Chemical Modification of Glycyrrhetinic Acid in Relation to the Biological Activities

18β-Olean-12-ene-3β, 30-diol (deoxoglycyrrhetol) (4a) was prepared with a view to eliminating pseudoaldosteronism, a side-effect of glycyrrhetinic acid (1b), which is the sapogenin of Licorice saponin, glycyrrhizin (1a), while maintaining or enhancing the therapeutic activities. On reduction of the 11-keto and 30-carboxyl groups of 1b with NaAlH2- (OCH2CH2OCH3) 2, olean-12-ene-3β, 11β, 30-triol (9) and olean-12-ene-3β, 11α, 30-triol (10) were obtained. On catalytic hydrogenation of 9 and 10 with Pd-C as a catalyst, 4a was formed in an overall yield of 80%. On treatment with conc. HCl, 9 yielded 18β-olean-9 (11), 12-diene-3β, 30-diol (11a), while 10 yielded olean-11, 13 (18) -diene-3β, 30-diol (12a). Mono-and di-β-carboxy-propionyl and mono-and di-ο-pbthaloyl esters of 4a, lla and 12a were prepared to increase the hydrophilic character. The competitive inhibition of 5β, Δ4-reductase of corticosteroids in the liver which is caused by lb to induce pseudoaldosteronism was not observed in the case of 4a. Compounds 4a, 11a and 12a and their β-carboxypropionyl and ο-phthaloyl esters were studied pharmacologically, and showed antiulcerogenic, antiallergic and antiinflammatory activities.