Abstract:

The total antioxidant activity (TAC) of ethanol extracts of different color types (white, yellow and purple) of maca (Lepidium meyenii Walpers) cultivated at different altitude areas (2000, 2500, 3000 m and 3200 m) in Yunnan was measured by ferric reducing antioxidant power (FRAP) assay. Also, their scavenging activities against hydroxyl free radicals generated from Fenton reaction, DPPH free radicals and superoxide anion free radicals by a pyrogallol autooxidation system were evaluated. The results indicated that ethanol extracts of 3 color types of maca cultivated in Yunnan all had dose-dependent total antioxidant and free radical scavenging effects. Purple maca presented the highest TAC, followed by yellow and white macas. The DPPH free radical scavenging activity of white maca was lower than those of other two color types of maca. A higher TAC and a higher DPPH free radical scavenging activity were both observed in maca cultivated at 3200 m-altitude area than that from lower altitude areas. Three color types of maca were all able to remarkably scavenge hydroxyl radicals, with a scavenging ratio of more than 90% at a dose of 200 μL and yellow maca cultivated at 3000 m-altitude area had the best hydroxyl free radical scavenging activity. Three color types of maca all had only weak scavenging effect on superoxide anion free radicals.

Key words: maca (Lepidium meyenii Walpers), color type, antioxidation, free radicals