HPLC-DAD-Guided Isolation of Diversified Chaetoglobosins from the Coral-Associated Fungus Chaetomium globosum C2F17.

Cytochalasans have continuously aroused considerable attention among the chemistry and pharmacology communities due to their structural complexities and pharmacological significances. Sixteen structurally diverse chaetoglobosins, 10-(indol-3-yl)-[13]cytochalasans, including a new one, 6-O-methyl-chaetoglobosin Q (1), were isolated from the coral-associated fungus Chaetomium globosum C2F17. Their structures were accomplished by extensive spectroscopic analysis combined with single-crystal X-ray crystallography and ECD calculations. Meanwhile, the structures and absolute configurations of the previously reported compounds 6, 12, and 13 were confirmed by single-crystal X-ray analysis for the first time. Chaetoglobosins E (6) and Fex (11) showed significant cytotoxicity against a panel of cancer cell lines, K562, A549, Huh7, H1975, MCF-7, U937, BGC823, HL60, Hela, and MOLT-4, with the IC50 values ranging from 1.4 µM to 9.2 µM.

Cytotoxic benzopyranone and xanthone derivatives from a coral symbiotic fungus Cladosporium halotolerans GXIMD 02502.

Coral-derived microorganisms have been historically proven to be prolific sources of bioactive secondary metabolites. Twelve benzopyranone and/or xanthone derivatives, including a new benzopyranone with an uncommon carboxyl group at C-8, coniochaetone K (1), were obtained from the Beibu Gulf-derived coral symbiotic fungus Cladosporium halotolerans GXIMD 02502. Their structures were determined by extensive spectroscopic data interpretation and comparison with literature values. The absolute configuration of 1 was accomplished by comparison of specific optical rotation as well as quantum chemical ECD calculations. The in vitro cytotoxicity of compounds 1-12 against two human prostatic cancer cell lines, C4-2B and 22RV1, were evaluated. And compounds 1, 3, 6-8, and 10-11 demonstrated significant cytotoxicity with inhibitions ranging from 55.8% to 82.1% at the concentration of 10 µM.