Study On Antioxidant Activity Of Natural Selenium-rich Plants And Its Application In Cosmetics

Gynostemma pentaphyllum(Thunb.)Makino is a taditional herb which is rich in flavonoids,polysaccharides,and other biological ingredients.Selenium has preventive effects in a variety of human cancers,and it participates in the synthesis of glutathione peroxidase,which can effectively scavenge free radicals.And Gynostemma has a good enrichment effect on selenium.At present,the development and utilization of selenium-rich Gynostemma and other plants mainly focus on the study of their selenium-rich laws and the processing of related agricultural and sideline products,but there are few studies on the application of selenium-rich active ingredients in moisturizing and anti-aging skin care products.Therefore,this paper proposed a two-step extraction process based on the acidic electrolyzed oxidizing water(AEOW)pretreatment and ethanol reflux to extract the active components in common Gynostemma and selenium-rich Gynostemma,and evaluated the antioxidant properties of the extracts by scavenging active free radicals.The anti-aging efficacy of Gynostemma was discussed by adding it into toner(lotion)and evaluating the human body efficacy,and to provide an experimental basis for the development of anti-aging skin care products with natural ingredients.The specific content of this paper is as follows:(1)The active components of Gynostemma pentaphyllum were extracted by two-step extraction process of AEOW pretreatment and ethanol reflux,and the antioxidant activity of the extract was used as the criterion.Single factor experiment and response surface experiment were carried out to optimize the four factors affecting the extraction process:ACC,pretreatment time,volume fraction of solvent ethanol and liquid-solid ratio in the extraction process.When ACC was 40.00mg/L,pretreatment time was 3.2h,ethanol volume fraction was 80% and liquid/solid ratio was 36:1 m L/g,The mean scavenging rate of DPPH radical was 92.86% and RSD was 0.16%.(2)In order to further explore the efficacy difference between ordinary gynostemma pentaphylla and selenium-rich gynostemma pentaphylla,the antioxidant capacity of the two extracts was compared using the clearance rate of three kinds of free radicals as the index.Different concentrations of selenomethionine were added into the extract of Gynostemma to determine its scavenging effect on free radicals.Among them,the highest scavenging rates of selenium-rich Gynostemma to three kinds of free radicals were 93.99%,69.69% and 73.37%,respectively,which were higher than those of ordinary Gynostemma.At the same time,the contents of selenium in Gynostemma and Gynostemma were determined by fluorescence spectrophotometry before and after the pretreatment with acid oxidizing water electrolysis.The selenium content of selenium-rich Gynostemma was0.21 and 0.13 μg/g,respectively.The selenium contents of common Gynostemma were0.06 μg/g and 0.02μg/g,respectively,before and after acid oxidizing electrolytic water pretreatment.Their corresponding free radical scavenging rates were 94.23%,83.05%,85.10% and 81.05%,respectively.The above experiments indicate that,on the one hand,the se-enriched Gynostemma sample group has more significant antioxidant effect than the ordinary Gynostemma sample because of its higher se-enriched components;On the other hand,it has been proved that acid oxidized water can promote the extraction of plant active ingredients.(3)In order to study the application effect of selenium-rich Gynostemma pentaphyllum extract in cosmetics,it was added into toner(lotion).The dosage range of different components in the formula was determined by multiple single factor tests,and the formula scheme of toner(lotion)was optimized by orthogonal test.Fuzzy comprehensive evaluation method is adopted to determine the optimal system.The experimental results show that the smoothing toner(lotion)does not stimulate human skin and has good stability.Through comprehensive analysis of the data obtained from the skin tester,the results showed that the moisturizing toner(lotion).containing the se-enriched Gynostemma extract had anti-aging and moisturizing effects.