HYDROGEN-BONDING EFFECTS, ELECTROSTATIC POTENTIAL, AND THE ANTITUMOR-ACTIVITY OF FLAVONE ACETIC-ACID AND RELATED-COMPOUNDS .1. AB-INITIO STUDIES ON THE FIRST STABLE CONFORMATIONS

Ab initio investigations have been carried out to account for the anti tumor activity of flavone acetic acid (FAA) and related compounds. The hydrogen-bonding conformation was chosen for all the compounds and ob tained through a restricted geometry optimization with the 3-21G basis set. Three key regions in the molecular electrostatic potential isosu rfaces [V(r) similar to -0.015 au] are found to be involved in the act ivity. Region 1 is the mast important. Its existence implies the activ ity and its size determines the strength of the activity. Region 2 is another factor which can change the strength of the activity. Region 3 corresponds to the hydrogen-bonding effects which have been analyzed in detail, but its role is still not clear. Finally, basis-set effects on the molecular electrostatic potential have been briefly discussed. (C) 1995 John Wiley and Sons, Inc.