ABSTRACT
Ursolic acid, a pentacyclic triterpene compound, naturally occurs in a large variety of plants, has at-tracted considerable interest owing to its significant biological activities. In recent years, more and more scientists have been working on the structural modification at the C-3 position , C_(12)-C_(13) double bond or C-28 position of ur-solic acid in order to improve their biological activities. Herein a brief introduction of the recent progresses on the chemical structural modification and the structure-activity relationship of ursolic acid and its derivatives are re-viewed.
ABSTRACT
Pectin, a polysaccharide extracted from the cell wall of plants, was used as the drug carrier to synthesize the pectin-adriamycin conjugates (P(A)n). The structure of the conjugates was confirmed by UV and IR. The degree of esterification (DE) of the pectin was assessed, and it was found that DE significantly influenced the carboxy group contents, inherent viscosity and galacturonic acid contents of the pectin. The results of drug release test in vitro showed that the conjugate was stable in normal saline, but was gradually enzymolyzed to release the adriamycin in blood plasma and in lymph nodes. The results of lymphatic targeting study of P(A), demonstrated that the modification of DE or drug coupling capacity of pectin significantly influenced the lymphatic targeting characteristics of P (A)n. The adriamycin concentration of lymph nodes was 208 times higher than that of plasma after local injection of the P(A)n, of which the adriamycin content was 27.9% and the pectin was deesterificated 120 minutes by the use of hypothermy alkaline deesterification method.