Repurposing of Mycobacterium indicus pranii for the severe form of COVID-19 patients in India: A cohort study.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) induces the production of proinflammatory cytokines, which results in a cytokine storm, and immune-modulators like Mycobacterium indicus pranii (MIP) might ameliorate coronavirus disease of 2019 (COVID-19) related cytokine storm. Therefore, the present study evaluates whether MIP offers an advantage in the treatment of severe COVID-19 patients infected with SARS-CoV-2. A prospective MIP cohort study was conducted in chest disease hospitals in Srinagar, Jammu and Kashmir, India. In the present prospective, randomized clinical study, critically severe COVID-19 patients were divided into two groups, the MIP group (n = 105) and the best standard treatment (BST) group (n = 210). Procalcitonin, ferritin, high-sensitive C-reactive protein, D-dimer levels, and interleukin levels on 5th-day posttreatment were significantly reduced in the MIP group compared to the BST group. Compared to the BST group, 105 consecutive patients with severe COVID-19 in the MIP group reported early weaning off ventilation, resolution of chest architecture (computed tomography [CT] scan), a significant increase in SpO2 levels, and decreased mortality with a hazard ratio: 0.234 (95% confidence interval: 0.264-2.31) (p = 0.001). MIP restored SpO2 , immune/inflammatory response, normalized lung abnormalities (chest CT scan), and reduced mortality without any serious complications. However, there is a need for placebo-controlled double-blind and controlled clinical trials to confirm the efficacy.

Organoids: A new approach in toxicity testing of nanotherapeutics.

Nanotechnology has revolutionized diverse fields, which include agriculture, the consumer market, medicine, and other fields. Widespread use of nanotechnology-based products has led to increased prevalence of these novel formulations in the environment, which has raised concerns regarding their deleterious effects. The application of nanotechnology-based formulations into clinical use is hampered by the lack of the availability of effective in vitro systems, which could accurately assess their in vivo toxic effects. A plethora of studies has shown the hazardous effects of nanoparticle-based formulations in two-dimensional in vitro cell cultures and animal models. These have some associated disadvantages when used for the evaluation of nano-toxicity. Organoid technology fills the space between existing two-dimensional cell line culture and in vivo models. The uniqueness of organoids over other systems for evaluating toxicity caused by nano-drug formulation includes them being a co-culture of diverse cell types, dynamic flow within them that simulates the actual flow of nanoparticles within biological systems, extensive cell-cell, cell-matrix interactions, and a tissue-like morphology. Thus, it mimics the actual tissue microenvironment and, subsequently, provides an opportunity to study drug metabolism and toxico-dynamics of nanotechnology-based novel formulations. The use of organoids in the evaluation of nano-drug toxicity is in its infancy. A limited number of studies conducted so far have shown good predictive value and efficiently significant data correlation with the clinical trials. In this review, we attempt to introduce organoids of the liver, lungs, brain, kidney intestine, and potential applications to evaluate toxicity caused by nanoparticles.

Medicinal plants: Treasure for antiviral drug discovery.

The pandemic of viral diseases like novel coronavirus (2019-nCoV) prompted the scientific world to examine antiviral bioactive compounds rather than nucleic acid analogous, protease inhibitors, or other toxic synthetic molecules. The emerging viral infections significantly associated with 2019-nCoV have challenged humanity's survival. Further, there is a constant emergence of new resistant viral strains that demand novel antiviral agents with fewer side effects and cell toxicity. Despite significant progress made in immunization and regenerative medicine, numerous viruses still lack prophylactic vaccines and specific antiviral treatments that are so often influenced by the generation of viral escape mutants. Of importance, medicinal herbs offer a wide variety of therapeutic antiviral chemotypes that can inhibit viral replication by preventing viral adsorption, adhering to cell receptors, inhibiting virus penetration in the host cell, and competing for pathways of activation of intracellular signals. The present review will comprehensively summarize the promising antiviral activities of medicinal plants and their bioactive molecules. Furthermore, it will elucidate their mechanism of action and possible implications in the treatment/prevention of viral diseases even when their mechanism of action is not fully understood, which could serve as the base for the future development of novel or complementary antiviral treatments.

Synthesis and in vitro evaluation of 2-(((2-ether)amino)methylene)-dimedone derivatives as potential antimicrobial agents.

The study was designed with an aim to synthesize a series of 2-(((2-ether)amino)methylene)-dimedone derivatives and evaluate the synthesized compounds for antimicrobial activity. Compound library was synthesized by reaction with alkyl, alkenyl, alkynyl and alicyclic bromo-compounds. Characterization of the synthesized compounds was performed by 1H NMR, 13C NMR and mass spectral techniques. The compounds were evaluated for their antibacterial activity against Gram-positive (Staphylococcus aureus, Bacillus subtilis, Clostridium sporogenes) and Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli). The activity of these compounds was also evaluated against fungi (Aspergillus fumigatus, Penicillium chrysogenum, Fusarium oxysporum, Candida albicans) and molds (A. niger and A. oryzae). Broth microdilution method and CLSI guidelines with minor modification were used for the determination of anti-bacterial and antifungal activity, respectively. Although four compounds (4i, 4j, 4k and 4l) showed good antibacterial activity but compound 4k was found to be most active chemotype in the series. Compound 4k was found to be active against S. aureus, B. cereus and B. subtilis bacterial strains at one dilution lower compared to the control ciprofloxacin. Antibacterial activity of compound 4k was comparable to ciprofloxacin against S. pyogenes and M. luteus. The compound 4d, 4e and 4s showed good antifungal and antimold activity compared to other chemotypes. However, in comparison to fluconazole both the compounds showed lower activity. The results merit the antimicrobial promise of the 2-(((2-ether)amino)methylene)-dimedone analogs.

Antimicrobial investigation of selected soil actinomycetes isolated from unexplored regions of Kashmir Himalayas, India.

The aim of the present study was to isolate and evaluate the antimicrobial potential of soil actinomycetes of Kashmir Himalayas. The secondary metabolites of actinomycetes are the prominent source of antibiotics. A total of 121 morphologically different actinomycete strains were isolated and screened for antimicrobial activity against various human pathogens. The ethyl acetate extract of fermented broth an actinomycete strain, identified as Streptomyces pratensis exhibited significant antimicrobial activity against Staphylococcus aureus ATCC 29213 with MIC 0.25 µg/ml and Mycobacterium tuberculosis Strain H37Rv with MIC 0.062 µg/ml. The strain S. pratensis IIIM06 was grown on large scale and their broth was extracted with ethyl acetate. The extract was subjected to various chromatography techniques which led to the isolation of four compounds whose structures were established as actinomycin C1, actinomycin C2, actinomycin C3 and actiphenol on the basis of spectral data analysis. Actinomycin C1, C2 and C3 exhibited potent antimicrobial activity against S. aureus as well as M. tuberculosis. The isolated indigenous actinomycetes exhibited good antibacterial activity and the study reveals that IIIM06 is a promising strain and could be of great potential for industrial applications.

Design and synthesis of indolopyridone hybrids as new antituberculosis agents.

Tuberculosis continues to be the most dangerous infectious disease globally and need for development of new therapies is of utmost importance. In this study we describe the rationale design for synthesis using molecular hybridization and subsequent in-vitro antimycobacterial activity of various indolo-pyridone hybrid molecules against Mycobacterium tuberculosis H37Rv. A total of 16 indolo-pyridone hybrid molecules were synthesized with 85-90% yields and characterized by various spectroscopic techniques. Four compounds were ineffective with MIC >256 µg/ml (highest concentration tested), six exhibited poor activity with MIC > 100 µg/ml, four showed moderate activity with MIC > 50 µg/ml and two had notable anti-TB activity with MIC values 32 µg/ml. Interestingly the last two compounds were observed equally effective against drug susceptible and various drug resistant strains including multidrug-resistant (MDR) strains, thereby clearly demonstrating their potential against MDR-TB. Our results showed that un-substituted aryl rings posses better antituberculosis activity than those having any kind of substitution and derivatives with small sized electron withdrawing groups in aryl ring exhibited activity while bigger groups lead to considerable loss in activity. The results of this study open up a new door for further SAR guided synthesis on one hand and on the other hand provide a promising opportunity that may lead to the discovery of a new class of antituberculosis agents.

Molecular docking analysis and evaluation of the antimicrobial properties of the constituents of Geranium wallichianum D. Don ex Sweet from Kashmir Himalaya.

Geranium wallichianum D. Don ex Sweet is a well-known medicinal plant in Kashmir Himalya. The evidence for its modern medicinal applications remains majorly unexplored. The present study was undertaken to elucidate the detailed antimicrobial promises of different crude extracts (methanolic, ethanolic, petroleum ether, and ethyl acetate) of G. wallichainum against common human bacterial and fungal pathogens in order to scientifically validate its traditional use. The LC-MS analysis of G. wallichainum yielded 141 bioactive compounds with the vast majority of them having therapeutic applications. Determination of minimum inhibitory concentrations (MICs) by broth microdilution method of G. wallichainum was tested against bacterial and fungal pathogens with MICs ranging from 0.39 to 400 µg/mL. Furthermore, virtual ligands screening yielded elatine, kaempferol, and germacrene-A as medicinally most active constituents and the potential inhibitors of penicillin-binding protein (PBP), dihydropteroate synthase (DHPS), elongation factor-Tu (Eu-Tu), ABC transporter, 1,3 beta glycan, and beta-tubulin. The root mean square deviation (RMSD) graphs obtained through the molecular dynamic simulations (MDS) indicated the true bonding interactions which were further validated using root mean square fluctuation (RMSF) graphs which provided a better understanding of the amino acids present in the proteins responsible for the molecular motions and fluctuations. The effective binding of elatine, kaempferol, and germacrene-A with these proteins provides ground for further research to understand the underlying mechanism that ceases the growth of these microbes.

In vitro and in silico evaluation of antimicrobial properties of Delphinium cashmerianum L., a medicinal herb growing in Kashmir, India.

ETHNOPHARMACOLOGICAL RELEVANCE: Microorganisms are developing resistance to synthetic drugs. As a result, the search for novel antimicrobial compounds has become an urgent need. Medicinal plants are commonly used as traditional medicine and Delphinium is one of the prominent genus used in the treatment of several diseases. AIM OF THE STUDY: The present study aimed to determine the in vitro and in silico antimicrobial activities of petroleum ether, ethyl acetate and methanol extracts from the leaf samples of plant (Delphinium cashmerianum L.) against various bacterial and fungal strains. MATERIAL AND METHODS: Three extracts of Delphinium cashmerianum prepared and 88 bioactive compounds were analyzed through LC-MS data with the vast majority of them having therapeutic applications. These extracts have been screened for the antimicrobial activity against various bacterial (Escherichia coli, Micrococcus luteus, Klebsiella pneumoniae, Streptococcus pneumonia, Haemophilus influenzae, Neisseria mucosa) and fungal (Candida albicans, Candida glabrata, Candida paropsilosis) species through in silico molecular docking approach using autodock vina software, molecular dynamic simulation (MDS), in vitro disc diffusion and broth microdilution method for minimum inhibitory concentration (MIC) evaluation. RESULTS: Our results demonstrated that all three extracts were active against the whole set of microorganisms. The ethyl acetate extract was the most active against S.pneumonia, K. pneumoniae and C. albicans with a minimum inhibitory concentration (MIC) value of 6.25, 25 and 50 µg/ml, respectively. The petroleum ether and methanol extracts were active against S.pneumonia and N.mucosa with MIC values of 25 and 50 µg/ml. Furthermore, we also performed the in silico virtual screening of all these compounds obtained from LC-MS data analysis against various known drug targets of bacterium and fungi. Upon analysis, we obtained 5 compounds that were efficiently binding to the drug targets. However, after performing exhaustive molecular docking and molecular dynamic simulation (MDS) analysis, it was observed that Daidzein compound is bound to drug targets more efficiently. CONCLUSION: The results showed that these plant extracts exhibit antimicrobial activity and ethyl acetate extract proved to exhibit the most effective antibacterial and antifungal properties.

Nanoceria laden decellularized extracellular matrix-based curcumin releasing nanoemulgel system for full-thickness wound healing.

Decellularized extracellular matrix (ECM) has been widely used for wound healing. But, ECM failed to integrate tissue and restore the tissue function properly, when elevated levels of free radicals and biofilm formation occur at the wound site. Here, nanoemulgel systems were fabricated, considering the combinatorial approach of nanotechnology (nanoceria and curcumin nanoemulsion) and ECM gel of goat small intestine submucosa. The curcumin was encapsulated in the nanoemulgel system to enhance bioavailability in terms of antibacterial, antioxidant, sustained release and permeation at the wound site. Nanoceria was also incorporated to enhance the antibacterial, antioxidant and wound healing properties of the fabricated nanoemulgel formulation. All the formulations were porous, hydrophilic, biodegradable, antioxidant, antibacterial, hemocompatible, biocompatible, and showed enhanced wound healing rate. The formulation (DG-SIS/Ce/NC) showed the highest free radicals scavenging capacity and antibacterial property with prolonged curcumin release (62.9% in 96 h), skin permeability (79.7% in 96 h); showed better cell growth under normal and oxidative-stressed conditions: it also showed full-thickness wound contraction (97.33% in 14 days) with highest collagen synthesis at the wound site (1.61 µg/mg in 14 days). The outcomes of this study suggested that the formulation (DG-SIS/Ce/NC) can be a potential nanoemulgel system for full-thickness wound healing application.

In vitro potency of 2-(((2-hydroxyphenyl)amino)methylene)-5,5-dimethylcyclohexane-1,3-dione against drug-resistant and non-replicating persisters of Mycobacterium tuberculosis.

OBJECTIVES: New antituberculosis agents active against drug-resistant and non-replicating tubercle bacilli are required. We evaluated a previously identified hit, 2-(((2-hydroxyphenyl)amino)methylene)-5,5-dimethylcyclohexane-1,3-dione (PAMCHD), against several clinical Mycobacterium tuberculosis isolates, including multidrug-resistant (MDR) strains and non-replicating drug-tolerant persisters of M. tuberculosis H37Rv. METHODS: PAMCHD's potential against drug-resistant M. tuberculosis was investigated by broth microdilution. CFU enumeration was performed to determine PAMCHD's activity against five types of dormant bacilli. RESULTS: No significant differences in MICs of PAMCHD were observed against M. tuberculosis H37Rv (2.5-5 µg/mL) and eight drug-susceptible strains (1.25-5 µg/mL) as well as drug-resistant strains including six isoniazid (INH)-resistant (2.5-10 µg/mL), one INH + ethambutol (EMB)-resistant (5 µg/mL), one rifampicin (RIF) + EMB-resistant (5 µg/mL) and three MDR (2.5-10 µg/mL) strains. Thus, PAMCHD maintains activity against all kinds of clinical strains, especially MDR. Regarding drug-tolerant persisters, INH and RIF killed, respectively, 0.5 and 5.0 log10 CFU of non-replicating persisters developed by hypoxia and 1.5 and 2.5 log10 CFU developed by nutrient starvation at 64 × of their respective MIC against actively dividing cultures. In contrast, PAMCHD sterilised persister cultures developed by hypoxia (killed 6.5 log10 CFU) or starvation (killed 7.5 log10 CFU). PAMCHD sterilised RIF-tolerant (tolerance level up to 100 µg/mL of RIF) 100-day-old static persisters at 64 × MIC, while moxifloxacin killed only 1.0 log10 CFU of these persisters at 64 × MIC. CONCLUSION: PAMCHD offers significant potential against MDR-TB and exhibits notable potency against non-replicating drug-tolerant M. tuberculosis persisters. These findings warrant further studies of PAMCHD for further anti-TB drug development.

An update on emerging therapeutics to combat COVID-19.

BACKGROUND: The COVID-19 pandemic has demanded effective therapeutic protocol from researchers and clinicians across the world. Currently, a large amount of primary data have been generated from several preclinical studies. At least 300 clinical trials are underway for drug repurposing against COVID-19; the clinician needs objective evidence-based medication to treat COVID-19. OBSERVATIONS: Single-stranded RNA viral genome of SARS-CoV-2 encodes structural proteins (spike protein), non-structural enzymatic proteins (RNA-dependent RNA polymerase, helicase, papain-like protease, 3-chymotrypsin-like protease) and other accessory proteins. These four enzymatic proteins on spike protein are rate-limiting steps in viral replications and, therefore, an attractive target for drug development against SARS-CoV-2. In silico and in vitro studies have identified various potential epitomes as candidate sequences for vaccine development. These studies have also revealed potential targets for drug development and drug repurposing against COVID-19. Clinical trials utilizing antiviral drugs and other drugs have given inconclusive results regarding their clinical efficacy and side effects. The need for angiotensin-converting enzyme (ACE-2) inhibitors/angiotensin receptor blockers and corticosteroids has been recommended. Western countries have adopted telemedicine as an alternative to prevent transmission of infection in the population. Currently, no proven, evidence-based therapeutic regimen exists for COVID-19. CONCLUSION: The COVID-19 pandemic has put tremendous pressure on researchers to evaluate and approve drugs effective against the disease. Well-controlled randomized trials should assess medicines that are not marketed with substantial evidence of safety and efficacy and more emphasis on time tested approaches for drug evaluation.

Ameliorative effects of Cuscuta reflexa and Peucedanum grande on letrozole induced polycystic ovary syndrome in Wistar rats.

OBJECTIVES: The current study was designed to examine the therapeutic role of hydroalcoholic extract of Cuscuta reflexa Roxb (CRE) and Peucedanum grande C.B. Clarke (PGE) on letrozole (1 mg/kg) induced polycystic ovary syndrome (PCOS) in female Wistar albino rats. METHODS: PCOS rats were treated with CRE (280 mg/kg), PGE (140 mg/kg) or CRE + PGE p.o. for 3 weeks. Vaginal smears for phase of estrous cycle determination, serum levels of sex androgens, lipid profile, oxidative stress parameters and histopathology of ovarian tissues were investigated. RESULTS: Diestrous cycle days treated with CRE (group III) or PGE (group IV) decreased significantly (p < 0.05) compared to PCOS control animals (group II). Moreover, weight of uteri in PCOS animals treated with the plant extracts also increased significantly (p < 0.05) compared to that of group II animals. Histopathological examination showed the protective effect of the CRE and PGE indicated by the disappearance of ovarian cyst. CONCLUSION: The study demonstrated that the CRE and PGE either alone or in combination hold a significant effect in letrozole induced PCOS rat models and could be useful in the management of reproductive and metabolic disorders related to PCOS.

In vitro bactericidal activity of 3-cinnamoyl-4-hydroxy-6-methyl-2-pyrone (CHP) against drug-susceptible, drug-resistant and drug-tolerant isolates of Mycobacterium tuberculosis.

OBJECTIVES: Tuberculosis (TB) poses a serious global threat to humans. New bactericidal agents that can shorten treatment duration and target drug resistance still remain a top priority in the discovery of anti-TB drugs. The objective of this study was to investigate the bactericidal potential of 3-cinnamoyl-4-hydroxy-6-methyl-2-pyrone (CHP) against drug-susceptible, drug-resistant clinical isolates and drug-tolerant Mycobacterium tuberculosis. METHODS: The minimum bactericidal concentration (MBC) was determined by colony-forming unit (CFU) enumeration. The kill curve analysis was done at different concentrations spanning over 16 days. Drug combination studies with antituberculosis drugs were done to investigate possible synergy. The potential against drug- resistant isolates of M. tuberculosis was done by broth dilution assay. CFU enumeration was done to determine its activity against nutrient-starved drug tolerants, and its feasibility for oral administration was tested by serum inhibitory titre. RESULTS: CHP displayed bactericidal activity with an MBC of 4 µg/mL against M. tuberculosis H37Rv. The kill curve analysis exhibited a biphasic pattern of killing. CHP showed synergy with rifampicin, isoniazid and amikacin but was indifferent towards ethambutol and levofloxacin. CHP retained its full activity against drug-susceptible, monoresistant and multidrug-resistant (MDR) clinical isolates. CHP showed very strong bactericidal activity against nondividing, drug-tolerant M. tuberculosis that on comparison was highly superior to rifampicin. Furthermore, CHP significantly improved the bactericidal activity of rifampicin and isoniazid in a combination study. The serum inhibitory titre in mice indicated its high oral bioavailability. CONCLUSION: Our results show strong bactericidal potential of CHP against M. tuberculosis that warrant its immediate mechanistic, pharmacokinetic and pharmacodynamic studies.

In vitro evaluation of dinactin, a potent microbial metabolite against Mycobacterium tuberculosis.

Current long duration treatment options and the emergence of drug resistance in tuberculosis (TB) have led to renewed interest in discovery of novel anti-tubercular agents or the scaffolds exhibiting enhanced efficacy with current anti-TB drugs. Herein, dinactin, a potent bioactive macrotetrolide isolated from Streptomyces puniceus AS13, was evaluated against Mycobacterium tuberculosis H37Rv and other susceptible and drug-resistant clinical isolates of M. tuberculosis. In vitro pharmacological assays showed that dinactin is bactericidal against laboratory standard strain M. tuberculosis H37Rv (minimum inhibitory concentration [MIC] 1 µg/mL and minimum bactericidal concentration [MBC] 4 µg/mL). Dinactin also retained its activity against various clinical isolates, including multidrug-resistant strains of M. tuberculosis. Whole cell interaction assays with standard first- and second-line anti-TB drugs showed the synergistic interaction of dinactin with rifampicin or amikacin, reflecting its suitability for use in combination regimens. The killing kinetics studies of dinactin against M. tuberculosis H37Rv revealed that it has strong concentration-dependent anti-TB activity that is also dependent on time. The kill curve also showed dynamic killing capacity of dinactin as it exhibited bactericidal potential at all concentrations tested. Kill curve data demonstrated that dinactin, like isoniazid, exerts its strong tuberculocidal activity within the first two days of exposure. This evidence strongly supports further evaluation of dinactin as a new option in the treatment of TB.

Drug targets exploited in Mycobacterium tuberculosis: Pitfalls and promises on the horizon.

Tuberculosis is an ever evolving infectious disease that still claims about 1.8 million human lives each year around the globe. Although modern chemotherapy has played a pivotal role in combating TB, the increasing emergence of drug-resistant TB aligned with HIV pandemic threaten its control. This highlights both the need to understand how our current drugs work and the need to develop new and more effective drugs. TB drug discovery is revisiting the clinically validated drug targets in Mycobacterium tuberculosis using whole-cell phenotypic assays in search of better therapeutic scaffolds. Herein, we review the promises of current TB drug regimens, major pitfalls faced, key drug targets exploited so far in M. tuberculosis along with the status of newly discovered drugs against drug resistant forms of TB. New antituberculosis regimens that use lesser number of drugs, require shorter duration of treatment, are equally effective against susceptible and resistant forms of disease, have acceptable toxicity profiles and behave friendly with anti-HIV regimens remains top most priority in TB drug discovery.

In vitro antimycobacterial activity of 2-(((2-hydroxyphenyl)amino)methylene)-5,5-dimethylcyclohexane-1,3-dione: a new chemical entity against Mycobacterium tuberculosis.

This study reports on the in vitro antituberculosis potential of 2-(((2-hydroxyphenyl) amino)methylene)-5,5-dimethylcyclohexane-1,3-dione (PAMCHD) against Mycobacterium tuberculosis H37Rv. PAMCHD has been proven to be a tuberculostatic as well as a tuberculocidal agent by agar and broth dilution methods with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values equivalent to some standard antituberculosis drugs (ATDs). The dynamics of M. tuberculosis killing revealed the time- as well as concentration-dependent antituberculosis activity of PAMCHD and it sterilized M. tuberculosis culture at or above 10.0 µg/mL. PAMCHD acts either synergistically or additively with ATDs. Isoniazid (INH) and PAMCHD post-antibiotic effects increased with concentration from 16.18 ± 13.30 and 31.64 ± 13.30 to 127.9 ± 27.60 and 138.71 ± 16.42 h, respectively, from 1 × MIC to 8 × MIC; no significant difference was observed between INH and PAMCHD post-antibiotic effects. M. tuberculosis mutation frequency against PAMCHD is lower than that of INH. Mutant prevention concentration (MPC) of INH, rifampin (RIF) and PAMCHD were observed to be 40, 160 and 160 µg/mL, respectively, and their MPC/MIC values were 128, 2051 and 64, respectively; this lowest MPC/MIC highlights the advantage of PAMCHD over RIF and INH.

Synthesis and in vitro evaluation of substituted 3-cinnamoyl-4-hydroxy-pyran-2-one (CHP) in pursuit of new potential antituberculosis agents.

Tuberculosis is an ever-evolving infectious disease that urgently needs new drugs. In the search for new antituberculosis agents, a library of 3-cinnamoyl-4-hydroxy-6-methyl-2H-pyran-2-ones (CHPs) (2a-2y) was synthesized and evaluated against a standard virulent laboratory strain of Mycobacterium tuberculosis H37Rv. Out of 25 compounds, 11, 5, 7 and 2 (2a and 2u) showed least, moderate, good and appreciable activities, respectively, based on minimum inhibitory concentrations (MICs). Both 2a and 2u exhibited an MIC value of 4 µg ml-1, which was close to those of standard antituberculosis drugs ethambutol, streptomycin and levofloxacin. Neither 2a nor 2u showed any activity against Gram-positive or Gram-negative bacteria and even against non-tuberculous mycobacterium, i.e. Mycobacterium smegmatis. Thus, like the antituberculosis drugs rifampicin, isoniazid and pretomanid, they are highly TB specific. All the pyrone-based chalcones showed no recognizable level of cytotoxicity against normal human kidney cell line (HEK-293) up to 80 µM concentration and 11 exhibited an IC50 ≤ 100 µM (highest tested concentration). On further investigation, both 2a and 2u proved to be nontoxic against four human cell lines but 2a proved to be a better choice as it did not reach IC50 even at 100 µM (highest tested concentration) while the IC50 of 2u was around 80 µM. In conclusion, our results demonstrate that 2a is specific against M. tuberculosis with no appreciable toxicity; its activity matches that of some clinically approved antituberculosis drugs and it therefore merits further evaluation.

Streptomyces puniceus strain AS13., Production, characterization and evaluation of bioactive metabolites: A new face of dinactin as an antitumor antibiotic.

A highly active actinobacterial strain isolated from untapped areas of Northwestern Himalayas and characterised as Streptomyces puniceus strain AS13 by 16S rRNA gene sequencing was selected for production of bioactive metabolites. The bioassay-guided fractionation of microbial cultured ethyl acetate extract of the strain, led to isolation of macrotetrolide compound 1 (Dinactin) and compound 2 (1-(2,4-dihydroxy-6-methylphenyl)-ethanone). Structures of the isolated compounds were elucidated by [corrected] interpretation of NMR and other spectroscopic data including HR-ESI-MS, FT-IR. These compounds are reported for first time from Streptomyces Puniceus. Compound 1 exhibited strong anti-microbial activity against all tested bacterial pathogens including Mycobacterium tuberculosis. The MIC values of compound 1 against Gram negative and Gram positive bacterial pathogens ranged between 0.019 - 0.156µgml-1 and 1µgml-1 against Mycobacterium tuberculosis H37Rv. Dinactin exhibited marked anti-tumor potential with IC50 of 1.1- 9.7µM in various human cancerous cell lines and showed least cytotoxicity (IC50∼80µM) in normal cells (HEK-293). Dinactin inhabited cellular proliferation in cancer cells, reduced their clonogenic survival as validated by clonogenic assay and also inhabited cell migration and invasion characteristics in colon cancer (HCT-116) cells. Our results expressed the antimicrobial potential of dinactin and also spotted its prospective as an antitumor antibiotic.

α-pyrones and their hydroxylated analogs as promising scaffolds against Mycobacterium tuberculosis.

Tuberculosis ranks as the leading cause of global human mortality from a single infectious agent. To address the uprising issues of drug resistance, intense research efforts have been directed towards drug discovery. However, it is a long and economically challenging process that is often associated with high failure rates. Therefore, it seems prudent to take forward the core scaffolds that have already acclaimed clinical relevance. In this direction, hydroxylated α-pyrone scaffold has received US FDA approval for human use against HIV. Interestingly, literature review reveals the potential applicability of α-pyrones in TB drug discovery. On one hand, α-pyrones play a vital role in the cell wall of Mycobacterium tuberculosis and on the other hand natural α-pyrones display appreciable anti-TB activity. This review aims to rekindle the interest of researchers toward α-pyrone as a new anti-TB drug that may possibly tackle drug resistance and open a dual frontier in TB and HIV drug discovery.

α-pyrones: Small molecules with versatile structural diversity reflected in multiple pharmacological activities-an update.

The investigations in the chemistry and biology of α-pyrone (2-pyrone) are of vital importance as they constitute an essential pharmacophore in many naturally occurring and biologically active synthetic agents. They are a promising class of biorenewable platform chemicals that provide access to an array of chemical products and intermediates. Literature survey reveals that a simple change in the substitution pattern on the 2-pyrone ring system often leads to diverse biological activities. In this review, we present a brief overview of 2-pyrone pharmacophore followed by highlighting their pharmacological properties and potential applicability till date. Particular attention is focused on the distinctive chemotherapeutic activities of 2-pyrones as anti-HIV, anti-TB and anti-cancer agents followed by their potential role against neurodegeneration, hypercholesterolemia, microbial infections, chronic obstructive lung disease, inflammation, antinociception and immunomodulation. Since 2005, when 2-pyrones came in limelight, their detailed pharmacological activities have been well documented. This review has mainly been prepared on the basis of original reports published in recent two decades with an aim to attract the attention of researchers towards this versatile scaffold for future endeavors that may lead to the development of potential drug candidates against above diseases.