Comprehensive characterization and antioxidant activities of the main biflavonoids of Garcinia madruno: A novel tropical species for developing functional products

The aim of the study was to determine the qualitative and quantitative plant secondary metabolite profile of Garcinia madruno by LC-MSn and to evaluate the structure-activity relationship (SAR) with its antioxidant properties. A total of 21 biflavonoids and 3 organic acids were identified. The leaves were the most promising source of biflavonoids, and the epicarp was the richest source of morelloflavone type biflavonoids (>10%). Morelloflavone and fukugiside were the major biflavonoids found in all samples as well as the compounds responsible for antioxidant activity. The inter-flavonoid bond did not increase the antioxidant activity by single electron transfer (SET) mechanism but increased the activity by single proton-loss electron transfer (SPLET) mechanism. The results suggest that G. madruno contains potentially useful amounts of bioactive biflavonoids; in particular, the leaves and epicarp may be a potential source of functional products.