Beyerane Derivatives and a Sesquiterpene Dimer from Japanese Cypress (Chamaecyparis obtusa)

Abstract

Social problems resulting from aging and degeneration of brain function have drawn attention around the world and especially in Japan. Biologically active constituents from plant resources are expected to suppress the development of these problems. We have studied various biologically active constituents from woody plants collected in the Chugoku area of Japan.1-3) In our previous work, the ethyl acetate (EtOAc) soluble fraction of Japanese Cypress (Chamaecyparis obtusa) showed neurite outgrowth-promoting activity on neuronal PC12 cells, and we isolated two novel compounds, 9-O-acetoxydihydrosesamin and a lignan-sesquiterpene conjugate, together with eleven known compounds, and some of the compounds showed potent neurite outgrowth activity. 4) In order to find more new constituents from this fraction, further chemical investigations of the residual fraction were carried out and four new beyerene type derivatives 1-4 (named obtsurins A-D) and a new sesquiterpene dimer ent-cryptomeridiol-4-yl-hinokiate (5), were obtained. Their structures were determined by means of spectral analysis including 2D-NMR and high-resolution (HR)-MS. This paper deals with the isolation and structural elucidation of the new compounds from C. obtusa.

Natural disesquiterpenoids

“…Furthermore, 287-288 possessed potent inhibition of NF-kB activity, which explains the use of the plant in traditional medicine for the treatment of inflammatory diseases. The chemical investigation of Chamaecyparis obtusa resulted in the isolation of a novel sesquiterpenoid dimer 289 formed between cryptomeridiol and hinokiic acid, 286 two compounds that are found to co-occur with 289. 287 Virgaurols C-D 290-291, two novel eremophilane sesquiterpenoid dimers, were found in the roots of Ligularia virgaurea.…”

Natural sesquiterpenoids

“…272 Further chemical investigation of this plant afforded the sesquiterpene dimer 318, formed between cryptomeridiol and hinokiic acid. 273 Another two new sesquiterpenelignans, eudeshonokiol B 319 and eudesobovatol B 320, and other known sesquiterpenes have been obtained from Magnolia obovata. 186,274 The pterolactone derivative 321 has been found in an extract of the leaves of Cyclocarya paliurus.…”

Diterpenoids

“…Further beyeranes, including some with a seco ring A structure, have been isolated from the heartwood of Excoecaria parvifolia, 238 Spirostachys africana, 239 and the Japanese cypress, Chamaecyparis obtusa. 240 16-Aza-ent-beyerane and 16-aza-enttrachylobane have been shown 241 to be powerful mechanismbased inhibitors of a recombinant ent-kaurene synthase from Arabidopsis thaliana. Some further aspects of the chemistry and microbial biotransformation of isosteviol and its relatives have been reported.…”