Effects on the Oxidation-of Human Low-density Lipoprotein and Antioxidant Activities of Tai-Long-57 Sweet Potato Vines

Antioxidant activities of sweet potato vines and their corresponding in vitro effects on the oxidation of human low-density lipoprotein (LDL) were studied in this subject. The results showed that total phenol and flavonoid contents in 80% methanol extracts were greater than their respective counterparts in water extracts. The effectiveness of 1,1-diphenyl-s-picryl-hydrazyl (DPPH) scavenging activity and Fe^(2+)-chelating activities of sweet potato vines of 80% methanol extracts were higher than those of water extract. The DPPH IC_(50) values of 80% methanol extracts and water extracts were 4.91 and 11.68 mg/mL, respectively; and the Fe^(2+)-chelating activities of vines 80% methanol extract were greater than those of water extract by 3.36~3.97 folds. The 80% methanol extract at 200 μg/mL decreased 83.3% (p＜0.01) thiobarbituric acid-reactive substances (TBARS) of human LDL, and extended the lag time of human LDL from 1 to 4 h at 20 μg/mL. These findings suggest that 80% methanol extract of sweet potato vines has significantly inhibitory activities against copper ion-induced LDL oxidation.