phytosterols and Leukemia

Structures of some bioactive phytochemicals in bran extract of the black rice cv. Riceberry that had demonstrated anti-cancer activity in leukemic cell line were investigated. After saponification with potassium hydroxide, separation of the unsaponified fraction by reversed-phase high performance liquid chromatography (HPLC) resulted in four sub-fractions that had a certain degree of anti-proliferation against a mouse leukemic cell line (WEHI-3 cell), this being IC50 at 24 h ranging between 2.80-467.11 μg/mL. Further purification of the bioactive substances contained in these four sub-fractions was performed by normal-phase HPLC. Structural characterization by gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance spectroscopy (NMR) resulted in, overall, the structures of seven phytosterols and four triterpenoids. Four phytosterols, 24-methylene-ergosta-5-en-3β-ol, 24-methylene-ergosta-7-en-3β-ol, fucosterol, and gramisterol, along with three triterpenoids, cycloeucalenol, lupenone, and lupeol, were found in the two sub-fractions that showed strong anti-leukemic cell proliferation (IC50 = 2.80 and 32.89 μg/mL). The other sterols and triterpenoids were campesterol, stigmasterol, β-sitosterol and 24-methylenecycloartanol. Together with the data from in vitro biological analysis, we suggest that gramisterol is a significant anti-cancer lead compound in Riceberry bran extract.

Topics: Animals; Antineoplastic Agents, Phytogenic; Cell Line, Tumor; Cholesterol; Chromatography, High Pressure Liquid; Gas Chromatography-Mass Spectrometry; Leukemia; Mass Spectrometry; Mice; Molecular Structure; Oryza; Pentacyclic Triterpenes; Phytosterols; Phytotherapy; Plant Extracts; Seeds; Sitosterols; Stigmasterol; Triterpenes

Fourteen sterols (1-14), including two new sterols, trihydroxysitosterol (2) and 5α,6β,7α-7α-acetoxysitosterol (3), were isolated from the branches and leaves of Phyllanthus emblica L. The isolated compounds and a structurally related sterol 15 from Aphanamixis grandifolia were screened for cytotoxicity in two tumor cell lines (HL-60 and SMMC-7721) and a non-tumor cell line (HL-7702) using RSB assay. Within the series of phytosterol derivatives tested, compound 15 was the most active, displaying potent cytotoxicity against HL-60 with IC(50) of 5.10μmol/L, and most of the active compounds showed selective cytotoxicity against tumor and non-tumor cell lines, especially compound 10 with a safety index of 4.42.

Topics: Antineoplastic Agents, Phytogenic; Carcinoma, Hepatocellular; Cell Line; Humans; Leukemia; Liver Neoplasms; Molecular Structure; Phyllanthus emblica; Phytosterols; Plant Components, Aerial; Structure-Activity Relationship