Study on the Anti-Mycobacterium marinum Activity of a Series of Marine-Derived 14-Membered Resorcylic Acid Lactone Derivatives.

With the emergence of drug-resistant strains, the treatment of tuberculosis (TB) is becoming more difficult and there is an urgent need to find new anti-TB drugs. Mycobacterium marinum, as a model organism of Mycobacterium tuberculosis, can be used for the rapid and efficient screening of bioactive compounds. The 14-membered resorcylic acid lactones (RALs) have a wide range of bioactivities such as antibacterial, antifouling and antimalarial activity. In order to further study their bioactivities, we initially constructed a 14-membered RALs library, which contains 16 new derivatives. The anti-M. marinum activity was evaluated in vitro. Derivatives 12, 19, 20 and 22 exhibited promising activity with MIC90 values of 80, 90, 80 and 80 µM, respectively. The preliminary structure-activity relationships showed that the presence of a chlorine atom at C-5 was a key factor to improve activity. Further studies showed that 12 markedly inhibited the survival of M. marinum and significantly reduced the dosage of positive drugs isoniazid and rifampicin when combined with them. These results suggest that 12 is a bioactive compound capable of enhancing the potency of existing positive drugs, and its effective properties make it a very useful leads for future drug development in combating TB resistance.

Diversity and antimicrobial activity of culturable fungi associated with sea anemone Anthopleura xanthogrammica

Background: The main objective of this study was to isolate fungi associated with Anthopleura xanthogrammica and measure their antimicrobial and enzymatic activities. A total of 93 fungal strains associated with A. xanthogrammica were isolated in this study, of which 32 isolates were identified using both morphological characteristics and internal transcribed spacer (ITS) sequence analysis. The antibacterial activities of 32 fungal isolates were tested against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Edwardsiella tarda, Vibrio harveyi, Fusarium oxysporum, and Pyricularia oryzae by agar diffusion assay. Extracellular hydrolytic enzyme activities of the fungal isolates were determined by agar diffusion assays. Enzyme activities were detected from clear halo size. Results: The isolated fungi belonged to 18 genera within 7 taxonomic orders of 1 phylum. The genera Aspergillaceae were the most diverse and common. The antimicrobial activities of 32 isolates were evaluated, and 19 (59.4%) of fungi isolate displayed unique antimicrobial activities. All fungal strains displayed at least one enzyme activity. The most common enzyme activities in the fungi isolates were amylase and protease, while the least common were pectinase and xylanase. Conclusions: This is first report on the sea anemone-derived fungi with antimicrobial and enzyme activities. Results indicated that sea anemone is a hot spot of fungal diversity and a rich resource of bioactive natural products.