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The agar overlay TLC–bioautography is one of the crucial methods for simultaneous in situ detection and separation of antimicrobial metabolites of pharmaceutical interest. The main focus of this research relies on the dereplication of an antimicrobial metabolite coriloxin derived from mycoendophytic Xylaria sp. NBRTSB-20 with a validation of agar overlay TLC–bioautography technique. This polyketide metabolite coriloxin was purified by column chromatography, and its purity was assessed by HPLC, UPLC-ESI-QTOF-MS, FT-IR and NMR spectral analysis. The antimicrobial capability of ethyl acetate extract and the purified compound coriloxin was determined by disc diffusion, minimal inhibitory concentration and agar overlay TLC–bioautography assay. The visible LOD of coriloxin antimicrobial activity was found at 10 μg for Escherichia coli and 20 μg for both Staphylococcus aureus and Fusarium oxysporum. Inter- and intra-day precision was determined as the relative standard deviation is less than 6.56%, which proved that this method was precise. The accuracy was expressed as recovery, and the values were found ranging from 91.18 to 108.73% with RSD values 0.94–2.30%, respectively. The overall findings of this investigation suggest that agar overlay TLC–bioautography assay is a suitable and acceptable method for the in situ determination of antimicrobial pharmaceuticals.

The need for a new antibiotic pipeline to confront threat imposed by resistant pathogens has become a major global concern for human health. To confront the challenge there is a need for discovery and development of new class of antibiotics. Nature which is considered treasure trove, there is re-emerged interest in exploring untapped microbial to yield novel molecules, due to their wide array of negative effects associated with synthetic drugs. Natural product researchers have developed many new techniques over the past few years for developing diverse compounds of biopotential. Taking edge in the advancement of genomics, genetic engineering, in silico drug design, surface modification, scaffolds, pharmacophores and target-based approach is necessary. These techniques have been economically sustainable and also proven efficient in natural product discovery. This review will focus on recent advances in diverse discipline approach from integrated Bioinformatics predictions, genetic engineering and medicinal chemistry for the synthesis of natural products vital for the discovery of novel antibiotics having potential application.

Background Endophyte bestows beneficial aspects to its inhabiting host, along with a contribution to diverse structural attributes with biological potential. In this regard, antimicrobial profiling of fungal endophytes from medicinal plant Adiantum philippense revealed bioactive Nigrospora sphaerica from the leaf segment. Chemical and biological profiling through TLC–bioautography and hyphenated spectroscopic techniques confirmed the presence of phomalactone as an antimicrobial metabolite. Results The chemical investigation of the broth extract by bioassay-guided fractionation confirmed phomalactone as a bioactive antimicrobial secondary metabolite. The antimicrobial activity of phomalactone was found to be highest against Escherichia coli by disc diffusion assay. The MIC was found to be significant against both Escherichia coli and Xanthomonas campestris in the case of bacteria and dermatophyte Candida albicans at 150 μg/ml, respectively. Conclusions Overall, the results highlighted the antimicrobial potential of phomalactone from the endophyte Nigrospora sphaerica exhibiting a broad spectrum of antimicrobial activity against human and phytopathogenic bacteria and fungi. This work is the first report regarding the antibacterial activity of phomalactone.

Bionanotechnology has gained wide attention in the research field of modern materials science over the past decade. Biogenic synthesis of zinc oxide nanoparticles (ZnO NP) has been focused by researchers due to their non-toxicity and a broad range of applications. In the present work, spherical shape nanoparticles (average 21 nm size) were obtained using plant extract of Ocimum americanum. The biosynthesized ZnO NPs showed a strong absorption peak at 316 nm which is a characteristic feature of ZnO NPs. Further, biophysical characterization of synthesized ZnO NPs was carried out using Fourier transform infrared spectroscopy in comparison with plant extract to determine the possible functional groups involved in ZnO NPs formation, X-ray diffraction and confirmed the crystalline nature which is in accordance with JCPDS ID for ZnO NPs, scanning electron microscopy and dynamic light scattering for shape and size. Evaluation of antimicrobial efficacy of the biosynthesized ZnO NPs was found to be significant against four Gram-positive, four Gram-negative bacteria and two human pathogenic fungi. These results affirm that plant mediated ZnO NPs are potential for effective antioxidant and antimicrobial therapeutics.

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