Antioxidant and Anti-Proliferative Active Constituents of Tecoma Stans against Tumor Cell Lines

Abstract

A new phenylethanoid, 2-(3,4-dihydroxyphenyl)ethyl-,2-O-(6-deoxy-α-L-mannopyranosyl-,4-(3,4-dihydroxyphenyl)-2-propenoate)-β-D-glucopyranoside (3) and a novel monoterpene alkaloid, 5-hydroxy-skytanthine hydrochloride (8), along with eleven known compounds have been isolated from Tecoma stans Juss. fruits and flowers. 4-O-E-Caffeoyl-α-L-rhamnopyranosyl-(1′→3)-α/β-D-glucopyranose (1), E/Z-acetoside (2), isoacetoside (4), rutin (5), luteolin 7-O-β-D-neohespridoside (6), luteolin 7-O-β-D-glucopyranoside (7) and sucrose (9) were isolated from the fruits, while luteolin 7-O-β-D-glucuronopyranoside (10), diosmetin 7-O-β-D-glucuronopyranoside (11), diosmetin 7-O-β-D-glucopyranoside (12), diosmetin 7-O-β-D-glucuronopyranoside methyl ester (13), and 2 from the flowers. Their structures were determined on the basis of chemical and spectroscopic evidence. It was found that the extract of T. stans fruits and compounds 1, 2 and 4 possess strong scavenging activity to DPPH, peroxyl and hydroxyl radicals. Unlike 4, which potentially induced NO generation in bacterial lipopolysaccharide-stimulated Raw murine macrophages (RAW 264.7), the extract, and compounds 1, 2, and 8 significantly inhibited NO generation. The extract, and compounds 2 and 4 exhibited a cytotoxic effect on human hepatocarcinoma cells (Hep-G2), while the extract, 2 and 8 were potent growth inhibitors of human breast carcinoma (MCF-7). Also, 1 and 2 were remarkable growth inducers of human lymphoblastic leukemia cells (1301), whereas the extract, 2, and 8 stimulated the macrophage proliferation rate.