1. Sonolysis Promotes Indirect Co−C Bond Cleavage of Alkylcob(III)alamin Bioconjugates
- Author
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Natarajan E, Bayomi A, el-Ahmady O, Aziza Ma, Howard Wa, West Fg, and Grissom Cb
- Subjects
Pharmacology ,Alkane ,chemistry.chemical_classification ,Magnetic Resonance Spectroscopy ,Aqueous solution ,Bioconjugation ,Stereochemistry ,Hydrolysis ,Organic Chemistry ,Corrin ,Biomedical Engineering ,Pharmaceutical Science ,Bioengineering ,Ring (chemistry) ,Sonochemistry ,Vitamin B 12 ,chemistry.chemical_compound ,chemistry ,Spectrophotometry, Ultraviolet ,Bond cleavage ,Biotechnology - Abstract
Sonolysis of aqueous solutions produces H. and HO. that lead to Co-C bond cleavage in methylcob-(III)alamin (CH3-CblIII) and 2-[4-[4'-[bis(2-chloroethyl)amino]phenyl]butyroxy]ethylcob (III)alamin (Chl-HE-CblIII). Under anaerobic conditions, H. reduces CH3-CblIII to the unstable 19 e-CH3-CblII that dissociates to the alkane and CblII. Under aerobic conditions, O2 scavenges H. and Co-C bond cleavage occurs via a HO.-mediated process along with modification of the corrin ring by HO.. When H. and HO. are scavenged, there is no evidence of Co-C bond cleavage. This suggests no direct sonolysis of the Co-C bond occurs, in spite of the fact that the Co-C bond is 80 kcal/mol weaker than the H-OH bond. A bioconjugate of cob(III)alamin and the alkylating agent chlorambucil has been synthesized to give 2-[4-[4'-[bis(2-chloroethyl)amino]phenyl]butyroxy]ethylcob(I II)alamin. The chlorambucil-cobalamin complex also undergoes Co-C bond cleavage in a manner similar to that of methylcob-(III)alamin. Sonorelease of an active alkylating agent from the bioconjugate may provide a new method for the selective release of anticancer drugs and thus potentially reduce systemic toxicity.
- Published
- 1997