O-Dealkylation of Coumarin Ethers and Effects of Inducers, Inhibitors, and Sulfonylureas on Rice Cytochrome P-450.

Yun, Min Soo; Deng, Fan; Usui, Kenji

doi:10.3719/weed.44.341

Cited by 4 publications

(5 citation statements)

References 29 publications

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“…It is considered that the protective action of dimepiperate and dymron was due to an enhancement of the O ‐demethylative metabolism of PSE in the safened rice seedlings. Similar increases have also been observed in 7‐ethoxycoumarin O ‐desethylation and 7‐methoxycoumarin O ‐desmethylation 18…”

Section: Resultssupporting

confidence: 80%

“…In previous reports, coumarin ethers were used instead of herbicide substrates to demonstrate the ability of cytochrome P‐450 enzymes to catalyze O ‐dealkylation by several safeners and herbicides, and to characterize inhibition patterns of cytochrome P‐450 activities by several inhibitors and sulfonylurea herbicides in paddy plants 18. 19 In the present study, pyrazosulfuron‐ethyl O ‐demethylase (PSEOD) activity was investigated for qualitative characteristics of cytochrome P‐450 and related activity in two plant species, rice and C serotinus .…”

Section: Introductionmentioning

confidence: 99%

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Involvement of cytochrome P‐450 enzyme activity in the selectivity and safening action of pyrazosulfuron‐ethyl

Yun¹,

Shim

Usui

2001

Pest Management Science

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To investigate the selectivity and safening action of the sulfonylurea herbicide pyrazosulfuron-ethyl (PSE), pyrazosulfuron-ethyl O-demethylase (PSEOD) activity involving oxidative metabolism by cytochrome P-450 was studied in rice (Oryza sativa L cv Nipponbare) and Cyperus serotinus Rottb. Cytochrome P-450-dependent activity was demonstrated by the use of the inducers 1,8-naphthalic anhydride and ethanol, the herbicides PSE, bensulfuron-methyl, dimepiperate and dymron, or the inhibitor piperonyl butoxide (PBO). Growth inhibition in C serotinus seedlings was more severe than that in rice seedlings. O-Dealkylation activities of PSE were induced differently in rice and in C serotinus, with distinctly higher activity in rice seedlings. The induced PSEOD activities were slightly inhibited by PBO in rice seedlings, whereas they were strongly inhibited in C serotinus seedlings. Dimepiperate and dymron were effective safeners of rice against PSE treatment. Treatments with herbicide alone resulted in less induction of PSEOD activity compared with combined treatments of the herbicide and safener. PSEOD activity in rice seedlings induced with herbicide alone was strongly inhibited by PBO, whereas it was weakly inhibited in rice seedlings induced with combinations of PSE and two safeners. These results suggest that O-demethylation by cytochrome P-450 enzymes may be involved in the metabolism of PSE and may contribute to its selectivity and safening action. Furthermore, these results suggest the existence of a multiple form of cytochrome P-450 in plants.

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Section: Resultssupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Involvement of cytochrome P‐450 enzyme activity in the selectivity and safening action of pyrazosulfuron‐ethyl

Yun¹,

Shim

Usui

2001

Pest Management Science

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“…P450s are a class of heme-containing enzymes that catalyze the biosynthesis of lignin, terpenoid, alkaloids, and many secondary compounds in plants. P450s are also known to play important roles in metabolizing herbicides, including SU [46,47], and are involved in non-target site herbicide resistance [48].…”

Section: Mechanism For Biophoton Emission In Plants Treated With Su Hmentioning

confidence: 99%

Biophoton Emissions in Sulfonylurea-Herbicide-Resistant Weeds

Nukui¹,

Inagaki²,

Iyozumi³

et al. 2013

Herbicides - Advances in Research

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“…may be dependent on cytochrome P-450 reactions (Shim et al 1990b). Dymron may display safening effects partially by enhancing the metabolism of not only a sulfonylurea herbicide, but also a chloroacetamide herbicide via enhancing cytochrome P-450 activity, as well as dimepiperate (Nishizaka et al 1991;Shirakura et al 1988Shirakura et al , 1996Yun et al 1999). Dymron is also known to reduce the uptake of bensulfuron-methyl by rice seedlings .…”

Section: Concentrationmentioning

confidence: 99%

“…The mechanism of this pathway is accomplished by elevating either the levels of reduced glutathione (GSH) or the activity of glutathione Stransferase (GST), or both. The other pathway includes oxidation or hydroxylation and subsequent glucose conjugation, mediated by cytochrome P450-dependent mono-oxygenases and uridine diphosphoglucose (UDPG) glucosyl transferase, respectively (Frazier & Nissen 1994;Shirakura et al 1988Shirakura et al , 1996Milhomme & Bastide 1990;Moreland et al 1990;Nishizaka et al 1991;Lamoureux & Rusness 1992;Yun et al 1999). These pathways appear to be important, predominantly in the selectivity and safener protection to aryloxyphenoxypropionate and sulfonylrea herbicides.…”

Section: Introductionmentioning

confidence: 99%

Relationship between safening activity of dymron and fenclorim to pretilachlor and glutathione S‐transferase activity in rice

Deng

Yamada

Usui

2001

Weed Biology and Management

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Dymron [1‐(α,α‐dimethybenzyl)‐3‐(p‐tolyl)urea] and fenclorim (4,6‐dichloro‐2‐phenylpyrimidine) were found to exhibit a safening activity on the growth of rice (Oryza sativa L.) seedlings against pretilachlor [2‐chloro‐2′,6′diethyl‐N‐(2‐propoxyethyl)acetanilide] injury. By pretilachlor treatment at 10–6 and 10–5 mol L–1, the elongation of the third leaves of rice seedlings was reduced by approximately 20 and 40%, and that of the fourth leaves was reduced by approximately 40 and 80%, respectively. Upon the treatment of dymron at 3 × 10–6 and 10–5 mol L–1 in combination with pretilachlor, the growth inhibition was half alleviated in the third leaves, and the length of the fourth leaves was almost recovered from 10–6 mol L‐1 pretilachlor injury, and was 20–25% recovered from 10–5 mol L–1 pretilachlor injury. Upon the treatment of fenclorim at 3 × 10–6 and 10–5 mol L–1 in combination with pretilachlor, the growth inhibition of rice seedlings was almost alleviated in both the third and the fourth leaves. This result indicated that dymron and fenclorim showed almost the same safening effect on the fourth leaf growth against 10–6 mol L‐1 pretilachlor injury, although fenclorim showed higher effects at higher concentrations of pretilachlor. Glutathione S‐transferase (GST) activities in rice seedlings were investigated after being treated with a herbicide and safener. By pretilachlor treatment at 10–6 and 10–5 mol L–1, the GST activity was approximately 32 and 72% increased in roots, respectively, and a little increased (7–13%) in shoots of two‐leaf‐stage rice seedlings. By dymron treatment at 3 × 10–6−10–5 mol L–1, the GST activity was 2–30% increased in roots, but was not increased in shoots. By their combination treatment, the GST activity was almost the same or less than that by treatment with pretilachlor alone. In contrast, by fenclorim treatment alone, the GST activity was 43–52 and 33–45% increased in roots and shoots of rice seedlings, respectively. By the combination treatment of pretilachlor and fenclorim, the GST activity was increased 73–126% in shoots and 101–139% in roots, and was much more increased in both shoots and roots compared with treatment of pretilachlor or fenclorim alone. It was found that dymron showed less effect in increasing the GST activity than fenclorim. It is also suggested that dymron did not increase the GST activity in shoots but did increase it slightly in roots, and showed almost no effect on GST increase by pretilachlor in shoots, or rather reduced the increase in roots. From the above results, fenclorim and dymron may have different mechanisms of safening effects on the protection of rice seedlings against pretilachlor injury.

show abstract

O-Dealkylation of Coumarin Ethers and Effects of Inducers, Inhibitors, and Sulfonylureas on Rice Cytochrome P-450.

Cited by 4 publications

References 29 publications

Involvement of cytochrome P‐450 enzyme activity in the selectivity and safening action of pyrazosulfuron‐ethyl

Involvement of cytochrome P‐450 enzyme activity in the selectivity and safening action of pyrazosulfuron‐ethyl

Biophoton Emissions in Sulfonylurea-Herbicide-Resistant Weeds

Relationship between safening activity of dymron and fenclorim to pretilachlor and glutathione S‐transferase activity in rice

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