Mayotamides

Cyclodidemnamide (60) is a weakly cytotoxic, heptapeptide from D. molle from the Philippines [90]. Total synthesis of the proposed structure of cyclodidemnamide gave a product with different spectral data to those of the natural product, which is thought to be a stereoisomer [91]. The stereochemistry of one of the two valine residues in cyclodidemnamide was revised from L-valine to D-valine as a result of the total synthesis of both isomers [92] and the configuration was also reassigned as a result of total synthesis [93]. The hexapeptides, comoramides A (61) and B (62), were isolated from D. molle from Mayotte lagoon in the Comoros Islands, while the heptapeptides, mayotamides A (63) and B (64) were isolated from a separate collection of D. molle from the Comoros Islands [94]. 

Another tunicate, Didemnum molle, has been shown to contain a novel series of cyclic peptides. They include the hexapeptides comoramides A (391) and B (392) [301] and the heptapeptides, mollamide (393) [302], cyclodidemnamide (394) [303], and mayotamides A (395) and B (396) [301]. The structures of these compounds were elucidated from spectral data, degradation experiments and, in the case of mollamide (393), by X-ray analysis. The total synthesis of cyclodidemnamide led to the revision of its structure [304]. All of them exhibited cytotoxic activity and 393 also inhibited RNA synthesis [302]. 

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