Spartinoxide, a new enantiomer of A82775C with inhibitory activity toward HLE from the marine-derived Fungus Phaeosphaeria spartinae.

The fungus Phaeosphaeria spartinae is an endophyte of the marine alga Ceramium sp. Investigation of this marine-derived fungus led to the isolation of spartinoxide (1), which is the enantiomer of the known compound A82775C (2). Additionally, the known metabolites 4-hydroxy-3-prenyl-benzoic acid (4) and anofinic acid (5) were obtained. The structures of all compounds were established from extensive spectroscopic investigations. Compounds 1, 4 and 5 were assayed against the enzymes human leukocyte elastase (HLE), trypsin, acetylcholinesterase and cholesterolesterase. Compounds 1 and 4 showed potent inhibition of HLE with IC50 values of 1.71 +/- 0.30 microg/mL (6.5 microM) and 1.67 +/- 0.32 microg/mL (8.1 microM), respectively.