Study On The Quality Identification And Activity Of Chinese Maca

Maca(Lepidium meyenii Walp.)is an annual or biennial herb belonging to the Brassicaceae family,which originates from the Andes region of South America.Maca has a long history of consumption,and is traditionally taken as a food to enhance physical strength and improve sexual function.Maca powder was approved as a new resource food by the Ministry of Health in May 2011 and was recognized by the market.Since then,Maca had been widely cultivated in some high-altitude areas such as Yunnan,Sichuan and Xizang.Due to the lack of scientific and standardized industry standards,the market was gradually flooded with low-quality Maca.The overall Maca industry fell from the peak to the bottom at the end of 2015.Therefore,this study took Chinese Maca as the research object.Through systematic research on processing methods,origin traceability and quality identification,we laid the foundation for Maca quality identification and standards.Moreover,the different extraction components and polysaccharides of Maca powder were studied in order to further reveal the material basis and mechanism of action about reducing blood glucose and adjust lipid metabolism.This research will contribute to the healthy development of the standardization of Maca industry.The main results were described as follows:(1)Construction of Maca origin traceability database systemBack propagation neural network(BP)algorithm was applied to build two levels traceability database of Maca origin based on electronic nose odor fingerprint.The database could accurately identify the origin of unknown Maca samples(accuracy of training and test sets were basically more than 70%).Through gas chromatography-mass spectrometry(GC-MS)in series TQ8040 triple quadrupole rod,combined with Shimadzu's Off-Flavor odor analysis system,we explored the differences in odor composition from different origins.The results showed that there were significant differences in the contents of volatile compounds in Maca from different origins,and 45 different metabolites were screened out by variable importance in projection(VIP).Regression analysis was performed on the sensor response value and the content of volatile compounds.The results showed that the 11 sensors optimized by the stepwise discriminant analysis had a very significant correlation with specific compounds.This experiment provided a method for identifying Maca from different origins based on the combination of electronic nose,GC-MS and pattern recognition methods,and finished theoretical and data support for the rapid traceability.(2)Construction of database system for Maca grading identificationThe total content of macamides and the response value of the odor sensors were detected by high performance liquid chromatography(HPLC)and electronic nose,respectively.Based on the results of the correlation analysis,the Maca quality rapid identification database was established using the soft independent modelling of class analogies(SIMCA)algorithm.The results showed that there was a significant correlation between the three sensors LY2/G,PA/2and T40/2 and the content of macamides.According to the SIMCA model established by the three sensors,the different Maca samples could be divided into 3 grades: special grade(the content of macamides ? 1.2 g/kg),first grade(0.8 g/kg ? the content of macamides < 1.2g/kg),second grade(0.2 g/kg ? the content of macamides < 0.8 g/kg).Using the electronic nose odor detection data combined with the SIMCA model could infer the content range of macamides in the measured samples,also quickly identify the grade of Maca.(3)Effect of different extract of Maca on the model of cell glucose and lipid metabolism disorderSix Maca extract components were obtained by extraction with different solvents.They were Maca crude polysaccharide(MPE),Maca alcohol extract(MEE),petroleum ether extract(PE),ethyl acetate extract(EA),n-butanol extract(NBT)and water extract(WAT).Among them,NBT contained the most polyphenols and flavonoids,and had the strongest antioxidant capacity in vitro.The results showed that high concentrations of MPE and MEE could promote the intracellular glucose uptake,and had a tendency to promote the release of intracellular triglyceride(TG)to the outside of the cell,but had little effect on the intracellular TG content.Among the graded extracts,NBT had the best effect on lowering blood glucose and regulating blood lipid.As the concentration exaltation,the effect of Maca on promoting the absorption of glucose by cells was gradually increased,and the content of intracellular and extracellular TG was elevated at the same time.At the genetic level,NBT could regulate cellular glucose and lipid metabolism by activating the phosphatidylinositol 3-kinase(PI3K)/protein kinase B(Akt)signaling pathway.And its effect was similar to that of metformin.(4)Using zebrafish model to investigate the effect of Maca polysaccharides on disorders of glucose and lipid metabolismUsing zebrafish as a model,the components of MPE were researched in depth.First of all,MPE was separated to obtain the total Maca polysaccharide(total MPS),which was further purified to obtain three Maca polysaccharide components(MPS1,MPS2 and MPS3).The molecular weight and monosaccharide composition of them were determined using a multi-angle laser light scattering gel chromatography system(SEC-MALLS)and ion chromatography.Secondly,the zebrafish model was established to evaluate the effect of three polysaccharide components,total MPS and Maca powder on regulating glucose and lipid metabolism.The results showed that the maximum detection concentration of MPS1,MPS2,MPS3 and total MPS had no obvious effect on blood glucose reduction,and had a significant lipid-lowering effect.However,the effect of Maca powder was more obvious.At the genetic level,this study explained that MPS1,MPS3,total MPS and Maca powder could enhance insulin sensitivity to lower blood glucose and regulate blood lipid by activating the PPAR?signaling pathway.And its effect was similar to that pioglitazone.