Isolation and characterization of cancer chemopreventive compounds from Barringtonia maunwongyathiae

A new plant species, Barringtonia maunwongyathiae W. Chuakul (Lecythidaceae), was recently discovered in Khuan Thon Forest, Ao Luek District, Krabi Province, Thailand. Chemical investigation of the leaves of this plant led to the isolation of 10 triterpenes, 3 steroids, and a vitamin E derivative. The structures of these compounds were identified as taraxerol (1), 3-(E)-coumaroyltaraxerol (2), 3-(Z)-coumaroyltaraxerol (3), 3-(E)-coumaroyl β-amyrin (4), 3-(Z)-coumaroyl β-amyrin (5), 3-(E)-coumaroyl α-amyrin (6), 3-(Z)-coumaroyl α-amyrin (7), 3-(E)-coumaroyllupeol (8), 3-(Z)-coumaroyllupeol (9), 3,19,24-trihydroxyurs-12-ene-28-oic acid (10), stigma-4,22-dien-3-one (11), β-stigmasterol (12), 3-O-β-D- glucopyranosyl-stigmasta-5,22-diene (13), and α-tocopherylquinone (14). All compounds were evaluated for their cancer chemopreventive potential based on inhibition of TPA-induced ornithine decarboxylase expression, COX-1 and COX-2 activities, and phorbol ester-induced NF-κB luciferase expression, as well as activation of antioxidant response element-mediated luciferase expression. Compounds 1, 2, and 14 demonstrated greatest promise, while 12 and 13 showed moderate activity.