Characterization of anthranilic acid produced by Virgibacillus salarius MML1918 and its bio-imaging application.

Anthranilic acid (AA) holds significant importance in the chemical industry. It serves as a crucial building block for the amino acid tryptophan by manipulating the tryptophan biosynthesis pathway, it is possible to increase the production of anthranilic acid. In this study, we utilized metabolic engineering approaches to produce anthranilic acid from the halophilic bacterium Virgibacillus salarius MML1918. The halophilic bacteria were grown in an optimized production medium, and mass production of secondary metabolites was made in ATCC medium 1097 Proteose peptone-for halophilic bacteria and subjected to column chromatography followed by sub-column chromatography the single band for the purified compound was confirmed. Further, various spectral analyses were made for the partially purified compounds, and fluorescence microscopy for fungal cell observation was performed. The purified compound was confirmed by single crystal X-ray diffraction (XRD) analysis, and it was identified as 2-amino benzoic acid. The Fourier transform infrared Spectroscopy (FT-IR) spectrum and nuclear magnetic resonance (NMR) spectrum also confirm the structural characteristic of 2-amino benzoic acid. The UV-Vis absorption spectrum of AA shows the maximum absorption at 337.86 nm. The emission spectrum of 2-amino benzoic acid showed the maximum emission at 453 nm. The bio-imaging application of 2-amino benzoic acid was examined with fungal mycelium of Rhizoctonia solani. It was effectively bound and emitted the blue color at the concentration of 200 and 300 µg/mL. The halophilic bacterium (V. salarius), may have unique metabolic pathways and requirements compared to non-halophilic organisms, to produce AA effectively. This could have implications for industrial biotechnology, particularly in manufacturing environments where high salt concentrations are present and also it can be used as bio-imaging agent.

Anti-fungal effects of novel N-(tert-butyl)-2-(pyridin-2-yl)imidazo[1,2-a]pyridin-3-amine derivative and it's in-vitro, in-silico, and mode of action against Candida spp.

Imidazoles are a category of azole antifungals that encompass compounds such as ketoconazole, miconazole, esomeprazole, and clotrimazole. In contrast, the triazoles group, which includes fluconazole, voriconazole, and itraconazole, also plays a significant role. The rise of antibiotic resistance in fungal pathogens has evolved into a substantial global public health concern. In this study, two newly synthesized imidazo[1,2-a]pyridine derivative (Probe I and Probe II) molecules were investigated for its antimicrobial potency against of a panel of bacterial (Gram-positive and Gram-negative bacteria) and fungal pathogens. Among the different types of pathogens, we found that Probe II showed excellent antifungal activity against fungal pathogens, based on the preliminary screening the potent molecule further investigated against multidrug-resistance Candida sp. (n = 10) and compared with commercial molecules. In addition, in-silico molecular docking, its dynamics, absorption, distribution, metabolism, excretion and toxicity (ADMET) were analyzed. In this study, the small molecule (Probe II) displayed potent activity only against the Candida spp. including several multidrug-resistant Candida spp. Probe II exhibited minimum inhibitory concentration ranges from 4 to 16 µg/mL and minimum fungicidal concentration in the range 4‒32 µg/mL as the lowest concentration enough to eliminate the Candida spp. The selected molecules inhibit the formation of yeast to mold as well as ergosterol formation by the computational simulation against Sterol 14-alpha demethylase (CYP51) and inhibition of ergosterol biosynthesis by in-vitro model show that the Probe II completely inhibits the formation of ergosterol in yeast cells at 2× MIC. The ADMET analysis Probe II could be moderately toxic to the human being, though the in-vitro toxicity studies will help to understand the real-time toxic level. The novel compound Probe II, which was synthesized during the study, shows promise for development into a new generation of drug treatments aimed at addressing the emerging drug resistance in Candida sp.

Antimicrobial potential of secondary metabolites and DNA gyrase B blocking molecules produced by a halophilic bacterium Virgibacillus salarius (MML1918).

AIM: The present study aims to determine the antimicrobial potential of Virgibacillus salairus (MML1918) against human pathogens and its in-vitro and in-silico properties. METHODS AND RESULTS: In this present study, totally 63 halophilic bacterial cultures were obtained and cultivated in nutrient broth medium containing 8% NaCl and the metabolites, were extracted using ethyl acetate and screened for their antimicrobial property by cell viability assay against 12 pathogenic bacteria and fungi, among 63 halophilic bacteria the Vir. salaries (MML1918) found to be the best producer for secondary metabolites production against clinical pathogens. The optimization of growth for important physiochemical parameters was characterized and applied for different production media and based on its highest activity as 17.5 ± .07 mm zone of inhibition (ZOI) for Bacillus cereus followed by 17.5 ± 00 mm ZOI for Staphylococcus aureus, the production medium ATCC1097 was chosen for mass production. The mass production of secondary metabolites from Vir. salaries MML1918 was carried out in a fermenter under controlled conditions and crude metabolites was extracted and condensed. The antimicrobial activity of crude metabolites showed B. cereus (19.3 ± 0.5 mm ZOI), Staph. aureus, and Candida albicans (18.3 ± 0.5 mm ZOI) as the highest ZOI in production media for halophilic bacteria ATCC1097. Further, the gas chromatography-mass spectrometry analysis showed 24 compounds present in crude metabolites. Among the 24 compounds, four molecules were found to be important based on molecule percentage in crude and structural similarity. The molecular docking studies show that the selected four molecules effectively bind with the active region DNA gyrase B. CONCLUSION: Virgibacillus salarius (MML1918) effectively showed antimicrobial activity against several pathogenic organisms and can be employed as a suitable candidate for producing novel antimicrobial agents.

Coordination of Distal Carboxylate Anion Alters Metal Ion Specific Binding in Imidazo[1,2-a]pyridine Congeners.

Imidazo[1,2-a]pyridine derivatives have excellent potential for chelation with transition metal ions. Two new imidazo[1,2-a]pyridine-8-carboxylates were synthesized and characterized by 1H NMR, 13C NMR, HRMS, and single crystal-XRD techniques. Methyl carboxylate (probe 1) turns on fluorescence upon coordination with Zn2+, while sodium carboxylate (probe 2) turns off its fluorescence upon coordination with Co2+ or Cu2+ ions present in aqueous acetonitrile medium. 13C NMR study revealed that the change in metal ion specific binding was due to the involvement of carboxylate anion in complex formation with Co2+ or Cu2+ ions. The carboxylate anion at 8-position also enhanced the sensitivity of detection of probe 2 by an order of magnitude (detection limits: 3.804 × 10-7 M, probe 1/Zn2+; 0.420 × 10-7 M, probe 2/Co2+ and 0.304 × 10-7 M, probe 2/Cu2+). The detection limits of probes 1 and 2 comply well with the World Health Organization (WHO) and US Environmental Protection Agency (US-EPA) guidelines for detection of heavy metal ions present in drinking water and ground water. Both the probes form a 1:1 complex with Zn2+, Co2+ or Cu2+, and the stoichiometry was verified by Job plot and ESI-mass analysis. The sensing mechanism is explained using 13C NMR experiments, ESI-mass analytical data and theoretical DFT calculations. The suitability of probes 1 and 2 for on-site detection and quantitative determination of Zn2+, Co2+ and Cu2+ ions present in biological, environmental and industrial samples is demonstrated. In addition, both 1 and 2 are used for detection of intracellular contamination of Zn2+, Co2+ or Cu2+ ions in onion epidermal cells.

Chelation of specific metal ions imparts coplanarity and fluorescence in two imidazo[1,2-a]pyridine derivatives: Potential chemosensors for detection of metal ions in aqueous and biosamples.

Synthesis and chelation induced fluorescence emission from two imidazo[1,2-a]pyridine derivatives are described. The nonfluorescent molecule 1 containing N and O donor atoms, achieves coplanarity upon interactions with trivalent cations Al3+, Fe3+ and Cr3+, that favors fluorescence emission. Molecule 2 containing two N donor atoms attains coplanarity upon interaction with the only Zn2+ and becomes fluorescent. Both molecules 1 and 2 form a 1:1 complex with interacting metal ions. Other trivalent metal ions (including Bi3+ and In3+) and common divalent metal ions (including Hg2+ and Cd2+) fail to form any complex with 1 or 2, and they do not interfere in the detection of Zn2+, Al3+, Fe3+ or Cr3+ ions. Noninterference of other metal ions renders 1 and 2 suitable for the detection of fungal cells contaminated with Zn2+, Al3+, Fe3+ or Cr3+ ions.

Plant-derived antimicrobials to fight against multi-drug-resistant human pathogens.

Antibiotic resistance is becoming a pivotal concern for public health that has accelerated the search for new antimicrobial molecules from nature. Numbers of human pathogens have inevitably evolved to become resistant to various currently available drugs causing considerable mortality and morbidity worldwide. It is apparent that novel antibiotics are urgently warranted to combat these life-threatening pathogens. In recent years, there have been an increasing number of studies to discover new bioactive compounds from plant origin with the hope to control antibiotic-resistant bacteria. This review attempts to focus and record the plant-derived compounds and plant extracts against multi-drug-resistant (MDR) pathogens including methicillin-resistant Staphylococcus aureus (MRSA), MDR-Mycobacterium tuberculosis and malarial parasites Plasmodium spp. reported between 2005 and 2015. During this period, a total of 110 purified compounds and 60 plant extracts were obtained from 112 different plants. The plants reviewed in this study belong to 70 different families reported from 36 countries around the world. The present review also discusses the drug resistance in bacteria and emphasizes the urge for new drugs.