Synthesis of ß-Glucan Nanoparticles from Red Algae-Derived ß-Glucan for Potential Biomedical Applications.

The present study highlights/demonstrates facile synthesis of ß-Glucan nanoparticles (ß-GluNPs) that can be used in the prevention of breast cancer and other infectious diseases. Moreover, this method is inexpensive and shows effectivity towards different biological applications. Further, the characterization of synthesized ß-GluNPs was exclusively confirmed through UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), zeta potential, scanning electron microscopy (SEM), high resolution-transmission electron microscopy (HR-TEM), and X-ray powder diffraction (XRD) analysis. The synthesized ß-GluNPs were further confirmed by FT-IR spectroscopy. The HR-TEM results demonstrated that the formation of polydispersed nanoparticles with a mean size of 20 ± 5 nm. The hydrostatic zeta potential was - 22.7 mV, which indicated their colloidal stability. The XRD pattern revealed the crystalline nature of the nanoparticles. Besides, ß-GluNPs showed better antibacterial activity against the tested pathogens. The apoptosis and DNA fragmentation observed to be IC50 42.5 µg/ml of the ß-GluNPs. The DNA fragmentation assay indicated the selective inhibition of the MCF-7 cell line by DNA damage. Hence, the study reports that the ß-GluNPs have a potential to be used as a promising alternative drug against human breast cancer.

Application of Optimized and Validated Agar Overlay TLC-Bioautography Assay for Detecting the Antimicrobial Metabolites of Pharmaceutical Interest.

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.

Intra-specific differentiation of fungal endosymbiont Alternaria longissima CLB44 using RNA secondary structure analysis and their anti-infective potential.

New antimicrobial agents derived from endosymbio-tic fungi with unique and targeted mode of action are crucially rudimentary to combat multidrug-resistant infections. Most of the fungi isolated as endosymbionts show close morphological feature resemblance to plant pathogenic or free-living forms, and it is difficult to differentiate these different lifestyles. A fungal endosymbiont strain CLB44 was isolated from Combretum latifolium Blume (Combretaceae). CLB44 was then identified as Alternaria longissima based on morphological and internal transcribed spacer (ITS) intervening 5.8S rRNA gene sequence analysis. ITS2 RNA secondary structure analysis was carried out using mfold server with temperature 37 °C, and anti-infective potential was determined by MIC and disk diffusion methods. ITS2 RNA secondary structure analysis clearly distinguished endosymbiotic A. longissima CLB44 from free-living and pathogenic A. longissima members in the same monophyletic clade. Secondary metabolites produced effectively inhibited Pseudomonas aeruginosa (25 µg/ml), Escherichia coli (25 µg/ml), methicillin-resistant Staphylococcus aureus (50 µg/ml), Candida albicans (100 µg/ml), and other human pathogens. This study emerges as an innovative finding that explores newly revealed ITS2 RNAs that may be an insight as new markers for refining phylogenetic relations and to distinguish fungal endosymbionts with other free-living or pathogenic forms. A. longissima CLB44, in the emerging field of endosymbionts, will pave the way to a novel avenue in drug discovery to combat multidrug-resistant infections. The sequence data of this fungus is deposited in GenBank under the accession no. KU310611.

Implication of PKS type I gene and chromatographic strategy for the biodiscovery of antimicrobial polyketide metabolites from endosymbiotic Nocardiopsis prasina CLA68.

Advanced approach in probing for polyketide antimicrobials requires novel genomics and chromatographic strategies. An endophytic strain CLA68 was isolated from the root of Combretum latifolium Blume (Combretaceae) collected from the Western Ghats of Southern India. Strain CLA68 was then identified as Nocardiopsis prasina by its characteristic culture morphology and analysis of 16S rRNA gene sequence. Biosynthetic polyketide synthase genes were investigated using two pairs of degenerate primers. Ethyl acetate extract of CLA68 exhibited broad spectrum activity against a panel of test human pathogens. PKS type-I gene detection and chromatographic strategy yielded a robust polyketide antimicrobial compound which identified as nocapyrone E. Minimum inhibitory concentration of the purified compound against MRSA and other human pathogens ranged between 25 and 100 µg/ml. The present work highlights the utility of N. prasina CLA68 as potential source for antimicrobial polyketide nocapyrone E which could help to combat multidrug-resistant pathogens. This study demonstrates feasibility of PKS type-I gene-based molecular approach and chemical investigation by chromatographic approach is the best method for prediction and rapid discovery of novel polyketides from endosymbiotic actinomycetes. The sequence data of this endosymbiotic actinomycete is deposited in GenBank under the accession no. KP269077.

Molecular profiling and antimicrobial potential of endophytic Gliomastix polychroma CLB32 inhabiting Combretum latifolium Blume.

Fungal endophytes as a source of bioactive metabolites have led to the development of pharmaceutical products finding new applications. In a survey of endophytic fungal biodiversity, an antimicrobial endophytic strain CLB32 was isolated from the leaf of Combretum latifolium Blume (Combretaceae) from the Western Ghats of Southern India. CLB32 was then identified as Gliomastix polychroma (KR704576) by morphological and phylogenetic analysis based on internal transcribed spacer (ITS) nuclear rDNA and intervening 5.8S rRNA gene. CLB32 here constituted the first report on incidence of endophytic fungi from C. latifolium Blume. Ethyl acetate fraction of strain CLB32 was evaluated for antimicrobial activity by disc diffusion assay. Secondary metabolites produced effectively inhibited methicillin-resistant Staphylococcus aureus (18.33 ± 0.33 mm), Pseudomonas aeruginosa (14.66 ± 0.33 mm) and Candida albicans (14.00 ± 0.57 mm). Biosynthesis of these antimicrobial compounds was detected by analytical TLC-bioautography method as depicted by zone of inhibition on intensive the band. These findings suggest that G. polychroma CLB32, as a producer of natural antimicrobial drugs, could help to combat against multidrug-resistant infections and also provide baseline information for industrial applications.