Two new flavonoid glycosides isolated from the fruits of Catalpa ovata

Background: Catalpa ovata, widespread in China, Japan, and Korea, is receiving greater attention due to its potent pharmacological properties. Objectives: This communication report presents the results of chemical investigation and antioxidant capacity of the fruits of C. ovata. Materials and Methods: The polar fraction from the fruits of C. ovata was isolated using various chromatographic methods and their structures were identified through nuclear magnetic resonance spectrometry and high-resolution mass spectrometry, and the data were compared with the reported literature. Total antioxidant activity was analyzed using the total antioxidant capacity assay kit with a rapid ABTS method. Results: Cavonosides A and B (1 and 2), two new flavonoid glycosides, together with 13 known phenols (3–15), were obtained from the fruits of C. ovata. The antioxidant capacity of compounds 4, 7, 10, 13, and 15 was approximately equal to that of Vitamin C at the same concentration. Conclusion: This research work resulted in two new flavonoid glycosides (1 and 2) and 13 known phenols isolated from the fruits of C. ovata; among them, compounds 4, 7–10, and 13 were newly isolated from this genus. According to our results, the antioxidant capacity of compounds 4, 7, 10, 13 and 15 was approximately same as that of Vitamin C at the same concentration. We also discuss the structure–activity relationships of the isolated compounds.