The Antioxidant Activity, Antimicrobial Activity And Extraction Of Flavonoids Of Leaves Of Rhamnus Utilis

Rhamnus utilis is a kind of green deciduous shrubs. It belongs to Rhamnaceae in plant taxonomy, and is distributed in Dongbei, Shanxi, Hebei and Northeast of China. Its leaves are bitter but sweet in favor and cool. In ancient China, R. is a kind of dye plant that can dye cloth green separately, and it is known as " Green of China " abroad. R. utilis has effect as "clearing away heat and promoting urinate and negative purge". And this species is used to treat edema, abdominal distension, hernia, scrofula, ulcers, constipation,and so on in folk.R. utilis is widely distributed in our country. It has high economic value. In this study, antioxidant activity and antimicrobial activity of leaves of R. utilis were studied; the active composition of the leaves of R. utilis is analyzed; Extraction of flavonoids from the leaves of R. utilis was optimized in order to maximize the extraction yield of flavonoids. This study provides theoretical basis for this species in the development of new drugs and health care products. The results of the study are as follows:(1)The leaves of R. utilis were extracted by 90% ethanol and distilled water, respectively. With Prussian blue method and Fenton method, the antioxidant activitiy of extraction was tested by various antioxidant assays, such as reducing power and hydroxyl radical scavenging activity. The results showed that extracts from the leaves of R. utilis exhibited antioxidant activities. The reducing power and hydroxyl radical scavenging activity, of ethanol extraction were better than that of distilled water extraction.(2)Filter paper diffusion method was used to test the inhibitory of the the water extract and the alcohol extract of the leaves of Rhamnus utilis for staphylococcus aureus, escherichia coli and bacillus subtilis. The result showed the distilled water extraction of the leaves of R. utilis has obvious antimicrobial actions on S. aureus. The ethanol extraction of the leaves of R. utilis has antimicrobial actions on S. aureus, E.coli and B. subtilis.(3)The mixture was extracted from leaves of R. utilis with distilled water, 95% ethanol and petroleum ether. The chemical components of leaves of R. utilis were demonstrated using precipitation reaction and color reaction. The results showed that leaves of R. utilis might contain polysaccharide, glycoside, organic acid, phenols and tannin, flavonoid, cardiac glycosides, anthraquinones, volatile oil, not contain amino acids, peptides, proteins, saponins, and coumarin, lactones, steroids, triterpenoid, grease.(4)Flavonoids in R. utilis were extracted with ultrasonic assisted extraction technology using ethanol as solvent. A series of single-factor experiments were conducted to investigate the effects of ethanol concentration, liquid-solid ratio, extraction time and temperature on flavonoids yield. Response surface method was used to optimize the extraction process. The optimum extraction parameters were ethanol concentration 70%, liquid-solid ratio 33:1, extraction time 50 min and temperature 30℃. Under these conditions, the predictive extraction yield of total flavonoids was 35.18 mg/g and the actual extraction rate was 35.07 mg/g.