Diversity and chemical fingerprinting of endo-metabolomes from endophytes associated with Ampelopsis grossedentata (Hand.-Mazz.) W. T. Wang possessing antibacterial activity against multidrug resistant bacterial pathogens

Antifungal polyketides from the marine-derived fungus Nigrospora sp. MG36-1

Three new polyketides, a griseofulvin derivative 1, a hydroanthraquinone derivative 8 and a pyranolactone derivative 10, together with eight known compounds (2-7, 9 and 11), were isolated from the marine-derived fungus Nigrospora sp. MG36-1. The structures of the three new compounds were unambiguously determined by nuclear magnetic resonance (NMR), mass spectrometry, ¹³C NMR calculation in combination with DP4+ and ECD calculations. The antitumor, antibacterial and antifungal activities of the compounds 1-9 were evaluated in vitro. Compound 1 showed antibacterial activity against Acinetobacter baumannii with MIC 42.5 μg/mL. Compounds 1 and 8 exhibited antifungal activity against Candida albicans with MICs 21.5 μg/mL and 17.5 μg/mL, respectively.

Spirocyclic polyketides from the marine fungus Talaromyces sp. CX11

Three new spirocyclic polyketides, talaromyacins A - C, were identified from the endophytic fungus Talaromyces sp. CX11. Their structures including absolute configurations were determined by extensive spectroscopic analysis, Snatzke's method and quantum chemical calculations. Talaromyacin A is identical to the known sequoiamonascin A, for which a structural revision is required.

Diversity, Antimicrobial Activity, and Antibiotic Susceptibility Pattern of Endophytic Bacteria Sourced From Cordia dichotoma L

Endophytic bacteria isolated from medicinal plants are crucial for the production of antimicrobial agents since they are capable of possessing bioactive compounds with diverse structures and activities. Cordia dichotoma, a plant of medicinal importance native to the Jammu region of India, was selected for the isolation and characterization of culturable endophytic bacteria and evaluation of their antimicrobial activities. Standardized surface sterilization methods were employed to isolate thirty-three phenotypically distinguishable endophytic bacteria from the root, stem, and leaf parts of the plant. Shannon Wiener diversity index clearly divulged diverse endophytes in roots (0.85), stem (0.61), and leaf (0.54) tissues. Physio-biochemical features of the isolates differentiated the distinct variations in their carbohydrate utilization profile and NaCl tolerance. The endophytes produced an array of enzymes, namely, catalase, oxidase, amylase, cellulase, nitrate reductase, and lipase. The bacterial isolates belong to the genera Bacillus, Pseudomonas, Paenibacillus, Acidomonas, Streptococcus, Ralstonia, Micrococcus, Staphylococcus, and Alcalignes predominantly. However, the antibiotic susceptibility pattern indicated that the isolates were mostly sensitive to erythromycin and streptomycin, while they were resistant to rifampicin, amoxicillin, and bacitracin. Interestingly, majority of the bacterial endophytes of C. dichotoma showed antimicrobial activity against Bacillus subtilis followed by Klebsiella pneumoniae. The 16S rRNA sequence of Bacillus thuringiensis has been deposited in the NCBI GenBank database under accession number OM320575. The major compounds of the crude extract derived from endophytic B. thuringiensis OM320575, according to the metabolic profile examination by GC-MS, are dibutyl phthalate, eicosane, tetrapentacontane, heneicosane, and hexadecane, which possessed antibacterial activities. In conclusion, results indicated the potential of C. dichotoma to host a plethora of bacterial endophytes that produce therapeutic bioactive metabolites.