Study On Biotransformation Of Seabuckthorn Aglycones And Antioxidant Activity Of Biotransformation Products

The fruits of seabuckthorn(Hippophae rhamnoides)plants are rich in flavonoids.A large number of medical researches in recent years has confirmed that seabuckthorn flavonoids have inhibition of cholesterol,antioxidant,antivirus,anticancer,anti-radiation,anti-myocardial ischemia,anti-heart disorders effect,so seabuckthorn flavonoids have wide industrialized foreground.The main ingredients of flavonoids in the seabuckthorn furit are glycosides,the antiosidant of which is lower than aglycones.Glycosides could be converted into aglycones by microorganism,which have higher antioxidant activity.At present,the researches of flavonoids of seabuckthorn are mainly in separation and extraction,biological activity and structure,but the modification of its structure is less.This paper studied extraction and purification of flavonoids of big fruit seabuckthorn(Hippophae rhamnoides var.sp),and converted them into aglycones to increase their antioxidant activity.Then studied the effect of biotransformation conditions on antioxidant activity.At present,main extraction methods of total flavonoids of seabuckthorn are water extraction,organic solvent extraction,ultrasonic-assisted extraction,microwave-assisted extraction and supercritical fluid extraction.Solvent extraction method was used in this paper to extract the total flavonoids of big fruit seabuckthorn.The Response Surface Method(RSM) was applied to research the influences of extraction temperature,concentration of alcohol,ratio of liquid to solid and extraction time on extraction rate to optimize the extraction condition on the base of the single factor experiments.The optimum extraction conditions were confimed as follow:extraction temperature 61.85℃,concentration of alcoho 71.36%,extraction time 2.59h, ratio of liquid to solid 18.33.The extraction rate of flavonoids under this condition was 0.741 %.RSM can optimize the extraction techniques of big fruit seabuckthorn and find optimum yield rate and extraction condition within proper range of effect factors.This method is simple, economic,and fit for industrial production compared with other methods.The flavonoids of big fruit seabuckthorn were purified by macroreticular resins,and the pH valuel,flow rate,concentration of sample,concentration of eluting agent were also studied. The optical concentration of ethanol was 60%and the optical pH value was 3.0.The flow rate of sample was 1mL/min and concentration of sample was 0.96mg/mL.Flavonoids purified by macroreticular resins were biotransformed by Aspergillus niger, Trichoderma viride,Streptomyces griseus and Mucor racemosus.Aspergillus niger and Streptomyces griseus were selected as biotransformed microorganism.The effects of initial pH of medium,conversion temperature,conversion time,the volume of substrate and inoculation quantity were also researched.When Aspergillus niger was biotransformed microorganism,the optical conditions of biotransformation were:culture temperature 34℃,conversion time 3 days,substrate quantity 6%,initial pH of medium value 5.5,inoculation quantity 9%.The conversion rate in this condition is 41.17%.The increase of total antioxidant activity and scavenging rate of·OH are 7.35U and 12.11%.When Streptomyces griseus was biotransformed microorganism,the optical conditions of biotransformation were:culture temperature 31℃,conversion time 4 days,substrate quantity 8%,initial pH of medium value 6.5,inoculation quantity 7%.The conversion rate in this condition is 48.20%.The increase of total antioxidant activity and scavenging rate of·OH are 9.35U and 15.06%.