Study On The Contents Of Polyphenol, Flavonoid And Antioxidant Activity In Vitro Of Houttuynia Cordata Thunb.

Houttuynia cordata Thunb., is a kind of plants belonging to Saururaceae, and it is recommend by the Ministry of health of China as a kind of plants both used as food and medical plant. Since ancient times, H. cordata has been favored as special vegetable. And now, H. cordata vegetable is still very popular. Polyphenol is a common plant secondary metabolite. It can affect the food's favor as well as the bioactivity. Polyphenol existed in H. cordata can exert its bioactivity as antioxidant, and also affect the favor. Sichuan province hosts abundant H. cordata genetic resources. Natural selection over long period makes them to form distinct populations. Study on the contents of polyphenol, flavonoid and its antioxidant activity in vitro could offer information for the utilization and development of the products of H. cordata, and also helps the breeding research. This study explored the methods for extracting and determination of polyphenol components, also detected the contents of polyphenol, flavonoid and its antioxidant activity in vitro of different parts and different accessions of H. cordata. The results are as following:1. To establish a quantitative method to assay total polyphenol in H cordata, four solvents (methanol, ethanol, acetone and water) were used to extract H cordata with the assistance of ultrasonic in order to explore the effects of extraction solvent type and length of extraction on the extraction of total polyphenol. Subsequently, the 2 h ethanol extract was used to optimize 20% sodium carbonate amount, Folin-Ciocalteu regent amount, reaction temperature and length of reaction. The results showed that methanol is the best solvent to extract polyphenol in H. cordata. And the optimum time for extraction is 2 h. The reaction condition was obtaining 0.5 mL extract by adding 2.0 mL 20% of sodium carbonate,1.5 mL Folin-Ciocalteu reagent, fixed volume of distilled water to 50.0 mL, incubated at 55℃for 1.5 h, and measured the absorption spectrum of complex atλ= 760 nm. Over all, the method is simple, accurate and suggested as an appropriate method to measure total polyphenol in H. cordata.2. Two accessions of H. cordata, W01-100 and W01-94 were studied for the content of polyphenol, flavoniod, DPPH,β-carotene bleaching activity, ABTS. The results indicated that the total polyphenol contents varied from 1.90 to 10.26 mg gallic acid g-1 dw; flavonoid contents were between 0.751～12.4 mg rutin g-1 dw; anti 3-carotene bleaching activities were among 19.62 to 88.62%. the ABTS fell to the interval of 78.4～218μM trolox g-1 dw. Antioxidant activities in vitro and polyphenol as well as flavonoid contents showed the same tendency in the four parts of H. cordata, i.e. flower=leaf> stem> root. Two accessions tested did not show any phenomenal significance among the four parts as to the parameters mentioned above. Based on the difference of the four parts, Ii is suggested to test the bioactivities of the parts separately before use them.The contents of polyphenol and flavonoid and antioxidant activity in vitro of the 16 H. cordata (1 H. emeiensis Z.Y. Zhu et S. L. Zhang was included) varied greatly. The total polyphenol contents changed between the interval of 7.01-15.0 mg gallic acid g-1 dw; the flavonoid contents varied from 3.56 to 11.0 mg gallic acid g"1 dw; the minimum and maximum of the DPPH were 84.7 and 248μM trolox g-1 dw respectively; and the ABTS were between 78.4～218μM trolox g-1 dw. All the parameters analysis (total phenol content, flavonoid content, DPPH, ABTS) in H. emeiensis were quite lower. The chromosome numbers did not show any phenomenal reverence to either contents of polyphenol, flavonoid, or antioxidant activity in vitro. Cluster analysis base on the contents of polyphenol, flavonoid, or antioxidant activities in vitro of the 16 H. cordata indicated that the 16 H. cordata could be classified into two subgroups. The group I included 11 H. cordata accessions with relatively lower total phenol content, flavonoid content, DPPH and ABTS, while the groupⅡcontained W01-52, W01-99, W01-94, W01-98 and W01-100 showed higher contents of polyphenol, flavonoid, and antioxidant activities in vitro.