Anticancer And Hypoglycemic Effects Of Epigallocatechin Gallate Derivates With Small Acyl Groups In Vitro

Close attention has been paid to the green tea due to the pharmacological active ingredients catechin,mainly including four kinds of polyphenols:Epicatechin(EC), Epigallocatechin(EGC), Epicatechin gallate (ECG) and Epigallocatechin gallate (EGCG), among them, EGCG is the main active ingredient.Studies have shown that EGCG has antioxidant, antibacterial, antiviral, anticancer and hypoglycemic activity, but the clinical applications are restricted because of its unstable low lipid-soluble and low bioavailability.In this paper, the acetylated EGCG, propionyl EGCG and butyryl EGCG had been synthesized.The objectives of this study are to investigate the Anti-cancer and hypoglycemic activity of Acylation EGCGs in HepG2cell, Hela cell, α-glycosidase and α-amylase.The dissertation is constituted by following parts:(1) Synthesis of acylation EGCGs:Anhydrides as the acylating agent react with EGCG, pyridine as catalyst, in40℃for hours. The reaction endpoint was monitored by thin layer chromatography(TLC)and high performance liquid chromatography (HPLC). The resulting liquid was washed repeatedly with distilled water,0.5mol/L of Na2CO3, then collect the organic layer, treated with saturated NaCl, dried by Na2SO4, and the desired product could be got after drying.The purity of acylation EGCGs were detected by HPLC, and the results are98.42%,98.86%and95.14%。(2) Physical and chemical properties research:determined the solubility, ultraviolet absorption and oil-water partition coefficient of acylation EGCGs. Our results show that the acylation EGCGs are almost insoluble in water, the solubility in organic solvent have been improved greatly. EGCG has a big absorption at210nm and280nm, but acylation products’maximum absorption wavelength is250nm, maximum absorption wavelength move to the blue shift has happened. Arrangement of Oil-water partition coefficient from low to high order for:lgPEGCG<lgPAcEGCG lgPprEGCG<lgPBuEGCG.(3) In addition, cancer cells inhibitory activities of active fractious were measured. In1～100μg/mL concentration range, in HepG2cell:PrEGCG and BuEGCG have higher anticancer activity, on the contrary, EGCG and AcEGCG are lower, and IC50s are54.63,23.08,17.12and15.35μg/mL; in Hela cell, the anticancer effect arrangement is EGCG<AcEGCG<PrEGCG<BuEGCG, IC50s are68.2,51.76,31.11,20.27μg/mL.Cell absorption experiments show that stronger the ability of the reagent access to the cell, the greater the antitumor activity. AcEGCG combined with Dox can obviously increase the inhibition of Dox in cancer cell, and high concentration of PrEGCG combined with low concentration of Dox show little synergies, but BuEGCG almost do not have the same effect.(4) Furthermore, we researched the hypoglycemic activity of the acylation products. The relationship with EGCG and acylation EGCGs on α-glycosidase inhibition was obvious dose-dependent, and the inhibition effect is stronger than the positive control (acarbose). Compared with EGCG, the inhibition rate of the acylation EGCGs is higher, IC50s were291.3,58.73,65.77and61.39μg/mL. α-amylase in the same conclusion, IC50s were125.0,101.4,81.47and61.59μg/mL.