Hydrogen‐bonding effects, electrostatic potential, and the antitumor activity of flavone acetic acid and related compounds. I. Ab initio studies on the first stable conformations

Abstract Ab initio investigations have been carried out to account for the antitumor activity of flavone acetic acid (FAA) and related compounds. The hydrogen‐bonding conformation was chosen for all the compounds and obtained through a restricted geometry optimization with the 3‐21G basis set. Three key regions in the molecular electrostatic potential isosurfaces [V(r) ∼ −0.015 au] are found to be involved in the activity. Region 1 is the most important. Its existence implies the activity 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. © 1995 John Wiley & Sons, Inc.