Binding of 14 kinds hydrophobic compounds of anthraquinones and flavonoids, which distribute extensively in many Chinese herbal medicine, to bovine serum albumin (BSA) were studied using centrifugal ultrafiltration. The binding data was analyzed according to Scatchard model, and the binding constants and the binding site no. were obtained, resp. The results show that the affinity of these compounds to BSA increases as their hydrophobicity higher except gertiopicrin. Competitive binding studies indicate that L-tryptophan and emodin share one primary site, addition of excess L-Trp will result in the displacement of one molar equivalence emodin. In the presence of low concentration oleate, the six homogeneous sites of emodin are distinguished into two classes: n1 = 2, n2 = 4, the total no. of binding sites remains unchangeable while the binding constants decrease. When the oleate concentration is high enough, emodin will not bind to BSA completely. The temperature dependence of the binding constants reveals that the binding enthalpy is nearly zero. On this basis, the mechanism of the binding reaction was discussed in brief.

Key words: TRYPTOPHAN, FLAVONOID, ANTHRAQUINONE P, CATTLE, EMODIN, SERUM ALBUMIN