Studies on the constituents of the leaves of Conandron ramondioides

Abstract

Conandron ramondioides Sieb. et Zucc. is a perennial herb of the family Gesneriaceae, which is distributed from southeastern China to the Tohoku district in Japan. In Japan, the plant is called iwatabako, and its whole herbs are used as a folk remedy for the treatment of stomachache [1]. In a previous paper [2], we reported the structural identification of 14 phenolic compounds including three with unique structures, named didymocalyxins A, B and C, isolated from the leaves of Didymocarpus leucocalyx (Gesneriaceae). In the course of our studies on the constituents of Gesneriaceae species, we have investigated the leaves of C. ramondioides, for which information on the chemical constituents has not been published. The present paper deals with the isolation and identification of eight compounds from this plant purchased in a Japanese market. MeOH extract (87 g) of the dried leaves (1.1 kg) was suspended in water and successively extracted with ether and ethyl acetate. The ether-soluble portion (18 g) was chromatographed on silica gel (benzeneCHCl3) and ODS (H2O-MeOH), and then purified by HPLC (fluofix, CHCN3-n-propanol-H2O) to give four triterpenoids (1–4) and a phytosterol (7). The ethyl acetate-soluble portion (4 g) was chromatographed on silica gel (n-hexane-acetone followed by CHCl3-MeOHH2O) to give two triterpenoids (5 and 6) and a phytosterol (8). Compounds 1–8 were identified as 3-epipomolic acid (1, 25.6 mg) [4], 3-epiursolic acid (2, 34.6 mg) [5], ursolic acid (3, 152.3 mg) [5], 3-epioleanolic acid (4, 3.0 mg) [5], barbinervic acid (5, 19.8 mg) [3], scutellaric acid