Hybrid polyketides from a Hydractinia-associated Cladosporium sphaerospermum SW67 and their putative biosynthetic origin.

Lee SR, Lee D, Eom HJ, Rischer M, Ko YJ, Kang KS, Kim CS, Beemelmanns C, Kim KH (2019) Hybrid polyketides from a Hydractinia-associated Cladosporium sphaerospermum SW67 and their putative biosynthetic origin. Mar Drugs 17(11), 606. PubMed Open Access PDF

Abstract

Five hybrid polyketides (1a, 1b, and 2–4) containing tetramic acid core including a new hybrid polyketide, cladosin L (1), were isolated from the marine fungus Cladosporium sphaerospermum SW67, which was isolated from the marine hydroid polyp of Hydractinia echinata. The hybrid polyketides were isolated as a pair of interconverting geometric isomers. The structure of 1 was determined based on 1D and 2D NMR spectroscopic and HR-ESIMS analyses. Its absolute configuration was established by quantum chemical electronic circular dichroism (ECD) calculations and modified Mosher’s method. Tetramic acid-containing compounds are reported to be derived from a hybrid PKS-NRPS, which was also proved by analyzing our 13C-labeling data. We investigated whether compounds 1–4 could prevent cell damage induced by cisplatin, a platinum-based anticancer drug, in LLC-PK1 cells. Co-treatment with 2 and 3 ameliorated the damage of LLC-PK1 cells induced by 25 μM of cisplatin. In particular, the effect of compound 2 at 100 μM (cell viability, 90.68 ± 0.81%) was similar to the recovered cell viability of 88.23 ± 0.25% with 500 μM N-acetylcysteine (NAC), a positive control.

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doi: 10.3390/md17110606 PMID: 31653089