Isolation and identification of colourless caffeoyl compounds in purple sweet potato by HPLC-DAD-ESI/MS and their antioxidant activities.
More than 10 red anthocyanins and related glucosides have been isolated and identified from purple sweet potato (Ipomoea batatas, Ayamurasaki) in the recent decades. This paper reports the isolation of colourless caffeoyl compounds from purple sweet potato using AB-8 macroresin absorption and semi-preparative HPLC-DAD. The structures of the five isolated monomers were identified as: 5-caffeoylquinic acid (1), 6-O-caffeoyl-β-d-fructofuranosyl-(2-1)-α-d-glucopyranoside (2) and trans-4,5-dicaffeoylquinic acid (3), 3,5-dicaffeoylquinic acid (4), 4,5-dicaffeoylquinic acid (5), and by ESI/MS and NMR. Compounds 1, 4 and 5 were reported previously in combination with anthocyanins in purple sweet potato, whereas 2 and 3 were found for the first time. In vitro antioxidant assay showed trans-4,5-dicaffeoylquinic acid has significant antioxidant activities. These results should lay the groundwork for further work identifying purple sweet potato as a healthy food.
Silk Biotechnology Laboratory, School of Biology and Basic Medical Sciences, Soochow University, RM702-2303, No. 199, Renai Road, Dushuhu Higher Edu. Town, Suzhou 215123, PR China.
Jin-Ge
JG
Zhao
Silk Biotechnology Laboratory, School of Biology and Basic Medical Sciences, Soochow University, RM702-2303, No. 199, Renai Road, Dushuhu Higher Edu. Town, Suzhou 215123, PR China.
Qian-Qian
QQ
Yan
Silk Biotechnology Laboratory, School of Biology and Basic Medical Sciences, Soochow University, RM702-2303, No. 199, Renai Road, Dushuhu Higher Edu. Town, Suzhou 215123, PR China.
Ren-Yu
RY
Xue
College of Pharmaceutical Science, Soochow University, No. 199, Renai Road, Dushuhu Higher Edu. Town, Suzhou 215123, PR China. Electronic address: jianzhang@suda.edu.cn.
Jian
J
Zhang
Silk Biotechnology Laboratory, School of Biology and Basic Medical Sciences, Soochow University, RM702-2303, No. 199, Renai Road, Dushuhu Higher Edu. Town, Suzhou 215123, PR China. Electronic address: sericult@suda.edu.cn.
Yu-Qing
YQ
Zhang
D000214:Acyl Coenzyme A / Q000737:chemistry*; D000872:Anthocyanins; D000975:Antioxidants; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D027723:Ipomoea batatas / Q000737:chemistry*; D013058:Mass Spectrometry / Q000379:methods*; D010084:Oxidation-Reduction
D000214:Acyl Coenzyme A; D000872:Anthocyanins; D000975:Antioxidants; C058645:caffeoyl-coenzyme A
Antioxidant activity; Caffeoyl; ESI/MS; NMR; Purple sweet potato; Semi-preparative HPLC