Interaction between optical isomerism and plant pharmacological action, change of modes of action and chirality of 1‐(α‐methylbenzyl)‐3‐p‐tolylurea

Abstract

The optical isomers, (R)‐1(α‐methylbenzyl)‐3‐p‐tolylurea ((R)‐MBU) and (S)‐1‐(α‐methylbenzyl)‐3‐p‐tolylurea ((S)MBU), which are analogues of daimuron [1‐(α,α‐dimethylbenzyl)‐3‐p‐tolylurea], a herbicide for Cyperaceae weeds and a safener for paddy rice, exhibited different biological responses. These two physiological properties of daimuron were observed separately in (R)‐MBU and (S)‐MBU. Only (R)‐MBU had herbicidal activity against Cyperaceae weeds, while the (S)‐isomer was a more effective safener against bensulfuron‐methyl (BSM) injury of rice seedlings than was (R)‐MBU. (S)‐MBU promoted root growth of rice seedlings, but the (R)‐enantiomer inhibited root growth. (S)‐MBU was a more potent inhibitor than (R)‐MBU on PS II reaction of spinach broken chloroplasts. Furthermore, (S)‐MBU and (R)‐MBU showed cross intergenus selective phytotoxicity among the Gramineae plants, Oryza sativa L. (rice, cv. Tsukinohikari, japonica), Triticum aestivum L. (wheat, cv. Norin No. 61) and Echinochloa crusgalli var. frumentacea Wight, on root growth inhibition in the dark.

Amelioration of the Salt-stressed Root Growth of Rice and Normalization of the Na+Distribution between the Shoot and Root by (S)-α-Methylbenzyl-2-fluoro-4-methylphenylurea

“…Optically active urea compounds (2-7) and daimuron have been found eŠective stress relievers of rice injured with the bensulfuron-methyl herbicide. 22,23,26) The data in Table 1 show the root-growth response of the just-germinated rice seedlings after treatment with 60 mM NaCl or with a stress reliever and with their combination in the agar culture medium. At this concentration of NaCl, the root growth rate was only 46.5z of the control value.…”

“…frumentacea Wight in the dark, and stress relieving activity against herbicide stress in rice. 22,23,26) Concomitant treatment with S-MBPUs (2-7) eŠectively ameliorated the growth inhibition of roots of NaCltreated rice plants. Salt-stressed rice plants decrease their dry weight, protein content, water content and chlorophyll content.…”

“…1) are presented in the literature. 22,24) Plant materials and growth response. Seeds of Oryza sativa L. (cv.…”

“…frumentacea Wight (barnyard millet) toward root-growth inhibition in the dark, while the S-enantiomer (2) has eŠectively relieved herbicide stress in rice. 22) The test compounds in this study (3)(4)(5)(6)(7) were developed as potent stress reliever for rice injured with the herbicide, bensulfuron-methyl (Londax), after the modiˆcation of 2. 23) We conducted this study to assess the amelioration potency of optically active MBPUs to the saltstressed growth of just-germinated rice seedlings, and discuss the relationship between the growth inhibition, Na + and protein contents, and dry weight.…”

Diverse responses of plants towards chiral chemicals

“…R 3 and R 4 are hydrogen and/or alkyl groups. et al 1993et al , Ryoo et al 1998Chemical structure of optical isomers of 1 -α -methylbenyl -3 -phenylurea. R -isomers : R 1 =CH 3 , R 2 =H.…”