A new triterpene from the plant of uncaria macrophylla.

Abstract: Our ongoing investigations on the stem bark of Uncaria macrophylla afforded a new ursolic triterpene, 3β,6β,19α-trihydroxy-urs-12-en-28-oic acid-24-carboxylic acid methyl ester ( 1 ), named uncariursanic acid, and three known ursolic triterpenes including 3β,6β,19α-trihydroxy-23-oxo-urs-12-en-28-oic acid ( 2 ), 3β,6β,19α-trihydroxy-urs-12-en- 28-oic acid ( 3 ) and ursolic acid ( 4 ). Their structures were elucidated by extensive spectral methods, including 1D and 2D NMR and HR-ESI-MS. The cytotoxicities of the four compounds were evaluated against two cancer cell lines (MCF-7 and HepG2) by the MTT method, and only compound 4 exhibited potent activity. Keywords: triterpene; 3β,6β,19α-trihydroxy-urs-12-en-28-oic acid-24-carboxylic acid methyl ester; Uncaria macrophylla ; Rubiaceae; antitumor activity 1. Introduction Uncaria, an important source of medicinal natural products from the Rubiaceae family, is widely distributed in tropical regions, in cluding Southern Asia, Africa and So uth America [1]. Many species of