Lactosidation Modification Of Genistein And Characterion Of Its Derivatives And Study On Their Biological Activities In Vitro

Genistein is the presentative of 3-droxide isoflavone in soybean. The inhibitory of genistein on breast cancer, gastric cancer, leukaemia and other cancer has been proved by tumor cells in vitro. To inhibit metastases of cancer cells is the key to cure cancer. The lectin banding with lactose existed on the surface of tumor cells was verified by Raz and Lotan. So tumor metastasis can be prevented by absconding the cognition among tumour cells and the cognition between tumour cells and host cells by means of lactose derivative. Lactose can also bind with cell surface receptors, the result is that the medicine binding with lactose can inrich on the tumor cells for a long time.To improve the targeting activity of genistein in vivo, chemical modification for genistein was carried out by using lactose, which has the potential selective affinity to the surface receptors of cancer cells. Two new compounds, genistein 7-O-β-D-lactoside and genistein 7,4'-di-O-β-D-lactoside, were synthesized by means of phase transfer catalysis, using genistein and O-acetyllactopyranosyl bromide as main raw materials and tetrabutylammonium bromide as catalyst and using KOH/CH₂Cl₂ two-phase system. They were isolated and purified by polyamide column and sephadex LH-20 column chromatography and characterized by IR, 1H NMR, 13C NMR and MS spectral data.After the synthesis, the free radical (·OH,·O₂^-, DPPH·) scavenging activities of genistein and genistein 7,4'-di-O-β-D-lactoside were investigated by method of Pyrograllol Autoxidation and Fenton system by O-phenanthroline Spectrophotometry and DPPH free-radical. The results showed that free radical scavenging activities of genistein 7,4'-di-O-β-D-lactoside on·OH,·O₂^- and DPPH·were slightly stronger than that of genistein.Antimicrobial acativities for seven common microbes(Bacillus Subtilis, Staphylococcus aureus, Escherichia coli, Proteus species, Rhizopus sp, Aspergillus sp and Mucor spp) in food were investigated with genistein and genistein 7,4'-di-O-β-D-lactoside by filter paper method. The results showed that both genistein and genistein 7,4'-di-O-β-D-lactoside exhibited antimicrobial activity to gram-positive bacterium, gram-negative bacterium and fugi.The mechanism of the interaction between genistein, genistein 7,4'-di-O-β-D-lactoside and DNA by using UV spectra, fluorescent spectra and viscosity methods were reported. The results showed both genistein and genistein 7,4'-di-O-β-D-lactoside can bind to DNA with weak interaction. And they bind to DNA by groove binding and electrostatic interaction modes.The fluorescence quenching mode between genistein, genistein 7,4'-di-O-β-D-lactoside and BSA by using fluorescence spectrum method were also studied. The experiment demonstrated that the quenching mechanism for the two compounds with BSA was static quenching process. The quenching constant of genistein was 3.68×10¹³ L·mol^-1·S^-1 and that of genistein 7,4'-di-O-β-D-lactoside was 6.33×10¹². The binding constant of genistein was 1.99×10⁵L·mol^-1 and that of genistein 7,4'-di-O-β-D- lactoside was 6.6×10⁴L·mol^-1.