Study on the Interaction and Properties of Cucurbit[8]uril with Oroxin B

The interaction between cucurbit[8]uril(Q[8]) and oroxin B(ORB) was investigated by UV-visible(UV-Vis) spectroscopy, isothermal titration calorimetry(ITC), mass spectrum(MS) and nuclear magnetic resonance(NMR) spectroscopy. The results showed that ORB formed a 2:1 inclusion complex with Q[8] with a binding constant of 8.266×10 5 L 2 ·mol −2 . ORB had good scavenging ability for 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate)(ABTS) free radicals(IC 50 =5.74 µmol/L) and the addition of Q[8] did not significantly affect the antioxidant activity of ORB(IC 50 =5.76 µmol/L). A phase solubility experiment revealed a 1.86-fold increase in the solubility of ORB when c(Q[8])=100 µ mol/L. In vitro drug release experiments showed that the release rate for ORB@Q[8] complex was lower than that of ORB in artificial intestinal juice, and higher than that of ORB in artificial gastric juice.