by intervening in the HMGB1/TLR4/NF-κB signaling pathway. This study will provide a theoretical basis for RSV treatment of T. gondii infection induced liver injury.

Phytochemistry and pharmacology of alkaloids from Glaucium spp

Glaucium Mill. comprising 28 species with 78 synonyms, 3 subspecies, and 3 varieties worldwide belongs to the Papaveraceae family. The plants are well known for their different types of alkaloids. In the present study, we attempted to review the chemistry and pharmacology of the alkaloids from the genus Glaucium. For this purpose, the relevant data were collected from different scientific databases including, "Google Scholar", "ISI Web of Knowledge", "PubMed", "Scopus", and available books and e-books. Our results showed that aporphine alkaloids are dominated in the species; however, other types of alkaloids including protopines, benzophenanthridines, benzylisoquinolines, protoberberines, and morphinanes have also been reported from the genus. The pharmacological studies have shown that the alkaloids from Glaucium species have several biological activities of which anti-cancer and anti-cholinesterase effects have been highly reported. Besides, the data indicated that most of the species have been investigated neither phytochemically nor pharmacologically. Glaucium flavum, known as yellow horn poppy, is the most studied species. According to the reports, the plants from this genus have anti-cancer and anti-cholinesterase potentials and can be used as a source for aporphine alkaloids.

New role of sertraline against Toxoplasma gondii-induced depression-like behaviours in mice

Toxoplasma gondii (T. gondii) is a neurotropic protozoan parasite, which can cause mental and behavioural disorders. The present study aimed to elucidate the effects and underlying molecular mechanisms of sertraline (SERT) on T. gondii-induced depression-like behaviours. In the present study, a mouse model and a microglial cell line (BV2 cells) model were established by infecting with the T. gondii RH strain. In in vivo and in vitro experiments, the underlying molecular mechanisms of SERT in inhibiting depression-like behaviours and cellular perturbations caused by T. gondii infection were investigated in the mouse brain and BV2 cells. The administration of SERT significantly ameliorated depression-like behaviours in T. gondii-infected mice. Furthermore, SERT inhibited T. gondii proliferation. Treatment with SERT significantly inhibited the activation of microglia and decreased levels of pro-inflammatory cytokines such as tumour necrosis factor-alpha, and interferon-gamma, by down-regulating tumour necrosis factor receptor 1/nuclear factor-kappa B signalling pathway, thereby ameliorating the depression-like behaviours induced by T. gondii infection. Our study provides insight into the underlying molecular mechanisms of the newly discovered role of SERT against T. gondii-induced depression-like behaviours.

Synthesis and Evaluation of Chiral Rhodanine Derivatives Bearing Quinoxalinyl Imidazole Moiety as ALK5 Inhibitors

BACKGROUND

TGF-β signaling pathway inhibition is considered an effective way to prevent the development of several diseases. In the design and synthesis of TGF-β inhibitors, a rhodanine compound containing a quinoxalinyl imidazole moiety was found to have strong antimicrobial activity.

OBJECTIVE

The purpose of this work was to investigate the antimicrobial activity of other chiral rhodanine TGF-β inhibitors synthesized.

METHODS

Two series of 3-substituted-5-((5-(6-methylpyridin-2-yl)-4-(quinoxalinyl-6-yl)- 1H-imidazol-2-yl)methylene)-2-thioxothiazolin-4-ones (12a-h and 13a-e) were synthesized and evaluated for their ALK5 inhibitory and antimicrobial activity. The structures were confirmed by their 1H NMR, 13C NMR, and HRMS spectra. All the synthesized compounds were screened against Gram-positive strains, Gram-negative strains, and fungi.

RESULTS

Among the synthesized compounds, compound 12h showed the highest activity (IC50 = 0.416 μM) against ALK5 kinase. Compound 12h exhibited a good selectivity index of > 24 against p38α MAP kinase and was 6.0-fold more selective than the clinical candidate, compound 2 (LY-2157299). Nearly all the compounds displayed high selectivity toward both Gram-positive and Gram-negative bacteria. They also showed similar or 2.0-fold greater antifungal activity (minimum inhibitory concentration [MIC] = 0.5 µg/mL) compared with the positive control compounds Gatifloxacin (MIC = 0.5 µg/mL) and fluconazole (MIC = 1 µg/mL).

CONCLUSION

The findings suggest that the synthesized rhodanine compounds have good ALK5 inhibitory activity and can be used for further research and development as potential antifungal drugs.

Licochalcone A inhibits proliferation and promotes apoptosis of colon cancer cell by targeting programmed cell death-ligand 1 via the NF-κB and Ras/Raf/MEK pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Glycyrrhiza glabra L., a traditional medicinal, has a history of thousands of years. It is widely used in clinic and has been listed in Chinese Pharmacopoeia. Licochalcone A is a phenolic chalcone compound and a characteristic chalcone of Glycyrrhiza glabra L. It has many pharmacological activities, such as anti-cancer, anti-inflammatory, anti-viral and anti-angiogenic activities.

AIM OF THE STUDY

In this study, we explored the anti-tumor activity and potential mechanism of licochalcone A in vitro and in vivo.

MATERIALS AND METHODS

In vitro, the mechanism of licochalcone A at inhibiting PD-L1 expression was investigated by molecular docking, western blotting, RT-PCR, flow cytometry, immunofluorescence and immunoprecipitation assays. The co-culture model of T cells and tumor cells was used to detect the activity of cytotoxic T lymphocytes. Colony formation, EdU labelling and apoptosis assays were used to detect changes in cellular proliferation and apoptosis. In vivo, anti-tumor activity of licochalcone A was assessed in a xenograft model of HCT116 cells.

RESULTS

In the present study, we found that licochalcone A suppressed the expression of programmed cell death ligand-1 (PD-L1), which plays a key role in regulating the immune response. In addition, licochalcone A inhibited the expressions of p65 and Ras. Immunoprecipitation experiment showed that licochalcone A suppressed the expression of PD-L1 by blocking the interaction between p65 and Ras. In the co-culture model of T cells and tumor cells, licochalcone A pretreatment enhanced the activity of cytotoxic T lymphocytes and restored the ability to kill tumor cells. In addition, we showed that licochalcone A inhibited cell proliferation and promoted cell apoptosis by targeting PD-L1. In vivo xenograft assay confirmed that licochalcone A inhibited the growth of tumor xenografts.

CONCLUSION

In general, these results reveal the previously unknown properties of licochalcone A and provide new insights into the anticancer mechanism of this compound.

Antimicrobials from Medicinal Plants: An Emergent Strategy to Control Oral Biofilms

Oral microbial biofilms, directly related to oral diseases, particularly caries and periodontitis, exhibit virulence factors that include acidification of the oral microenvironment and the formation of biofilm enriched with exopolysaccharides, characteristics and common mechanisms that, ultimately, justify the increase in antibiotics resistance. In this line, the search for natural products, mainly obtained through plants, and derived compounds with bioactive potential, endorse unique biological properties in the prevention of colonization, adhesion, and growth of oral bacteria. The present review aims to provide a critical and comprehensive view of the in vitro antibiofilm activity of various medicinal plants, revealing numerous species with antimicrobial properties, among which, twenty-four with biofilm inhibition/reduction percentages greater than 95%. In particular, the essential oils of Cymbopogon citratus (DC.) Stapf and Lippia alba (Mill.) seem to be the most promising in fighting microbial biofilm in Streptococcus mutans, given their high capacity to reduce biofilm at low concentrations.

Taraxacum mongolicum protects against Staphylococcus aureus-infected mastitis by exerting anti-inflammatory role via TLR2-NF-κB/MAPKs pathways in mice

ETHNOPHARMACOLOGICAL RELEVANCE

As a traditional Chinese medicine, Taraxacum mongolicum has been widely used for the prevention and treatment of a variety of inflammatory and infectious diseases, and also clinically used as a remedy for mastitis. However, the scientific rationale and mechanism behind its use on mastitis in vivo are still unclear.

AIM OF THE STUDY

This study aimed to investigate the protective effect and potential mechanism of Taraxacum mongolicum Hand.-Mazz. (T. mongolicum) on mastitis infected by Staphylococcus aureus (S. aureus).

MATERIALS AND METHODS

Female ICR mice were given intragastrically 2.5, 5 and 10 g/kg of T. mongolicum extract twice per day for 6 consecutive days, and infected with S. aureus via teat canal to induce mastitis. Pro-inflammatory cytokine tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) levels were determined by ELISA. Myeloperoxidase (MPO) activity and distribution were measured by reagent kit and immunohistochemistry. Histopathological changes of mammary gland tissues were observed by H&E staining. Toll-like receptor 2 (TLR2) expression, phosphorylations of related proteins in nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs) signaling pathways were detected by western blot.

RESULTS

T. mongolicum decreased TNF-α, IL-6 and IL-1β levels, and reduced MPO activity and distribution in sera and mammary glands with S. aureus-infected mastitis. In addition, T. mongolicum effectively attenuated histopathological damages and cell necrosis of mammary gland tissues infected by S. aureus. Moreover, T. mongolicum inhibited the expression of TLR2, and the phosphorylations of inhibitor κBα (IκBα), p65, p38, extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun N-terminal kinase (JNK) proteins in mammary glands with S. aureus-infected mastitis.

CONCLUSIONS

This study suggests that T. mongolicum protects against S. aureus-infected mastitis by exerting anti-inflammatory role, which is attributed to the inhibition of TLR2-NF-κB/MAPKs pathways.

Synthesis and evaluation of the epithelial-to- mesenchymal inhibitory activity of indazole-derived imidazoles as dual ALK5/p38α MAP inhibitors

Drugs of targeting both activin receptor-like kinase 5 (ALK5) and p38α have therapeutic advantages, making them attractive treatment options for tumors. Two series of 4-(1H-indazol-5-yl)-5-(6-methylpyridin-2-yl)-1H-imidazoles 13a-g and 4-(1-methyl-1H-indazol-5-yl)-5-(6-methylpyridin-2-yl)-1H-imidazoles 20a-g were synthesized and evaluated for ALK5 and p38α mitogen-activated protein kinase inhibitory activity. The most potent compound, 13c (J-1090), inhibited ALK5- and p38α-mediated phosphorylation with half-maximal inhibitor concentrations of 0.004 μM and 0.004 μM, respectively, in the enzymatic assay. In this study, the effectiveness of 13c in transforming growth factor (TGF-β)-exposed U87MG cells was investigated using western blotting, immunofluorescence assays, cell migration assay, invasion assay, and RT-PCR analysis. 13c inhibited the protein expression of Slug and the protein and RNA expression of the mesenchymal-related proteins N-cadherin and vimentin. Furthermore, 13c markedly suppressed TGF-β-induced epithelial-to-mesenchymal transition (EMT), migration, and invasion in U87MG cells. These results suggest that 13c is a novel inhibitor of ALK5 with potential utility in the treatment of human glioma.

Chelidonine Induces Apoptosis via GADD45a-p53 Regulation in Human Pancreatic Cancer Cells

Chelidonium majus has been used as a traditional medicine in China and western countries for various diseases, including inflammation and cancer. However, the anti-cancer effect of chelidonine, a major compound of C. majus extracts, on pancreatic cancer remains poorly understood. In this study, we found that treatment with chelidonine inhibited proliferation of BxPC-3 and MIA PaCa-2 human pancreatic cancer cells. Annexin-V/propidium iodide staining assay showed that this growth inhibitory effect of chelidonine was induced through apoptosis. We found that chelidonine treatment upregulated mRNA levels and transcription factor activity in both cell lines. Increases in protein expression levels of p53, GADD45A, p21 and cleaved caspase-3 were also observed, with more distinct changes in MIA PaCa-2 cells compared to the BxPC-3 cells. These results suggest that chelidonine induces pancreatic cancer apoptosis through the p53 and GADD45A pathways. Our findings provide new insights into the use of chelidonine for the treatment of pancreatic cancer.

Sanguinarine and Chelidonine Synergistically Induce Endosomal Toll-like Receptor and M1-Associated Mediators Expression

Natural compounds represent the great capability to stimulate several cell types. Macrophage plays an important role for an effective immune response for infection and inflammation. Isoquinoline alkaloid, sanguinarine, and chelidonine are active compounds that exhibit activity on various tumor cells and immune cells. However, the effect of these compounds on the endosomal toll-like receptor (enTLR) and type I interferon (IFN) are still unclear. The monocyte-derived macrophages (MDMs) were cultured and were determined their cell viability and phagocytic activity to Staphylococcus aureus DMST8840. The nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) expression were also examined. The expression of enTLRs, type I IFN, and cytokines were determined by real-time PCR. Result shows that the compounds did not affect on MDM cell viability. Sanguinarine and chelidonine enhance phagocytic activity of MDM against Staphylococcus aureus DMST8840 by revealing a higher number of bacterial survival than the MDM treated by polyI:C, and the cell control after co-culture for 3 h. The production of NO has no difference amount but iNOS mRNA production was down-regulated in sanguinarine, chelidonine and their mixed treated MDM. The expressions of enTLRs and IFN-β1 mRNA were up-regulated in both compounds and their combination. Additionally, these compounds also enhance M1-liked cytokine by up-regulated IL-6 and down-regulated IL-10 and TGF-β1, respectively. Therefore, sanguinarine and chelidonine enhance enTLR and IFN-β1 expression and trend to stimulate the cell into M1-liked MDM.

Biologically active isoquinoline alkaloids covering 2014-2018

Isoquinoline alkaloids, an important class of N-based heterocyclic compounds, have attracted considerable attention from researchers worldwide since the early 19th century. Over the past 200 years, many compounds from this class were isolated, and most of them and their analogs possess various bioactivities. In this review, we survey the updated literature on bioactive alkaloids and highlight research achievements of this alkaloid class during the period of 2014-2018. We reviewed over 400 molecules with a broad range of bioactivities, including antitumor, antidiabetic and its complications, antibacterial, antifungal, antiviral, antiparasitic, insecticidal, anti-inflammatory, antioxidant, neuroprotective, and other activities. This review should provide new indications or directions for the discovery of new and better drugs from the original naturally occurring isoquinoline alkaloids.

Arctigenin protects against depression by inhibiting microglial activation and neuroinflammation via HMGB1/TLR4/NF-κB and TNF-α/TNFR1/NF-κB pathways

BACKGROUND AND PURPOSE

Arctigenin, a major bioactive component of Fructus arctii, has been reported to have antidepressant-like effects. However, the mechanisms underlying these effects are still unclear. Neuroinflammation can be caused by excessive production of proinflammatory cytokines in microglia via high-mobility group box 1 (HMGB1)/TLR4/NF-κB and TNF-α/TNFR1/NF-κB signalling pathways, leading to depression. In this study, we have investigated the antidepressant mechanism of arctigenin by conducting in vitro and in vivo studies.

EXPERIMENTAL APPROACH

The effects of chronic unpredictable mild stress (CUMS) on wild-type (WT) and TLR4^-/- mice were examined. Antidepressant-like effects of arctigenin were tested using the CUMS-induced model of depression in WT mice. The effects of arctigenin were assessed on the HMGB1/TLR4/NF-κB and TNF-α/TNFR1/NF-κB signalling pathways in the prefrontal cortex (PFC) of mouse brain and HMGB1- or TNF-α-stimulated primary cultured microglia. The interaction between HMGB1 and TLR4 or TNF-α and TNFR1 with or without arctigenin was examined by localized surface plasmon resonance (LSPR) and co-immunoprecipitation assays.

KEY RESULTS

The immobility times in the tail suspension test (TST) and forced swimming test (FST) were reduced in TLR4^-/- mice, compared with WT mice. Arctigenin exhibited antidepressant-like effects. Arctigenin also inhibited microglia activation and inflammatory responses in the PFC of mouse brain. Arctigenin inhibited HMGB1 and TLR4 or TNF-α and TNFR1 interactions, and suppressed both HMGB1/TLR4/NF-κB and TNF-α/TNFR1/NF-κB signalling pathways.

CONCLUSIONS AND IMPLICATIONS

Arctigenin has antidepressant-like effects by attenuating excessive microglial activation and neuroinflammation through the HMGB1/TLR4/NF-κB and TNF-α/TNFR1/NF-κB signalling pathways. This suggests that arctigenin has potential as a new drug candidate suitable for clinical trials to treat depression.

Antidepressive Effect of Arctiin by Attenuating Neuroinflammation via HMGB1/TLR4- and TNF-α/TNFR1-Mediated NF-κB Activation

Inflammation is a potential factor in the pathophysiology of depression. A traditional Chinese herbal medicine, arctiin, and its aglycone, arctigenin, are the major bioactive components in Fructus arctii and exhibit neuroprotective and anti-inflammatory activities. Arctigenin has been reported to have antidepressant-like effects. However, the antidepressant-like effects of arctiin, its precursor, remain unknown. In this study, we investigated the antidepressant-like effects of arctiin and its underlying mechanisms by in vivo and in vitro experiments in mice. Our results showed that arctiin significantly attenuated sucrose consumption and increased the immobility time in tail suspension and forced swimming tests. Arctiin decreased neuronal damage in the prefrontal cortex (PFC) of the brain. Arctiin also attenuated the levels of three inflammatory mediators, indoleamine 2,3-dioxygenase, 5-hydroxytryptamine, and dopamine, that were elevated in the PFC or serum of chronic unpredictable mild stress (CUMS)-exposed mice. Arctiin reduced excessive activation of microglia and neuroinflammation by reducing high mobility group box 1 (HMGB1)/toll-like receptor 4 (TLR4)- and tumor necrosis factor-α (TNF-α)/TNF receptor 1 (TNFR1)-mediated nuclear factor-kappa B (NF-κB) activation in the PFC of CUMS-exposed mice and HMGB1- or TNF-α-stimulated primary cultured microglia. These findings demonstrate that arctiin ameliorates depression by inhibiting the activation of microglia and inflammation via the HMGB1/TLR4 and TNF-α/TNFR1 signaling pathways.

Chelidonine selectively inhibits the growth of gefitinib-resistant non-small cell lung cancer cells through the EGFR-AMPK pathway

Tyrosine kinase inhibitors (TKIs) have been widely used for the clinical treatment of patients with non-small cell lung cancer (NSCLC) harboring mutations in the EGFR. Unfortunately, due to the secondary mutation in EGFR, eventual drug-resistance is inevitable. Therefore, to overcome the resistance, new agent is urgently required. Chelidonine, extracted from the roots of Chelidonium majus, was proved to effectively suppress the growth of NSCLC cells with EGFR double mutation. Proteomics analysis indicated that mitochondrial respiratory chain was significantly inhibited by chelidonine, and inhibitor of AMPK effectively blocked the apoptosis induced by chelidonine. Molecular dynamics simulations indicated that chelidonine could directly bind to EGFR and showed a much higher binding affinity to EGFR^L858R/T790M than EGFR^WT, which demonstrated that chelidonine could selectively inhibit the phosphorylation of EGFR in cells with EGFR double-mutation. In vivo study revealed that chelidonine has a similar inhibitory effect like second generation TKI Afatinib. In conclusion, targeting EGFR and inhibition of mitochondrial function is a promising anti-cancer therapeutic strategy for inhibiting NSCLC with EGFR mutation and TKI resistance.

Targeting NRAS-Mutant Cancers with the Selective STK19 Kinase Inhibitor Chelidonine

PURPOSE

Oncogenic mutations in NRAS promote tumorigenesis. Although novel anti-NRAS inhibitors are urgently needed for the treatment of cancer, the protein is generally considered "undruggable" and no effective therapies have yet reached the clinic. STK19 kinase was recently reported to be a novel activator of NRAS and a potential therapeutic target for NRAS-mutant melanomas. Here, we describe a new pharmacologic inhibitor of STK19 kinase for the treatment of NRAS-mutant cancers.

EXPERIMENTAL DESIGN

The STK19 kinase inhibitor was identified from a natural compound library using a luminescent phosphorylation assay as the primary screen followed by verification with an in vitro kinase assay and immunoblotting of treated cell extracts. The antitumor potency of chelidonine was investigated in vitro and in vivo using a panel of NRAS-mutant and NRAS wild-type cancer cells.

RESULTS

Chelidonine was identified as a potent and selective inhibitor of STK19 kinase activity. In vitro, chelidonine treatment inhibited NRAS signaling, leading to reduced cell proliferation and induction of apoptosis in a panel of NRAS-mutant cancer cell lines, including melanoma, liver, lung, and gastric cancer. In vivo, chelidonine suppressed the growth of NRAS-driven tumor cells in nude mice while exhibiting minimal toxicity.

CONCLUSIONS

Chelidonine suppresses NRAS-mutant cancer cell growth and could have utility as a new treatment for such malignancies.

Convallatoxin promotes apoptosis and inhibits proliferation and angiogenesis through crosstalk between JAK2/STAT3 (T705) and mTOR/STAT3 (S727) signaling pathways in colorectal cancer

BACKGROUND

Aberrant activation of STAT3 is frequently encountered and promotes survival, cellular proliferation, migration, invasion and angiogenesis in tumor cell. Convallatoxin, triterpenoid ingredient, exhibits anticancer pharmacological properties.

PURPOSE

In this work, we investigated the anticancer potential of convallatoxin and explored whether convallatoxin mediates its effect through interference with the STAT3 activation in colorectal cancer cells.

METHODS

In vitro, the underlying mechanisms of convallatoxin at inhibiting STAT3 activation were investigated by homology modeling and molecular docking, luciferase reporter assay, MTT assay, RT-PCR, Western blotting and immunofluorescence assays. Changes in cellular proliferation, apoptosis, migration, invasion and angiogenesis were analyzed by EdU labeling assay, colony formation assay, flow cytometry assay, wound-healing assay, matrigel transwell invasion assay and tube formation assays. And in vivo, antitumor activity of convallatoxin was assessed in a murine xenograft model of HCT116 cells.

RESULTS

Convallatoxin decreased the viability of colorectal cancer lines. Moreover, convallatoxin reduced the P-STAT3 (T705) via the JAK1, JAK2, and Src pathways and inhibited serine-727 phosphorylation of STAT3 via the PI3K-AKT-mTOR-STAT3 pathways in colorectal cancer cells. Interestingly, we discovered the crosstalk between mTOR and JAK2 in mTOR/STAT3 and JAK/STAT3 pathways, which collaboratively regulated STAT3 activation and convallatoxin play a role in it. Convallatoxin also downregulated the expression of target genes involved cell survival (e.g., Survivin, Bcl-xl, Bcl-2), proliferation (e.g., Cyclin D1), metastasis (e.g., MMP-9), and angiogenesis (e.g., VEGF). Indeed, we found that convallatoxin inhibited tube formation, migration, and invasion of endothelial cells, and inhibited the proliferation. Finally, in vivo observations were confirmed by showing antitumor activity of convallatoxin in a murine xenograft model.

CONCLUSION

The result of the current study show that convallatoxin promotes apoptosis and inhibits proliferation and angiogenesis through crosstalk between JAK2/STAT3 (T705) and mTOR/STAT3 (S727) signaling pathways in colorectal cancer cells and indicate that convallatoxin could be a valuable candidate for the development of colorectal cancer therapeutic.

Chelidonine enhances the antitumor effect of lenvatinib on hepatocellular carcinoma cells

Background

Lenvatinib is a newly approved molecular targeted drug for the treatment of advanced hepatocellular carcinoma (HCC). However, the high cost associated with this treatment poses a huge financial burden on patients and the entire public health system. Therefore, there is an urgent need to develop novel strategies that enhance the antitumor effect of lenvatinib.

Methods

The antitumor effects of chelidonine or/and lenvatinib on HCC cell lines MHCC97-H and LM-3 were examined using the 3-[4,5-dimethyl-2-thiazolyl]-2,5-diphenyl-2- H-tetrazolium bromide (MTT) assay. For the in-vivo investigation, the effect on subcutaneous or intrahepatic tumor growth in nude mice was also determined. The mRNA levels of epithelial mesenchymal transition (EMT)-related factors were examined through quantitative polymerase chain reaction or Western blot.

Results

In the present study, we found that treatment with chelidonine enhanced the apoptotic effect of lenvatinib on HCC cells and the in-vivo growth of HCC tumors in nude mice. Mechanistically, treatment with chelidonine increased the expression of epithelial indicator E-cadherin, whereas it decreased the expression of mesenchymal indicators N-cadherin and Vimentin. These findings suggest that chelidonine restricted the EMT in HCC cells.

Conclusion

Chelidonine inhibits the process of EMT and enhances the antitumor effect of lenvatinib on HCC cells.

Papaver nudicaule (Iceland poppy) alleviates lipopolysaccharide-induced inflammation through inactivating NF-κB and STAT3

BACKGROUND

Papaver nudicaule belongs to the Papaveraceae family, which is planted as an annual herbaceous species generally for ornamental purpose. Papaver rhoeas in the same family has been reported to have various pharmacological activities such as antioxidant and analgesic effects. In contrast, little is known about the pharmacological activity of Papaver nudicaule. In this study, the anti-inflammatory activity of Papaver nudicaule extracts and the action mechanisms were investigated in RAW264.7 macrophage cells.

METHODS

To investigate the anti-inflammatory activity of five cultivars of Papaver nudicaule with different flower color, samples were collected from their aerial parts at two growth stages (60 and 90 days) and their ethanol extracts were evaluated in the lipopolysaccharide (LPS)-treated RAW264.7 cells by measuring nitric oxide (NO) and prostaglandin E2 (PGE2) levels. Interleukin 1-beta (IL-1β), Interleukin-6 (IL-6) and Tumor necrosis factor alpha (TNF-α) production were also analyzed by RT-PCR and multiplex assays. Nuclear Factor-kappa-light-chain-enhancer of activated B cells (NF-κB) and Signal transducer and activator of transcription 3 (STAT3) signaling pathways were examined using western blotting and luciferase reporter assays to reveal the action mechanism of Papaver nudicaule extracts in their anti-inflammatory activity.

RESULTS

All of the Papaver nudicaule extracts were effective in reducing the LPS-induced NO, which is an important inflammatory mediator, and the extract of Papaver nudicaule with white flower collected at 90 days (NW90) was selected for further experiments because of the best effect on reducing the LPS-induced NO as well as no toxicity. NW90 lowered the LPS-induced PGE2 level and decreased the LPS-induced Nitric oxide synthase 2 (NOS2) and Cyclooxygenase 2 (COX2). In addition, NW90 reduced the LPS-induced inflammatory cytokines, IL-1β and IL-6. Furthermore, NW90 inhibited the LPS-induced activation of NF-κB and STAT3.

CONCLUSIONS

These results indicate that NW90 may restrain inflammation by inhibiting NF-κB and STAT3, suggesting the potential therapeutic properties of Papaver nudicaule against inflammatory disease.

In vitro wound healing of tumor cells: inhibition of cell migration by selected cytotoxic alkaloids

Background

Cell migration is involved in several pathological processes such as tumor invasion, neoangiogenesis and metastasis. Microtubules are needed in directional migration.

Methods

To investigate the effects of microtubule-binding agents (paclitaxel, vinblastine, colchicine, podophyllotoxin), benzophenanthridine alkaloids (sanguinarine, chelerythrine, chelidonine) and other anti-tumor drugs (homoharringtonine, doxorubicin) on cell migration, we performed the in vitro wound healing assay. The interactions between selected alkaloids and microtubules were studied via U2OS cells expressing microtubule-GFP markers.

Results

The microtubule-binding natural products paclitaxel, vinblastine, colchicine and podophyllotoxin significantly altered microtubule dynamics in living cells and inhibited cell migration at concentrations below apparent cytotoxicity. The benzophenanthridine alkaloid sanguinarine, chelerythrine and chelidonine which affected microtubules in living cells, did not inhibit cell migration. Homoharringtonine (protein biosynthesis inhibitor) and doxorubicin significantly inhibited cell migration, however, they did not exert obvious effects on microtubules.

Conclusion

In this study, we demonstrated that microtubule-binding agents are effective anti-migrating agents; moreover, homoharringtonine and doxorubicin can be referred as anti-migrating agents, but direct microtubule dynamics are not involved in their mode of action. Our study provides evidence that some alkaloids and other microtubule-binding natural products may be interesting candidates for the development of novel agents against metastasis.

Electronic supplementary material

The online version of this article (10.1186/s40360-018-0284-4) contains supplementary material, which is available to authorized users.

Sertraline ameliorates inflammation in CUMS mice and inhibits TNF-α-induced inflammation in microglia cells

Evidence indicates that inflammation plays a crucial role in depression. Therefore, new antidepressants might be identified by screening drugs for their anti-inflammatory actions. Sertraline hydrochloride (SERT), a widely used antidepressant, has anti-inflammatory effects in clinical studies, but the mechanism involved is unclear. In this study, we used cell and molecular biology to determine the possible anti-inflammatory mechanism of SERT in vivo and in vitro. Experimental data from the in vivo study showed that mice exposed to chronic unpredictable mild stress (CUMS) had significantly higher levels of major inflammatory cytokines (tumor necrosis factor-α [TNF-α], interleukin-1β [IL-1β] and inducible nitric oxide synthase [iNOS]) in peripheral and central tissues compared with the control group. Treatment of CUMS mice with SERT significantly reduced the levels of these inflammatory cytokines and inhibited the phosphorylation of nuclear factor-κB (NF-κB) and nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκB-α). Moreover, SERT reduced serum levels of transaminase in CUMS mice. Our in vitro study revealed that SERT suppressed TNF-α-induced NF-κB activation in a dose-dependent manner. SERT also inhibited the TNF-α-induced nuclear translocation of NF-κB by inhibiting IκB-α phosphorylation. Furthermore, SERT inhibited TNF-α-induced inflammatory cytokines in BV2 microglia cells. SERT directly bound to TNF-α and TNF-α receptor 1 (TNFR1) to potently block TNF-α/TNFR1-triggered signaling. These results indicate that SERT might treat depression by inhibiting the activation of microglia via the NF-κB signaling pathway. This study provides a basis for the research and development of antidepressants that act to reduce inflammation and the expression of inflammatory mediators.

Greater Celandine's Ups and Downs-21 Centuries of Medicinal Uses of Chelidonium majus From the Viewpoint of Today's Pharmacology

As antique as Dioscorides era are the first records on using Chelidonium as a remedy to several sicknesses. Inspired by the "signatura rerum" principle and an apparent ancient folk tradition, various indications were given, such as anti-jaundice and cholagogue, pain-relieving, and quite often mentioned-ophthalmological problems. Central and Eastern European folk medicine has always been using this herb extensively. In this region, the plant is known under many unique vernacular names, especially in Slavonic languages, associated or not with old Greek relation to "chelidon"-the swallow. Typically for Papaveroidae subfamily, yellow-colored latex is produced in abundance and leaks intensely upon injury. Major pharmacologically relevant components, most of which were first isolated over a century ago, are isoquinoline alkaloids-berberine, chelerythrine, chelidonine, coptisine, sanguinarine. Modern pharmacology took interest in this herb but it has not ended up in gaining an officially approved and evidence-based herbal medicine status. On the contrary, the number of relevant studies and publications tended to drop. Recently, some controversial reports and sometimes insufficiently proven studies appeared, suggesting anticancer properties. Anticancer potential was in line with anecdotical knowledge spread in East European countries, however, in the absence of directly-acting cytostatic compounds, some other mechanisms might be involved. Other properties that could boost the interest in this herb are antimicrobial and antiviral activities. Being a common synanthropic weed or ruderal plant, C. majus spreads in all temperate Eurasia and acclimates well to North America. Little is known about the natural variation of bioactive metabolites, including several aforementioned isoquinoline alkaloids. In this review, we put together older and recent literature data on phytochemistry, pharmacology, and clinical studies on C. majus aiming at a critical evaluation of state-of-the-art from the viewpoint of historical and folk indications. The controversies around this herb, the safety and drug quality issues and a prospective role in phytotherapy are discussed as well.