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Natural Product Research Part A
Year: 2012  |  Volume: 26  |  Issue: 3  |  Page No.: 243 - 254

Activity-guided isolation and identification of free radical-scavenging components from various leaf extracts of Sorbus aria (L.) Crantz

Monika A. Olszewska and Piotr Michel    

Abstract: Nine phenolics were obtained from the leaves of Sorbus aria (L.) Crantz by activity-directed isolation: isorhamnetin 3-O-β-glucopyranoside (1), astragalin (2), isoquercitrin (3), hyperoside (4), kaempferol 3-O-β-glucopyranoside-7-O-α-rhamnopyranoside (5), quercetin 3-O-β-glucopyranoside-7-O-α-rhamnopyranoside (6), rutin (7), chlorogenic acid (8) and neochlorogenic acid (9). The isolates were identified by spectral methods (UV, 1H- and 13C-NMR, COSY, HMQC and HMBC), and their free radical-scavenging activity was tested using the l,l-diphenyl-2-picrylhydrazyl (DPPH) method. The antioxidant potential of the different extracts obtained in the fractionation process was evaluated using the DPPH test in relation to the HPLC contents of the isolates 19, total phenolics and total proanthocyanidins. Among the analytes tested, superior activity was expressed by isoquercitrin (3, EC50 = 2.76 mg L−1) and the ethyl acetate extract (EC50 = 2.99 mg L−1). Five strongly active isolates 3, 6, 7, 8 and 9 were found to be major components and to be principally responsible for the radical-scavenging activity of S. aria extracts.

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