Interaction And Properties Of Cucurbituril With Dihydrogen Flavonoids

Cucurbiturils have a larger hydrophobic cavity and polarity carbonyl modified port,which can form stable host-guest complexes with object molecular by the cage body,hydrogen bond and van der Waals force,etc.Cucurbiturils are a promising pharmaceutical carrier,because of its innocuity,good stability and extensive host-guest recognition.Dihydrogen flavonoids have anti-cancer,anti-inflammatory,antiviral and other physiological activities,but its poor water solubility limits its furtherclinicalapplication.Inthispaper,cucurbit[7]uril（Q[7]）and cucurbit[8]uril（Q[8]）were selected as the hosts,Alpinetin（ALP）,flavanone（FL）,Naringenin（NAR）,pinocembrin（PCB）,6-hydroxy flavanone（6-HF）and 7-hydroxy flavanone（7-HF）as the guest molecules,focuses on the composition,characterization and properties of dihydrogen flavonoids-Cucurbit[n=7,8]uril supramolecular system.And investigated the cucurbit[n=7,8]uril influence the stability,water solubility,antioxidant activity and in vitro release pathway on dihydrogen flavonoids.Which provided a theoretical basis for the utilization of dihydrogen flavonoids.Ⅰ:UV-Vis spectroscopy was used to investigate the interactions of the Alpinetin,flavanone,Naringenin,pinocembrin,6-hydroxy flavanone and 7-hydroxy flavanone with Q[7]and Q[8].The results showed that Alpinetin,flavanone,Naringenin,pinocembrin,6-hydroxy flavanone,7-hydroxy flavanone had no interaction with Q[7],possibly of the larger molecular volume of the above dihydroflavonoids was not matched with the Q[7]cavity.Q[8]formed a 2:1 inclusion complex with pinocembrin,flavanone and 7-hydroxyflavanone,respectively,and the binding constants by UV absorption were 6.08×10⁹ L²·mol^-2,3.7×10⁹ L²·mol^-22 and 9.0×10⁹ L²·mol^-2,respectively.Fluorescencespectroscopy,infraredspectroscopy,and thermogravimetric characterization further confirmed the interaction of pinocembrin,flavanone,and 7-hydroxyflavanone with Q[8].¹HNMR spectroscopy showed that pinocembrin,flavanone,and 7-hydroxyflavanone were located between the two Q[8]ports.In addition,we investigated the effect of different pH values between pinocembrin,flavanone,7-hydroxyflavanone and Q[8]interaction.The results showed that Q[8]formed a 2:1 inclusion complex with pinocembrin,flavanone,and7-hydroxyflavanone under acidic and neutral conditions.Ⅱ:The Q[8]influence the water solubility,stability and cumulative release on PCB,FL and 7-HF has been studied by means of ultraviolet absorption spectroscopy.Phase solubility experiments showed that the solubility of PCB,FL and 7-HF could be increased 4.3-fold,3-fold and 2.4-fold by interacting with Q[8].In vitro release studies have shown that Q[8]improved the PCB,FL and 7-HF cumulative release quantity in theartificial gastric intestinal juice and artificial gastric juice.A study of the evolution of UV absorption spectra with time showed that Q[8]signficantly increase the stability of PCB in artificial intestinal juice.The antioxidant activity of PCB-Q[8]has been tested by the ABTS method.The PCB-Q[8]inclusion complex showed a slightly lower scavenging effect towards the ABTS radical than PCB,with respective IC₅₀0 values of 4.3×10^–6mol·L^-1and 3.2×10^–6mol·L^-1,indicating that Q[8]had little effect on the antioxidant activity of PCB.