Sweetpotato (Ipomoea batatas l.) leaf: its potential effect on human health and nutrition

Previous experiments revealed that sweetpotato leaves contain a high content of polyphenolics, namely anthocyanins and phenolic acids, compared with the major commercial vegetables. Sweetpotato leaves contain at least 15 biologically active anthocyanins that have significant medicinal value for certain human diseases and may also be used as natural food colorants. The anthocyanins were acylated cyanidin and peonidin type. The phenolic acids were composed of caffeic acid (CA) and 5 kinds of caffeoylquinic acid derivatives, 3-mono-O-caffeoylquinic acid (chlorogenic acid, ChA), 3,4-di-O-caffeoylquinic acid (3,4-diCQA), 3,5-di-O-caffeoylquinic acid (3,5-diCQA), 4,5-di-O-caffeoylquinic acid (4,5-diCQA), and 3,4,5-tri-O-caffeoylquinic acid (3,4,5-triCQA). These polyphenolics showed various kinds of physiological functions, radical scavenging activity, antimutagenic activity, anticancer, antidiabetes, and antibacterial activity in vitro or in vivo, which may be helpful for maintaining and promoting human health. The physiological function of caffeoylquinic acid (CQA) derivatives with the plural caffeoyl group is more effective than with a monocaffeoyl one. This review describes the nutritional composition and physiological functions of sweetpotato leaves when used as a vegetable, and as a resource for products with these functions.