Relationship Between Physicochemical Properties and Herbicidal Activity of 1,2,5-Oxadiazole N-Oxide Derivatives
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The relationship between the herbicidal activity of a number of novel 1,2,5- oxadiazole N-oxides and some physicochemical properties potentially related with this bioactivity, such as polarity, molecular volume, proton acceptor ability, lipophilicity, and reduction potential were studied. The semiempirical molecular orbital method AM1 was used to calculate theoretical descriptors such as dipolar moment, molecular volume, MullikenÂ´s charge and the octanol/water partition coefficients (log Po/w). The values of the reduction potentials (Er) were obtained by cyclic voltammetry. In addition, the retention factors (log kâ€™w) on a reversed-phase high-performance liquid chromatography (RP-HPLC) column in pure aqueous mobile phases were measured for several N-oxide derivatives. The log kâ€™w values show good correlation with the calculated values of log Po/w, showing that the chromatographic parameter can be used as lipophilicity descriptor for these compounds. The multiple regression analysis between the descriptors for the Noxide derivatives and the herbicide activity indicate that the variance in the biological activity can be explained by changes in the lipophilicity and in the reduction potential.
Financial support from the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET-Argentina), Consejo de Investigaciones Científicas y Tecnológicas de la Provincia de Córdoba (CONICOR-Argentina), Agencia Nacional de Promoción Científica y Tecnológica (FONCYT-Argentina), Secretaría de Ciencia y Técnica de la Universidad Nacional de Río Cuarto (SECYT-UNRC). Collaborative work was performed under the auspices of the Iberoamerican Program for Science and Technology (CYTED), SubProgram X, network X-E, RIIDDMED. M. Risso thanks to the RELAQ for the fellowship.
Quote ItemMOLECULES, V.: 10, issue: 9, p. 1197-1208, SEP 2005