Antioxidant Activities And Antiproliferative Activities On HepG2 Of Tea Flower Extracts

Scientific achievements promote the development of human life quality as well as the society,which,however,cause many environmental issues like air pollution,pesticide residue,heavy metal pollution and radiation at the same time,bringing people extra oxidative stress and leading to the generation of radical oxygen species(ROS).ROS,including O2,H2O2 and ·OH,are mutagens produced under the influences of radiation or byproducts of natural metabolism.Once accumulating in the body,ROS can damage macromolecules such as DNA,proteins and lipids,which eventually cause aging and degenerative diseases including cardiovascular disease,immune system decline,brain function disorder,etc.Oxidative damage on DNA often give rise to DNA distortion,proto-oncogene and tumor suppressor gene mutations,which are the major causes of tumor and cancer.In recent years,inspired by the concept of “medicinal and edible plant”,scavenging redundant ROS inside the body to prevent chronic diseases and delay aging has become an important healthcare method.Studies involving functional foods are being further explored,and many natural plant,tea leaf for an example,have already been proved capable for anti-oxidation,anti-proliferation,anti-radiation and preventing multiple diseases.Tea flower,which has similar biochemical structure with tea leaf,has rich bioactive components and a great yield.As a result,tea flower should theoretically possess strong antioxidant and antiproliferative effects.However,tea flower has always been considered as a useless byproduct besides tea leaf,lacking of systematic research and causing a resource waste.Based on above reasons,this paper focused on the exploring the antioxidative and antiproliferative activities of different varieties and positions(full,petal and pollen)of tea flower as the correlations between the antioxidative and antiproliferative activities.The major research contents and results are presented as follows:1.Using ORAC,PSC and CAA method to evaluate the antioxidant activities of six varieties of tea flower(full)extracts.The result indicated that Sichuan population possessed the highest values of ORAC,PSC and no PBS wash CAA at 3504.99 ± 281.65 ?mol Trolox/g,1442.73 ± 75.01 ?mol VC/g and 24.01 ± 0.20 ?mol Quercetin/g separately;PBS wash CAA value of Sichuan population was 10.53 ± 0.42 ?mol Quercetin/g which had no significant difference with the highest value of Fuxuan No.9.Therefore,Sichuan population possessed the overall strongest in vitro antioxidant activity and cellular antioxidant activity among the six varieties.2.Using ORAC,PSC and CAA method to evaluate the antioxidant activities of six varieties of tea flower(petal and pollen)extracts.The result indicated that the petal and pollen from Sichuan population possessed the highest(or had no significant difference with the highest)values of ORAC(2947.48 ± 165.99 ?mol Trolox/g and 4575.16 ± 170.74 ?mol Trolox/g),PSC(632.09 ± 73.91 ?mol VC/g and 1060.50 ± 82.28 ?mol VC/g),PBS wash CAA(11.19 ± 0.37 ?mol Quercetin/g and 11.73 ± 0.56 ?mol Quercetin/g)and no PBS wash CAA(24.29 ± 1.39 ?mol Quercetin/g and 25.71 ± 0.26 ?mol/g)?Therefore,petal and pollen from Sichuan population possessed the overall strongest in vitro antioxidant activity and cellular antioxidant activity among the six varieties.3.Correlation analysis was conducted between ORAC,PSC,CAA values of each variety(full,petal and pollen)extracts and their corresponding total phenolic,caffeine and catechin contents.The result indicated that the contents of total phenolic,total catechin were significantly of highly significantly positively correlated with ORAC,PSC and CAA values;EGCG among all the catechin monomers had high significant(p < 0.01)positive correlations with ORAC,PSC and CAA values,besides,the correlations were more significant and stable than other monomers.As a result,EGCG's content have a strongest relation with antioxidant activity and could effectively predict tea flower sample's antioxidant ability.4.The antiproliferative activities on HepG2 cancer cell of six varieties of tea flower(full,petal and pollen)extracts were evaluated and described with proliferation rate and EC50 value.The result showed that Fuxuan No.9 possessed the lowest EC50 value in its full flower and pollen at 55.28 ± 17.98 and 63.95 ± 9.77 mg/L,indicating that the full flower and pollen of Fuxuan No.9 had the strongest antiproliferative activity;Sichuan population's petal had the lowest EC50 value at 72.56 ± 26.22 mg/L,so Sichuan population's petal exhibited the strongest antiproliferative activity.5.Correlation analysis was conducted between ORAC,PSC,CAA values of each variety(full,petal and pollen)extracts and their corresponding EC50 values.The result showed that EC50 values had high significant negative correlation with ORAC values(R2 =-0.389,p < 0.01)but no correlation with PSC values(R2 =-0.179,p > 0.05),so was it with CAA values(p > 0.05).Therefore,ORAC values were highly significantly positively correlated with antiproliferative activity.Besides,ORAC,PSC and CAA values were all significantly correlated with each other,indicating there exited a consistent result among the antioxidant evaluation on tea flower extracts.6.Significance analysis was conducted between the biochemical component contents,antioxidant activities and antiproliferative activities of tea flower extracts(full,petal and pollen).The results showed that the total phenolic contents of petal and pollen were significantly higher(p < 0.05)than full flower,and no significant differene(p > 0.05)was found beteen petal and pollen;pollen samples had the highest(p < 0.05)contents in total catechins and galloylated catechins;the ORAC values of pollen and petal extracts were significantly higher(p < 0.05)than full flower extracts while there was no significant difference(p > 0.05)between pollen and petal samples;pollen samples had the highest PSC values(p < 0.05)and the lowest(p < 0.05)EC50 values;no significant differences(p > 0.05)were found in the CAA values of full flower,petal and pollen samples.To sum up,among all the six commonly seen tea flower varieties in Chongqing area,pollen extracts had higher contents of phenolics,stronger in vitro antioxidant activities and the strongest antiproliferative activities,followed by petal extracts;CAA values had nothing to do with the selection of full flower,petal or pollen.