title: Spectroscopic identification of new ellagitannins and a trigalloyl-glucosylkaempferol from an extract of Euphorbia cotinifolia L. with antitumour and antioxidant activity.
abstract: From an extract of leaves and small branches of Euphorbia cotinifolia L., 17 polyphenols were isolated including two new ellagitannins and a trigalloyl-glucosylkaempferol. Based on extensive spectral data (UV, ESI-MS, 1H NMR, DEPT and 1D/2D NMR) and chemical studies, their structures were characterized as 1-O-galloyl-3,6-hexahydroxydiphenoyl-D-B1,4-glucopyranose (5), 1-O-galloyl-3,6-valoneoyl-D-B1,4-glucopyranose (6), and kaempferol 3-O-(2",3",6"-tri-O-galloyl)-beta-D-glucopyranoside (13). Biological evaluation indicated that the 80% aqueous methanol extract (AME), chloroform extract (CE), and some pure compounds have potent scavenging activity in the DPPH assay with SC50 values lower than that of ascorbic acid, especially 5, 7-9, and a mixture of hyperin 6"-gallate (11) and isoquercitrin 6"-gallate (12). Moreover, using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) cell viability assay, 6 and 8 exhibited the highest inhibition of human hepatocellular carcinoma cells (Hep-G2), while AME, CE, 5, 7, 9, and the mixture of 11 and 12 were found to be moderate growth inhibitors according to their IC50 values. In addition, AME, 5, and 8 exhibited significant antiproliferative activity against colon carcinoma cells (HCT-116); however, CE and the other examined compounds displayed moderate to low antitumour activity against HCT-116 cells.
authors.affiliation: Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh 11451, Saudi Arabia. msmarzouk@yahoo.co.uk
authors.forename: Mohamed S
authors.initials: MS
authors.lastname: Marzouk
authors.forename: Fatma A
authors.initials: FA
authors.lastname: Moharram
authors.forename: Amira
authors.initials: A
authors.lastname: Gamal-Eldeen
authors.forename: Iman M
authors.initials: IM
authors.lastname: Damlakhy
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology*; D028481:Euphorbia / Q000737:chemistry*; D006801:Humans; D047348:Hydrolyzable Tannins / Q000494:pharmacology*; D044949:Kaempferols / Q000494:pharmacology*; D009682:Magnetic Resonance Spectroscopy; D010936:Plant Extracts / Q000494:pharmacology*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D000975:Antioxidants; D047348:Hydrolyzable Tannins; D044949:Kaempferols; D010936:Plant Extracts; C006552:kaempferol