• Applied Biological Chemistry
• /
• v.38 no.1
• /
• pp.90-94
• /
• 1995

Post emergence herbicidal activities$(pI_{50})$ of X-substituted phenylvinylsulfone derivatives(S) in-vivo against rice(Oryza sativa L.), Barnyard grass(Echinochloa crus-galli) and Pickerelweed(Monochoria vaginalis Presl) were measured by the pot test under paddy conditions. The (S) showed herbicidal symptom rapidly with lower activity(average $pI_{50}=2.0$) as proherbicide, which was excellent tolerance to rice. The structure activity relationships(SAR) were analyzed using such a physicochemical parameters as hydrophobic$({\pi})$ and molecular orbital(MO) quantity by the multiple regression technique, and discussed with quantum pharmacology. The herbicidal activities were related to the hydrophobic$({\pi})$ effect of X-substituent and orbital(HOMO & LUMO) energy. In case of Pickerelweed, the effect was rationalized by parabolic function of ${\pi}$ constant, where the optimal value of ${\pi}$ was 1.10. An increase in hydrophobicity and negative orbital energy by the electron attracting X-substituent may contribute to the herbicidal activity. Based on results proposed from SAR analysis, the mode of herbicidal action could be assumed.