| Tea(Camellia sinensis L) is the second most consumed beverage in the world next to water which is widely used especially in China and Japan.Since lots of bioactive components are existed in tea,it has been wildly used in the areas of functional foods and cosmetics.In recent years,green tea polysaccharide(TPS)has been gaining increasing attention due to its various bioactivities such as antioxidant activity,immunomodulation,antitumor and hypoglycemic effects.Firstly,based on the previous study in our lab,coarse TPS was extracted from green tea and precipitated in ethanol.The TPS was then subjected to DEAE-52 anion exchange chromatography for purification and the main components TPS-2 was acquired.Sephadex G-100 was employed for further purification and TPS-22 was acquired by this experiment.The characteristics of TPS-22 were determined by The molecular distribution,monosaccharide composition,FTIR,UV-vis and SEM.To determine the lipid alleviation effect of TPS,TPS-22 was applied to the in vitro palmitate induced HepG2 cells model.The results suggested that TPS-22 has the characteristic spectrum of polysaccharide and had a homogenous structure.The images under SEM showed that the TPS-22 had a smooth surface and no hole was observed in the inner structure,which suggested that TPS-22 has a high purity and strong molecular inter-atomic forces.The moosaccharide was revealed in TPS-22 with glucose,galactose,mannose and rhamnose,and the molecular weight of TPS-22 was detected as 5.3×104 Da?The in vitro lipid alleviation study was suggested that TPS-22 could eliminate the red lipid droplets in HepG2 cells model after the red oil O staining and has a dose depended manner.The bioactivity results suggested that the TPS would ameliorate the hyperlipidemia in diabetes and also protect organs from damages.Secondly,in order to investigate the hypoglycemic effects and potential mechanism of TPS on diabetes,the TPS was acquired by water extraction and precipitated in ethanol.Type 2 diabetes mellitus(T2DM)mice were established and treated with TPS.Results showed that TPS treatment could result in the increase of body weight and the decrease of blood glucose.The contents of TC and LDL-c were decreased significantly(p < 0.05)while the contents of TG and HDL-c were almost restored to the normal levels.TPS possessed the efficacy of insulin resistancealleviation and exerted cytoprotective action.The enzyme activities were notably upregulated in both liver and kidney tissues(p < 0.05).Furthermore,the expressions of PI3Kp85/p-Akt/GLUT4 were upregulated by TPS,which indicated the involvement of the PI3K/Akt signal pathway in the hypoglycemic mechanism of TPS.Results suggested that TPS could ameliorate the T2 MD and might be a promising candidate functional food or medicine for T2 DM treatment.Finally,to study the effect of tea polysaccharide exhibit on drug delivery system,a newly conformed bipolymer paclitaxel(PTX)-nanoparticle using tea polysaccharide(TPS)and zein was prepared and characterized.Tea polysaccharide was used as a biopolymer shell and zein was as the core and the optimal formula was subjected to the characteristic study by TEM,DSC,FTIR and in vitro release study.Results showed that the optimal particle was acquired with particle yield at 40.01 %,drug loading at 0.12 % and diameters around 165 nm when the concentration of tea polysaccharide was set at 0.2 %,and the amount of PTX: zein = 1: 10.The particle was a nanoparticle with spherical surface and the encapsulated PTX was in an amorphous form rather than cystalline form.PTX was interacted with zein and polysaccharide through O-H and C= O groups and it had a sustained release.The results suggested that the novel bipolymer might be a promising agent for PTX delivery and tea polysaccharide was demonstrated its potential function in drug delivery system. |
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