Preparation And Antioxidation Of Novel Inclusion Complexes Formed Between Flavonoids And Cyclodextrins

Baicalein(BC)and Wogonin(WG)are the flavonoid widely distributed and constituents extracted from Chinese herb.BC and WG have attracted considerable attention in the recent years primarily because of its various interesting activities,such as anti-inflammatory,antithrombotic,allergy,reducing blood fat,diuresis,etc.In addition,the BC and WG have antioxidant effect,reducing oxidative stress injury,both of them can be used in the treatment of diseases associated with free radicals and oxidative stress.However,the clinical application of BC and WG has been seriously influenced by their low solubility and instability.Therefore,finding an effective workaround to improve the apparent solubility of BC and WG to facilitateits clinical application is necessary.Cyclodextrins(CD)and its derivatives with hydrophobic central cavity and hydrophilic outer surface are known to be able to encapsulate model substrates to form host-guest complexes or superamolecular species as results to usually enhance drug solubility in aqueous solution and affect the chemical characterization of drugs.Because of the existence of"N"on the edge of the atom,β-CD modified polyamine have more recognition sites and enhance the molecular recognition ability.However,there is few report about the antioxidant effect of BC,WG supramolecular system.In order to best our knowledge,nine CD_S derivatives and ten superamolecular species involved in this article are prepared via a simple method.Specific work is as follows:1.The 9 kinds of modifiedβ-CDs(hosts 1-9)have been synthesized,including five kinds of polyamine modifiedβ-CDs,two kinds of polyamine bridgingβ-CDs(hosts 6,7)and two kinds of new type of hydrazide bis-β-CDs(hosts 8,9)characterized by ~1 HNMR.2.By using ~1H NMR,TG,XRD,IR,2D ROESY and other methods,we investigated the inclusion complexation behaviour of 5 kinds of polyamine modifiedβ-CDs(hosts 1-5)inclusion comolexes with BC.UV titration is used to calculate the stability constant and inclusion ratio between host and guest,the results show that the host and guest formed 1:1 inclusion complexes,hosts 1-5/BC stability constant of the order as follows:K host 5/BC>K host 4/BC>K host 1/BC>K host 2/BC>K host 3/BC.In addition,there is a discussion about the influence of size ratio of host and guest for stability constant.Compared with free flavonoids,inclusion complexes have more satisfactory solubility which show a relatively consistent trend as good as stability constant of inclusion complexes.3.By ~1H NMR,TG,XRD,IR and other methods,we investigated the inclusion complexation behaviour of the 5 kinds of supramolecular system(hosts 1-5/WG).Ultraviolet spectrum experiment results show that hosts 1-5 with WG were formed1:1 supramolecular system.Determination of the supramolecular system stability constant size order:Khost 5/WG>K host 1/WG>K host 4/WG>K host 2/WG>K host 3/WG.Water soluble experimental results showed that the host 5/WG solubilization effect is best.4.The antioxidation effect of ten kinds of flavonoids inclusion complexes were investigated by UV spectra,and the results showed that the antioxidant activity is gradually enhanced with the increase of the concentration of the inclusion complexes.In a certain concentration range,the antioxidant activity is greater than the free BC.The antioxidant activity of BC supermolecule system was significantly stronger than that of WG supermolecule system.