The search for new cancerostatic agents.

Following the lead given by Albert Szent-Györgyi's bioelectronic theory of cancer, work was continued in two major directions: (i) designing new electrophilic molecules, related to methylglyoxal, and (ii) using L-ascorbic acid as a (non-toxic) carrier for methylglyoxal and its derivatives in the form of its acetals. The vinylogue of methylglyoxal, 4-oxopent-2-enal, was expected to be a most reactive electron acceptor, on the basis of quantum mechanical calculations by J.J. Ladik's group. A new reaction, the formation of the ene-2, 3-diol acetal and hemiacetal-hemiketal, was found to occur with 'conjugated' aldehydes, such as methylglyoxal, glyoxal, phenylglyoxal, malealdehyde and acrylaldehyde; the reaction proceeded very smoothly with 4-oxopent-2-enal. The structural determination of these new types of acetals by 1H and 13C n.m.r. spectroscopy and by chemical methods is discussed.