Molecules Hydration And Antioxidant Activity Of Flavonoids Drug Quantum Chemistry Studies

Flavonoids are a kind of phenol compounds which are widely distributed in nature. It's proved that the flavonoids have extensive biological activity such as anti-mutation, anti-tumor, the treatment of cardio ascular disease and reduce the formation of free radicals and free radical biological activity which is the most important one. All of the property made the flavonoids be attended and applied in the biomedical and clinic field more and more.We have selected three typical flavonids (quercetin, morin and silybin) as the object of studying in this paper. DFT&TD-DFT method and SCRF model are all considered to simulate the UV absorption spectra and predicate pKa value respectively, and then investigate relationship between the hydration and antioxidant properties and their structure. This work includes four parts.1.B3LYP method in connection with the 6-311+G(d,p) basis set was used to optimize the quercetin-water and quercetin-anion–water molecular geometries. DFT method, TD-DFT method and SCRF model are used for the calculating of ground sate, the excited state and the salvation to getting the optimized configures, UV absorption spectra and pKa respectively. 3OH is proved the most optimum hydration group site and has the lowest pKa value for quercetin. The UV spectrum of quercetin anion turns redshift.2.B3LYP method in connection with the 6-311+G(d,p) basis set was used to optimize the molecular geometries of morin isomers. DFT method, TD-DFT method and SCRF model are used for the calculating of ground sate, the excited state and the salvation to getting the optimized configures, UV absorption spectra respectively. It indicated that the acidity of morin-a is stronger than morin-b and 2'OH of morin-a has the lowest pKa value, while the morin-b is more stability and suit to hydrate.3.B3LYP method in connection with the 6-311+G(d,p) basis set was used to optimize the silybin, silybin anion, silybin anion and water complexes considering 3-OH and 7-OH molecular geometries. The TD-DFT calculation is also used to simulate the UV absorption spectra of silybin anion and water complexes. The results is that acidity of 7OH is stronger than the 3OH's and it verifies that the pH value has connection with change of UV absorption spectra.4.MPWB1K method in connection with the 6-311+G(d,p) basis set was used to optimize the quercetin radical. BDEs (bond dissociation enthalpies) , spin density and HOMO were calculated to analyse the structure-activity relationship. Result indicates that the ring B of flavonoidal drugs play a role in scavenging free radical and antioxidant properties.