Terpenoids from Ardisia squamulosa

Abstract

The genus Ardisia Swartz belongs to the family Myrsinaceae. Ardisia has 68 recorded species in the Philippines [1], 60 of which are endemic. The hexane extract from A. squamulosa was reported to have a significant effect on sperm count but has a negligible effect on sperm morphology and viability [2]. No chemical study of A. squamulosa has been reported. However, we earlier studied a congener of this plant, Ardisia pyramidalis, which afforded spinasterol, spinasteryl acetate, a mixture of -amyrin, -amyrin and bauerenol, squalene, lutein, and triglycerides from the dichloromethane (DCM) extract of the leaves. Spinasterol was found to exhibit anti-angiogenic potential [3]. This study was conducted as part of our research on the chemical constituents of Ardisia species found in the Philippines. We report herein the chemical constituents of the DCM extract of the leaves of A. squamulosa. Fresh leaves of Ardisia squamulosa were collected from Kanawan, Morong Bataan, Philippines in 2010 by Ramon Bandong. The sample was authenticated by the Jose Vera Herbarium Collection at the Institute of Biology of the University of the Philippines-Diliman and the Philippine National Museum, Manila. The DCM extracts of the air-dried leaves of A. squamulosa afforded terpenoids by silica gel chromatography. These compounds were identified by comparison of their 13C NMR data with those of -caryophyllene (1) [4], squalene (2) [5], bauerenone (3a) [6], ursenone (3b) [7], oleanone (3c) [7], bauerenol (4a) [6], -amyrin (4b) [8], -amyrin (4c) [8], and lutein (5) [9] reported in the literature. Air-dried leaves of Ardisia squamulosa (1 kg) were ground in an Osterizer and then soaked in DCM for three days and filtered. The filtrate was concentrated in vacuo to afford a crude extract (55 g), which was chromatographed in increasing proportions of acetone in dichloromethane at 10% increment. The DCM fraction was rechromatographed (6 ) in petroleum ether to afford 1 (5 mg) and 2 (20 mg). The 10% acetone in DCM and 20% acetone in DCM fractions were combined and rechromatographed (4 ) with 2.5% ethyl acetate in petroleum ether as eluent to afford a mixture of 3a–3c (12 mg). The 30% acetone in DCM fraction was rechromatographed (5 ) using 5% ethyl acetate in petroleum ether to afford a mixture of 4a–4c (15 mg). The 40% acetone in DCM and 50% acetone in DCM fractions were combined and rechromatographed (3 ) with DCM–diethyl ether–acetonitrile (9:0.5:0.5) as eluent to afford 5 (18 mg) after washing with diethyl ether.