Multiple therapeutic effects of adjunctive baicalin therapy in experimental bacterial meningitis

Protective and therapeutic effects of Scutellaria baicalensis and its main active ingredients baicalin and baicalein against natural toxicities and physical hazards: a review of mechanisms

OBJECTIVES

Scutellaria baicalensis (SB) has been traditionally used to combat a variety of conditions ranging from ischemic heart disease to cancer. The protective effects of SB are due to the action of two main flavonoids baicalin (BA) and baicalein (BE). This paper aimed to provide a narrative review of the protective and antidotal effects of SB and its main constituents against natural toxicities and physical hazards.

EVIDENCE ACQUISITION

Scientific databases Medline, Scopus, and Web of Science were thoroughly searched, based on different keywords for in vivo, in vitro and clinical studies which reported protective or therapeutic effects of SB or its constituents in natural and physical toxicities.

RESULTS

Numerous studies have reported that treatment with BE, BA, or total SB extract prevents or counteracts the detrimental toxic effects of various natural compounds and physical hazards. The toxic agents include mycotoxins, lipopolysaccharide, multiple plants and animal-derived substances as well as physical factors which negatively affected vital organs such as CNS, liver, kidneys, lung and heart. Increasing the expression of radical scavenging enzymes and glutathione content as well as inhibition of pro-inflammatory cytokines and pro-apoptotic mediators were important mechanisms of action.

CONCLUSION

Different studies on the Chinese skullcap have exhibited that its total root extract, BA or BE can act as potential antidotes or protective agents against the damage induced by natural toxins and physical factors by alleviating oxidative stress and inflammation. However, the scarcity of high-quality clinical evidence means that further clinical studies are required to reach a more definitive conclusion.

Scutellaria baicalensis and its constituents baicalin and baicalein as antidotes or protective agents against chemical toxicities: a comprehensive review

Scutellaria baicalensis (SB), also known as the Chinese skullcap, has a long history of being used in Chinese medicine to treat a variety of conditions ranging from microbial infections to metabolic syndrome and malignancies. Numerous studies have reported that treatment with total SB extract or two main flavonoids found in its root and leaves, baicalin (BA) and baicalein (BE), can prevent or alleviate the detrimental toxic effects of exposure to various chemical compounds. It has been shown that BA and BE are generally behind the protective effects of SB against toxicants. This paper aimed to review the protective and therapeutic effects of SB and its main components BA and BE against chemical compounds that can cause intoxication after acute or chronic exposure and seriously affect different vital organs including the brain, heart, liver, and kidneys. In this review paper, we had a look into a total of 221 in vitro and in vivo studies from 1995 to 2021 from the scientific databases PubMed, Scopus, and Web of Science which reported protective or therapeutic effects of BA, BE, or SB against drugs and chemicals that one might be exposed to on a professional or accidental basis and compounds that are primarily used to simulate disease models. In conclusion, the protective effects of SB and its flavonoids can be mainly attributed to increase in antioxidants enzymes, inhibition of lipid peroxidation, reduction of inflammatory cytokines, and suppression of apoptosis pathway.

Baicalin regulates Treg/Th17 cell imbalance by inhibiting autophagy in allergic rhinitis

BACKGROUND

Baicalin has many biological properties such as anti-oxidation and anti-allergy. The current study aimed to explore the effect of Baicalin on allergic rhinitis (AR) and its potential mechanism of action.

METHODS

Peripheral blood mononuclear cells (PBMCs) were isolated by density gradient centrifugation. Expression levels of Th17 and Treg cells-related proteins in nasal mucosa and peripheral blood cells were detected by real-time quantitative PCR, flow cytometry and Western blot. The mice were randomly divided into Control, ovalbumin (OVA), l-Baicalin, H-Baicalin, DSGC, 3-MA, and H-Baicalin + Rapa groups. Changes of allergic rhinitis conditions and eosinophil infiltration of the mice were detected and scored by Diff-Quik staining, and histological changes were observed by Hematoxylin & Eosin (H&E) staining and Periodate Schiff (PAS) staining. Serological changes, expression levels of interleukin-17A (IL-17A), interleukin-10 (IL-10), eosinophilic cationic protein (ECP) and anti-OVA-specific antibodies were detected by Enzyme-linked immunosorbent assay (ELISA).

RESULTS

Clinical case analysis found that AR patients had a Th17/Treg imbalance and activated autophagy, however, Baicalin restored Th17/Treg cell balance and inhibited autophagy in vitro. in vivo experiments demonstrated that Baicalin inhibited OVA-induced allergic nasal symptoms and the activation of autophagy pathway, which was the same as the regulation of 3-MA, while Rapa could weaken the effects of H-baicalin. Moreover, Baicalin reduced the infiltration of different inflammatory cells of the nasal lavage fluid, prevented the damages to epithelial cells, and improved nasal mucosal thickness and mucus secretion. In addition, Baicalin regulated the balance of mouse anti-OVA-specific antibody levels and expressions of Th17/Treg-associated cytokines.

CONCLUSION

Our study revealed that Baicalin can be used to treat AR, and the effect is realized through inhibiting autophagy to regulate Th17/Treg cell differentiation.

Antimicrobial Effects of Chemical Compounds Isolated from Traditional Chinese Herbal Medicine (TCHM) Against Drug-Resistant Bacteria: A Review Paper

Infectious diseases caused by pathogenic bacteria seriously threaten human lives. Although antibiotic therapy is effective in the treatment of bacterial infections, the overuse of antibiotics has led to an increased risk of antibiotic resistance, putting forward urgent requirements for novel antibacterial drugs. Traditional Chinese herbal medicine (TCHM) and its constituents are considered to be potential sources of new antimicrobial agents. Currently, a series of chemical compounds purified from TCHM have been reported to fight against infections by drug-resistant bacteria. In this review, we summarized the recent findings on TCHM-derived compounds treating drug-resistant bacterial infections. Further studies are still needed for the discovery of potential antibacterial components from TCHM.

Baicalin inhibits pressure overload-induced cardiac fibrosis through regulating AMPK/TGF-β/Smads signaling pathway

AMP-activated protein kinase (AMPK) is a central regulator of multiple metabolic pathways. It has been shown that activation of AMPK could inhibit fibroblast proliferation and extracellular matrix (ECM) accumulation, thereby suppressing cardiac fibrosis. Baicalin, the major component found in skullcap, possesses multiple protective effects on the cardiovascular system. However, little is known about the effect of baicalin on cardiac fibrosis and the molecular mechanism by which baicalin exerts its anti-fibrotic effects has not been investigated. In this study, we revealed that baicalin could inhibit cell proliferation, collagen synthesis, fibronectin (FN) and Connective tissue growth factor (CTGF) protein expression in cardiac fibroblasts induced by angiotensin Ⅱ (Ang Ⅱ). It also ameliorated cardiac fibrosis in rats submitted to abdominal aortic constriction (AAC). Moreover, baicalin inhibited transforming growth factor-β (TGF-β)/Smads signaling pathway stimulated with Ang Ⅱ through activating AMPK. Subsequently, we also demonstrated that baicalin attenuated Ang Ⅱ-induced Smad3 nuclear translocation, and interaction with transcriptional coactivator p300, but promoted the interaction of p300 and AMPK. Taken together, these results provide the first evidence that the effect of baicalin against cardiac fibrosis may be attributed to its regulation on AMPK/TGF-β/Smads signaling, suggesting the therapeutic potential of baicalin on the prevention of cardiac fibrosis and heart failure.

A Novel Strategy for Bitter Taste Masking of Gankeshuangqing Dispersible Tablets Based on Particle Coating Technology

BACKGROUND

Currently, acute upper respiratory tract infections (AURTIs) are increasingly becoming a significant health burden. Gankeshuangqing dispersible tablets (GKSQDT) which have a good effect on treating AURTIs. GKSQDT is composed of baicalin and andrographolide. However, its severe bitterness limits application of patients. Due to the addition of plentiful accessories, common masking methods are unsuitable for GKSQDT. It is thus necessary to develop a new masking method.

MATERIALS AND METHODS

The Previous study showed that baicalin was less bitter than andrographolide. Thus, particle coating technology was adapted to prepare composite particles that baicalin coated on the surface of andrographolide to decrease bitterness. Initially, particle size of baicalin and coating time of composite was investigated to prepare composite. Then, scanning electron microscopy, wettability, and infrared (IR) spectrogram were used to characterize the microstructure of composite. Furthermore, electronic tongue test, animal preference experiment, and human sensory test were applied to evaluate the masking effect.

RESULTS

To produce composite, baicalin should be ground in vibromill for 6 min. Then, andrographolide fine powder was added to grind together for 6 min. Contact angle of composite was smaller than mixture, and more similar to baicalin. Other physical characterization including microstructure, wettability, and IR also suggested that andrographolide was successfully coated by baicalin superfine. Furthermore, taste-masking test indicated taste-masked tablets was less bitter than original tablets.

CONCLUSION

The study indicated that particle coating technology can be used for taste masking of GKSQDT without adding other substance. Moreover, it provides a new strategy of taste masking for national medicine.

SUMMARY

A new strategy to mask bitterness without adding any other substance based on coating technology was providedThe masking effect was confirmed by electronic tongue test, animal preference experiment and human sensory test. Abbreviations used: AURTIs: Acute Upper Respiratory Tract Infections; GSQDT: Gankeshuangqing Dispersible Tablets; IR: Infrared Spectrogram; LHPC: Low-substituted Hydroxypropyl Cellulose; CAs: Contact Angles; FTIR: Fourier Transform Infrared Spectra.

Baicalin ameliorates renal fibrosis via inhibition of transforming growth factor β1 production and downstream signal transduction

Previous studies have demonstrated the potential antifibrotic effects of baicalin in vitro, via examination of 21 compounds isolated from plants. However, its biological activity and underlying mechanisms of action in vivo remain to be elucidated. The present study aimed to evaluate the effect of baicalin on renal fibrosis in vivo, and the potential signaling pathways involved. A unilateral ureteral obstruction (UUO)‑induced renal fibrosis model was established using Sprague‑Dawley rats. Baicalin was administrated intraperitoneally every 2 days for 10 days. The degree of renal damage and fibrosis was investigated by histological assessment, and detection of fibronectin and collagen I mRNA expression levels. Epithelial‑mesenchymal transition (EMT) markers, transforming growth factor-β1 (TGF-β1) levels and downstream phosphorylation of mothers against decapentaplegic 2/3 (Smad2/3) were examined in vivo and in an NRK‑52E rat renal tubular cell line in vitro. Baicalin was demonstrated to markedly ameliorate renal fibrosis and suppress EMT, as evidenced by reduced interstitial collagen accumulation, decreased fibronectin and collagen I mRNA expression levels, upregulation of N‑ and E‑cadherin expression levels, and downregulation of α‑smooth muscle actin and vimentin expression. Furthermore, baicalin decreased TGF‑β1 expression levels in serum and kidney tissue following UUO, and suppressed Smad2/3 phosphorylation in rat kidney tissue. In vitro studies identified that baicalin may inhibit the phosphorylation of Smad2/3 under the same TGF‑β1 concentration. In conclusion, baicalin may protect against renal fibrosis, potentially via inhibition of TGF‑β1 production and its downstream signal transduction.

The Protective Effect of Baicalin Against Lead-Induced Renal Oxidative Damage in Mice

Lead (Pb) exposure is a global environmental problem that can deplete body antioxidant enzymes, causing damage to various macromolecules and ultimately cell death. Pb exposure could lead to serious renal damage. Baicalin, a traditional Chinese medicine, could protect against renal injury through inhibition of oxidative stress and apoptosis. This study was designed to investigate the protective efficacy of baicalin against Pb-induced nephrotoxicity in mice and to elucidate the potential mechanisms using animal experiment. The results revealed that baicalin decreased Pb-induced bodyweight loss, declined kidney coefficients, and ameliorated renal function and structure in a dose-dependent manner. Meanwhile, baicalin dose dependently increased Pb-induced activity of SOD and GSH-Px, while the content of MDA in the kidney was decreased. In addition, baicalin enhanced the Bcl-2/Bax ratio associated with apoptosis in the kidney. These data indicated that further investigation of the use of baicalin as a new natural chemopreventive agent against Pd poisoning is warranted.

Nanocarrier improves the bioavailability, stability and antitumor activity of camptothecin

Camptothecin (CPT) nanosuspension was prepared by anti-solvent precipitation with TPGS as stabilizer to improve the solubility, stability and antitumor activity of CPT. And an increased solubility, stability and dissolution rate was achieved after nanosuspension being prepared. While, enhanced intracellular accumulation and cellular cytotoxicity was also observed for CPT nanosuspension than that of CPT solution.In addition, nanosuspension could increase bioavailability and intratumor accumulation of CPT in vivo after intravenous administration, and then produced a much higher antitumor effect and biocompatibility than that of CPT solution. Meanwhile, an enhanced cellular CPT uptake in hypoxic or acid conditions could also be observed for nanosuspension. As a result, nanosuspension represents a potentially feasible formation for insoluble drug in antitumor research.

Baicalin ameliorates H2O2 induced cytotoxicity in HK-2 cells through the inhibition of ER stress and the activation of Nrf2 signaling

Renal ischemia-reperfusion injury plays a key role in renal transplantation and greatly affects the outcome of allograft. Our previous study proved that Baicalin, a flavonoid glycoside isolated from Scutellaria baicalensis, protects kidney from ischemia-reperfusion injury. This study aimed to study the underlying mechanism in vitro. Human renal proximal tubular epithelial cell line HK-2 cells were stimulated by H₂O₂ with and without Baicalin pretreatment. The cell viability, apoptosis and oxidative stress level were measured. The expression of endoplasmic reticulum (ER) stress hallmarks, such as binding immunoglobulin protein (BiP) and C/EBP homologous protein (CHOP), were analyzed by western blot and real-time PCR. NF-E2-related factor 2 (Nrf2) expression was also measured. In the H₂O₂ group, cell viability decreased and cell apoptosis increased. Reactive Oxygen Species (ROS) and Glutathione/Oxidized Glutathione (GSH/GSSG) analysis revealed increased oxidative stress. ER stress and Nrf2 signaling also increased. Baicalin pretreatment ameliorated H₂O₂-induced cytotoxicity, reduced oxidative stress and ER stress and further activated the anti-oxidative Nrf2 signaling pathway. The inducer of ER stress and the inhibitor of Nrf2 abrogated the protective effects, while the inhibitor of ER stress and the inducer of Nrf2 did not improve the outcome. This study revealed that Baicalin pretreatment serves a protective role against H₂O₂-induced cytotoxicity in HK-2 cells, where the inhibition of ER stress and the activation of downstream Nrf2 signaling are involved.

The protective effect of baicalin against renal ischemia-reperfusion injury through inhibition of inflammation and apoptosis

Background

Renal ischemia-reperfusion injury (IRI) increases the rates of acute kidney failure, delayed graft function, and early mortality after kidney transplantation. The pathophysiology involved includes oxidative stress, mitochondrial dysfunction, and immune-mediated injury. The anti-oxidation, anti-apoptosis, and anti-inflammation properties of baicalin, a flavonoid glycoside isolated from Scutellaria baicalensis, have been verified. This study therefore assessed the effects of baicalin against renal IRI in rats.

Methods

Baicalin was intraperitoneally injected 30 min before renal ischemia. Serum and kidneys were harvested 24 h after reperfusion. Renal function and histological changes were assessed. Markers of oxidative stress, the Toll-like receptor (TLR)2 and TLR4 signaling pathway, mitochondrial stress, and cell apoptosis were also evaluated.

Results

Baicalin treatment decreased oxidative stress and histological injury, and improved kidney function, as well as inhibiting proinflammatory responses and tubular apoptosis. Baicalin pretreatment also reduced the expression of TLR2, TLR4, MyD88, p-NF-κB, and p-IκB proteins, as well as decreasing caspase-3 activity and increasing the Bcl-2/Bax ratio.

Conclusions

Baicalin may attenuate renal ischemia-reperfusion injury by inhibiting proinflammatory responses and mitochondria-mediated apoptosis. These effects are associated with the TLR2/4 signaling pathway and mitochondrial stress.

Flavones induce neutrophil apoptosis by down-regulation of Mcl-1 via a proteasomal-dependent pathway

Neutrophil apoptosis and subsequent nonphlogistic clearance by surrounding phagocytes are key to the successful resolution of neutrophilic inflammation, with dysregulated apoptosis reported in multiple human inflammatory diseases. Enhancing neutrophil apoptosis has proresolution and anti-inflammatory effects in preclinical models of inflammation. Here we investigate the ability of the flavones apigenin, luteolin, and wogonin to induce neutrophil apoptosis in vitro and resolve neutrophilic inflammation in vivo. Human neutrophil apoptosis was assessed morphologically and by flow cytometry following incubation with apigenin, luteolin, and wogonin. All three flavones induced time- and concentration-dependent neutrophil apoptosis (apigenin, EC₅₀=12.2 μM; luteolin, EC₅₀=14.6 μM; and wogonin, EC₅₀=28.9 μM). Induction of apoptosis was caspase dependent, as it was blocked by the broad-spectrum caspase inhibitor Q-VD-OPh and was associated with both caspase-3 and caspase-9 activation. Flavone-induced apoptosis was preceded by down-regulation of the prosurvival protein Mcl-1, with proteasomal inhibition preventing flavone-induced Mcl-1 down-regulation and apoptosis. The flavones abrogated the survival effects of mediators that prolong neutrophil life span, including lipoteichoic acid, peptidoglycan, dexamethasone, and granulocyte-macrophage colony stimulating factor, by driving apoptosis. Furthermore, wogonin enhanced resolution of established neutrophilic inflammation in a zebrafish model of sterile tissue injury. Wogonin-induced resolution was dependent on apoptosis in vivo as it was blocked by caspase inhibition. Our data show that the flavones induce neutrophil apoptosis and have potential as neutrophil apoptosis-inducing anti-inflammatory, proresolution agents.—Lucas, C. D., Allen, K. C., Dorward, D. A., Hoodless, L. J., Melrose, L. A., Marwick, J. A., Tucker, C. S., Haslett, C., Duffin, R., Rossi, A. G. Flavones induce neutrophil apoptosis by down-regulation of Mcl-1 via a proteasomal-dependent pathway.

Baicalin improves survival in a murine model of polymicrobial sepsis via suppressing inflammatory response and lymphocyte apoptosis

BACKGROUND

An imbalance between overwhelming inflammation and lymphocyte apoptosis is the main cause of high mortality in patients with sepsis. Baicalin, the main active ingredient of the Scutellaria root, exerts anti-inflammatory, anti-apoptotic, and even antibacterial properties in inflammatory and infectious diseases. However, the therapeutic effect of baicalin on polymicrobial sepsis remains unknown.

METHODOLOGY/PRINCIPAL FINDINGS

Polymicrobial sepsis was induced by cecal ligation and puncture (CLP) in C57BL/6 mice. Mice were infused with baicalin intraperitoneally at 1 h, 6 h and 12 h after CLP. Survival rates were assessed over the subsequent 8 days. Bacterial burdens in blood and peritoneal cavity were calculated to assess the bacterial clearance. Neutrophil count in peritoneal lavage fluid was also calculated. Injuries to the lung and liver were detected by hematoxylin and eosin staining. Levels of cytokines, including tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-10 and IL-17, in blood and peritoneum were measured by enzyme-linked immunosorbent assay. Adaptive immune function was assessed by apoptosis of lymphocytes in the thymus and counts of different cell types in the spleen. Baicalin significantly enhanced bacterial clearance and improved survival of septic mice. The number of neutrophils in peritoneal lavage fluid was reduced by baicalin. Less neutrophil infiltration of the lung and liver in baicalin-treated mice was associated with attenuated injuries to these organs. Baicalin significantly reduced the levels of proinflammatory cytokines but increased the level of anti-inflammatory cytokine in blood and peritoneum. Apoptosis of CD3(+) T cell was inhibited in the thymus. The numbers of CD4(+), CD8(+) T lymphocytes and dendritic cells (DCs) were higher, while the number of CD4(+)CD25(+) regulatory T cells was lower in the baicalin group compared with the CLP group.

CONCLUSIONS/SIGNIFICANCE

Baicalin improves survival of mice with polymicrobial sepsis, and this may be attributed to its antibacterial property as well as its anti-inflammatory and anti-apoptotic effects.

Polyphosphate kinase 1 is required for the pathogenesis process of meningitic Escherichia coli K1 (RS218)

Aim: Polyphosphate kinase 1 (PPK1), encoded by the ppk1 gene, is one of the major enzymes to reversibly catalyze the synthesis of polyphosphate (poly P) from the terminal phosphate of ATP. Poly P confers resistance to stress in a number of bacterial species but its role in the virulence of meningitic bacterial pathogens is unknown. The aim of this study was to determine the role of PPK1 in the pathogenesis of Escherichia coli meningitis. Materials & methods: An isogenic in-frame ppk1 deletion mutant (PD44) of E. coli K1 strain E44 was constructed and characterized. Human brain microvascular endothelial cells and neonatal rats were used as the in vitro and in vivo models, respectively, to evaluate bacterial adhesion/invasion and the abilities of bacteria crossing the blood–brain barrier (BBB) to cause meningitis. The survival of PD44 and E44 under osmotic and acid stress conditions were also examined. Results: Poly P levels in E44 were clearly higher than those in PD44, especially at the stationary phase (SP). The ppk1 deletion mutant PD44 also showed poor survival rates during osmotic shock and acidic challenge, which the bacteria would face during pathogenesis. In vitro and in vivo assays revealed that PD44 was defective in bacterial adhesion and translocation across the BBB. By using the Evans blue method, we found that E44-induced permeability of the BBB in neonatal rats was significantly higher than that of the animals infected with PD44. Cytokine ELISA results showed that the TNF-α and IL-1β levels in the serum and brain tissues of the neonatal rats infected with PD44 were lower than that of the E44 group. A more obvious meningeal inflammation could be observed in the brain tissues of the rats infected with E44 when compared with that of the PD44 group by histopathological examination. Furthermore, the mRNA expression of IbeR, which is an RpoS-like regulator contributing to the SP regulation in E44, was found to be decreased in PD44 when compared with the parent strain. PD44 was also deficient in mRNA expression of the invasin IbeA, the adhesin FimH and the outer member protein A, which contributes to E44 penetration across BBB and resistance to the stimulations of low pH and high osmolarity. Conclusion: These results indicate that ppk1 plays an important role in stress adaption and virulence in meningitic E. coli K1 strain E44, and controls the relevant phenotypes by modulating the expression of the SP regulatory gene ibeR and the virulence genes ibeA, fimH and ompA.