AUTHOR=Huo Ruiyun , Zhang Jinxin , Niu Shubin , Liu Ling TITLE=New prenylated indole diketopiperazine alkaloids and polyketides from the mangrove-derived fungus Penicillium sp JOURNAL=Frontiers in Marine Science VOLUME=Volume 9 - 2022 YEAR=2022 URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.1097594 DOI=10.3389/fmars.2022.1097594 ISSN=2296-7745 ABSTRACT=Two new prenylated indole diketopiperazine alkaloids (PIDAs) penicamides A and B (1 and 2), and three new polyketides penicinones A−C (6−8), along with four known compounds deoxybrevianamide E (3), brevianamide V (4), 12,13-dehydroprolyl-2-(1,1-dimethylallyltryptophyl)diketopiperazine (5), and 4-hydroxyphenethyl 2-(4-hydroxyphenyl)acetate (9) were isolated and identified from the culture extract of the mangrove-derived fungus Penicillium sp. Their structures were fully elucidated by analyzing spectroscopic data. The absolute configurations of these compounds were determined by comparison of experimental and calculated electronic circular dichroism (ECD) data, Mo2(OAc)4-induced and Rh2(OCOCF3)4-induced ECD experiments. Structurally, compound 1 is the first example of PIDA featuring a 6/5/8/6/5 pentacyclic ring system with an α-hydroxy group at C-11, while compound 2 is new analogue of PIDA possessing the unique 3-methyleneindolin-2-ol moiety. In addition, compound 6 is a new lactone with the furo[3,4-b]pyran-5-one moiety. Compound 6 displayed potent cytotoxicity against murine melanoma (B16) cells, human breast adenocarcinoma (MCF-7) cells, and human hepatocellular carcinoma (HepG2) cells at 50.0 µM with inhibitory ratios of 82.7%, 75.1% and 95.9%, respectively. In addition, compound 6 exhibited significantly cytotoxic activity against the HepG2 cells, with IC50 value of 3.87 ± 0.74 µM.