Composition of anthocyanins in pomegranate flowers and their antioxidant activity

Anthocyanins in the flowers of pomegranate (Punica granatum L.) were extracted and separated by reverse-phase high-performance liquid chromatography and Sephadex LH-20 chromatography. Two anthocyanins were identified to be pelargonidin 3,5-diglucoside and pelargonidin 3-glucoside by spectral methods, ultraviolet–visible spectroscopy, 1H nuclear magnetic resonance spectroscopy, mass spectroscopy and comparisons with the literature. These two anthocyanins were identified from pomegranate flowers for the first time. Furthermore, the antioxidant activities of purified anthocyanins were screened for their antioxidative potential using 2,2′-diphenyl-1-picryl hydrazyl (DPPH) and 3-ethyl-benzo-thiazoline-6-sulphonate (ABTS) systems. The purified anthocyanins showed strong radical scavenging activities. Pelargonidin 3-glucoside showed higher antioxidant activity (50% inhibition values of 19.56 μg/ml for DPPH and Trolox equivalents antioxidant activity of 2.39 μg/μg for ABTS) than pelargonidin 3,5-diglucoside.