Maceaene and macamide contents as well as antioxidant effect of petroleum ether extract of black maca (BM), yellow maca (YM), and purple maca (PM) on diabetes mellitus (DM) rats were investigated. The results showed that seven, six, and five analogues of macamides were identified from the petroleum ether extracts of BM, YM, and PM, respectively. BM extract exhibited the highest contents of total macamides. Comparatively, the PM extract has the lowest macamide quantity. The maceaene contents in all the extracts showed no significant difference (p>0.05). Macamide contents in maca with the same color were not statistically different. Pharmacological results showed that 60-day oral administration of the petroleum ether extract of maca (100 mg/kg.d) can significantly decrease lipid oxidation as indicated by the decreased thiobarbituric acid reactive substances (TBARS) and carbonylated proteins (CP) concentrations on DM rat model (P<0.05). Among them, oral administration of PM extract showed the lowest TBRAS and CP concentrations. All maca extracts can enhance antioxidant enzyme (SOD, superoxide dismutase; CAT, catalase) activity of liver and red blood cells (RBC) of DM rat. However, only oral administration of PM extract can increase SOD and CAT activity of both RBC and liver. The glutathion (GSH) contents in plasma were significantly increased in DM rats treated with PM extract (p<0.05). But, oral administration of BM and YM extracts did not enhance GSH levels. Take together, the data suggested that PM extract exhibited the most potent antioxidant activity on DM rat model. And, maceaene and macamide in maca extract was not correlated with its antioxidant ability.
maca extract; antioxidant activity; maceaene; macamide; diabetes mellitus rat