title: Antioxidant and structure-activity relationships of five tetraoxygenated xanthones from Swertia minor (Griscb.) Knobl.
abstract: Antioxidant activity-guided fractionations of chloroform extract of Swertia minor yielded five known tetraoxygenated xanthones (1-5), of which compound 3 was isolated for the first time from plant sources. Compounds 1-5 were identified with the aid of extensive NMR spectroscopic studies. A relationship between the structural features of 1-5 and their antioxidant activity was also determined. Among these bioactive isolates (1-5), compound 4 exhibited strong scavenging effect in DPPH (IC(50) = 10.31 µg mL(-1)), FRAP (8536.32 ± 34.1 Mmol Fe (II) g(-1)) and metal chelating (17.2 ± 0.88 mg EDTA g(-1)) assays. Compound 5 was potently active in secondary antioxidant assay (i.e. binding to metal ions strongly); however, its primary antioxidant capacity was found to be feeble.
authors: Department of Chemistry, School of Chemical Sciences, Bharathiar University, Coimbatore, Tamil Nadu, India.
authors: Chokkalingam
authors: C
authors: Uvarani
authors: Kumarasamy
authors: K
authors: Chandraprakash
authors: Mathan
authors: M
authors: Sankaran
authors: Athar
authors: A
authors: Ata
authors: Palathurai Subramaniam
authors: PS
authors: Mohan
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D001713:Biphenyl Compounds / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010851:Picrates / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry*; D013329:Structure-Activity Relationship; D029967:Swertia / Q000737:chemistry*; D044004:Xanthones / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D001713:Biphenyl Compounds; D010851:Picrates; D010936:Plant Extracts; D044004:Xanthones; C004931:1,1-diphenyl-2-picrylhydrazyl