Spirobisnaphthalenes and lactones from the seeds of Strychnos angustiflora with potential anti-inflammatory activity.

Three new spirobisnaphthalenes (1-3), a new, natural spirobisnaphthalene product (4), and two new 12-membered ring lactones (11-12), with six known compounds (5-10), were isolated from the seeds of Strychnos angustiflora. Their structures were elucidated by extensive spectroscopic analysis. The absolute configurations of 1-4 were assigned by computational methods. Compounds 1, 5 and 9 inhibited lipopolysaccharide-induced NO production in BV2 cells with IC50 values of 4.85, 2.05, and 1.16μM, respectively (positive control curcumin, IC50=1.42μM). This is the first report on the anti-inflammatory activities of spirobisnaphthalenes.