A MOLECULAR-ORBITAL STUDY OF 2 VASOCONSTRICTING MYCOTOXINS - BUTENOLIDE AND ERGOTAMINE

A semiempirical molecular orbital study of the molecular structure and properties was performed for two mycotoxins: butenolide (4-acetamido- 2-buten-4-olide) and ergotamine. The purpose of the study was to exami ne the possible relationship between the mode of action between the tw o molecules and the structural similarity between the butenolide and t he corresponding fragment of ergotamine. The minimum-energy conformati ons for both species were analysed and one of the lowest energy confor mations of ergotamine, within this fragment, closely resembles that of the butenolide. Values of the heat of formation, the ionization poten tials, the electron affinities and the dipole moments are reported.