Cis -decalin tetramic acid metabolite from a mangrove derived endophytic fungus Nigrospora oryzae

Most of the natural products containing tetramic acid have trans configuration of the decalin moiety. Undana A (1), a new cis decalin-bearing tetramic acid metabolite was isolated from endophytic fungi Nigrospora oryzae associated with Avicennia marina. The structure was determined based on the mass and NMR spectral data together with the comparison of the literature. This is the first report of cis decalin-tetramic acid metabolite from the mangrove endophytic fungus. Compound 1 was tested for cytotoxic against L5178Y mouse cancer cells and antibacterial activity against several gram-positive including MRSA and gram-negative bacteria but was found inactive.