Two new diterpenoids from Plectranthus nummularius BRIQ.

Two new antioxidative diterpenoids, plectranthol A (3)[19-O-(3,4-dihydroxybenzoyl)-11,12-dihydroxy-20(10 -->5) -abeo-abieta-1(10),6,8,11,13-tetraene] and plectranthol B (4)[12-O-(3-methyl-2-butenoyl)-19-O-(3, 4-dihydroxybenzoyl)-11-hydroxyabieta- 8,11,13-triene] along with two known diterpenoids, parvifloron E (1) and F (2) were isolated from the leaves of Plectranthus nummularius B-RIQ. Antioxidative activities of the compounds were measured by the alpha,alpha -diphenyl-beta -picrylhydrazyl (DPPH) method.