ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Inhibitory Effects of Substituted Benzanilides on Photosynthetic Electron Transport in Spinach Chloroplasts

K. Král'ová, F. Šeršeň, L. Kubicová, and K. Waisser

Institute of Chemistry, Faculty of Natural Sciences, Comenius University, SK-842 15 Bratislava

Abstract: The inhibitory activity of 18 benzanilides substituted in the acyl (R¹ = H, 3-Br, 4-Cl, 4-OCH₃, 3-NO₂, 3-F, 4-F) as well as in the anilide part of the molecule (R-2 = 3-Cl, 3-OCH₃, 3-NO₂, 3-F, 4-OCH₃, 4-NO₂, 4-CH₃, 4-CH(CH₃)₂, 4-CH₂CH₂CH₂CH₃) on oxygen evolution rate in spinach chloroplasts has been investigated. The dependence of photosynthesis-inhibiting activity upon the lipophilicity of the substituents showed a quasi-parabolic course. The IC₅₀ values in the investigated set varied in the range from 41 μmol dm^-3 (R¹ = 3-NO2, R² = 4-CH(CH₃)₂) to 497 μmol dm^-3 (R¹ = 4-F, R² = H). Using ESR spectroscopy the site of action of these compounds in the photosynthetic apparatus of spinach chloroplasts has been studied. It was confirmed that the site of action of the studied anilides are the intermediates D⁺, i.e. tyrosine radicals which are situated in the 161st position in D₂ protein on the donor side of photosystem 2.

Full paper in Portable Document Format: 535a328.pdf

Chemical Papers 53 (5) 328–331 (1999)