Profiling of phenolic acids and flavonoids in sweet potato (Ipomoea batatas L.) leaves and evaluation of their anti-oxidant and hypoglycemic activities

Sweet potato (Ipomoea batatas L.) leaf phenolic acids (SPLPA) and sweet potato leaf flavonoids (SPLF) were characterized using ultra-high-performance liquid chromatography (UHPLC)-hybrid quadrupole-orbitrap mass spectrometry and UHPLC coupled with a diode array detector. The anti-oxidant and hypoglycemic activities were analyzed using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), 1,1-diphenyl-2-picrylhydrazyl radical scavenging capacity and ferric reducing anti-oxidant powder assays, and alpha-glucosidase and alpha-amylase inhibitory assays. The mechanism of inhibition of SPLPA and SPLF against alpha-glucosidase was studied using kinetic analysis. Thirteen phenolic acids were identified in SPLPA, of which three di-caffeoylquinic acids (60.6%) were most prominent. Ten flavonoids were identified in SPLF and astragalin (28.1%) was the major component. Protocatechualdehyde, ethyl caffeate and quercetin were also identified, showing strong anti-oxidant capacities and inhibition of alpha-glucosidase and alpha-amylase. Kinetic analysis showed that SPLPA and SPLF both reversibly inhibited alpha-glucosidase, in a mixed-type manner, with IC50 values of 330 and 250 mu g/mL, respectively. The results suggested the potential benefits of using sweet potato leaves.

Automated summary

The study characterized phenolic acids and flavonoids in sweet potato leaves using advanced chromatography techniques and demonstrated their antioxidant and hypoglycemic activities through various assays. Results showed the potential health benefits of sweet potato leaves, indicating positive effects on inhibiting alpha-glucosidase and other enzymes.