Baicalin protects mice against Salmonella typhimurium infection via the modulation of both bacterial virulence and host response

Probiotic cocktails accelerate baicalin metabolism in the ileum to modulate intestinal health in broiler chickens

BACKGROUND

Baicalin and probiotic cocktails are promising feed additives with broad application prospects. While probiotic cocktails are known to enhance intestinal health, the potential synergistic impact of combining baicalin with probiotic cocktails on the gut health of broiler chickens remains largely unexplored. Therefore, this study aims to investigate the influence of the combined administration of baicalin and probiotic cocktails on the composition of ileal and cecal microbiota in broiler chickens to elucidate the underlying mechanisms responsible for the health-promoting effects.

RESULTS

A total of 320 1-day-old male Arbor Acres broilers were divided into 4 groups, each with 8 replicates of 10 chicks per replicate. Over a period of 42 d, the birds were fed a basal diet or the same diet supplemented with 37.5 g/t baicalin (BC), 1,000 g/t probiotic cocktails (PC), or a combination of both BC (37.5 g/t) and PC (1,000 g/t). The results demonstrated that BC + PC exhibited positive synergistic effects, enhancing intestinal morphology, immune function, and barrier function. This was evidenced by increased VH/CD ratio, sIgA levels, and upregulated expression of occludin and claudin-1 (P < 0.05). 16S rRNA analysis indicated that PC potentiated the effects of BC, particularly in the ileum, where BC + PC significantly increased the α-diversity of the ileal microbiota, altered its β-diversity, and increased the relative abundance of Flavonifractor (P < 0.05), a flavonoid-metabolizing bacterium. Furthermore, Flavonifractor positively correlated with chicken ileum crypt depth (P < 0.05). While BC + PC had a limited effect on cecal microbiota structure, the PC group had a very similar microbial composition to BC + PC, suggesting that the effect of PC at the distal end of the gut overshadowed those of BC.

CONCLUSIONS

We demonstrated the synergistic enhancement of gut health regulation in broiler chickens by combining baicalin and probiotic cocktails. Probiotic cocktails enhanced the effects of baicalin and accelerated its metabolism in the ileum, thereby influencing the ileal microbiota structure. This study elucidates the interaction mechanism between probiotic cocktails and plant extract additives within the host microbiota. These findings provide compelling evidence for the future development of feed additive combinations.

Therapeutic effects of Stemmoside C against Salmonella enterica serotype typhimurium infected BALB/c mice

Salmonella is a Gram-negative bacterium that causes gastrointestinal diseases in 20 to 40 million people globally. Stemmoside C is a steroidal glycoside isolated from Argel, although its antibacterial and antibiofilm properties have not been studied. The antibacterial activity of Stemmoside C against Salmonella enterica was revealed, where MIC of the compound was 16 μg/mL (0.15 µM). Biofilm-associated Stemmoside C treatment destroyed S. typhi cells and reduced viable S. typhi numbers below detectable levels. When compared to Stemmoside C or Ciprofluxacin-treated mice, infected BALB/c mice had a greater death rate and a larger bacterial blood burden. The protective effects of orally administered Stemmoside C at dose of 25 and 50 mg/kg b.wt. against bacterial infection was associated with reduction in the levels of inflammatory cytokines (IFN-γ, Il-1β, IL-2, IL-6, MPO, and TNF-α) and elevation of anti-inflammatory cytokine (IL-10 and IL-12) in serum. Where, Stemmoside C at dose of 50 mg/kg b.wt. regulated the levels almost as normal control group and demonstrated apparently normal intestinal sections. It also resulted in a decrease in the number of viable S. typhi retrieved from feces. Stemmoside C is a promising drug for the treatment or prevention of S. typhimurium infection.

Development of an amoxicillin-radix scutellaria extract formulation and evaluation of its pharmacokinetics in pigs

BACKGROUND

A new antibacterial compound powder of amoxicillin (AMO)/Radix Scutellaria extract (RSE) was developed, and its pharmacokinetics were determined in pigs following oral administration.

RESULTS

The MIC ranges of AMO against Escherichia coli, Staphylococcus aureus and Streptococcus were 1-8 μg/mL, 0.5-4 μg/mL and 0.5-64 μg/mL, respectively. The MIC ranges of RSE against E. coli, S. aureus, and Streptococcus were greater than 2.5 mg/mL, 0.156-2.5 mg/mL, and greater than 2.5 mg/mL, respectively. For S. aureus, the combined drug susceptibility test showed that AMO and RSE had an additive or synergistic effect. The results of compatibility test, the excipient screening test and the drug quality control test showed that the formulation had stable quality and uniform properties under the test conditions. Two studies were conducted to investigate the pharmacokinetics of the compound product in pigs. First, the pharmacokinetics of the AMO-RSE powder were compared with those of their respective single products. The results showed no significant change in the main pharmacokinetic parameters when either component was removed from the compound formulation; thus, AMO and RSE have no pharmacokinetic interaction in pigs. Second, pigs were orally administered three different doses of AMO-RSE powder. The Cmax and AUC increased proportionally with increasing p.o. dose; thus, the λz, t1/2λ, MRT, and Tmax were unchanged for the doses of 10, 20, and 30 mg/kg AMO and the doses of 5, 10, and 15 mg/kg BCL, showing that AMO/baicalin in AMO-RSE powder showed linear pharmacokinetic characteristics in pigs.

CONCLUSIONS

The combined drug sensitivity test of AMO and RSE against S. aureus showed that the combination was additive or synergistic. Pharmacokinetic studies indicated that AMO and BCL do not interfere with each other in pigs when used in a compound formulation. The pharmacokinetic parameters remained unchanged regardless of the dose for p.o. administration, indicating linear pharmacokinetic properties over the tested dose range. The quality of the AMO-RSE powder was good and stable, providing a foundation for its clinical application in veterinary medicine. Further bioavailability, PK/PD and clinical trials are still needed to determine the final dosage regimen.

Mitogen-Activated Protein Kinases (MAPKs) and Enteric Bacterial Pathogens: A Complex Interplay

Diverse extracellular and intracellular cues activate mammalian mitogen-activated protein kinases (MAPKs). Canonically, the activation starts at cell surface receptors and continues via intracellular MAPK components, acting in the host cell nucleus as activators of transcriptional programs to regulate various cellular activities, including proinflammatory responses against bacterial pathogens. For instance, binding host pattern recognition receptors (PRRs) on the surface of intestinal epithelial cells to bacterial pathogen external components trigger the MAPK/NF-κB signaling cascade, eliciting cytokine production. This results in an innate immune response that can eliminate the bacterial pathogen. However, enteric bacterial pathogens evolved sophisticated mechanisms that interfere with such a response by delivering virulent proteins, termed effectors, and toxins into the host cells. These proteins act in numerous ways to inactivate or activate critical components of the MAPK signaling cascades and innate immunity. The consequence of such activities could lead to successful bacterial colonization, dissemination, and pathogenicity. This article will review enteric bacterial pathogens' strategies to modulate MAPKs and host responses. It will also discuss findings attempting to develop anti-microbial treatments by targeting MAPKs.

Protective effect of 13-methylberberine against mouse enteritis caused by MRSA

ETHNOPHARMACOLOGICAL RELEVANCE

The emergence and spread of antibiotic resistance bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), urgently need to develop alternative strategies or novel antibacterial drugs. Coptis chinensis Franch., one ancient Chinese herb, has been widely used for the treatment of intestine disease, such as diarrhea. Alkaloids are the major active compounds of Coptis chinensis Franch., and has anti-inflammatory, antioxidant, and antimicrobial effects.

AIM OF THE STUDY

The aim of the study was tried to investigate the potential antibacterial effects of the alkaloids from Coptis chinensis Franch. and explore the mechanism.

MATERIALS AND METHODS

A checkerboard assay, time-killing analysis, membrane functions assay, transcriptome analysis, and inducible resistance test showed the antibacterial effects and mechanisms of alkaloids from Coptis chinensis Franch. Hemolytic assay and MRSA-infected RAW264.7 cells were used to evaluate anti-virulence and anti-inflammatory activities of 13-methylberberine (13-MB). MRSA-infected Vero cells and mouse enteritis models were used to evaluate the anti-infectious effect of 13-MB against MRSA both in vitro and in vivo.

RESULTS

13-methylberberine (13-MB) displayed high bactericidal efficiency against methicillin-resistant S. aureus (MRSA). Mechanistic studies showed that 13-MB rapidly killed MRSA by interfering with the proton motive force, ROS generation and membrane fluidity via direct interaction with membrane phospholipids. 13-MB suppressed the virulence of MRSA, modulated the host immune response, and effectively eliminated MRSA in Vero cells. Importantly, 13-MB suppressed weight loss, inflammatory response, bacterial colonization and intestinal lesion in mouse enteritis caused by 13-MB susceptible and resistant S. aureus.

CONCLUSION

These results supported the 13-MB has promising potential to be developed as natural drug with antibacterial activity, anti-virulence activity, and host modulation activity for the treatment of enteritis caused by MRSA.

Research Progress on Small Molecular Inhibitors of the Type 3 Secretion System

The overuse of antibiotics has led to severe bacterial drug resistance. Blocking pathogen virulence devices is a highly effective approach to combating bacterial resistance worldwide. Type three secretion systems (T3SSs) are significant virulence factors in Gram-negative pathogens. Inhibition of these systems can effectively weaken infection whilst having no significant effect on bacterial growth. Therefore, T3SS inhibitors may be a powerful weapon against resistance in Gram-negative bacteria, and there has been increasing interest in the research and development of T3SS inhibitors. This review outlines several reported small-molecule inhibitors of the T3SS, covering those of synthetic and natural origin, including their sources, structures, and mechanisms of action.

Sanhuang Xiexin decoction ameliorates DSS-induced colitis in mice by regulating intestinal inflammation, intestinal barrier, and intestinal flora

ETHNOPHARMACOLOGICAL RELEVANCE

Sanhuang Xiexin decoction (SXD) is a widely applicated traditional Chinese medicine (TCM) with a significant intestinal anti-inflammatory effect.

AIM OF THE STUDY

To evaluate the therapeutic effect and elucidate the possible underlying mechanisms of SXD on dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) in mice.

METHODS

To model UC, 3% DSS was added to the drinking water for 7 days. The UC mice were grouped and treated with three doses of SXD (1.3, 2.6, and 6 g/kg) orally for 7 days. Mice body weight and disease activity index (DAI) scores were recorded daily. After treatment with SXD, the colon was removed, and the colon length and histopathological changes were recorded. Blood cells were counted and colonic inflammatory cytokines and oxidative stress indicators were examined. The key proteins in TLR4-MyD88-NF-κB signaling and the colonic barrier were determined by Western blot analysis. The restorative effect of SXD on intestinal flora was determined.

RESULTS

Treatment with SXD reduced DAI scores, increased body weight, improved colon shortening, and decreased colonic damage. SXD decreased the numbers of white blood cells (WBCs), increased the numbers of red blood cells (RBCs), and inhibited the expression of inflammatory cytokines and oxidative stress indicators. In addition, SXD displayed an effective anti-inflammatory effect by inhibiting the expression levels of p-IκBα, TLR4, MyD88, and p65. Furthermore, SXD significantly restored the integrity of the colonic barrier and the abundance of beneficial flora.

CONCLUSIONS

SXD significantly reduced DSS-induced colon damage when the dose was higher than 1.3 g/kg, and the middle dose group (2.6 g/kg) indicated the best effect. SXD effectively ameliorated DSS-induced UC in mice, possibly by inhibiting oxidative stress, protecting the mucosal barrier, inhibiting the TLR4-MyD88-NF-κB signaling pathway, and regulating the intestinal flora.

Bioactive components of Banxia Xiexin Decoction for the treatment of gastrointestinal diseases based on flavor-oriented analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Banxia Xiexin Decoction (BXD) was first recorded in a Chinese medical classic, Treatise on Febrile Diseases and Miscellaneous Diseases, which was written in the Eastern Han dynasty of China. This ancient prescription consists of seven kinds of Chinese herbal medicine, namely, Pinellia ternata, Rhizoma Coptidis, Radix scutellariae, Rhizoma Zingiberis, Ginseng, Jujube, and Radix Glycyrrhizaepreparata. In clinic practice, its original application in China mainly has focused on the treatment of chronic gastritis for several hundred years. BXD is also effective in treating other gastrointestinal diseases (GIDs) in modern medical application. Despite available literature support and clinical experience, the treatment mechanisms or their relationships with the bioactive compounds in BXD responsible for its pharmacological actions, still need further explorations in more diversified channels. According to the analysis based on the five-flavor theory of TCM, BXD is traditionally viewed as the most representative prescription for pungent-dispersion, bitter-purgation and sweet-tonification. Consequently, based on the flavor-oriented analysis, the compositive herbs in BXD can be divided into three flavor groups, namely, the pungent, bitter, and sweet groups, each of which has specific active ingredients that are possibly relevant to GID treatment.

AIM OF THE REVIEW

This paper summarized recent literatures on BXD and its bioactive components used in GID treatment, and provided the pharmacological or chemical basis for the further exploration of the ancient prescription and the relative components.

METHOD

ology: Relevant literature was collected from various electronic databases such as Pubmed, Web of Science, and China National Knowledge Infrastructure (CNKI). Citations were based on peer-reviewed articles published in English or Chinese during the last decade.

RESULTS

Multiple components were found in the pungent, bitter, and sweet groups in BXD. The corresponding bioactive components include gingerol, shogaol, stigmasterol, and β-sitosterol in the pungent group; berberine, palmatine, coptisine, baicalein, and baicalin in the bitter group; and ginsenosides, polysaccharides, liquiritin, and glycyrrhetinic acid in the sweet group. These components have been found directly or indirectly responsible for the remarkable effects of BXD on GID.

CONCLUSION

This review provided some valuable reference to further clarify BXD treatment for GID and their possible material basis, based on the perspective of the flavor-oriented analysis.

Natural Antibacterial and Antivirulence Alkaloids From Macleaya cordata Against Methicillin-Resistant Staphylococcus aureus

The emergence and spread of antibiotic-resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), underly the urgent need to develop novel antibacterial drugs. Macleaya cordata, a traditional medicinal plant, has been widely used in livestock animals, plants, and humans. Alkaloids are the primary bioactive compounds of Macleaya cordata and exhibit antibacterial, antiinflammatory, and antioxidant activities. Nevertheless, the antibacterial compounds and mode of action of Macleaya cordata remain unclear. In the present study, we investigated the antibacterial activity and mode of action of alkaloids from Macleaya cordata. Sanguinarine, 6-ethoxysanguinarine (6-ES), 6-methoxydihydrosanguinarine (6-MS), chelerythrine (CH), and dihydrochelerythrine (DICH) exhibited good antibacterial activity against Gram-positive bacteria, including MRSA. 6-ES rapidly killed MRSA, possibly by interfering with membrane and metabolic functions including ROS production by targeting the membrane and FtsZ in S. aureus. Additionally, 6-ES directly suppressed the hemolytic activity of α-hemolysin, alleviated inflammatory responses, and eliminated intracellular MRSA, as well as displayed low development of drug resistance, in vitro. Finally, a 6-ES-loaded thermosensitive hydrogel promoted wound healing in mice infected with MRSA. These results supported 6-ES as a novel potential candidate or leading compound with antibacterial, antivirulence, and host immunomodulatory activities in fighting against bacterial infections.

Evaluation of Toxicity, Bacteriostatic, Analgesic, Anti-Inflammatory, and Antipyretic Activities of Huangqin-Honghua-Pugongying-Jinyinhua Extract

The extensive use of antibiotics has caused the global spread of multidrug-resistant bacteria and genes, seriously reducing antibiotic efficacy and threatening animal and human health. As an alternative, traditional Chinese veterinary medicine (TCVM) was used in this study for its lack of drug resistance and low toxicity. Huangqin-honghua-pugongying-jinyinhua extract (HHPJE), a novel TCVM, consists of the extracts of Huangqin (Scutellaria baicalensis), Honghua (Carthami Flos), Pugongying (Taraxacum) and Jinyinhua (Lonicerae Japonicae Flos), and was developed to treat bovine mastitis. In this study, we evaluated the toxicity, bacteriostatic, analgesic, anti-inflammatory, and antipyretic activities of HHPJE. Our results show that HHPJE did not show any acute oral toxicity and can be considered safe for oral administration. Additionally, HHPJE possessed a dose-dependent antibacterial effect on Staphylococcus aureus, Escherichia coli, Streptococcus agalactiae and Streptococcus dysgalactiae. HHPJE (60, 30 and 15 g/kg) can reduce the abdominal pain by 44.83 ± 7.69%, 43.15 ± 9.50% and 26.14 ± 4.17%, respectively. The percentages of anti-inflammation inhibition (60, 30 and 15 g/kg) were 35.34 ± 2.17%, 22.29 ± 2.74% and 12.06 ± 3.61%, respectively. The inhibition rates (60, 30 and 15 g/kg) of antipyretic activity were 82.05%, 65.71% and 52.80%, respectively. The evaluation of pharmacodynamics and toxicity indicate that HHPJE possesses significant bacteriostatic, analgesic, anti-inflammatory and antipyretic potential, and also that it is safe for acute oral toxicity, which means it has potential value for treating bovine mastitis in future and alleviating clinical symptoms with no drug resistance or side effects.

Lactobacillus plantarum FNCC 0137 fermented red Moringa oleifera exhibits protective effects in mice challenged with Salmonella typhi via TLR3/TLR4 inhibition and down-regulation of proinflammatory cytokines

Background

Salmonella typhi is a foodborne pathogenic bacterium that threatens health. S. typhi infection exacerbated the antibiotic resistance problem that needs alternative strategies. Moringa oleifera possesses anti-inflammatory and antimicrobial effects. However, there is a lack of information about the pharmacological value of red M. oleifera. The fermentation of red M. oleifera leaves extract (RMOL) is expected to add to its nutritional value.

Objective

The present study aimed to evaluate non-fermented RMOL (NRMOL) and fermented RMOL (FRMOL) effects on S. typhi infection in mice.

Materials and methods

Female Balb/C mice were randomly divided into eight groups. The treatment groups were orally administered with NRMOL or FRMOL at doses 14, 42, and 84 mg/kg BW during the 28 days experimental period. Then S. typhi was introduced to mice through intraperitoneal injection except in the healthy groups. The NRMOL or FRMOL administration was continued for the next seven days. Cells that expressed CD11b⁺ TLR3⁺, CD11b⁺TLR4⁺, CD11b⁺IL-6⁺, CD11b⁺IL-17⁺, CD11b⁺TNF-a⁺, and CD4⁺CD25⁺CD62L⁺ were assessed by flow cytometry.

Results

Our result suggested that NRMOL and FRMOL extracts significantly reduced (p < 0.05) the expression of CD11b⁺TLR3⁺, CD11b⁺TLR4⁺, CD11b⁺IL-6⁺, CD11b⁺IL-17⁺, and CD11b⁺TNF-α⁺ subsets. In contrast, NRMOL and FRMOL extracts significantly increased (p < 0.05) the expression of CD4⁺CD25⁺CD62L⁺ subsets. NRMOL at dose 14 and 42 mg/kg BW was more effective compared to FRMOL in reducing the expression of CD11b⁺TLR3⁺, CD11b⁺TLR4⁺, and CD11b⁺TNF-α⁺ subsets.

Conclusion

Our findings demonstrated that NRMOL and FRMOL extracts could be promising agents for protection against S. typhi infection via modulation of TLR3/TLR4, regulatory T cells, and proinflammatory cytokines.

A review: antimicrobial properties of several medicinal plants widely used in Traditional Chinese Medicine

Due to the dramatic increase in the use of antibiotics and growing health threat of bacterial resistance to many commonly used antibiotics, many studies have been directed at developing new and effective antibacterial compounds, among which many new, natural, and effective antibacterial compounds discovered from medicinal plants have drawn great interest and raised new hope for treating the challenges of antibiotic resistance. This review aimed to summarize the most important and widely used medicinal plants that were reported to have antibacterial activities. A general literature search from 2010 to 2020 was conducted using different databases, including Science Direct, Web of Science, and PubMed. According to the literature, three medicinal plants with outstanding antibacterial activities, Taraxacum officinale, Coptis Rhizome, and Scutellaria baicalensis, were screened and reviewed by prioritization. The extraction methods, antibacterial activities of different parts of plants or the plant-derived compounds, spectra of antibacterial activities, and toxicity were described, respectively. However, the antibacterial activities of the extracts or pure compounds as reported in the reviewed literature were mostly based on in vitro assays, and moreover, the deeper antibacterial mechanisms have not been elucidated clearly. Therefore, further studies are required in the fields of purification and identification of the antibacterial compounds, its mechanisms of action, and synergistic effects in combination with other antibacterial drugs, which may be helpful in the development of new antibacterial drugs.

Phytochemicals: A Promising Weapon in the Arsenal against Antibiotic-Resistant Bacteria

The extensive usage of antibiotics and the rapid emergence of antimicrobial-resistant microbes (AMR) are becoming important global public health issues. Many solutions to these problems have been proposed, including developing alternative compounds with antimicrobial activities, managing existing antimicrobials, and rapidly detecting AMR pathogens. Among all of them, employing alternative compounds such as phytochemicals alone or in combination with other antibacterial agents appears to be both an effective and safe strategy for battling against these pathogens. The present review summarizes the scientific evidence on the biochemical, pharmacological, and clinical aspects of phytochemicals used to treat microbial pathogenesis. A wide range of commercial products are currently available on the market. Their well-documented clinical efficacy suggests that phytomedicines are valuable sources of new types of antimicrobial agents for future use. Innovative approaches and methodologies for identifying plant-derived products effective against AMR are also proposed in this review.

Baicalin decreases somatic cell count in mastitis of dairy cows

Baicalin is a flavonoid that has an influence on molecular processes. It possesses anticancer, anti-inflammatory, antiviral, antioxidative, and antithrombotic properties. It was found that baicalein treatment attenuated the damage of the mammary gland induced by LPS, suppressed the activity of myeloperoxidase, TNFα, and IL-1β in mice with mastitis. The aim of the study was a pilot analysis of baicalin tolerability after intramammary (IMM) administration and its impact on somatic cell count (SCC) after multiple IMM treatment on dairy cows with clinical mastitis. Moreover, the determination of baicalin in milk was performed by the sensitive ultra-high performance liquid chromatography with tandem mass spectrometry. The pharmacokinetic analyses were performed using Phoenix® WinNonlin® 6.4 and ThothPro v 4.1 software. Twelve dairy cows with clinical mastitis were selected for this study. The pharmacodynamic endpoint was SCC level and the clinical investigation was also carried out. Baseline SCC analysis was performed every 24 h among all cows three days before the first dose (B1–B3). After the baseline monitoring, 8 days of treatment (T1–T8) was performed and 8 days within recovery period SCC level was observed (R1–R8). Starting from T1 to T8, a decrease of SCC in relation to baseline was characterized by a declining trend. The presented results confirm the effect of baicalin on the reduction of SCC in mastitis in dairy cows after this therapy. The current study has shown that baicalin accumulation was not confirmed.

Baicalin and the liver-gut system: Pharmacological bases explaining its therapeutic effects

With the development of high-throughput screening and bioinformatics technology, natural products with a range of pharmacological targets in multiple diseases have become important sources of new drug discovery. These compounds are derived from various plants, including the dried root of Scutellaria baicalensis Georgi, which is often used as a traditional Chinese herb named Huangqin, a popular medication used for thousands of years in China. Many studies have shown that baicalin, an extract from Scutellaria baicalensis Georgi, exerts various protective effects on liver and gut diseases. Baicalin plays a therapeutic role mainly by mediating downstream apoptosis and immune response pathways induced by upstream oxidative stress and inflammation. During oxidative stress regulation, PI3K/Akt/NRF2, Keap-1, NF-κB and HO-1 are key factors associated with the healing effects of baicalin on NAFLD/NASH, ulcerative colitis and cholestasis. In the inflammatory response, IL-6, IL-1β, TNF-α, MIP-2 and MIP-1α are involved in the alleviation of NAFLD/NASH, cholestasis and liver fibrosis by baicalin, as are TGF-β1/Smads, STAT3 and NF-κB. Regarding the apoptosis pathway, Bax, Bcl-2, Caspase-3 and Caspase-9 are key factors related to the suppression of hepatocellular carcinoma and attenuation of liver injury and colorectal cancer. In addition to immune regulation, PD-1/PDL-1 and TLR4-NF-κB are correlated with the alleviation of hepatocellular carcinoma, ulcerative colitis and colorectal cancer by baicalin. Moreover, baicalin regulates intestinal flora by promoting the production of SCFAs. Furthermore, BA is involved in the interactions of the liver-gut axis by regulating TGR5, FXR, bile acids and the microbiota. In general, a comprehensive analysis of this natural compound was conducted to determine the mechanism by which it regulates bile acid metabolism, the intestinal flora and related signaling pathways, providing new insights into the pharmacological effects of baicalin. The mechanism linking the liver and gut systems needs to be elucidated to draw attention to its great clinical importance.

Baicalin ameliorates Mycoplasma gallisepticum-induced lung inflammation in chicken by inhibiting TLR6-mediated NF-κB signalling

1. Mycoplasma gallisepticum (MG) causes severe lung inflammation and cell damage by activating toll-like receptor (TLR) signalling, the nuclear factor-kappaB (NF-κB) pathway and pro-inflammatory cytokine gene expression. Baicalin (BA) is a flavonoid extracted from Scutellaria baicalensis, which possesses anti-inflammatory and anti-bacterial properties. This study investigated the effect of BA in MG-induced lung inflammation and its potential mechanism in MG-infected chicken embryo lungs and DF-1 cells.2. The histopathological examination result showed that BA treatment alleviated MG-induced lung pathological changes. In addition, CCK-8 and cell cycle assays showed that BA treatment inhibited MG-induced cell proliferation and cell cycle progression in DF-1 cells.3. The ELISA and RT-qPCR results demonstrated that BA treatment decreased the expression of interleukin-1beta (IL-1β), IL-6, and tumour necrosis factor-alpha (TNF-α) both in MG-infected chicken embryo lungs and DF-1 cells.4. The results revealed that BA inhibited mRNA expression levels of toll-like receptor-6 (TLR6), myeloid differentiation primary response gene-88 (MyD88) and nuclear factor-κB (NF-κB), and the nuclear translocation of NF-κB-p655. In conclusion, the results showed that BA has a protective effect against MG-induced lung inflammation in chicken by inhibiting the TLR6-mediated NF-κB signalling.

Effect of enzymatic treatment of citrus by-products on bacterial growth, adhesion and cytokine production by Caco-2 cells

Citrus by-products are inexpensive sources of polyphenols, important bioactive compounds with wide pharmaceutical and food applications. This study aimed to investigate the effect of enzymatic treatment of citrus by-products on the polyphenolic profile of extracts and assess the influence of extracts on the growth and adhesion of probiotics and foodborne pathogenic bacteria and on the inflammatory response of epithelial cells. Enzyme-assisted extraction altered the polyphenolic profile (as assessed by HPLC-DAD), increasing the content of aglycone flavanones (naringenin and hesperetin). Enzymatic extracts and aglycone flavanones exhibited higher antibacterial and prebiotic activities than non-enzymatic extracts and glycoside flavanones. However, a higher content of aglycones was not associated with higher anti-adhesion activity. Citrus extracts significantly (P ≤ 0.05) decreased the inflammatory response of Caco-2 cells to Salmonella Typhimurium adhesion. These results support the sustainable reuse of citrus agroindustrial wastes and indicate the potential of citrus extracts in preventing infection by foodborne pathogenic bacteria and inducing proliferation of probiotics in foods and the gut environment.

Baicalin inhibits Salmonella typhimurium-induced inflammation and mediates autophagy through TLR4/MAPK/NF-κB signalling pathway

Baicalin has been reported to protect mice against Salmonella typhimurium (S. typhimurium) infection, while its molecular mechanisms are unclear. In this study, multiplicity of infection (MOI) and observation time were measured. Cell viability and LDH levels were examined in RAW264.7 cells and H9 cells. RAW264.7 cells were stimulated with S typhimurium in the presence or absence of Baicalin, and the levels of pro-inflammatory cytokines were detected by enzyme-linked immunosorbent assay (ELISA). The changes in reactive oxygen species (ROS) production were determined by fluorescence microscopy and ELISA. The autophagy and TLR4/MAPK/NF-κB signalling pathway were examined by immunofluorescence microscopy, quantitative reverse transcription-polymerase chain reaction and Western blotting. The results indicated that MOI of 30 and duration of autophagy evident at 5 h were applicable to this study. Baicalin prevented death of macrophages, promoted bactericidal activity, decreased the levels of pro-inflammatory cytokines and ROS and reduced the changes of key biomarkers in autophagy and TLR4/MAPK/NF-κB signalling pathway infected by S typhimurium. TLR4-overexpressed cells, autophagy and TLR4/MAPK/NF-κB signalling pathway were activated by S typhimurium, which was suppressed by Baicalin. Our findings indicated that Baicalin exerts anti-inflammatory and cell-protective effects, and it mediates autophagy by down-regulating the activity of TLR4 infected by S typhimurium.

Efficacy and mechanism of actions of natural antimicrobial drugs

Microbial infections have significantly increased over the last decades, and the mortality rates remain unacceptably high. The emergence of new resistance patterns and the spread of new viruses challenge the eradication of infectious diseases. The declining efficacy of antimicrobial drugs has become a global public health problem. Natural products derived from natural sources, such as plants, animals, and microorganisms, have significant efficacy for the treatment of infectious diseases accompanied by less adverse effects, synergy, and ability to overcome drug resistance. As the Chinese female scientist Youyou Tu received the Nobel Prize for the antimalarial drug artemisinin, antimicrobial drugs developed from Traditional Chinese Medicine are expected to receive increasing attention again. This review summarizes the antimicrobial agents derived from natural products approved for nearly 20 years and describes their efficacy and mode of action. The aim of this unit is to review the current status of antimicrobial drugs from natural products in order to increase the value of natural products as a source of novel drug candidates for infectious diseases.

High-throughput metabolomic method based on liquid chromatography: high resolution mass spectrometry with chemometrics for metabolic biomarkers and pathway analysis to reveal the protective effects of baicalin on thyroid cancer

Cell metabonomics focuses on discovering metabolic biomarkers and pathway changes in cells from biological systems to obtain the cell properties and functional information under different conditions. Baicalin possesses various pharmacological activities, and plays a vital role in the oncology research field. However, the detailed mechanism of its action is still unclear. In this work, we employed ultra-high performance liquid chromatography-mass spectrometry (UPLC-MS) based non-targeted metabolomics method associated with chemometrics analysis to explore metabolic pathways and biomarkers for investigating the efficacy and pharmacological targets of baicalin against thyroid cancer cells. In addition, morphological observation, parameter calculation of cell proliferation and apoptosis were carried out, which assisted in elucidation of pharmacological activity of baicalin on the human thyroid cancer cells. The results showed that baicalin possesses an intense stimulative apoptosis and inhibits proliferation activity on SW579 human thyroid cancer cells, and partially reversed the cell metabolite abnormalities. A total of nineteen differentiated metabolites in SW579 cells were identified and deemed as potential biomarkers after the baicalin treatment, involving nine metabolic pathways, such as taurine and hypotaurine metabolism, pyrimidine metabolism, fructose and mannose metabolism, steroid hormone biosynthesis and sphingolipid metabolism. High-throughput non-targeted metabolomics provide an insight into specialized mechanism of baicalin against thyroid cancer and contributes to novel drug discovery and thyroid cancer management in clinical practice.

The effects of baicalin on piglets challenged with Glaesserella parasuis

Glaesserella parasuis (G. parasuis) causes porcine vascular inflammation and damage. Baicalin is reported to have antioxidant and anti-inflammatory functions. However, whether baicalin protects piglets against G. parasuis challenge and the potential protective mechanism have not been investigated. Therefore, in this study, we comprehensively examined the protective efficacy of baicalin in piglets challenged with G. parasuis and the possible protective mechanism. Our results show that baicalin attenuated the release of the inflammation-related cytokines interleukin (IL) 1β, IL6, IL8, IL10, and tumour necrosis factor α (TNF-α) and reduced high mobility group box 1 (HMGB1) production and cell apoptosis in piglets infected with G. parasuis. Baicalin also inhibited the activation of the mitogen-activated protein kinase (MAPK) signalling pathway and protected piglets against G. parasuis challenge. Taken together, our data suggest that baicalin could protect piglets from G. parasuis by reducing HMGB1 release, attenuating cell apoptosis, and inhibiting MAPK signalling activation, thereby alleviating the inflammatory response induced by the bacteria. Our results suggest that baicalin has utility as a novel therapeutic drug to control G. parasuis infection.

Gegen Qinlian decoction maintains colonic mucosal homeostasis in acute/chronic ulcerative colitis via bidirectionally modulating dysregulated Notch signaling

BACKGROUND

Gegen Qinlian decoction (GQ) is a well-known traditional Chinese medicine that has been clinically proven to be effective in treating ulcerative colitis (UC). However, its therapeutic mechanism has not been fully elucidated. Notch signaling plays an essential role in the regeneration of the intestinal epithelium.

PURPOSE

This study was designed to ascertain the mechanism by which GQ participates in the recovery of the colonic mucosa by regulating Notch signaling in acute and chronic UC models.

METHODS

Acute and chronic UC mice (C57BL/6) were established with 3 and 2% dextran sulfate sodium (DSS), respectively, and treated with oral administration of GQ. The expression of the Notch target gene Hes1 and the Notch-related proteins RBP-J, MAML and Math1 was analyzed by western blotting. PTEN mRNA levels were detected by qRT-PCR. Mucin production that is characteristic of goblet cells was determined by Alcian blue/periodic acid-Schiff staining and verified by examining MUC2 mRNA levels by qRT-PCR. Cell proliferation was assayed by immunohistochemistry analysis of Ki67. HT-29 and FHC cells and Toll-like receptor 4 knockout (TLR4^-/-) acute UC mice were also used in this study.

RESULTS

GQ restored the injured colonic mucosa in both acute and chronic UC models. We found that Notch signaling was hyperactive in acute UC mice and hypoactive in chronic UC mice. GQ downregulated Hes1, RBP-J and MAML proteins and augmented goblet cells in the acute UC models, whereas GQ upregulated Hes1, RBP-J and MAML proteins in chronic UC mice, reducing goblet cell differentiation and promoting crypt base columnar (CBC) stem cell proliferation. Hes1 mRNA was suppressed in TLR4^-/- UC mice, and GQ treatment reversed this effect. In vitro, GQ reduced Hes1 protein in Notch-activated HT29 and FHC cells but increased Hes1 protein in Notch-inhibited cells.

CONCLUSIONS

GQ restored the colonic epithelium by maintaining mucosal homeostasis via bidirectional regulation of Notch signaling in acute/chronic UC models.

Natural Products That Target Virulence Factors in Antibiotic-Resistant Staphylococcus aureus

The increase in the incidence of antibiotic-resistant Staphylococcus aureus (S. aureus) associated infections necessitates the urgent development of novel therapeutic strategies and antibacterial drugs. Antivirulence strategy is an especially compelling alternative strategy due to its low selective pressure for the development of drug resistance in bacteria. Plants and microorganisms are not only important food and medicinal resources but also serve as sources for the discovery of natural products that target bacterial virulence factors. This review discusses the mechanisms of the major virulence factors of S. aureus, including the accessory gene regulator quorum-sensing system, bacterial biofilm formation, α-hemolysin, sortase A, and staphyloxanthin. We also provide an overview of natural products isolated from plants and microorganisms with activity against the major virulence factors of S. aureus and their adjuvant effects on existing antibiotics to overcome antibiotic-resistant S. aureus. Finally, the limitations and solutions of these antivirulence compounds are discussed, which will help in the development of novel antibacterial drugs against antibiotic-resistant S. aureus.

Saikosaponin A protects chickens against pullorum disease via modulation of cholesterol

The worsening problem of antibiotic resistance prompts the need for alternative strategies that do not directly target bacteria. Virulent Salmonella pullorum strains can invade macrophages and lead to a systemic infection. Saikosaponin A (SSa), a bioactive saponin isolated from Radix bupleuri, has been demonstrated to exhibit anti-inflammatory, hepatoprotective, and cholesterol regulatory activity. The aim of this study was to investigate the effects of SSa on Salmonella-induced pullorum disease in chickens and clarify the possible mechanism. A S. pullorum-induced pullorum disease chicken model was used to confirm the protective effect of SSa in vivo. The model of HD11 cells infected with S. pullorum was used to investigate the molecular mechanism of SSa in vitro. In vivo, SSa prolonged the survival time and decreased the liver bacterial burdens in the pullorum disease model. In vitro, SSa dose-dependently suppressed the invasion of HD11 cells by S. pullorum. SSa depleted cholesterol in the lipid rafts, disrupted the formation of lipid rafts, and promoted the transcription of LXRα, ABCA1, and ABCG1. Moreover, the addition of water-soluble cholesterol and inhibition of LXRα with the LXRα antagonist geranylgeranyl pyrophosphate reversed the inhibitory effects of SSa on the invasion of HD11 cells by S. pullorum. In conclusion, the protective effect of SSa against S. pullorum infection is associated with the upregulation of the LXRα-ABCG1/ABCA1 pathway, which results in a decrease in cholesterol in the lipid rafts of HD11 cells, thereby suppressing the invasion of HD11 cells by S. pullorum. These results validate SSa as a host-target drug for the prevention of bacterial diseases, including those caused by S. pullorum.

Therapeutic effect of n-butanol fraction of Huang-lian-Jie-du Decoction on ulcerative colitis and its regulation on intestinal flora in colitis mice

Huang-lian-Jie-du Decoction (HLJDD) is a classical prescription for clearing away heat and detoxification. In order to screen the effective fraction of HLJDD in the treatment of ulcerative colitis (UC) in mice and explore its effects on intestinal flora in UC mice, we prepared different polar fractions of HLJDD by system solvent extraction method. Subsequently, the contents of 13 active compounds in different polar fractions of HLJDD were determined by HPLC. Further, the UC model induced by dextran sodium sulfate was used to evaluate the therapeutic effects of different polar fractions of HLJDD. Finally, cecal contents were used for sequencing and analysis of bacterial 16S rRNA genes. The results showed that the yield of HLJDD-n-butanol (HLJDD-NBA) fraction was the highest, and the content or proportion of 13 active compounds in HLJDD-NBA fraction were the most similar to HLJDD. In addition, in vivo pharmacodynamic experiments showed that HLJDD-NBA intervention not only significantly alleviated the clinical symptoms of UC mice and ameliorated the pathological damage of colon tissue, but also showed significant anti-inflammatory and antioxidative effects (p < 0.05), which were comparable to HLJDD (p > 0.05). Moreover, both HLDD and HLJDD-NBA treatments can restore the intestinal flora homeostasis of UC mice by inhibiting the growth of intestinal pathogens and preventing the decrease of beneficial bacteria. Meanwhile, they can also significantly correct the dysfunction of intestinal flora in UC mice. In conclusion, we proved that HLJDD-NBA fraction is an effective fraction of HLJDD in treating UC in mice, and it can maintain the intestinal flora homeostasis of UC mice, which increases our understanding of the mechanism of HLJDD in treating UC and lays a foundation for the development of new anti-ulcer drugs.

Antibacterial Effect and Mode of Action of Flavonoids From Licorice Against Methicillin-Resistant Staphylococcus aureus

Staphylococcus aureus is a bacterial pathogen that causes food poisoning, various infections, and sepsis. Effective strategies and new drugs are needed to control S. aureus associated infections due to the emergence and rapid dissemination of antibiotic resistance. In the present study, the antibacterial activity, potential mode of action, and applications of flavonoids from licorice were investigated. Here, we showed that glabrol, licochalcone A, licochalcone C, and licochalcone E displayed high efficiency against methicillin-resistant Staphylococcus aureus (MRSA). Glabrol, licochalcone A, licochalcone C, and licochalcone E exhibited low cytotoxicity without hemolytic activity based on safety evaluation. Glabrol displayed rapid bactericidal activity with low levels of resistance development in vitro. Meanwhile, glabrol rapidly increased bacterial membrane permeability and dissipated the proton move force. Furthermore, we found that peptidoglycan, phosphatidylglycerol, and cardiolipin inhibited the antibacterial activity of glabrol. Molecular docking showed that glabrol binds to phosphatidylglycerol and cardiolipin through the formation of hydrogen bonds. Lastly, glabrol showed antibacterial activity against MRSA in both in vivo and in vitro models. Altogether, these results suggest that glabrol is a promising lead compound for the design of membrane-active antibacterial agents against MRSA and can be used as a disinfectant candidate as well.

Antibiofilm activity of coenzyme Q0 against Salmonella Typhimurium and its effect on adhesion-invasion and survival-replication

Salmonella Typhimurium, a common Gram-negative foodborne pathogen, threatens public health and hinders the development of the food industry. In this study, we evaluated the antibiofilm activity of coenzyme Q0 (CoQ0) against S. Typhimurium. Besides, the inhibition of the S. Typhimurium's adhesion to and invasion of Caco-2 cells and its survival and replication in RAW 264.7 cells by CoQ0 were also explored. The minimum inhibitory concentrations and minimal bactericidal concentrations of CoQ0 against Salmonella were both 100-400 μg/mL. Salmonella Typhimurium biofilm formation was effectively inhibited by subinhibitory concentrations (SICs) of CoQ0. The CoQ0-affected biofilm morphology was observed with light microscopy and field-emission scanning electron microscopy. CoQ0 at SICs reduced the swimming motility and quorum sensing of S. Typhimurium and repressed the transcription of critical virulence-related genes. CoQ0 at SICs also clearly reduced the adhesion of S. Typhimurium to and its invasion of Caco-2 cells and reduced its survival and replication within RAW 264.7 macrophage cells. These findings suggest that CoQ0 has strong antibiofilm activity and can be used as an anti-infectious agent against Salmonella.

Supplemental Plant Extracts From Flos lonicerae in Combination With Baikal skullcap Attenuate Intestinal Disruption and Modulate Gut Microbiota in Laying Hens Challenged by Salmonella pullorum

Dietary inclusions of baicalin and chlorogenic acid were beneficial for intestinal health in pigs. Nevertheless, it is unknown whether these plant-derived products had protection for intestine against bacterial challenge in chickens. This study was aimed at evaluating the potential mitigating effects of plant extracts (PE) from Flos lonicerae combined with Baikal skullcap (the active components are chlorogenic acid and baicalin) on intestinal disruption and dysbacteriosis induced by Salmonella pullorum in laying hens. A total of 216 41-week-old layers were randomly divided into 3 groups (6 replicates per group): negative control (NC), S. pullorum-infected positive control (PC), and the S. pullorum-infected group with supplementation of PE at 1000 mg/kg. All birds except those in NC were challenged with S. pullorum at the end of 4 weeks of the experiment. S. pullorum challenge impaired (P < 0.05) the production performance (egg production, feed intake, and feed efficiency) of laying hens, increased (P < 0.05) serum endotoxin content and frequency of Salmonella-positive organs, as well as up-regulated (P < 0.05) ileal expression of pro-inflammatory cytokines including IFNG, TNFA, IL8, and IL1B, whereas PE addition reversed (P < 0.05) these changes and increased (P < 0.05) ileal IL10 expression. Supplemental PE moderated ileal microbiota dysbiosis in challenged birds, characterized by a reduced abundance of Firmicutes along with increased abundances of Bacteroidetes (Bacteroides), Deferribacteres and several butyrate-producers such as Prevotellaceae, Faecalibacterium, Blautia, Butyricicoccus, Lachnoclostridium, and Olsenella, which may assist with energy harvesting and boost anti-inflammatory capacity of host. The decreased abundance of Firmicutes with the increased abundance of Bacteroidetes caused by PE addition had positive correlations with the decreased expression of ileal pro-inflammatory cytokines. The increased abundances of Bacteroidetes (Bacteroides) and Prevotellaceae following PE addition were also positively correlated with the improvement of performance (egg production and feed intake) of laying hens. Collectively, supplemental PE from Flos lonicerae in combination with Baikal skullcap alleviated S. pullorum-induced intestinal disruption and performance impairment in laying hens, which could be at least partially responsible by the modulation of gut microbial composition.

Effect of Baicalin-Aluminum Complexes on Fecal Microbiome in Piglets

The gut microbiome has important effects on gastrointestinal diseases. Diarrhea attenuation functions of baicalin (BA) is not clear. Baicalin-aluminum complexes (BBA) were synthesized from BA, but the BBA's efficacy on the diarrhea of piglets and the gut microbiomes have not been explored and the mechanism remains unclear. This study has explored whether BBA could modulate the composition of the gut microbiomes of piglets during diarrhea. The results showed that the diarrhea rate reduced significantly after treatment with BBA. BBA altered the overall structure of the gut microbiomes. In addition, the Gene Ontology (GO) enrichment analysis indicated that the functional differentially expressed genes, which were involved in the top 30 GO enrichments, were associated with hydrogenase (acceptor) activity, nicotinamide-nucleotide adenylyltransferase activity, and isocitrate lyase activity, belong to the molecular function. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that flagellar assembly, bacterial chemotaxis, lipopolysaccharide biosynthesis, ATP-binding cassette transporters (ABC) transporters, biosynthesis of amino acids, and phosphotransferase system (PTS) were the most enriched during BBA treatment process. Taken together, our results first demonstrated that BBA treatment could modulate the gut microbiomes composition of piglets with diarrhea, which may provide new potential insights on the mechanisms of gut microbiomes associated underlying the antimicrobial efficacy of BBA.