Comparative Study On Polyphenol Contents And Antioxidant Activities Of Different Ploidy Echinacea Purpurea(L.)moench

Echinacea purpurea（L.）Moench is a perennial herb of Echinacea in Asteraceae.It is a kind of popular medicinal plant with great development and utilization value.E.purpurea not only has good immune enhancement,anti-inflammatory and anti-viral activities,but also has strong antioxidant activity.Its main medicinal components contain not only polysaccharide glycoproteins and alkylamides,but also polyphenols（caffeic acid derivatives and flavonoids）.However,the accumulation dynamics of polyphenols in different parts of E.purpurea and its relationship with antioxidant activity,especially the changes in the anti-oxidation activity accompanying with polyphenols accumulation in E.purpurea need to be further studied after doubling the number of chromosomes,in order to provides important reference materials for improving the clinic efficacy of medicinal materials.Therefore,this study systematically studied the growth and development characteristics of diploid and tetraploid E.purpurea in different harvest months,biomass accumulation in different parts,dynamics accumulation of total polyphenol,including cichoric acid and caffeic acid in two ploidy E.purpurea and their antioxidant effects.The main results and conclusions are as follows:1.The plant height,crown width,fresh weight and dry weight of diploid and tetraploid E.purpurea in different harvest months were measured and compared.The results showed that the plant shape of tetraploid E.purpurea was shorter,but stronger compared with diploid.Although the plant height of diploid E.purpurea was higher than that of tetraploid,the crown width of diploid E.purpurea was obviously smaller than that of tetraploid.Further statistics showed that in vegetative growth period,fresh and dry weight of above ground parts of tetraploid E.purpurea increased by 7.37%and 8.38%,while fresh and dry weight of underground parts increased by 7.01%and 4.10%respectively compared with diploid.During reproductive growth period,fresh weight and dry weight of underground part,inflorescence axis,leaf and flower of tetraploid E.purpurea increased by 15.58%,4.96%,3.05%,8.39%and 13.88%,8.21%,5.43%and 8.72%respectively compared with diploid.Therefore,the fresh and dry weight of tetraploid E.purpurea was significantly higher than that of diploid.2.The total polyphenol content in different parts of diploid and tetraploid E.purpurea in different harvesting months was measured by Folin-Ciocalteu method.The results showed that the dynamics accumulation of total polyphenols in diploid and tetraploid E.purpurea were basically the same,and the total polyphenol content was higher in July and August（flower>leaf>underground part>inflorescence axis）.In the same part,the total polyphenol content of tetraploid E.purpurea was higher than diploid in same month.Further analysis by DPPH,FRAP,ABTS and Fe²⁺chelation showed that the antioxidant activity of the two ploidy Echinacea species was stronger in July and August,and the antioxidant activity showed the same changing rule as changes of the total polyphenol content（flower>leaf>underground part>inflorescence axis）.At the same time,the antioxidant activity of tetraploid E.purpurea was stronger than that of diploid.The results showed that the antioxidant activity of E.purpurea was increased by doubling the number of chromosomes,which was related to the increase of total polyphenol content in tetraploid E.purpurea.3.The results of HPLC showed that the components of caffeic acid derivatives in diploid and tetraploid E.purpurea were basically the same,but the accumulation of cichoric acid,caffeic acid and chlorogenic acid in tetraploid E.purpurea（13.97-107.27 mg/g,0.05-0.43mg/g and 0.04-0.48 mg/g）was significantly higher than that in diploid（10.02-96.96 mg/g,0.03-0.42 mg/g and 0.03-0.47 mg/g）.Combined with chemometric analysis,the antioxidant capacity of two ploidy E.purpurea was positively correlated with cichoric acid,caffeic acid,chlorogenic acid and caftaric acid（P<0.05）,especially with the contents of cichoric acid,caffeic acid and chlorogenic acid.4.Further comprehensively analyzing regulation of biomass and chemical components accumulation,data revealed that the accumulation yields of cichoric acid,caffeic acid,chlorogenic acid,caftaric acid and 1,5-dicaffeoyl quinic acid were higher in July（11.99 g,0.052 g,0.055 g,2.58 g and 0.30 g）and August（13.44 g,0.074 g,0.076 g,4.01 g and 0.30g）in diploid E.purpurea.Similarly,tetraploid E.purpurea contained higher accumulation yields of cichoric acid,caffeic acid,chlorogenic acid,caftaric acid and 1,5-dicaffeoyl quinic acid in July（13.53 g,0.055 g,0.061 g,2.82 g and 0.39 g）and August（14.94 g,0.087 g,0.091g,4.13 g and 0.45 g）.These results further showned that doubling the number of chromosomes increased the production of most caffeic acid derivatives in E.purpurea.The yield and antioxidant activity of total polyphenols,cichoric acid,caffeic acid and chlorogenic acid in diploid and tetraploid E.purpurea were higher in July and August.Therefore,we suggest that these two months of July and August should be the best harvest time for diploid and tetraploid E.purpurea.