Study On Chemical Compositions And Antioxidant Activies Of Maca From Different Habitats

Maca(Lepidium meyenii),a Peruvian plant with a long history,is growing in the Central Andean Region of Peru between 4000 and 4500 m altitude.It is also planted in Yunnan,Sichuan and Qainghai Province,in China.At present,a large amount of Maca planted in China's western region brought local economic benefit,however,the resulting question is the quality of the Maca products,which should be paid more attention due to the large diversity of nutrient components and active ingredient.Therefore,it is necessary and essential for establishing the quality standards which are applied for differentiating advantages and disadvantages of Maca grown in different districts,thus the quality of Maca products could be cotrolled.In the present work,Maca from Yunnan,Sichuan and Qinghai Province in China was used as raw material.Firstly,conventional nutrient components including protein,energy,moisture,ash,fat,carbohydrate sugar,trace elements,and amino acids,was analysed.Subsequently,the contents of flavonoids,polyphenols,specific components of glucosinolates,and Maca amide were measured for Maca grown different districts.Finally,the effect of Maca extracts on antioxidant activity was investigated.These results indicate that Maca growing in Peru contains significantly less proteins and amino acids than others.The contents of protein and amino acid for Maca growing in Peru are 9.24/100 g and 98 mg/g,respectively,while the contents of protein and amino acids for others are more than 16 g/100g and 150 mg/g,respectively.However,the contents of trace elements have no obvious diversity in Maca growing in different districts,among which potassium element has largest content up to 1697 mg/g.In addition,Maca growing in Yunnan,Peru,Sichuan and Qinghai Province contains 18,16,15 and 15 types of fatty acid,respectively.Among these fatty acid,unsaturated linoleic acid accounts for more than 50%for all Maca.The comparison of the measurement of active component content shows that total flavonoids contents of Maca from Yunnan,Sichuan,Qinghai,and Peru are 2.23%,2.35%,1.88%,and 2.63%,respectively,while total polyphenol contents are 3.12%,3.08%,2.76%,and 3.47%,respectively.The detection via palladium chloride method indicates that the contents of glucosinolate from Maca growing in Sichuan,Peru,Yunnan,and Qinghai are 7.55 mg/g,6.45 mg/g,5.29 mg/g,and 4.52 mg/g,respectively.The relative contents of Macamides are also calculated via HPLC-MS,indicating that the relative contents of Macamides from Maca growing in Yunnan,Peru,Sichuan and Qinghai province are 39.73,26.46,23.72,and 13.14,respectively.The antioxidant activities of extracts from Maca in vitro were also tested.The results show that,for the extracts in ethanol,water,and the mixture of Yunnan Maca,the free radical scavenging rates of DPPH are 85.98%,68.97%,and 94.22%,respectively;the free radical scavenging rates of ABTS are 98.5%,and 94.75%,respectively;absorbance of reduction force are 2.872,2.69 and 1.005,respectively;free radical scavenging rates of hydroxyl are 95.43%,63.71%,and 94.12%,respectively.In this study,the results of component analysis and comparison for Maca growing in different district may offer a valuable reference,which contributes to establish quality standards of Maca.