Thielavin A and B, new inhibitors of prostaglandin biosynthesis produced by Thielavia terricola.

Abstract
Two potent inhibitors of prostaglandin [PG] biosynthesis, thielavin A (C31H34O10) and B (C29H30O10), were isolated from cultures of Thielavia terricola. Both of these compounds are structurally related to depsides, consisting of 3 hydroxybenzoic acid groups. Concentrations required for 50% inhibition of the conversion of 14C-arachidonic acid into PGF2.alpha. plus PGE2 by microsomes of ram seminal vesicles were 12 .mu.M for thielavin A and 9 .mu.M for thielavin B, respectively. Of the enzymatic steps involved in PG synthesis, thielavin A specifically inhibited the conversion of arachidonic acid into PGH2, wihle PGE2 synthesis from the endoperoxide was the most sensitive to thielavin B. Thromboxane A2 synthesis from PGH2 in bovine platelet microsomes were inhibited by 50% at concentrations of 150 and 350 .mu.M of thielvain A and B, respectively. Thielavin B was significantly effective on carrageenan-induced edema of rats i.v. but not orally. The antiinflammatory activity was not detectable with thielvain A either i.v. or orally.