Stability and Antioxidant Activity of Polyphenols in Methanolic Extracts of Sonneratia caseolaris Seeds
Polyphenols in methanolic extracts from Sonneratia caseolaris seeds were determined by HPLC coupled with electrospray mass spectrometry and quantified by HPLC coupled with ultraviolet/visible detection in order to evaluate their stability of the extracts during 6 months of storage. Antioxidant activity was measured by using TEAC assay, and the free radical scavenging activity was monitored in the initial 3 months of the stability evaluation. Study on the effect of temperature on the stability of the methanolic extract indicated that gallic acid, luteolin-7-O-glucoside, and luteolin were unstable at 25 and 45°C during storage time. At -80 and 4°C the quantities of luteolin-7-O-glucoside reduced while those of luteolin increased at the same time. The results suggested that luteolin-7-O-glucoside was hydrolyzed to luteolin. Therefore the polyphenols should be kept at low temperature. Antioxidant activity of methanolic extract was preserved in all temperatures during the first 3 months.
Sihai Jiao, Zhengyi Jiang and Jinglong Bu
C. Limmatvapirat (1) et al., "Stability and Antioxidant Activity of Polyphenols in Methanolic Extracts of Sonneratia caseolaris Seeds", Advanced Materials Research, Vols. 146-147, pp. 1062-1065, 2011