Discovery and characterization of amentoflavone as a naturally occurring inhibitor against the bile salt hydrolase produced by Lactobacillus salivarius.

Bile salt hydrolases (BSHs), a group of cysteine-hydrolases produced by gut microbes, play a crucial role in the hydrolysis of glycine- or taurine-conjugated bile acids and have been validated as key targets to modulate bile acid metabolism. This study aims to discover one or more efficacious inhibitors against a BSH produced by Lactobacillus salivarius (lsBSH) from natural products and to characterize the mechanism of the newly identified BSH inhibitor(s). Following screening of the inhibition potentials of more than 100 natural compounds against lsBSH, amentoflavone (AMF), a naturally occurring biflavone isolated from various medicinal plants, was discovered to be an efficacious BSH inhibitor (IC50 = 0.34 µM). Further investigation showed that AMF could strongly inhibit the lsBSH-catalyzed hydrolytic reaction in living gut microbes. Inhibition kinetic analyses demonstrated that AMF reversibly inhibited the lsBSH-catalyzed hydrolytic reaction in a mixed-inhibition manner, with an apparent Ki value of 0.65 µM. Fluorescence quenching assays suggested that AMF could quench the fluorescence of lsBSH via a static quenching procedure. Docking simulations suggested that AMF could be fitted into lsBSH at two distinct ligand-binding sites, mainly via hydrophobic interactions and hydrogen bonding, which explained well the mixed inhibition mode of this agent. Animal tests showed that the hydrolytic activities of BSHs in mice feces could be significantly blocked by AMF. In summary, this study reports that AMF is a strong, naturally occurring inhibitor of lsBSH, which offers a promising lead compound to develop novel agents for modulating bile acid metabolism in the host via targeting BSHs.

[Aflatoxins and fungal community distribution during harvesting and processing of Platycladi Semen].

This study aimed to analyze aflatoxins content and fungal community distribution in the harvesting and processing of Platycladi Semen, and explore the key link that affects aflatoxins contamination. The related Platycladi Semen samples of different maturity periods(cone non-rupture period, early rupture, and complete rupture period) and different processing periods(before drying, during 2-d drying, during 7-d drying, before and after seed scale removal, before and after peeling, 1 d after color sorting, and 7 d after color sorting) were collected for identifying the fungal community composition on sample surface by ITS amplicon sequencing. Then the content of aflatoxins B_1, B_2, G_1 and G_2 was determined by HPLC-MS/MS. The results showed that during the harvesting of Platycladi Semen from cone non-rupture to complete rupture, aflatoxins were only detected in the seed scale and seed coat, with aflatoxin G_2 in the seed scale and aflatoxin B_1 in the seed coat. During the drying, with the prolongation of drying time, aflatoxins B_1 and G_2 were detected simultaneously in the seed scale, aflatoxin B_1 in the seed coat, and low-content aflatoxin B_1 in the seed kernel. During subsequent processing, the aflatoxin content in seed kernel during subsequent processing was slighted increased. As demonstrated by fungal detection, Aspergillus flavus was not present during the harvesting of Platycladi Semen, but present during the drying and processing. Its content in the seed coat during the drying process was relatively higher. In short, Platycladi Semen should be harvested as soon as possible after it becomes fully mature. Drying process is the key link of preventing aflatoxin contamination. It is advised to build a sunlight room or adopt similar settings, standardize the operations in other processes, and keep the surrounding environment clean to minimize aflatoxin contamination.

Human carboxylesterase 1A plays a predominant role in the hydrolytic activation of remdesivir in humans.

Remdesivir, an intravenous nucleotide prodrug, has been approved for treating COVID-19 in hospitalized adults and pediatric patients. Upon administration, remdesivir can be readily hydrolyzed to form its active form GS-441524, while the cleavage of the carboxylic ester into GS-704277 is the first step for remdesivir activation. This study aims to assign the key enzymes responsible for remdesivir hydrolysis in humans, as well as to investigate the kinetics of remdesivir hydrolysis in various enzyme sources. The results showed that remdesivir could be hydrolyzed to form GS-704277 in human plasma and the microsomes from human liver (HLMs), lung (HLuMs) and kidney (HKMs), while the hydrolytic rate of remdesivir in HLMs was the fastest. Chemical inhibition and reaction phenotyping assays suggested that human carboxylesterase 1 (hCES1A) played a predominant role in remdesivir hydrolysis, while cathepsin A (CTSA), acetylcholinesterase (AchE) and butyrylcholinesterase (BchE) contributed to a lesser extent. Enzymatic kinetic analyses demonstrated that remdesivir hydrolysis in hCES1A (SHUTCM) and HLMs showed similar kinetic plots and much closed Km values to each other. Meanwhile, GS-704277 formation rates were strongly correlated with the CES1A activities in HLM samples from different individual donors. Further investigation revealed that simvastatin (a therapeutic agent for adjuvant treating COVID-19) strongly inhibited remdesivir hydrolysis in both recombinant hCES1A and HLMs. Collectively, our findings reveal that hCES1A plays a predominant role in remdesivir hydrolysis in humans, which are very helpful for predicting inter-individual variability in response to remdesivir and for guiding the rational use of this anti-COVID-19 agent in clinical settings.

Flavonoids in Ampelopsis grossedentata as covalent inhibitors of SARS-CoV-2 3CLpro: Inhibition potentials, covalent binding sites and inhibitory mechanisms.

Coronavirus 3C-like protease (3CLpro) is a crucial target for treating coronavirus diseases including COVID-19. Our preliminary screening showed that Ampelopsis grossedentata extract (AGE) displayed potent SARS-CoV-2-3CLpro inhibitory activity, but the key constituents with SARS-CoV-2-3CLpro inhibitory effect and their mechanisms were unrevealed. Herein, a practical strategy via integrating bioactivity-guided fractionation and purification, mass spectrometry-based peptide profiling and time-dependent biochemical assay, was applied to identify the crucial constituents in AGE and to uncover their inhibitory mechanisms. The results demonstrated that the flavonoid-rich fractions (10-17.5 min) displayed strong SARS-CoV-2-3CLpro inhibitory activities, while the constituents in these fractions were isolated and their SARS-CoV-2-3CLpro inhibitory activities were investigated. Among all isolated flavonoids, dihydromyricetin, isodihydromyricetin and myricetin strongly inhibited SARS-CoV-2 3CLpro in a time-dependent manner. Further investigations demonstrated that myricetin could covalently bind on SARS-CoV-2 3CLpro at Cys300 and Cys44, while dihydromyricetin and isodihydromyricetin covalently bound at Cys300. Covalent docking coupling with molecular dynamics simulations showed the detailed interactions between the orthoquinone form of myricetin and two covalent binding sites (surrounding Cys300 and Cys44) of SARS-CoV-2 3CLpro. Collectively, the flavonoids in AGE strongly and time-dependently inhibit SARS-CoV-2 3CLpro, while the newly identified SARS-CoV-2 3CLpro inhibitors in AGE offer promising lead compounds for developing novel antiviral agents.

Discovery of naturally occurring inhibitors against SARS-CoV-2 3CLpro from Ginkgo biloba leaves via large-scale screening.

3-Chymotrypsin-like protease (3CLpro) is a virally encoded main proteinase that is pivotal for the viral replication across a broad spectrum of coronaviruses. This study aims to discover the naturally occurring SARS-CoV-2 3CLpro inhibitors from herbal constituents, as well as to investigate the inhibitory mechanism of the newly identified efficacious SARS-CoV-2 3CLpro inhibitors. Following screening of the inhibitory potentials of eighty herbal products against SARS-CoV-2 3CLpro, Ginkgo biloba leaves extract (GBLE) was found with the most potent SARS-CoV-2 3CLpro inhibition activity (IC50 = 6.68 µg/mL). Inhibition assays demonstrated that the ginkgolic acids (GAs) and the bioflavones isolated from GBLE displayed relatively strong SARS-CoV-2 3CLpro inhibition activities (IC50 < 10 µM). Among all tested constituents, GA C15:0, GA C17:1 and sciadopitysin displayed potent 3CLpro inhibition activities, with IC50 values of less than 2 µM. Further inhibition kinetic studies and docking simulations clearly demonstrated that two GAs and sciadopitysin strongly inhibit SARS-CoV-2 3CLprovia a reversible and mixed inhibition manner. Collectively, this study found that both GBLE and the major constituents in this herbal product exhibit strong SARS-CoV-2 3CLpro inhibition activities, which offer several promising leading compounds for developing novel anti-COVID-19 medications via targeting on 3CLpro.

[Systematic review and Meta-analysis of efficacy and safety of Compound Glycyrrhizin Injection in improving chronic hepatitis B liver damage].

To evaluate the efficacy and safety of Compound Glycyrrhizin Injection(CGI) in improving liver damage in chronic hepatitis B(CHB). PubMed, Web of Science, SinoMed, CNKI, Wanfang and VIP databases were retrieved from their inception to February 10, 2020. The randomized controlled trial(RCT) of CGI in the treatment of CHB was included. Data were independently extracted by two authors, and the methodological quality was evaluated using the Cochrane bias risk assessment tool by other two authors. Statistical analysis was performed using RevMan 5.3 software. A total of 18 two-armed RCTs were included, involving 1 915 participants. The methodological quality of all studies included was generally low. In the comparison between CGI and diammonium glycyrrhizinate, the results showed that CGI was superior to the control group in improving the overall clinical effectiveness, but there was no statistical difference between the two groups in increasing ALT normalization rate, reducing ALT and AST level. In the comparison between CGI and diammonium glycyrrhizinate+other general hepatoprotective drugs, the results showed that CGI was superior to the control group in reducing AST level, while there was no statistical difference between the two groups in reducing ALT level and increasing overall clinical effectiveness. In the comparison between CGI+other commonly used drugs(including energy mixture, glutathione, vitamins, potassium magnesium aspartate) and diammonium glycyrrhizinate+other commonly used drugs, the results showed that CGI combined with other commonly used drugs was better than the control group in reducing ALT and AST level and improving the clinical total effective rate, and there was no statistical difference between the two groups in increasing the rate of ALT normalization. In the comparison between CGI+other commonly used drugs and other commonly used drugs, the results showed that CGI combined with other commonly used drugs was superior to the control group in reducing ALT and AST level and improving the overall clinical effectiveness. In the comparison between CGI+vitamins and diammonium glycyrrhizinate+potassium magnesium aspartate+vitamins, the results showed no statistical difference between the two groups in reducing AST level. A small number of studies included reported that CGI caused mild adverse reactions when used alone or in combination with other drugs. Based on the results, CGI has a certain effect in improving CHB liver damage, but the evidence is not enough to prove that CGI would cause serious adverse events. In the future, more well-designed and strictly-enforced RCT with an adequate sample size are needed to further evaluate the effect CGI in alleviating CHB liver damage.

Isochlorogenic acid (ICGA): natural medicine with potentials in pharmaceutical developments.

Natural products have attracted a great deal of attention as significant resources in traditional Chinese medicine (TCM) and in chemical medicine, as well as in cosmetic ingredients, nutraceuticals and food products. Isochlorogenic acid (ICGA), which has medicinal value, has been discovered in various plants. As a widespread natural medicine, ICGA should be the subject of further research and development. However, there have been no systematic analyses of ICGA. According to our investigation, ICGA was initially isolated from green coffee extracts by Barnes et al. in 1950. To date, it has been discovered in a variety of tea, vegetables, medicinal diet and TCM materials. ICGA is used as a chemical marker for the quality control of these TCM materials. The metabolic process of ICGA has been studied in detail, conforming to be linear dynamics. Thus, the clear pharmacokinetics of ICGA offers a solid foundation for its research and development. ICGA has multiple biological and pharmacological effects, and studies have mainly focused on its antioxidant, anti-inflammatory, antimicrobial, hypoglycemic, neuroprotective, and cardiovascular protective effects, and hepatoprotective properties. The mechanisms underlying these effects are summarized in this review to provide scientific support and inspiration for the future research and development of ICGA and ICGA-rich natural products.

Supplementation of the maternal diet during pregnancy with chocolate and fructose interacts with the high-fat diet of the young to facilitate the onset of metabolic disorders in rat offspring.

Obesity and non-alcoholic fatty liver disease are the most common metabolic disorders in society today. Previously, we found that supplementing the maternal diet during pregnancy with chocolate and fructose has negative effects on the well-being of the offspring that were ameliorated if the offspring were fed a normal diet during postnatal life. In the present study, we investigated whether feeding offspring a high-fat diet would augment the maternal programming effects and whether extra protein supply can correct the low birth weight resulting from the chocolate-supplemented maternal diet. Pregnant Sprague-Dawley rats were divided into three groups and fed either standard chow (normal nutrition; NN), chocolate- and fructose-supplemented standard chow with casein sodium (overnutrition; ON) or the supplemented standard chow without casein sodium (malnutrition; MN) throughout pregnancy. Male offspring were weaned on either standard or high-fat chow. Dams in the MN group exhibited moderate weight gain, consumed 50% less protein (P < 0.001) but more carbohydrates during gestation and delivered pups with a 12% lower birth weight (P < 0.05) than pups in the NN group, results that are consistent with previous findings. When fed on a high-fat diet after birth, pups from dams in the MN group (MNHD) had 30% more body fat (P = 0.023) and liver triglyceride (TG) levels that were double (P < 0.01) those in offspring in the other groups, leading to fatty livers in these offspring at 14 weeks of age. Hepatic expression of the PPARα, ApoB100, MTTP, CPT1 and SREBP1c genes was significantly downregulated in the MNHD group (P < 0.05 for all), indicating changes in lipid metabolism. Although dams in the ON group exhibited marked gestational weight gain (P < 0.01), they gave birth to normal weight pups that only manifested mild increases in body fat and liver TG content (P < 0.05), without significant changes in the expression of most genes when fed with the high-fat diet. The results suggest that the extra protein supply in the form of casein sodium was able to correct some negative programming effects of the chocolate and fructose supplementation of the maternal diet, which, in conjunction with a high-fat diet in the offspring, may facilitate the onset of metabolic disorders, with impaired liver gene expression possibly a key contributor.