Extraction Storage and Qualitative Analysis of Active Substance for Scavenging Free Radicals in Sweet Potato Leaves

[Objective] The research aimed to provide theoretical basis for applying extracts from sweet potato leaves in antiaging cosmetics.[Method] The extraction and storage conditions of active substances for scavenging free radicals in sweet potato leaves were optimized by orthogonal test and the active components for scavenging free radicals in the extracts were discussed by correlation analysis.[Result] Sweet potato leaves contained the active substances that scavenged DPPH free radicals and hydroxyl free radicals.The extractant species were the most important factors that affected the extraction rate of active substances.The optimum extraction and storage conditions were as follows: with water as extraction solvent,the pH value of the extraction liquid was 8 and the optimum storage temperature was 25 ℃.The total phenol content in the extracts from sweet potato leaves showed direct proportional relations with the scavenging rates of DPPH free radicals and hydroxyl free radicals and they had good linear relationships.The total flavone content only had better linear relations with the scavenging rate of hydroxyl free radicals.[Conclusion] Phenols in the extracts can effectively scavenge DPPH free radicals and hydroxyl free radicals,while flavonoids in the extracts only can effectively scavenge hydroxyl free radicals.