title: Antioxidant compounds from the stem bark of Garcinia atroviridis.
abstract: A new xanthone, namely garcinexanthone G (1), along with eight known compounds, stigmasta-5,22-dien-3β-ol (2), stigmasta-5,22-dien-3-O-β-glucopyranoside (3), 3β-acetoxy-11α,12α-epoxyoleanan-28,13β-olide (4), 2,6-dimethoxy-p-benzoquinone (5), 1,3,5-trihydroxy-2-methoxyxanthone (6), 1,3,7-trihydroxyxanthone (7), kaempferol (8) and quercetin (9), were isolated from the stem bark of Garcinia atroviridis. Their structures were elucidated based on spectroscopic methods including nuclear magnetic resonance (NMR-1D and 2D), UV, IR, and mass spectrometry. All the isolated compounds were evaluated for their antioxidant properties based on the DPPH radical scavenging activities. Results showed that 1,3,7-trihydroxyxanthone and quercetin showed significant antioxidant activities with EC50 values of 16.20 and 12.68 μg/ml, respectively, as compared to the control, ascorbic acid (7.4 μg/ml).
authors.affiliation: a School of Distance Education , Universiti Sains Malaysia , Penang , Malaysia.
authors.forename: Wen-Nee
authors.initials: WN
authors.lastname: Tan
authors.affiliation: b School of Chemical Sciences , Universiti Sains Malaysia , Penang , Malaysia.
authors.forename: Melati
authors.initials: M
authors.lastname: Khairuddean
authors.affiliation: b School of Chemical Sciences , Universiti Sains Malaysia , Penang , Malaysia.
authors.forename: Keng-Chong
authors.initials: KC
authors.lastname: Wong
authors.affiliation: c Section of Bioengineering Technology , Universiti Kuala Lumpur (UNIKL) MICET , Kuala Lumpur , Malaysia.
authors.forename: Woei-Yenn
authors.initials: WY
authors.lastname: Tong
authors.affiliation: d Industrial Biotechnology Research Laboratory, School of Biological Sciences , Universiti Sains Malaysia , Penang , Malaysia.
authors.forename: Darah
authors.initials: D
authors.lastname: Ibrahim
mesh_terms: D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D016227:Benzoquinones; D001713:Biphenyl Compounds / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D029760:Garcinia / Q000737:chemistry*; D008296:Malaysia; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010851:Picrates / Q000494:pharmacology; D044004:Xanthones / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D016227:Benzoquinones; D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D010851:Picrates; D044004:Xanthones; C000611363:garcinexanthone G; C436833:gentisein; C030511:2,6-dimethoxy-1,4-benzoquinone; C004931:1,1-diphenyl-2-picrylhydrazyl
keywords: DPPH radical scavenging activity; Garcinia atroviridis; xanthone