Cytotoxic Constituents from the Stems of Diospyros maritima

Abstract

One novel coumaric acid ester of lupeol, dioslupecin A (1), three naphthoquinones, 8′-hydroxyisodiospyrin (2), isodiospyrin (3), and plumbagin (4), three triterpenes, lupeol, lupenone and taraxerone, and four sterols, β-sitosterol, stigmasterol, stigmast-4-en-3-one and ergosta-4,6,8(14),22-tetraen-3-one were isolated from the n-hexane extract of the stems of Diospyros maritima Blume. The structural determination of 1 was based on 1D and 2D NMR spectra (including ¹H-¹H COSY, ¹H-¹³C COSY, and HMBC). All compounds were evaluated for in vitro cytotoxicity in 4 cancer cell lines. Compound 2 showed similar cytotoxicity against hepatoma (HEPA-3B, ED₅₀ = 1.72 µg/ml), nasopharynx carcinoma (KB, ED₅₀ = 1.85 µg/ml), colon carcinoma (COLO-205, ED₅₀ = 2.24 µg/ml) and cervical carcinoma (HELA, ED₅₀ = 1.92 µg/ml). Compounds 3 and 4 exhibited strong cytotoxicity against HEPA-3B, KB, COLO-205 and HELA (ED₅₀ = 0.25, 1.81, 0.13 and 0.27 µg/ml for 3; ED₅₀ = 0.87, 3.27, 0.56 and 0.35 µg/ml for 4, respectively.