Isolation and identification of colourless caffeoyl compounds in purple sweet potato by HPLC-DAD–ESI/MS and their antioxidant activities

Identification and quantification of phenolic compounds responsible for the antioxidant activity of sweet potatoes with different flesh colours using high performance thin layer chromatography (HPTLC)

“…Our results are consistent with those published in previous reports for uncooked (Padda and Picha, 2008) and cooked sweet potatoes (Zhao et al, 2014). However, for TCQAs, the coefficients of variation (CVs) of the means were quite high (50-70%), indicating significant variation among accessions within groups, as indicated by a comparison of their minimum and maximum values.…”

“…Microwaving did not reduce the antioxidant capacity of cooked sweet potatoes compared to raw roots (Bellail et al, 2012) and no differences in antioxidant activity were detected between purées made from whole or peeled roots . In cooked sweet potatoes, CGA and 3,5-diCQA were found to be the most abundant (Zhao et al, 2014). Evaluation at harvest indicated that curing did not significantly affect total phenolic acid content.…”

Phenolic compounds and antioxidant activity in sweet potato after heat treatment

“…These hydroxybenzoic acids are acylated with anthocyanin. 3,5‐Diglucoside derivatives from cyanidin and peonidin acylated with p ‐hydroxybenzoic acid, ferulic acid, and caffeic acid, respectively, are found in the highest amounts in purple‐fleshed sweet potato roots; these compounds possess strong antioxidant and 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging activities . Chlorogenic acid is the caffeoylquinic acid derivative present in the highest amounts in different sweet potato varieties.…”

“…3,5-Diglucoside derivatives from cyanidin and peonidin acylated with p-hydroxybenzoic acid, ferulic acid, and caffeic acid, respectively, are found in the highest amounts in purple-fleshed sweet potato roots; these compounds possess strong antioxidant and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities. 25 Chlorogenic acid is the caffeoylquinic acid derivative present in the highest amounts in different sweet potato varieties. Chlorogenic acid is capable of preventing hydroxyl radical formation, scavenging free radicals, and eliminating oxidative activity, in addition to exerting antimutagenic and anticarcinogenic effects in vitro and in vivo.…”

Grown to be Blue—Antioxidant Properties and Health Effects of Colored Vegetables. Part I: Root Vegetables

“…Starch is the main calorific component of sweet-potato tubers with significant variation in its structural and functional properties which depend mostly on the genotype and are not correlated with flesh color [118], although, using a proteomic approach, a recent study revealed that starch degradation may contribute to anthocyanin biosynthesis and accumulation in purple sweet-potato roots [119]. Chlorogenic acid, protocatechuic acid, salicylic acid, and caffeoylquinic acid derivatives are the main phenolic acids detected in purple sweet-potato roots and are responsible for their antioxidant capacity [48,120,121], while orange-fleshed sweet-potato cultivars are rich in provitamin A and also show significant antioxidant activity [113,122,123]. Moreover, in the study of Lebot et al [124], the antioxidant activity of sweet-potato cultivars with purple, orange, and white flesh was correlated mostly with the presence of caffeoylquinic acid derivatives and less with total anthocyanin content, whereas, according to Oki et al [8], the contribution of phenolic compounds in radical-scavenging activity is also dependent on the genotype.…”