Synthesis and herbicidal activity of novel 1-(Diethoxy-phosphoryl)-3-(4-one-1H-1,2,3-triazol-1-yl)-propan-2-yl carboxylic esters.

A series of novel compounds, namely 1-(diethoxyphosphoryl)-3-(4-ones-1H-1,2,3-triazol-1-yl)propan-2-yl carboxylic esters, were designed on the basis of the diazafulvene intermediate of imidazole glycerol phosphate dehydratase (IGPD) and high-activity inhibitors of IGPD, and synthesized as inhibitors targeting IGPD in plants. Their structures were confirmed by 1H-NMR, 13C-NMR, 31P-NMR and HR-MS. The herbicidal evaluation performed by a Petri dish culture method showed that most compounds possessed moderate to good herbicidal activities. Six compounds were chosen for further herbicidal evaluation on barnyard grass by pot experiments. 1-(Diethoxyphosphoryl)-3-(4-phenyl-1H-1,2,3-triazol-1-yl)propan-2-yl 2-(naphthalen-1-yl)acetate (5-A3) and ethyl 1-(2-acetoxy-3-(diethoxyphosphoryl)propyl)-1H-1,2,3-triazole-4-carboxylate (5-B4) showed good herbicidal activities. Compared with the compounds with the best herbicidal activity ever reported, both compounds 5-A3 and 5-B4, which can inhibit the growth of barnyard grass at the concentration of 250g/hm2, efficiently gave rise to a nearly 4-fold increase of the herbicidal potency. However, their herbicidal activities were lower than that of acetochlor (62.5 g/hm2) in the pot experiments.

A conserved aromatic residue regulating photosensitivity in short-wavelength sensitive cone visual pigments.

Visual pigments have a conserved phenylalanine in transmembrane helix 5 located near the ß-ionone ring of the retinal chromophore. Site-directed mutants of this residue (F207) in a short-wavelength sensitive visual pigment (VCOP) were studied using UV-visible spectroscopy to investigate its role in photosensitivity and formation of the light-activated state. The side chain is important for pigment formation: VCOP(F207A), VCOP(F207L), VCOP(F207M), and VCOP(F207W) substitutions all bound 11-cis-retinal and formed a stable visual pigment, while VCOP(F207V), VCOP(F207S), VCOP(F207T), and VCOP(F207Y) substitutions do not. The extinction coefficients of all pigments are close, ranging between 35800 and 45600 M⁻¹ cm⁻¹. Remarkably, the mutants exhibit an up to 5-fold reduction in photosensitivity and also abnormal photobleaching behavior. One mutant, VCOP(F207A), forms an isomeric composition of the retinal chromophore after illumination comparable to that of wild-type VCOP yet does not release the all-trans-retinal chromophore. These findings suggest that the conserved F207 residue is important for a normal photoactivation pathway, formation of the active conformation and the exit of all-trans-retinal from the chromophore-binding pocket.