Chemical characterization of the in vitro degradation products of vindesine sulfate

Abstract

Vindesine (VDS) was incubated in 0.2 M glycine buffer (pH 4.0, 7.4, or 8.8) containing bovine serum albumin (1%) at 37 °C for 24 or 72 h. The reaction mixture was extracted with CH 2Cl 2. 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 ml/min; detector, 254 nm) of the extract gave three major peaks A, B, and C with retention times of 4.3, 5.3, and 13.0 min, respectively. At pH 8.8, peaks A and C accounted for about 11 and 28%, respectively, of the parent VDS. VDS in this system corresponded with peak B and its spectral data (UV, IR, MS, and 1H and 13C NMR) were identical to those of the parent compound. The UV, IR, and MS spectral properties of these peaks were as follows: peak A: UV (λ max): 208, 258, 290, 310 nm; IR (cm −1): 3450, 1731, 1673, 1611, 1503, 1460, 1380, 1228, 743; MS ( m z ): 752 (MH +); peak B: UV (λ max): 210, 263, 279, 290, 306 nm; IR (cm −1): 3457, 2922, 2850, 1723, 1676, 1500, 1456, 1369, 812, 733; MS ( m z ): 754 (MH +); peak C: UV (λ max): 212, 268, 280, 290, 310 nm; IR (cm −1): 3457, 2922, 2850, 1727, 1662, 1456, 1380, 1040, 740; MS ( m z ): 768 (MH +). On the basis of these spectral data and 1H NMR spectroscopy, peaks A and C are tentatively identified as an enamine/ether derivative of VDS and 3′,4′-epoxyvindesine N-oxide, respectively.