Indole and monoterpene alkaloids from the leaves of Kopsia dasyrachis Toh-Seok Kam a, *, Yeun-Mun Choo a , Wei Chen a , Jia-Xing Yao b a Department of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia b Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom Received 12 April 1999; accepted 28 April 1999 Abstract A new monoterpene alkaloid, kinabalurine G, in addition to 11 indole alkaloids and the catechine±skytanthine compound, kopsirachine, was obtained from the leaf extract of Kopsia dasyrachis. The structure of the novel alkaloid, danuphylline, was con®rmed by an X-ray analysis. # 1999 Elsevier Science Ltd. All rights reserved. Keywords: Kopsia species; Apocynaceae; Indole and monoterpene alkaloids 1. Introduction We recently reported the alkaloidal composition of the stem bark extract of Kopsia dasyrachis Ridl., one of about seventeen Malaysian Kopsia species, which is found in Sabah, Malaysian Borneo (Kam, Subramaniam & Chen, 1999). A previous study of the leaf alkaloids of K. dasyrachis from Borneo yielded three new indoles, viz., kopsidasine, kopsidasine N- oxide, kopsidasinine (Homberger & Hesse, 1982) and in addition, kopsirachine, which is constituted from the union of catechine and two units of skytanthine (Homberger & Hesse, 1984). We have also reported the structure elucidation (Kam, Lim, Choo & Subramaniam, 1998), as well as a biomimetic, electro- chemically-mediated semisynthesis (Kam, Lim & Choo, 1999) of the novel pentacyclic indole, danuphyl- line, which was obtained in minute amount from the leaf extract of this plant. We now report the full alka- loidal composition of the leaf, including the isolation of a new monoterpene alkaloid, as well as con®r- mation of the structure of danuphylline by X-ray analysis. 2. Results and discussion The ethanol extract of the leaves furnished a basic fraction which upon extensive chromatography yielded a total of 13 alkaloids, viz., methyl chanofruticosinate 1 (Chen, Li, Kirfel, Will & Breitmaier, 1981), methyl 11,12-methylenedioxychanofruticosinate 2 (Chen et al., 1981; Kam, Tan, Hoong & Chuah, 1993), methyl N- decarbomethoxychanofruticosinate 3 (Chen et al., 1981; Kam et al., 1993), methyl 11,12-methylenedioxy- N-decarbomethoxychanofruticosinate 4 (Chen et al., 1981; Kam et al., 1993), kopsamine 5 (Crow & Michael, 1962; Feng, Kan, Potier, Kan & Lounasmaa, 1983; Gilbert, 1965; Kam & Sim, 1998; Zheng, Zhou & Huang, 1989), 11,12-dimethoxykopsamine 6 (Kam & Sim, 1998; Zheng et al., 1989), kopsamine N(4)- oxide 7 (Kam & Sim, 1998; Zheng et al., 1989), pleio- carpine 8 (Homberger & Hesse, 1982), 12-methoxy- pleiocarpine 9 (Kam & Sim, 1998), kopsi®ne 10 (Kam et al., 1999; Kam & Subramaniam, 1998), kopsirachine 11 (Homberger & Hesse, 1984), danuphylline 12 (Kam Phytochemistry 52 (1999) 959±963 0031-9422/99/$ - see front matter # 1999 Elsevier Science Ltd. All rights reserved. PII: S0031-9422(99)00265-4 * Corresponding author. Tel.: +603-759-4266; fax: +603-759- 4193. E-mail address: tskam@kimia.um.edu.my (T.S. Kam).