Photosynthetic Electron Transport Inhibition by Pyrimidines and Pyridines Substituted with Benzylamino, Methyl and Trifluoromethyl Groups

Abstract

PET Inhibitory Activity, Atrazine-Resistant Chenopodium album , 4-Benzylamino-2-methyl-6-trifluoromethylpyrimidines The decrease of the num ber of ring nitrogen atoms of 2-benzylamino-4-methyl-6-trifluoromethyl-l,3,5-triazines on herbicidal activity and inhibition of photosynthetic electron trans port (PET) was assayed using thylakoids from Spinacia oleracea or atrazine-resistant Cheno podium album. Three 2-benzylamino-4-methyl-6-trifluoromethyl-l,3,5-triazines, nine pyrimi dines with a benzylamino-, methyl-and trifluoromethyl-group, 2-benzylamino-6-methyl-4-trifluoromethyl-pyridine and N-benzyl-S-methyl-S-trifluoromethylaniline were synthesized and assayed. 2-(4-Bromobenzylamino)-4-methyl-6-trifluoromethylpyrimidine exhibited the highest PET inhibitory activity against Spinacia oleracea thylakoids of all compounds tested. The 2-benzylaminopyrimidines and 2-methylpyrimidines having a 4-halobenzylamino group exhibited higher PET inhibition than atrazine and 2-trifluoromethylpyrimidines against Spi nacia oleracea thylakoids. These PET inhibitory active compounds also exhibited a strong and similar inhibition both against atrazine-resistant Chenopodium album thylakoids as well as against thylakoids from wild-type Chenopodium. The herbicidal activity of 4-(4-bromobenzylamino)-2-methyl-6-trifluoromethylpyrimidine was equivalent to that of known herbicides like simetryne, simazine or atrazine.

Synthesis and Inhibitory Effect on Photosynthetic Electron Transport of 1,3,5-Triazinylcarboxylic Acid Derivatives

“…The inhibition of PET by the compounds assayed was determined using an oxygen electrode as in our previous paper. 5) The activity was determined by the system H 2 O → potassium ferricyanide, uncoupled by NH 4 Cl. The molar concentration (I 50 ) required for 50% inhibition was calculated for each compound by the probit method.…”