Antimicrobial and Cytotoxic Secondary Metabolites from a Marine-Derived Fungus Penicillium Citrinum VM6.

Investigation of an antimicrobial and cytotoxic ethyl acetate extract prepared from solid fermentation of the marine-derived fungus Penicillium citrinum VM6 led to the isolation of eight metabolites (1-8), including one citrinin dimer dicitrinone F (1). Of these, compound 7 was isolated for the first time from the Penicillium genus and compound 1 with carbon-bridged C-7/C-7' linkage is rarely reported. All compounds (1-8) exhibited selective antimicrobial activity against the tested Gram-positive bacteria and Candida albicans with MICs of 32-256 µg/mL. Compounds 1 and 8 exhibited cytotoxicity against all tested cell lines A549, MCF7, MDA-MB-231, Hela, and AGS with IC50 values of 6.7 ± 0.2 to 29.6 ± 2.2 µg/mL, whereas compound 5 had selective cytotoxicity against the MCF7 cell lines with IC50 of 98.1 ± 7.8 µg/mL.

A Pair of Undescribed Alkaloid Enantiomers from Marine Sponge-Derived Fungus Hamigera avellanea and Their Antimicrobial and Cytotoxic Activities.

From marine sponge-associated fungus Hamigera avellanea, thirteen secondary metabolites including a pair of undescribed alkaloid enantiomers (+)-hamiavemin A (4S) (+)-1 and (-)-hamiavemin A (4R) (-)-1. Compound 1 was enantiomers resolved by the Chiralpak AS-3 column, using a hexane/isopropanol mobile phase. Their structures were determined based on extensive analyses of HR-ESI-MS, 1D and 2D NMR spectra. The absolute configuration of (+)-1 and (-)-1 were assigned tentatively by ECD calculations. Among the isolates, compound 6 showed strongest antibacterial activity against Enterococcus faecalis, Staphylococcus aureus, Bacillus cereus, Escherichia coli, Salmonella enterica, and Candida albicans with the MIC values of 2, 2, 16, 32, 64, and 16 µg/mL, respectively, which were stronger than that of the positive control compound, kanamycin (MIC values ranging from 4 to 128 µg/mL). In addition, compounds 1, 2, and 9 showed moderate cytotoxic activity against three cancer cell lines, HepG2, A549, and MCF-7 with the IC50 values ranging from 55.35±1.70 to 83.02±2.85 µg/mL.

Pharmacological Properties, Volatile Organic Compounds, and Genome Sequences of Bacterial Endophytes from the Mangrove Plant Rhizophora apiculata Blume.

Mangrove plant endophytic bacteria are prolific sources of bioactive secondary metabolites. In the present study, twenty-three endophytic bacteria were isolated from the fresh roots of the mangrove plant Rhizophora apiculata. The identification of isolates by 16S rRNA gene sequences revealed that the isolated endophytic bacteria belonged to nine genera, including Streptomyces, Bacillus, Pseudovibrio, Microbacterium, Brevibacterium, Microbulbifer, Micrococcus, Rossellomorea, and Paracoccus. The ethyl acetate extracts of the endophytic bacteria's pharmacological properties were evaluated in vitro, including antimicrobial, antioxidant, α-amylase and α-glucosidase inhibitory, xanthine oxidase inhibitory, and cytotoxic activities. Gas chromatography-mass spectrometry (GC-MS) analyses of three high bioactive strains Bacillus sp. RAR_GA_16, Rossellomorea vietnamensis RAR_WA_32, and Bacillus sp. RAR_M1_44 identified major volatile organic compounds (VOCs) in their ethyl acetate extracts. Genome analyses identified biosynthesis gene clusters (BGCs) of secondary metabolites of the bacterial endophytes. The obtained results reveal that the endophytic bacteria from R. apiculata may be a potential source of pharmacological secondary metabolites, and further investigations of the high bioactive strains-such as fermentation and isolation of pure bioactive compounds, and heterologous expression of novel BGCs in appropriate expression hosts-may allow exploring and exploiting the promising bioactive compounds for future drug development.

Molecular design of anticancer drugs from marine fungi derivatives.

Heat shock protein 90 (Hsp90) is one of the most potential targets in cancer therapy. We have demonstrated using a combination of molecular docking and fast pulling of ligand (FPL) simulations that marine fungi derivatives can be possible inhibitors, preventing the biological activity of Hsp90. The computational approaches were validated and compared with previous experiments. Based on the benchmark of available inhibitors of Hsp90, the GOLD docking package using the ChemPLP scoring function was found to be superior over both Autodock Vina and Autodock4 in the preliminary estimation of the ligand-binding affinity and binding pose with the Pearson correlation, R = -0.62. Moreover, FPL calculations were also indicated as a suitable approach to refine docking simulations with a correlation coefficient with the experimental data of R = -0.81. Therefore, the binding affinity of marine fungi derivatives to Hsp90 was evaluated. Docking and FPL calculations suggest that five compounds including 23, 40, 46, 48, and 52 are highly potent inhibitors for Hsp90. The obtained results enhance cancer therapy research.