Compounds derived from 5-fluoropyridine and benzo[b]thiophene: killing Mycobacterium tuberculosis and reducing its virulence.

The rise of drug-resistant Mycobacterium tuberculosis (Mtb) has extended the duration of tuberculosis (TB) treatment and reduced the likelihood of cure. One strategy to combat this issue is the development of inhibitors targeting the virulence factors of bacterial pathogens. Mtb' catalase (KatG) is crucial for its detoxification mechanisms and also serves as a significant virulence factor for the bacterium. In this study, twelve derivatives synthesized from 5-fluoropyridine and benzo[b]thiophene demonstrated antimycobacterial efficacy with minimum inhibitory concentrations (MICs) varying between 0.5 and 32 µg/mL. Compound 2, 2-(benzo[b]thiophene-2-ylmethylene) hydrazine-1-carbothioamide, emerged as the most potent candidate. It effectively inhibited Mtb KatG. Molecular docking revealed that compound 2 binds  to the active site of Mtb-KatG with  docking score of 114. The rabbit skin tuberculosis model was employed to assess the virulence of Mtb. Animal study results indicated that the granulomas induced by Mtb after treatment with compound 2 were reduced in size, exhibited a lower bacterial load, and the bacteria were no longer aggregated, in contrast to those caused by untreated Mtb. Hence, compound 2 can be regarded as a molecule capable of neutralizing the virulence factors of Mtb. This research offers insights into the design of anti-Mtb molecules with novel mechanisms of action.

Synthesis of narrow-spectrum anti-mycobacterial molecules without effect on the diversity of gut microbiota in mice based on the structure of rifampicin.

Rifampicin (RIF) is a broad-spectrum antimicrobial agent that is also a first-line drug for treating tuberculosis (TB). Based on the naphthyl ring structure of RIF this study synthesized 16 narrow-spectrum antimicrobial molecules that were specifically anti-Mycobacterium tuberculosis (Mtb). The most potent candidate was 2-((6-hydroxynaphthalen-2-yl) methylene) hydrazine-1-carbothioamide (compound 3c) with minimum inhibitory concentration (MIC) of 1 µg/mL against Mtb. Synergistic anti-Mtb test indicated that none of the combinations of 3c with the major anti-TB drugs are antagonistic. Consistent with RIF, compound 3c induced large amounts of reactive oxygen radicals (ROS) in the cells of Mtb. The killing kinetics of compound 3c and RIF are very similar. Furthermore, molecular docking showed that compound 3c was able to access the RIF binding pocket of the ß subunit of Mtb RNA polymerase (RNAP). Experiments in mice showed that compound 3c increased the variety of intestinal flora in mice, while RIF significantly decreased the diversity of intestinal flora in mice. In addition, compound 3c is non-toxic to animal cells with a selection index (SI) much more than 10. The evidence from this study suggests that the further development of 3c could contribute to the development of novel drug for TB treatment.

A systematic review of ginsenoside biosynthesis, spatiotemporal distribution, and response to biotic and abiotic factors in American ginseng.

American ginseng (Panax quinquefolius) has gained recognition as a medicinal and functional food homologous product with several pharmaceutical, nutritional, and industrial applications. However, the key regulators involved in ginsenoside biosynthesis, the spatiotemporal distribution characteristics of ginsenosides, and factors influencing ginsenosides are largely unknown, which make it challenging to enhance the quality and chemical extraction processes of the cultivated American ginseng. This review presents an overview of the pharmacological effects, biosynthesis and spatiotemporal distribution of ginsenosides, with emphasis on the impacts of biotic and abiotic factors on ginsenosides in American ginseng. Modern pharmacological studies have demonstrated that American ginseng has neuroprotective, cardioprotective, antitumor, antidiabetic, and anti-obesity effects. Additionally, most genes involved in the upregulation of ginsenoside biosynthesis have been identified, while downstream regulators (OSCs, CYP450, and UGTs) require further investigation. Futhermore, limited knowledge exists regarding the molecular mechanisms of the impact of biotic and abiotic factors on ginsenosides. Notably, the nonmedicinal parts of American ginseng, particularly its flowers, fibrous roots, and leaves, exhibit higher ginsenoside content than its main roots and account for a considerable amount of weight in the whole plant, representing promising resources for ginsenosides. Herein, the prospects of molecular breeding and metabolic engineering based on multi-omics to improve the unstable quality of cultivated American ginseng and the shortage of ginsenosides are proposed. This review highlights the gaps in the current research on American ginseng and proposes solutions to address these limitations, providing a guide for future investigations into American ginseng ginsenosides.

19 Schiff bases as antimycobacterial agents: synthesis, molecular docking and a plausible mechanism of action.

Aim: To discover novel anti-Mycobacterium tuberculosis (Mtb) drugs, 19 compounds were synthesized; their anti-Mtb effects were evaluated and mechanisms of action were preliminarily explored. Materials & methods: The compounds were synthesized and their anti-Mtb activity was elucidated using resazurin microtiter assays. The plausible target of the potential compound was investigated by microimaging techniques, gas chromatography-mass spectrometry analysis and molecular docking. Results: 19 compounds inhibited Mtb growth with minimum inhibitory concentrations ranging from 1 to 32 µg/ml. Compounds 1-17 showed inhibition of Mtb KatG enzyme. Compound 19, the most potent, might be an inhibitor of Pks13 polyketide synthase. Conclusion: This study suggests that 2-((6-fluoropyridin-3-yl)methylene) hydrazine-1-carbothioamide (19) is a potential anti-Mtb lead compound with a novel mechanism of action.

Globally, more than 1.6 million people die of tuberculosis (TB) and about 11 million new cases occur each year. The emergence of drug-resistant Mycobacterium tuberculosis (Mtb) has made it difficult to effectively treat TB. Therefore, 19 drugs were synthesized and assayed in the laboratory to verify whether they could inhibit the growth of Mtb. All compounds exhibit anti-Mtb effects at relatively low concentrations. Among them, compound 19 had a strong anti-Mtb effect, and its bactericidal effect on Mtb even exceeded that of isoniazid. In addition, it was preliminarily determined that compound 19 is a novel inhibitor of a key enzyme in the biosynthesis of Mtb cell walls. These findings demonstrate a potential new treatment option for TB but more research is needed to confirm the safety of these drugs.

Synthesis, antimycobacterial evaluation, and molecular docking study of 1,2,4-triazole derivatives.

Fifteen 1,2,4-triazole derivatives were synthesised in this study and their MIC values against Mycobacterium tuberculosis (Mtb) ranged from 2 to 32 µg/mL. Furthermore, their antimycobacterial activity was positively correlated with the KatG enzyme docking score. Among the 15 compounds, compound 4 showed the strongest bactericidal activity with an MIC of 2 µg/mL. The selectivity index of compound 4 is more than 10, indicating that the compound has low toxicity to animal cells and has the potential to become a drug. Molecular docking indicates that compound 4 can bind firmly to the Mtb KatG active site. The experimental results showed that compound 4 inhibited Mtb KatG and caused the accumulation of ROS in Mtb cells. We speculate that compound 4 causes the accumulation of ROS by inhibiting KatG, and ROS produces oxidative destruction, leading to the death of Mtb. This study provides a new idea for the development of novel anti-Mtb drugs.

Antimycobacterial Compound of Cynoglossum lanceolatum Forsk.: Bioassay Guided Isolation, Molecular Docking, Synthesis of Analogs, and a Plausible Mechanism of Action.

Tuberculosis (TB) remains a major threat to human health. Due to the prevalence of drug-resistant Mycobacterium tuberculosis (Mtb), it is urgent to discover drugs with new mechanisms of action (MOA) to ensure effectiveness against strains that are resistant to existing TB drugs. Cynoglossum lanceolatum Forsk was used to treat TB in Traditional Chinese Medicine. In this article, shikonin, the anti-Mtb active component, was obtained from the whole herb extract of C. lanceolatum by bioassay-guided isolation. Using the microplate alamar blue assay (MABA), the minimum inhibitory concentration (MIC) of shikonin against Mtb was determined to be 128 µg/mL. In order to obtain a more efficient anti-Mtb molecule, (E)-1-(6-bromo-2,3-dihydrochromen-4-ylidene)thiosemicarbazide was synthesized based on the scaffold of shikonin, which exhibited potent activity against Mtb (MIC=4 µg/mL). These results highlight that both naphthalene-1,4-dione and chroman-4-one are pharmacophores with activities against Mtb. To investigate a plausible mechanism of action, the molecular docking was firstly performed against catalase-peroxidase enzyme (KatG) of Mtb using AutoDock 4 software. The results demonstrated that both shikonin and (E)-1-(6-bromo-2,3-dihydrochromen-4-ylidene)thiosemicarbazide could bind to the active site of Mtb KatG. KatG enzyme activity and intracellular reactive oxygen species (ROS) levels in Mtb cells were then measured by ultraviolet spectrophotometric method and fluorescence microplate reader assay, respectively. The experiments confirmed that above compounds could inhibit the catalytic activity of Mtb KatG, and cause the ROS accumulation in Mtb cells. Therefore, inhibition of KatG may be a novel mechanism of action for these two compounds to fight against Mtb.

Quinoline derivatives as potential anti-tubercular agents: Synthesis, molecular docking and mechanism of action.

Development of new drugs with novel mechanisms of action is required to combat the problem of drug-resistant Mycobacterium tuberculosis. The present investigation is aimed at combining two pharmacophores (quinoline or isoquinolines and thiosemicarbazide) to synthesize a series of compounds. Seven compounds were synthesized based on combination principle in this study. The compound 1-7 showed activities against M. tuberculosis H37Rv strain with MIC values rang from 2 to 8 µg/ml. Compound 5 exhibited remarkable antimycobacterial activity (MIC = 2 µg/ml), and was therefore selected for study of the mechanism of action. Molecular docking suggested initially that compound 5 could occupy the active site of KatG of M. tuberculosis. Furthermore compound 5 exhibited potent inhibitory effect on activity of KatG. RT-PCR finally displayed that compound 5 could up-regulate the transcription of katG of M. tuberculosis. Together, these studies reveal that compound 5 might be the inhibitor of KatG of Mycobacterium tuberculosis. One of the more significant findings to emerge from this study is that KatG of M.tuberculosis can be used as a putative novel target for new anti-tubercular drug design.

Increasing Structural Diversity of Prenylated Chalcones by Two Fungal Prenyltransferases.

Prenylated chalcones are found mainly in plants and exhibit diverse biological and pharmacological activities. Some of these compounds are components of food and dietary supplements with significant health benefits. In plants, they are derived from chalcones by prenylation with membrane-bound prenyltransferases. In this study, we demonstrate prenylations of 10 chalcones by two fungal prenyltransferases (AtaPT/AnaPT) in the presence of dimethylallyl diphosphate. Eleven mono- (1a-10a and 9b) and four diprenylated products (8b, 9c, 10b, and 10c) were obtained. Among them, 12 have new structures (1a, 2a, 4a-6a, 8a, 8b, 9b, 9c, 10a, 10b, and 10c). Most of the obtained prenylated chalcones are products of AnaPT and carry prenyl moieties at ring B. Our study provides an excellent example for increasing structural diversity of plant metabolites with microbial enzymes.

C19-diterpenoid alkaloids from the rhizomes of Aconitum pendulum.

Six new C19-aconitine-type diterpenoid alkaloids, pendulumines A-F (1-6), together with six known ones (7-12), were isolated from the rhizomes of Aconitum pendulum. Their structures were elucidated using extensive spectroscopic data analysis, including 1D and 2D NMR, MS, and single-crystal X-ray diffraction analysis. The isolates were also tested for their analgesic activity based on the thermal avoidance response of the roundworm Pirstionchus pacificus, and 9 showed significant biological activity with an EC50 value of 0.08 ± 0.02 mg.mL-1.

Trends in the Prevalence and Antibiotic Resistance of Non-tuberculous Mycobacteria in Mainland China, 2000-2019: Systematic Review and Meta-Analysis.

Background: China is a high-burden country of tuberculosis. The proportion of diseases caused by non-tuberculous mycobacteria (NTM) has increased, seriously affecting the prevention, control, and management of tuberculosis (TB) and posing a significant threat to human health. However, there is a lack of an organized monitoring system for NTM such as that used for tuberculosis. Comprehensive data on patient susceptibility, dominant species, and drug resistance profiles are needed to improve the treatment protocols and the management of NTM. Methods: Primary research reports of NTM clinical specimens from mainland China published between January 1, 2000 and May 31, 2019 were retrieved from four online resources (BIOSIS, Embase, PubMed, and Web of Science) and three Chinese medical literature databases (CNKI, Wanfang, and Vip) as the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Results: In total, 339 publications were included in the systematic review, 129 were used in the drug susceptibility analysis, and 95 were used in the meta-analysis. Traditional culture using Lowenstein-Jensen slants combined with P-nitrobenzene acid and thiophene-2-carboxylic acid hydrazine differential medium and proportional method was most commonly used for the isolation, identification, and drug susceptibility testing of NTM in China. The crude isolation rate for NTM among TB suspected cases was 4.66-5.78%, while the proportion of NTM among Mycobacterium isolates was 11.57%. Mycobacterium abscessus and Mycobacterium avium complex were the most common clinical NTM species. NTM only showed general sensitivity to ethambutol, linezolid, clofazimine, amikacin, tobramycin, and clarithromycin. Conclusions: The prevalence of NTM in China has shown a decreasing trend. M. abscessus was replaced as the dominant species by Mycobacterium intracellulare over the course of the study. The geographic diversity of different species showed the effects of environmental and economic factors on the distribution of NTM and indicated that there were important factors still not identified. While there were only a limited number of antibiotics to which NTM showed any sensitivity, the drug resistance profiles of the isolates were highly variable and thus more caution should be taken when empirically treating NTM infection.

Bioassay-guided isolation of a Mycobacterium tuberculosis bioflim inhibitor from Arisaema sinii Krause.

Mycobacterium tuberculosis biofilms harbour drug-tolerant bacteria. Identification of drugs that inhibit biofilm formation could enable the dramatic shortening of tuberculosis treatments using standard antibiotics. Arisaema sinii Krause is used to treat pulmonary and lymphatic tuberculosis by Dong People of China. Current study was aimed to purify the active components against M. tuberculosis biofilms from Arisaema sinii extract by using bioassay-guided isolation. (E)-2-(methyl (phenyl) amino) ethyl 2-(2-hydroxyundecanamido)-7, 11-dimethyl-3-oxotetradec-4-enoate, compound 1, was identified as the active component. It could inhibit mycobacterial biofilm formation, disperse the preformed biofilms, and disrupt the mature biofilms at concentration of 4, 8, and 32 µg/ml, respectively. At the dose of 32 µg/ml, it could potentiate the bactericidal activity of isoniazid against M. tuberculosis in mature biofilms. The results of this study indicate that compound 1 might be a novel lead compound against mycobacterial biofilm formation.

[Studies on flavonoids from Derris eriocarpa].

Derris eriocarpa, a traditional Chinese medicine belonging to the family of Leguminosae, is widely distributed mainly over Yunnan, Guangxi and Guizhou of China. Modern pharmacological researches on this herb showed that it had extensive bioactivities, such as promoting urination, removing dampness and cough and reducing inspissated mucus and other biological activities. The extensive studies on the chemical constituents of this plant have resulted in the isolation of triterpenoids, steroids, fatty acid and others, but the flavone compounds haven't reported before. In our further research on the ethyl acetate of this plant, nine flavone compounds were obtained by column chromatography on silica gel, Sephadex LH-20, semi-prep HPLC, polyamide column chromatography and recrystallization for separation and purification. The structures were determined on the basis of extensive spectroscopic analysis, including MS, NMR experiments and comparison with spectroscopic data in the literature, respectively, as diosmetin (1), 3, 3'-di-O-methylquercetin (2), afromosin (3), 6, 3'-dihydroxy-7, 4'-dimethoxyisoflavone (4), odoratin (5), 7, 3'-dihydroxy-8, 4'-dimethoxyisoflavone (6), 6, 4'-dihydroxy-7, 3'-dimethoxyisoflavone (7), 5, 7, 4'-trihydroxy-3, 3', 5'-trimethoxyflavone (8), and alpinumisoflavone (9). All these compounds were isolated from Derris eriocarpa How for the first time. And the in vitro assays showed that compound 2 possessed moderate inhibitory activity against human cancer cells K562 and HEL.

A novel franchetine type norditerpenoid isolated from the roots of Aconitum carmichaeli Debx. with potential analgesic activity and less toxicity.

Further investigation on the phytochemistry of the plant Aconitum carmichaeli Debx. led to isolate a new franchetine type C(19)-diterpenoid alkaloid, guiwuline 1. Its structure was established on the basis of the spectroscopic data (1D and 2D NMR, HRESIMS, UV, IR). In mouse hot-plate test and acute toxicity assay, compound 1 exhibited potential analgesic activity (ED(50), 15 mg/kg) and showed little toxicity to mice (LD(50), 500 mg/kg). The results indicate that compound 1 may be used as a lead molecule to develop novel analgesic agents.

Bioassay-guided isolation of an alkaloid with antiangiogenic and antitumor activities from the extract of Fissistigma cavaleriei root.

Fissistigma cavaleriei (Levl) Rehd (Annonaceae) is used as a folklore medicine for treatment of inflammation, arthritis, and tuberculosis by Miao people in China. In the present study, the antiangiogenic activity of F. cavaleriei was investigated. The chorioallantoic membrane of the fertilized hen's egg (CAM assay) was used to determine antiangiogenic activity of the plant extract. Compound (1), a compound with antiangiogenic activity, was isolated by bioassay-guided fractionation from F. cavaleriei for the first time. The structure of compound (1) was elucidated on the basis of spectroscopic methods. Colorimetric COX (ovine) inhibitor screening assay was used to determine its inhibitory effect on COX-1 and COX-2. MTT and Sulforhodamine B assays were used to investigate its cytotoxic effects on tumor cell lines. As a result, compound (1) showed a selectively inhibiting effect on COX-2 and could inhibit the growth of tumor cells in vitro. The antitumor activity of compound (1) was further confirmed by the observation that compound (1) administration significantly inhibited the growth of S-180 cells in mice. Moreover, compound (1) was able to enhance the antitumor activity of doxorubicin in the mice bearing with S-180 cells while combined with doxorubicin. In conclusion, compound (1) is a multi-target molecule and further experimental investigations are needed to determine whether it can be used as a lead molecule for tumor treatment.

Beta-lactamase inhibitory component from the roots of Fissistigma cavaleriei.

Therapeutic control of beta-lactamase-producing bacteria has been a major clinical problem. Development of drug combinations containing the beta-lactamase inhibitors has given clinicians a novel approach to controlling resistant organisms. In our search for beta-lactamase inhibitors from natural resources, we found that the methanol extract of the roots of Fissistigma cavaleriei showed an inhibitory effect on beta-lactamase. Bioassay-guided isolation of the extract yielded an active compound that was identified as salicylsalicylic acid by physical and spectroscopic methods. The compound showed inhibitory effects on beta-lactamase in a dose-dependent manner with IC(50) values of 71 microM. Salicylsalicylic acid is not as potent as the original inhibitors such as clavulanic acid, but it may be developed to be potent beta-lactamase inhibitor by chemical modification.

[Study on skin toxicology and penetration enhancement of skin absorption of volatile oil extracted from tender branchers of Camellia oleifera].

OBJECTIVE: To study the toxicity on skin and penetration effect of volatile oil from tender branchers of Camellia oleifera on nitrendipine, baicalin, nimesulide for percutaneous obsorption. METHOD: Acute skin toxicity, irritation and allergy on rats were tested, and mouse skin in vitro was applied for studying the effects of different concentrations of volatile oil in nitrendipine, baicalin, nimesulide on drug permeation. RESULT: Different dosage volatile oil had no acute toxicity, irritation or hypersensitive effects. Compared to azone, more powerful enhancement effects of volatile oil at different concentration on nitrendipine, baicalin, nimesulide were very obvious. CONCLUSION: This paper firstly reported the results of experiment about the toxicity to skin and penetr-ation effect of volatile oil from tender branches of C. oleifera.

[Structure-activity relationships of salicylic acid and its analogs in the inhibitory action on beta-lactamase].

AIM: Nineteen compounds related to salicylic acid were evaluated for their in vitro activity of inhibiting beta-lactamase isolated from a resistant strain of Pseudomonas aeruginosa, and their structure-activity relationships were examined. METHODS: Nitrocefin method was used. RESULTS: The 50% inhibitory concentration (IC50) of salicylic acid inhibiting beta-lactamase was 22 mmol x L(-1); four analogs had IC50 lower than that of salicylic acid; fifteen analogs had IC50 higher than that of salicylic acid. CONCLUSION: Examination of the structure-activity relationships of the compounds revealed that carboxyl group and adjoining hydroxyl group were active group, and replacement of adjoining hydroxyl by carboxyl increased activity nearly 4-fold. Moreover, addition of a sulfonic group at C-5 and nitro group at C-3, 5 of benzenoic ring of salicylic acid resulted in a 2-fold to 3-fold increase in activity, addition of a amino group at C-5 of benzenoic ring of salicylic acid decreased activity, add addition of -Cl or -F at C-2,4 position of benzenoic ring of benzoic acid did not show activity.

The synergistic activity of antibiotics combined with eight traditional Chinese medicines against two different strains of Staphylococcus aureus.

The ethanolic extracts of eight traditional Chinese medicines and four antibiotics were investigated for their combined effects on the resistance of Staphylococcus aureus (S. aureus) in vitro. Methicillin resistant S. aureus, which was isolated from patient and a standard strain, were used. Our results showed that there are differences in the effects of many combinations used on the standard strain and resistant strain of S. aureus. The ethanolic extracts of Isatis tinctoria, Scutellaria baicalensis and Rheum palmatum can improve the antimicrobial activity of four antibiotics we used.