title: Chemical constituents from Tribulus terrestris and screening of their antioxidant activity.
abstract: Two oligosaccharides (1,2) and a stereoisomer of di-p-coumaroylquinic acid (3) were isolated from the aerial parts of Tribulus terrestris along with five known compounds (4-8). The structures of the compounds were established as O-β-D-fructofuranosyl-(2→6)-α-D-glucopyranosyl-(1→6)-β-D-fructofuranosyl-(2→6)-β-D-fructofuranosyl-(2→1)-α-D-glucopyranosyl-(6→2)-β-D-fructofuranoside (1), O-α-D-glucopyranosyl-(1→4)-α-D-glucopyranosyl-(1→4)-α-D-glucopyranosyl-(1→2)-β-D-fructofuranoside (2), 4,5-di-p-cis-coumaroylquinic acid (3) by different spectroscopic methods including 1D NMR ((1)H, (13)C and DEPT) and 2D NMR (COSY, TOCSY, HMQC and HMBC) experiments as well as ESI-MS analysis. This is the first report for the complete NMR spectral data of the known 4,5-di-p-trans-coumaroylquinic acid (4). The antioxidant activity represented as DPPH free radical scavenging activity was investigated revealing that the di-p-coumaroylquinic acid derivatives possess potent antioxidant activity so considered the major constituents contributing to the antioxidant effect of the plant.
authors: Department of Pharmacognosy, Faculty of Pharmacy, Alexandria University, Egypt. hala_hammoda@yahoo.com
authors: Hala M
authors: HM
authors: Hammoda
authors: Nabila M
authors: NM
authors: Ghazy
authors: Fathalla M
authors: FM
authors: Harraz
authors: Mohamed M
authors: MM
authors: Radwan
authors: Mahmoud A
authors: MA
authors: ElSohly
authors: Ingy I
authors: II
authors: Abdallah
mesh_terms: D000975:Antioxidants / Q000737:chemistry* / Q000302:isolation & purification; D015394:Molecular Structure; D009844:Oligosaccharides / Q000737:chemistry* / Q000302:isolation & purification; D011801:Quinic Acid / Q000737:chemistry* / Q000302:isolation & purification; D032444:Tribulus / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D009844:Oligosaccharides; D011801:Quinic Acid