Tetrapetalone A, a Novel Lipoxygense Inhibitor from Streptomycessp.

A simple new assay was designed for lipoxygenase inhibitors. This assay was used to find the novel lipoxygenase inhibitor, tetrapetalone A (1). Tetrapetalone A (1), C26H33NO7, was isolated from Streptomycessp. USF-4727 strain. Its planar structure was determined by spectroscopic evidence and by methylating with diazomethane to show the presence of a novel tetracyclic skeleton and a β-D-rhodinosyl moiety. The stereochemistry of 1was investigated by the coupling constant in the 1H-NMR spectrum, NOE correlations, modified Mosher’s method and derivation. We have reported the structural elucidation of 1in our previous paper. However, further investigation gave another structure for 1, which is described in this paper. Tetrapetalone A showed similar inhibitory activity against soybean lipoxygenase to the two well-known lipoxygenase inhibitors, kojic acid and NDGA, while methylated tetrapetalone A (2) showed little inhibitory activity, even at a concentration of 1 mM.