Indole Alkaloids from the Roots of Catharanthus roseus

Abstract

Catharanthus roseus (L.) G. Don is a well-known traditional herbal medicine, which is rich in indole alkaloids [1]. The chemical constituents of C. roseus have been investigated in our group [2, 3], and our further research has led to nine indole alkaloids (1–9) from the roots of C. roseus. Among them, compounds 1 and 2 were first isolated from the natural source, and their NMR data are reported for the first time. The roots of C. roseus were collected in March 2010 in Haikou City, Hainan Province, P. R. China. The plant was authenticated by Prof. Guang-Xiong Zhou of Jinan University. A voucher specimen (No. W1003021) has been deposited in the Institute of Traditional Chinese Medicine and Natural Products, Jinan University, Guangzhou, P. R. China. Air-dried and powdered roots (5 kg) of C. roseus were extracted with 95% EtOH, and the residue was dissolved in H2O to form a suspension and extracted with CHCl3 to obtain an extract (62 g). The CHCl3 extract was subjected to silica gel column chromatography (CHCl3–CH3OH, 100:0 0:100) to give 9 fractions (Fr. 1–Fr. 9). Fractions 5–7 were subjected to ODS column chromatography in CH3OH–H2O separately, followed by preparative-HPLC in MeOH–H2O, leading to nine indole alkaloids. Compounds 1 and 2 were identified using MS, IR, UV, and 1D and 2D NMR analysis, and compounds 3–9 were identified by comparing their spectral data with those in the literature as 3-epi-yohimbine (3) [4], lochnerine (4) [5], antirhine (5) [6], 18-hydroxystrictamine (6) [7], (–)-dihydrocorynantheol (7) [8], corynanthine (8) [9], and 21-hydroxycyclolochnerine (9) [10].