Theoretical investigations of the effect of a homologous series of anionic Surfactants on the metabolism bioactivity of Chromobacterium violaceum

Theoretical calculations were performed to obtain physicochemical properties associated with the effect of homologous anionic n-alkylsulfate surfactants on the metabolism of Chromobacterium violaceum. The quantitative experimental effects on the respiration process were those obtained from calorimetric data and were used to correlate the Structure-Activity-Relationship (SAR) of these compounds. Semiempirical AM1 and ab initio DFT levels, employing the set CEP-31G, were used for the theoretical calculations and were parameterized using the continuum-solvation model COSMO for solvent contributions. Chemometric analyses (HCA: hierarchical cluster analysis and PCA: principal component analysis) were used to correlate the physicochemical properties of these compounds and their biological activities. The results indicate that the biological activities of these compounds increase as the hydrocarbon chain length, volume, molar volume and exothermic enthalpy of formation (Delta H-f degrees) increase; in contrast they decrease with decreases of the solvent effect (SE), ionization enthalpy (IE) and HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energies.