Absolute Configuration of a Diterpene with an Acyclic 1,2-Diol Moiety and Cytotoxicity of Its Analogues from the Aerial Parts of Aralia cordata

摘要

Aralia cordata Thunb. (Araliaceae) is a perennial herb which is distributed in Korea, China and Japan. Traditionally, the root of A. cordata has been widely used to treat rheumatism, lumbago and lameness in Japan. Previous phytochemical investigations on this plant have reported the isolation of several kinds of diterpenes having pimarane and kaurane skeletons. In our current phytochemical investigation on the aerial parts of this plant has led to the isolation of a new ent-pimarane diterpene, ent-15S,16-dihyroxypimar-8(14)-en-19-oic acid (1), together with three known diterpenes, ent-pimar-8(14),15-dien-19-oic acid (2), ent-16α-hydroxykauran-19-oic acid (3) and ent-kaur-16-en-19-oic acid (4) (Figure 1). Although the structure of compound 1 was reported previously, there has been no report of the isolation from natural sources. Moreover, there has been no report on the determination of the absolute configuration of the 1,2-dihydroxyethyl moiety in 1. Therefore, in order to deduce the absolute configuration of this moiety, a CD method employing dimolybdenum tetraacetate [Mo2(AcO)4] developed by Snatzke and Frelek was applied to 1. The present paper reports the isolation and structure elucidation of isolated compounds (1-4) from the aerial parts of A.