Study On Preparation And Antidiabtic Mechanisms Of Polysaccharides From Natural Portulaca Oleracea L.

Diabetes melltitus (DM) is one of the main threat to human health in the21st century. In all different forms, the global figure of people with DM is set rise from current estimate of200million to366million in2030. Clinical drugs has been famous for controlling blood glucose level in short time, nevertheless, it will not only make damage to islet cells but also can not reduce the development and progression of DM and its complications. The increasing interest has been attracted for development and utilization of antidiatic plants because they have less side effects, efficacy and stability.Portulaca oleracea L. polysaccharide (POP), extracted from the traditional Chinese herb Portulaca oleracea L., has been reported to possess a variety of bioactivities such as inhibition activity of preadipocytes proliferation, antioxidant and antidiatics. Nevertheless, many papers investigating hypoglycemic mechanisms of polysaccharides are mainly based on animal experiments, or crude polysaccharides, few from the cellular and molecular experiments. The extraction, isolation, structural features and antidiabetic mechanisms of polysaccharide from Portulaca oleracea L were studied in this research.Hot water extraction and response surface analysis was applied to optimize the extraction technology POP from Portulaca oleracea L. The optimal extraction conditions of the POP were obtained. The ratio of water to material is20:1, extraction temperature is100℃, extraction time is90minutes, and extraction time is3times. And the yield of polysaccharide is up to24.25%. The AB-8macroporous resin and response surface analysis was employed to optimize the decolorization technology POP. The optimal decolorization conditions of polysaccharides solution are concluded, the content of AB-8macroporous resin is60g/L, decolorizing time is3.5h, decolorizing temperature is50℃, and the decolorization rate yield of polysaccharide is up to74.25%.The structure of POP â… , POP â…¡ and POP III were analyzed with chemical methods. By using the technique of FT-IR, GC-MS and HPLC associated with methods of acid hydrolysis periodate oxidation, Smith degradation. POP I were composed of Rha, Rra, Xyl, Man, Gac and Gal with molar ratio of1:1.07:1.3:1.9:2.4:3.4, and the chain were connected by1â†'2linkage and1â†'6linkage. Sulfate was detected by FT-IR. POP II was composed of Rha, Rra, Xyl, Man, Gac and Gal with molar ratio of1:1.4:1.7:1.4:1.6:1.6. And the chain was mainly connected by1â†'3linkage, besides,1â†'2linkage,1â†'4linkage1â†'6linkage were included. POP III was composed of Rha, Rra, Xyl, Man, Gac and Gal with molar ratio of1:1.16:1.39:2.23:3.19. And the chain was connected by1â†'2linkage and1â†'6linkage. Sulfate was detected by FT-IR.The antioxidant activity of three polysaccharides from Portulaca oleracea L.(POP I, POP II and POP III) was evaluated by colorimetric method, the results showed that POP I exerted stronger scavenging activity of-OH, DPPH and inhibiting activity of Fe-induced lipid peroxidation than POP â…¡ and POP III.The antidiatic activities of POP on alloxan-induced HIT-T15cells were investigated. Intracellular ATP, insulin release, SOD activity, cytosolic free Ca2+and mitochondrial membrane potential were assayed. POP promoted HIT-T15cells proliferation, increased intracellular ATP, insulin release and SOD, inhibited increase of cytosolic free Ca2+and decrease of mitochondrial membrane potential induced by alloxan. It can be concluded that antidiatic mechanisms of polysaccharides from Portulaca oleracea L.was related to the scavenging activity of oxygen species, antioxidant activity and islet β cells renovation.Preservation time and temperature on antioxidant activity of polysaccharides from Portulaca oleracea L. were investigated in vitro. The results showed that scavenging.OH activity of polysaccharides is associated with time and temperature.The extraction, isolation, purification, chemical structure, antidiatic mechanisms of polysaccharides from Portulaca oleracea L. were researched in this paper. It provided comprehensive, scientific evidence for development of polysaccharides from Portulaca oleracea L. as candidate of natural antidiatic herb.