Communesin B

Communesin B is a cytotoxic chemical compound isolated from Penicillium strains found on the marine alga Ulva intestinalis. It exhibits cytotoxicity in vitro against human lung carcinoma, prostate carcinoma, colorectal carcinoma, cervical adenocarcinoma, and breast adenocarcinoma cell lines.

Biosynthesis

Communesin B is a dimeric indole alkaloid with a hexadienoyl moiety originating from polyketide synthesis. Biosynthesis starts with two L-tryptophan molecules processed by different pathways. The first pathway involves a decarboxylation step catalyzed by CnsB to produce tryptamine. The second pathway starts the synthesis of 4-L-dimethylallyl tryptophan by CnsF followed by further processing of CnsA and CnsD to form aurantioclavine. These two indole-containing fragments are combined through a radical oxidative coupling by CnsC, a cytochrome P450 enzyme, to form the core scaffold of communesin alkaloids. CnsE transfers a methyl group to the indole nitrogen, and CnsJ creates an epoxide ring on the dimethylallyl substituent off the ring structure to form communesin I. Separately, CnsI synthesizes a hexadienoyl group using acetyl-CoA as a starting material and extending it with two malonyl-CoA units. Then, CnsK performs N-acylation with the CnsI-synthesized hexadienoyl chain to form communesin B.