Cytochalasin Derivatives from the Endozoic Curvularia verruculosa CS-129, a Fungus Isolated from the Deep-Sea Squat Lobster Shinkaia crosnieri Living in the Cold Seep Environment

A new cytochalasin dimer, verruculoid A (1), three new cytochalasin derivatives, including 12-nor-cytochalasin F (2), 22-methoxycytochalasin B-6 (3), and 19-hydroxycytochalasin B (4), and 20-deoxycytochalasin B (5), a synthetic product obtained as a natural product for the first time, together with four known analogues (6-9), were isolated and identified from the culture extract of Curvularia verruculosa CS-129, an endozoic fungus obtained from the inner fresh tissue of the deep-sea squat lobster Shinkaia crosnieri, which was collected from the cold seep area of the South China Sea. Structurally, verruculoid A (1) represents the first cytochalasin homodimer containing a thioether bridge, while 12-nor-cytochalasin F (2) is the first 12-nor-cytochalasin derivative. Their structures were elucidated by detailed interpretation of the NMR spectroscopic and mass spectrometric data. X-ray crystallographic analysis and ECD calculations confirmed their structures and absolute configurations. Compound 1 displayed activity against the human pathogenic bacterium Escherichia coli (MIC = 2 mu g/mL), while compounds 4, 8, and 9 showed cytotoxicity against three tumor cell lines (HCT-116, HepG-2, and MCF-7) with IC50 values from 5.2 to 12 mu M. The structure-activity relationship was briefly discussed.

Automated summary

New cytochalasin compounds were isolated from an endozoic fungus obtained from the deep-sea squat lobster in the cold seep area of the South China Sea. These compounds included a novel cytochalasin homodimer containing a thioether bridge and the first 12-nor-cytochalasin derivative. Some of these compounds exhibited activity against human pathogenic bacteria and cytotoxicity against tumor cell lines.