Emulsifiable concentrate formulation (EC) of triflumizole (TFZ, trade name: trifmine^®), (E)-4-chloro-α, α, α-trifluoro-N-(1-imidazol-1-yl-2-propoxyethylidene)-o-toluidine, showed higher efficacy to Bakanae disease (Gibberella fujikuroi) in seed treatment than its wettable powder formulation (WP). One of the reasons for this was that the amount of TFZ on the seeds was higher in EC treatment than in WP treatment. Another reason was that TFZ in EC treatment permeated more easily into the seeds through husks than in WP treatment.

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The inhibition of acetolactate synthase (ALS) from etiolated pea seedlings by 2-(4, 6-dimethoxypyrimidine-2-yloxy) benzoic acid (compound 2), one of the pyrimidinylsalicylic acid (PS) compounds, was desensitized by SH inhibitors but not at the alkaline pH. PS compounds including pyrithiobac (2-chloro-6-(4, 6-dimethoxypyrimidine-2-ylthio)benzoic acid) tested in this study inhibited ALS activity in the mixed-type manner with respect to pyruvate and in the non-competitive with respect to thiamine pyrophosphate (TPP). These compounds inhibited both of the two molecular species of ALS which were partially purified from pea seedlings and exhibited slow-binding properties to the crude preparation of ALS from pea seedlings in the extended-time-course experiments. The inhibition constants of the initial inhibition by PS compounds were 13- to 26-fold larger than those of the final steady state and the maximal first order rate constant (0.69min^-1) for transition from the initial to the final steady state of the inhibition of pyrithiobac was nearly identical to those reported on other widely acknowledged ALS inhibitors. From these results, we conclude: PS compounds are slow-binding inhibitors to ALS activity, categorized in the sulfonylurea type. The binding site of PS compounds on the enzyme is considered to be located on the similar site to sulfonylureas. This binding site is judged not to be located on the regulatory center(s) but on the allosteric site in a wide sense near the catalytic center, which overlaps partially with the binding site of pyruvate and does not overlap with the binding site of TPP.

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2, 5-Diphenyl-Δ⁴-1, 2, 4-thiadiazolin-3-ones were synthesized and their insecticidal activities were examined. These compounds exhibited the disruption of larval molting and ovicidal actions, similar to the function of benzoylphenylurea insecticides. Substituent effect of the benzene ring on the insecticidal activity was similar to that of benzoylphenylureas. The introduction of fluorine atom into the aniline moiety markedly enhanced the activity. The potency of the insecticidal activities of Δ⁴-1, 2, 4-thiadiazolin-3-ones against the larvae of Pseudaletia separata and Spodoptera litura were almost the same as benzoylphenylureas, but their ovicidal activity against S. litura was lower than that of benzoylphenylureas. 2, 5-Diphenyl-Δ⁴-1, 2, 4-oxadiazolin-3-ones were also synthesized, and their insecticidal activity decreased compared with those of Δ⁴-1, 2, 4-thiadiazolin-3-ones. Metabolism of a Δ⁴-1, 2, 4-thiadiazolin-3-one derivative was investigated by feeding the compound to S. litura and a benzoylphenylurea derivative was detected as a metabolite in the homogenized insect one day after the feeding. This result may suggest that Δ⁴-1, 2, 4-thiadiazolin-3-ones were partly metabolized into benzoylphenylureas in the insect body and consequently exhibited the insecticidal activity.

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Monodemethylation of fenitrothion catalyzed by any of five purified glutathione S-transferases from rat liver predominantly produced the (S)_P-(-)-enantiomer of desmethyl fenitrothion. Mouse liver cytosolic fraction demethylated fenitrothion in the presence of glutathione to produce predominantly the (R)_P-(+)-isomer. The absolute configuration of the (+)-desmethyl fenitrothion was determined as (R)_P by X-ray crystallography of its brucine salt.

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The metabolism of ipconazole, (1RS, 2SR, 5RS; 1RS, 2SR, 5SR)-2-(4-chlorobenzyl)-5-isopropyl-1-(1H-1, 2, 4-triazol-1-ylmethyl) cyclopentanol, in rice seedlings and mature plants after seed treatment was investigated. Seeds were treated with two different types of ¹⁴C-labeled ipconazole, [T-¹⁴C]-ipconazole labeled at the triazole ring and [B-¹⁴C]-ipconazole labeled at the benzylmethylene position. After 22 days of seeding, 40-41% of the applied radioactivity was recovered from soil, 27% from roots and seeds, and only 0.36-0.42% from rice shoots. The main metabolites of ipconazole in rice seedlings after seed treatment or root application were oxidative products at the carbons of the isopropyl group (methyl and methine) and the benzylmethylene, although trace amounts of conjugated metabolites were observed. Seedlings from seeds treated with ¹⁴C-ipconazole were cultivated for 144 days in Wagner pots, and radioactive residues in harvested grains were analyzed. Residues in hulled rice from the plants treated with [T-¹⁴C]-ipconazole and [B-¹⁴C]-ipconazole were 2.5μg eq./kg and 0.2μg eq./kg, respectively. Ipconazole and its metabolites detected in seedlings were not found in hulled rice, and most of the radioactivity derived from [T-¹⁴C]-ipconazole was detected in the unextractable residue and water soluble fraction from hulled rice.

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Geraniol and isothymol in the essential oil of Alpinia speciosa K. SCHUM. possess high antimicrobial activity against plant pathogenic bacteria. The twenty-three kinds of 1, 3, 2-oxazaphospholidine 2-sulfides were synthesized by reacting (S)-2-aminoalcohols, PSCl₃ and the components of essential oil; geraniol, isothymol, thymol, citronellol and eugenol. Among the prepared compounds, (4S)-2-citronelloxy-4-isopropyl-1, 3, 2-oxazaphospholidine 2-sulfide (6) and (4S)-2-geranioxy-4-isopropyl-1, 3, 2-oxazaphospholidine 2-sulfide (5) had the strongest antimicrobial activity against Pythium sp. and Corticium sp. respectively. L-Valine derivatives showed stronger activity than the other L-amino acids derivatives.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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Government organization actually working on pesticide residue in the Philippines is as follows: Bureau of Plant Industry (BPI), Department of Agriculture has the Central Pesticide Analytical Laboratory (PAL) in Manila and four Satellite PALs in major areas of the country. These laboratories are expected to generate baseline pesticide data in order to establish national MRLs through conducting pesticide residue surveys at each regions by well-trained experts which would contribute to the formation of pesticide regulatory policies. The analytical capability of the BPI laboratories, however, has considerably declined due to the aging facilities and equipment. On the other hand, with the introduction of new pesticides on the market, requirements for improved analytical capability are urgently needed everyday. Accordingly, it is necessary for the BPI laboratories to introduce modern equipment and to upgrade their facilities, which may well derive technical innovation. In addition, the Philippines does not have its own legal standards of pesticide residue tolerance (or MRLs) at the moment due to insufficiency in data collection needed for the establishment of the tolerance. Therefore, the Philippines is still in a condition that people are not sure whether actual pesticide residues in food are tolerable or not. Absence of such standards leaves the government in a difficult position without legal and scientific basis to guide the farmers and, therefore, is a major cause of ineffective regulation policy. In the meantime, the indiscriminate application of pesicide has caused substantial problems, such as hazards to human health and the environment if setting aside residues in food. Thus, the establishment of MRLs by the government for the reasonable pesticide policy is really urgent. During my stay there for two years (1991-1993) as an expert sent by the Japan International Cooperation Agency (JICA), up-grading and modernization of PAL facilities were remarkably progressed by implementation of the JICA project. Analytical capabilities of the PALs will be much improved this way in terms of precision, accuracy and capacity, and the national network on pesticide monitoring will be strengthened. Data generated from the network will accelerate the establishment of national MRLs.

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The safety of pyridaben for users and consumers can be summarized as follows. The acute studies with technical material showed pyridaben to have moderate to low toxicity. Pyridaben caused no irritation of skin and eye and no contact sensitization. Pyridaben did not show mutagenic potential, was not oncogenic in rats and mice, did not affect reproductive performance in rats and was not teratogenic in rats and rabbits although decreases in bodyweight and food consumption were seen in teratology studies. In addition, the main effects seen in subchronic to chronic toxicity studies were the reduction of bodyweight gain, depression of food consumption and impairment of food conversion efficiency. A specific target organ, however, was not identified. The NOEL's for chronic studies in rats, mice and dogs on a mg/kg bodyweight basis were comparable. The minimum value of the maximum no-effect level was 8ppm in the oncogenicity study of mice. In conclusion, there were no adverse toxicological findings based on the above studies.
Sanmite^® WP and Sanmite^® SC containing 20% pyridaben were registered by Japanese MAFF in 1991 as an acaricide and insecticide for various fruits as well as for tea. Pyridaben and its formulations were specified by Japanese MHW as harmful substances because of the acute toxicity data. However, the products are not considered to be a cause for concern in the safety of users and consumers provided they are used carefully and in accordance with the established standard for safe use.

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