Isolation and Structure Elucidation of Highly Antioxidative 3,8 %26apos;%26apos;-Linked Biflavanones and Flavanone-C-glycosides from Garcinia buchananii Bark

作者：Stark Timo D^*; Matsutomo Toshiaki; Loesch Sofie; Boakye Paul A; Balemba Onesmo B; Pasilis Sofie P; Hofmann Thomas

来源：Journal of Agricultural and Food Chemistry, 2012, 60(8): 2053-2062.

DOI：10.1021/jf205175b

• 3,8 %26apos
• %26apos
• -linked biflavanones
• flavanone-6-C-glycosides
• Garcinia buchananii
• (2R,3S,2 %26apos
• %26apos
• R,3 %26apos
• %26apos
• R)-manniflavanone
• (2R,3S,2 %26apos
• %26apos
• S)-buchananiflavanone
• antioxidants

The aim of this study was to identify antioxidants from Garcinia buchananii bark extract using hydrogen peroxide scavenging and oxygen radical absorbance capacity (ORAC) assays. LC-MS/MS analysis, 1D- and 2D-NMR, and circular dichroism (CD) spectroscopy led to the unequivocal identification of the major antioxidative molecules as a series of three 3,8 %26apos;%26apos;-linked biflavanones and two flavanone-C-glycosides. Besides the previously reported (2R,3R,2 %26apos;%26apos; R,3 %26apos;%26apos; R)-naringenin-C-3/C-8 %26apos;%26apos; dihydroquercetin linked biflavanone (GB-2; 4) and (2R,3S,2 %26apos;%26apos; R,3 %26apos;%26apos; R)-manniflavanone (3), whose stereochemistry has been revised, the antioxidants identified for the first time in Garcinia buchananii were (2R,3R)-taxifolin-6-C-beta-D-glucopyranoside (1), (2R,3R)-aromadendrin-6-C-beta-D-glucopyranoside (2), and the new compound (2R,3S,2 %26apos;%26apos; S)-buchananiflavanone (5). The H2O2 scavenging and the ORAC assays demonstrated that these natural products have an extraordinarily high antioxidative power, especially (2R,3S,2 %26apos;%26apos; R,3 %26apos;%26apos; R)-manniflavanone (3) and GB-2 (4), with Egg) values of 2.8 and 2.2 mu M, respectively, and 13.73 and 12.10 mu mol TE/mu mol. These findings demonstrate that G. buchananii bark extract is a rich natural source of antioxidants.

• 出版日期2012-2-29