Extraction Of Feruloyl Oligosaccharides From Tibetan Hull-less Barley Bran And The Study Of Antiglycation Activities

Tibetan hull-less barley(Hordeum vulgare L. var. nudum hook. F.)(THB) has been grown in the Qinghai-Tibet Plateau for thousands of years, which is a kind of special grain resources containing high levels of protein, dietary fiber and vitamin, but low fats and carbohydrates. Because of being cultivated in high altitudes, Tibetan hull-less barley has a lot of secondary metabolite in the condition of extream cool temperature, hypoxia and intense UV radiation. For example, Feruloyl oligosaccharides (FOs). FOs has many physiological functions, such as proliferation of intestinal probiotics, prevention of obesity and constipation, and also strong antioxidant activity. FOs also can inhibit the antiglycation in vivo and prevent diabetes, which makes FOs a good prospect of application in the health industry.This paper took processing by-products of Tibetan hull-less barley as material, extracted the FOs from Tibetan hull-less barley and studied the antiglycation activity of FOs, in order to learn its heathy meaning and health efficacy, and provide basis for the comprehensive utilization of the Tibetan hull-less barley bran. The major findings were presented as follows:1. The total THB bran polysaccharide (named E-J) was isolated and purified by the method of waterextraction and ethanol precipitation. The yield of E-J was8.11%(THB bran equivalent per gram). The content of Polysaccharide E-J was41.12%, the content of reducing sugar was3.07%and the content of protein4.19%.2. The total THB bran polysaccharides (E-J) was divided into4parts with different molecular weight through being treated with different concentration of ethanol with the concentration of30%,50%,70%and90%. They were named by E-30, E-50, E-70and E-90respectively. The extraction ratios were2.14%,1.64%,2.95%and0.82%. Detection of chemical compounds of E-30, E-50, E-70and E-90showed that:polysaccharide content of E-30, E-50, E-70and E-90were 42.04%,40.34%,50.86%and41.58%, reducing-sugar content of them were3.83%,2.30%,4.17%and4.67%, protein content were1.57%,1.47%,1.28%and0.84%, respectively, the average molecular weight of polysaccharide of these4extracts were683.20kDa,100.78kDa,41.15kDa and8.84kDa.3. The antiglycation of E-J, E-30, E-50, E-70and E-90were studied through fluorescence of AGEs assay in BSA-MGO system and BSA-Glu system. The results demonstrated that the antiglycation ability of E-30, E-50, E-70and E-90tended to be E-70>E-90>E-50>E-30. The antiglycation ability was affected by the molecular weight of polysaccharide. The suger which had the molecular weight around40kDa had the best antiglycation activity.4. The qFOs was purified from E-70with Amberlite XAD-2, subsequent analysis with UPLC indicated that FOs consisted of esterified ferulic acid and xylose. The yield of qFOs isl3.15%. There were0.5mmol/g FOs (THB bran equivalent per gram).5. The antiglycation of qFOs was studied through fluorescence of AGEs assay in BSA-MGO system and BSA-Glu system, using aminoguanidine as positive control. The result was that qFOs has a better effect of antiglycation than E-70, and rather than the positive control aminoguanidine1/10. What was more, qFOs could inhibit AGEs in a high speed and get increased with time prolong.Because of the rich source and edible safety, the antiglycation activity of Tibetan hull-less barley bran was worth studying more deeply.