Extraction Of Proanthocyanidins In Larch Bark And Study On Related Properties

As by-product of the Larch Timber industry,Larch Bark is abundant in resources and cheap in price.Therefore,it has significant meaning to develop the potential value of Larch Bark and to use the larch resource fully.In this study,by using the flash extraction,we extracted the proanthocyanidins from the Larch bark.After purifying the product,we studied the stability,antioxidant and inhibitory on?-glucosidase of proanthocyanidins.The research is focused on the following parts:1.The optimal conditions for extracting proanthocyanidins by the flash extraction from larch bark are determined.when the water was solvent,the optimal conditions were as follows:raw material to liquid ratio was 1:30(g/mL),extraction time was 3 minutes,extraction temperature was 40?,extraction pH was 4.0.Under above conditions,the extraction rate of proanthocyanidins was 8.74%;when ethanol solution was solvent the optimal conditions were as follows:raw material to liquid ratio was 1:25(g/mL),extraction time was 4 minutes,extraction temperature was 40,C,volume fraction of ethanol was 60%.Under above conditions,the extraction rate of proanthocyanidins was 11.42%.2.The effects of temperature,light,oxygen on the stability of proanthocyanidins were studied.In the chromogenic reaction,the absorbance reflects the proanthocyanidins content in the larch bark.when the absorbance falled from 0.17 to 0.13,we can see that destruction of temperature,oxygen and light is strong on the structure of proanthocyanidins.3.By using the methods of DPPH,pyrogallol autoxidation,salicylic and reducing force,the antioxidant activity of proanthocyanidins was studied.the result showed that proanthocyanidins extraction from larch bark has a good antioxidant ability including the reducing power and the free radical scavenging ability in DPPH.In lmg/mL,0.5mg/mL condition,the antioxidant ability of proanthocyanidins is same as Vitamin C,the IC50 of DPPH was 0.026mg/mL.Compared to hydroxyl radicals and Vitamin C,proanthocyanidins has weak scavenging ability while the IC50 of superoxide anion was 4.43mg/mL,the IC50 of hydroxyl radicals was 4.73mg/mL.4.The inhibitory of proanthocyanidins to ?-glucosidase was studied.When the concentration of extraction was 1.2 mg/mL,inhibitory rate to ?-glucosidase was 17.65%.It showed that the proanthoc-yanidins from Larch Bark can restrain the enzyme activity of ?-glucosidase effectively.