Mariannamides A and B, new cyclic octapeptides isolated from Mariannaea elegans NBRC102301.

Two new cyclic octapeptides, mariannamides A (1) and B (2), have been isolated from Mariannaea elegans NBRC102301, a Pinus densiflora-derived filamentous fungus. Their structures were elucidated to be cyclo-(l-Leu-l-Pro-l-Pro-l-Leu-l-Ile-l-Pro-l-Val-l-Ile) and cyclo-(l-Leu-l-Pro-l-Pro-l-Leu-l-Ile-l-Pro-l-Val-l-Val) based on spectroscopic data and Marfey's method. Mariannamide A (1) promoted mRNA expression of sirtuin 1 (SIRT1) in C2C12 cells, a mouse skeletal muscle myoblast cell line, and showed the antimicrobial activity against Escherichia coli and Cryptococcus neoformans.