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

Abstract 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 -Leu1- l -Pro1- l -Pro2- l -Leu2- l -Ile1- l -Pro3- l -Val1- l -Ile2) and cyclo-( l -Leu1- l -Pro1- l -Pro2- l -Leu2- l -Ile1- l -Pro3- l -Val1- l -Val2) 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.