Chemical constituents and cytotoxic activity of the root wood of Magnolia kachirachirai

Abstract

Magnolia kachirachirai (Kanehira Yamamoto) Dandy (Magnoliaceae) is a large endemic evergreen tree growing in the southeastern part of Taiwan. The methanolic extract of the root wood of this species has shown cytotoxicity on high-throughput screening against MCF-7 (breast cancer), NCI-H460 (lung cancer) and SF-268 (central nervous cancer) cancer cell lines and was partitioned into neutral CHCl3, tertiary base, n-BuOH, and H2O-soluble layers. The neutral CHCl3-soluble layer showed cytotoxicity against these cancer cell lines. Investigation of the active CHCl3-soluble layer by column chromatography and prep. TLC has led to the isolation of one new compound: kachiraterpenol (1), along with twenty known compounds: costunolide (2), α-cyclocostunolide (3), T-cadinol (4), dehydrosaussurea lactone (5), dihydro-β-cyclocostunolide (6), N-acetylanonaine (7), N-acetyldehydroanonaine (8), N-acetylnorstephalagine (9), glaberide I (10), a mixture of 6-(3-methoxy-4-hydroxyphenyl)-3,7-dioxabicyclo-[3.3.0]-octan-2-one (11) and 6-(3-hydroxy-4,5-dimethoxyphenyl)-3,7-dioxabicyclo-[3.3.0]octan-2-one (12), syringaldehyde (13), linoleic acid (14), 1,2-dipalmitoyl-3-oleoylglycerol (15), a mixture of β-sitosterol (16) and stigmasterol (17), a mixture of (24R)-stigmast-4-en-3-one (18) and (22E,24S)-stigmast-4,22-dien-3-one (19), a mixture of (24R)-6β-hydroxystigmast-4-en-3-one (20) and (22E,24S)-6β-hydroxystigmast-4,22-dien-3-one (21). The structures of these isolates were elucidated by spectral analysis. The sesquiterpenoid costunolide (2) as major component showed cytotoxicity against MCF-7, NCI-H460 and SF-268 (IC50: 5.3, 6.9, 5.3µg/mL) cancer cell lines in vitro.