Chemical Constituents of the Plant Antidesma ghaesembilla

Abstract

Antidesma ghaesembilla Gaertn. of the family Phyllanthaceae is a plant indigenous to the Philippines. Locally known as binayuyo, the young shoots are used as a vegetable and as a spice [1]. The leaves are used as a poultice to treat headaches, scurf, abdominal swellings, and fevers; the stems are emmenagogue, and the fruit is purgative. The fully ripe fruit can be eaten raw, cooked, or made into jams and jellies [2]. A previous study reported that the crude methanolic extract of A. ghaesembilla Gaertn. leaves exhibited moderate to strong antioxidant potential and significant hypoglycemic potential [3]. Recently, the methanol extract of A. ghaesembilla Gaertn. leaves was reported to exhibit antithrombotic, cytotoxic, and antibacterial activities [4]. The poultice of the flower was used in Thailand to treat herpes simplex and herpes zoster [5]. Chemical studies on the leaves of A. ghaesembilla reported the isolation of a megastigmane, vomifoliol [6], and the flavone glycosides vitexin, orientin, isovitexin, and homoorientin [7]. We earlier reported the isolation of β-friedelinol, lupeol, squalene, polyprenol, β-sitosterol, long-chain hydrocarbons, and chlorophyll a from the leaves, and β-sitosterol and triacylglycerols from the fruit of A. ghaesembilla [8]. In this study, chemical investigation of the dichloromethane extracts of A. ghaesembilla has led to the isolation of 5,7-dihydroxy-2-heneicosyl4H-chromen-4-one (1), β-sitosteryl-3β-glucopyranoside-6′-O-palmitate (2), betulinic acid (3), lupeol fatty acid ester (4), alkyl trans-ferulates (5), β-sitosterol (6), saturated long-chain alkyl fatty acid esters (7) from the bark; 1, 7, squalene (8), and friedelin (9) from the twigs; 6–8, long-chain fatty alcohols (10), and long-chain hydrocarbons (11) from the flowers; and 1, 3, and a mixture of pseudotaraxasterol (12a), taraxasterol (12b), β-amyrin (12c), and α-amyrin (12d) in about 4:1.5:1:1 ratio from the roots. The structure of 1 was elucidated by extensive 1D and 2D NMR spectroscopy and confirmed by EI-MS, while those of 2–12d were identified by comparison of their NMR data with literature data. To the best of our knowledge, this is the first report on the isolation of 1–5, 7, 9, 10, and 12a–12d from A. ghaesembilla. The air-dried A. ghaesembilla bark (173.4 g), twigs (197.5 g), flowers (136.8 g), and roots (156.7 g) were ground in a blender, soaked in CH2Cl2 for 3 days, and then filtered. The solvent was evaporated under vacuum to afford crude extracts of bark (0.35 g), twigs (1.16 g), flowers (2.64 g), and roots (0.40 g), which were each chromatographed using increasing proportions of acetone in CH2Cl2 at 10% increment by volume. The CH2Cl2 fraction from the chromatography of the crude bark extract was rechromatographed using petroleum ether (PE) to afford 7 (1.8 mg). The 10% and 20% acetone in CH2Cl2 fractions were rechromatographed using 2.5% EtOAc in PE. The less polar fractions yielded 4 (1.6 mg), while the more polar fractions were rechromatographed using 10% EtOAc in PE to provide 5 (3.8 mg). The 30% and 40% acetone in CH2Cl2 fractions were rechromatographed using 15% EtOAc in PE.