31P nuclear magnetic resonance spectroscopic observation of the intracellular transformations of oncostatic cyclophosphamide metabolites.

Abstract

31P NMR spectroscopy was used to directly monitor, for the first time, the intracellular chemistry of the ultimate active metabolite of cyclophosphamide, namely, phosphoramide mustard. These NMR studies utilized a human histiocytic lymphoma cell line (U937), embedded in agarose gel threads, and perfused with medium containing synthetically derived metabolites (4-hydroxycyclophosphamide, aldophosphamide, and phosphoramide mustard). Metabolites 2 or 3 or both readily crossed the cell membrane; in contrast, the membrane was relatively impermeable to 4. Intracellular concentrations of 4 could, therefore, be attributed primarily to the intracellular fragmentation of 3. Signals suggestive of either carboxyphosphamide or 4-ketophosphamide were not detected. Spectral data were used to calculate a rate constant of (5.4 +/- 0.3) X 10(-3) min-1 for the intracellular disappearance of 4 at 23 degrees C. The intracellular pH was determined to be 7.1 from the chemical shift of the internal inorganic phosphate signal.

• Authors: V L Boyd, J D Robbins, W Egan, S M Ludeman
• Journal: Journal of medicinal chemistry (J Med Chem) Vol. 29 Issue 7 Pg. 1206-10 (Jul 1986) ISSN: 0022-2623 [Print] United States
• PMID: 3543359 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Cyclophosphamide

Topics

• Biotransformation
• Cell Line
• Cyclophosphamide (analogs & derivatives, metabolism)
• Humans
• Lymphoma, Large B-Cell, Diffuse
• Magnetic Resonance Spectroscopy (methods)
• Structure-Activity Relationship