Structural investigations of the products of vincristine sulfate formed after in vitro incubation of the alkaloid in bile of dogs

Abstract

Vincristine (VCR) was incubated in bile from dogs at 37 °C for 72 h. At the end of the incubation, the mixture was extracted with methylene chloride. HPLC analysis (μBondapak C 18, 10-μm, reverse-phase steel column; isocratic solvent system, 50% MeOH in 10 m M KH 2PO 4, pH 4.0; flow rate, 1.3 ml/min; detector, 254 nm) of the extract gave four peaks, A, B, C, and D with retention times of 3.8, 4.8, 7.0, and 21.9 min, respectively. In this system, VCR corresponded with peak C and its spectral properties were identical to those of the parent compound. The UV, IR, and MS spectral properties of these peaks were as follows [UV (λ max); IR (cm −1); MS ( m z )] peak A: 210, 250, 295 nm; 3424, 2919, 2850, 1738, 1680, 1601, 1461, 1382, 1231, 1032, 748; 783 (MH +); peak B: 210, 252, 295, 306 nm; 3465, 2919, 2851, 1739, 1679, 1599, 1034, 746; 825 (MH +); peak C: 220, 255, 295 nm; 3456, 2920, 2851, 1742, 1683, 1615, 1456, 1385, 734; 825 (MH +); peak D: 217, 252, 293, 312 nm; 3435, 2920, 2852, 1739, 1677, 1460, 1377, 1032, 726; 839 (MH +). These data suggest the following tentative structures: peak A, 4-deacetylvincristine; peak B, 4′-deoxy-3′-hydroxyvincristine; and peak D, 3′,4′-epoxyvincristine N-oxide. The structure of peak A as 4-deacetylvincristine was confirmed by chemical synthesis.