**5. Based on the type of pest to control**

Accordingly propesticides are classified as proinsecticides, proherbicides, profungicides and prorodenticides.

#### **5.1. Proinsecticides**

*N*-Methylcarbamates are another major group of insecticides inhibiting AChE.Although the proinsecticidal features of OP compounds were discovered after their development, proinsecticidal carbamates were designed in Fukuto's laboratory by systematic derivatization to *N*-phosphoryl, *N*-sulfenyl, and related carbamates [14–16]. The biological and toxicological properties of these carbamates could be tailored according to particular use requirements by changing the derivatizing moiety, and thus the physicochemical properties, such as lipophilicity (log P), of the resulting product. The propesticide is activated in the insect by chemical hydrolysis by thiols or other nucleophiles. Nereistoxin is a cyclic disulfide isolated from a marine annelid [17, 18]. It served as the lead compound for the development of the proinsecticides cartap and thiocyclam, both converted into dithiolane acting at the nicotinic acetylcholine receptor of insects. The precocenes, such as precocene 2, on the other hand, were isolated from *Ageratum* sp. plants and found to inhibit the terminal (oxidative) step of JH biosynthesis in the corpora allata, causing precocious development of the insect larva. These anti-juvenile hormones, also called proallatotoxins, are "suicide inhibitors" because the cytochrome P450 catalyzed oxidation of the chromene generates epoxide that reacts with neighboring nucleophiles of the enzyme protein, causing massive cellular damage. Diafenthiuron is a thiourea insecticide inhibiting mitochondrial ATPase and acts via its carbodiimide metabolite [19]. The phenylpyrazole fipronil contains a sulfoxide group that can undergo cytochrome P450-catalyzed oxidation in insects to yield a more potent sulfone metabolite. These are meant for controlling insect pest [20]. Some of the proinsecticides along with their active metabolite and activation processes are given in the **Table 1**.

#### **5.2. Rodenticides precursors**

Fluoroacetic acid and fluoroacetamide are "lethal precursors" to 2-fluorocitrate. Bitter scilliroside, from the red squill, can be hydrolyzed by glycosidases *in vivo* to scillirosidin, its



**Propesticide Active metabolite Activation process**

Propesticides and Their Implications http://dx.doi.org/10.5772/intechopen.71532 113

Benomyl Carbendazim and butyl isocyanate Elimination/hydrolysis Thiophanate-methyl Carbendazim Hydrolysis/cyclization

Thiram *N,N*-dimethylthiocarbamate Reduction Dinobuton Dinoseb Hydrolysis

Triadimefon Triadimenol Reduction Bupirimate Ethirimol Hydrolysis Pyrazaphos Hydrolysis Probenazole Saccharin Hydrolysis Acibenzolar-S-methyl CGA 210007 Hydrolysis

**Propesticides Active metabolite Activation process** MCPB MCPA β-oxidation Naproanilide 2-Naphthoxyacetic acid Hydrolysis Chlorazine Trietazine Dealkalization Trietazine Simazine Dealkalization EPTC EPTC sulfoxide Oxidation Triallate Triallate sulfoxide Oxidation

Diuron DCPMU Oxidative dealkylation

Linuron DCPMU Demethoxylation Methazole DCPMU Hydrolysis/reduction Chlorthiamid Dichlobenil Dehydrosulfuration Metflurazone Norflurazon Oxidative dealkylation

Flamprop-methyl Flamprop Hydrolysis Bilanafos Phosphinothricin Hydrolysis

Pyrazolynate Destosyl pyrazolinate Hydrolysis Pyridate CL9673 Hydrolysis Ethephon Ethylene Elimination

**Table 3.** Active metabolites of proherbicides and activation processes.

2,4-DEP 2,4-D Hydrolysis/oxidation Cinmethylin 2-Hydroxy-1,4-cineole Oxidative dealkylation

**Table 2.** Active metabolites of profungicides and activation processes.

**Table 1.** Active metabolites of proinsecticides and activation processes.

aglycone, which was suggested to be the ultimate rat toxicant. There are a few rodenticides that have either been designed to act as prorodenticides or were found to act as such.

#### **5.3. Profungicides**

Profungicides is thiram, or tetramethylthiuram disulfide that is reduced to the corresponding dithiocarbamate, the actual bioactive principle. Dithiocarbamate derivatives of glycerol and other polyols releasing or other related fungicides have also been prepared. The carbonyl group was shown to be reduced stereoselectively into the more potent fungicide triadimenol in fungi and plants, as well as in bacteria. Spirolactone derivatives of the benzoquinone fungicide chloranil provided photostable derivatives that release the parent compound by slow hydrolysis. These are meant for controlling pathogens causing plant diseases. Some of the profungicides along with their active metabolites and activation processes are given in **Table 2**.

#### **5.4. Proherbicides**

MCPB and related homologous aryloxyalkanoic acids with an odd number of CH2 groups provide aryloxyacetic acids, such as (2-methyl-4-chlorophenoxy) acetic acid, whereas


**Table 2.** Active metabolites of profungicides and activation processes.

aglycone, which was suggested to be the ultimate rat toxicant. There are a few rodenticides

Profungicides is thiram, or tetramethylthiuram disulfide that is reduced to the corresponding dithiocarbamate, the actual bioactive principle. Dithiocarbamate derivatives of glycerol and other polyols releasing or other related fungicides have also been prepared. The carbonyl group was shown to be reduced stereoselectively into the more potent fungicide triadimenol in fungi and plants, as well as in bacteria. Spirolactone derivatives of the benzoquinone fungicide chloranil provided photostable derivatives that release the parent compound by slow hydrolysis. These are meant for controlling pathogens causing plant diseases. Some of the profungicides along with their active metabolites and activation processes are given in **Table 2**.

that have either been designed to act as prorodenticides or were found to act as such.

**Propesticides Active metabolite Activation process** Parathion Paraoxon Oxidative disulfuration Malathion Malaoxon Oxidative disulfuration

Trichlorfon Dichlorvos Rearrangement/dehydrochlorination

Thiocyclam Nereistoxin Sulfur extrusion/cyclization Diafenthiuron — Oxidative desulfuration

Disulfoton Oxydisulfoton Oxidation

112 Insecticides - Agriculture and Toxicology

Acephate Methamidophos Hydrolysis Carbosulfan Carbofuran Hydrolysis Furathiocarb Carbofuran Hydrolysis Benfuracarb Carbofuran Hydrolysis Thiodicarb Methomyl Hydrolysis Cartap Nereistoxin Hydrolysis Bensultap Nereistoxin Hydrolysis/

Cycloporate Cyclopropanecarboxylic acid Hydrolysis Chlorfenapyr — Oxidation Sulfluramide — Hydrolysis Fipronil Fipronil sulfon Oxidation Tralomethrin Deltamethrin Debromination

**Table 1.** Active metabolites of proinsecticides and activation processes.

MCPB and related homologous aryloxyalkanoic acids with an odd number of CH2

provide aryloxyacetic acids, such as (2-methyl-4-chlorophenoxy) acetic acid, whereas

groups

**5.3. Profungicides**

**5.4. Proherbicides**


**Table 3.** Active metabolites of proherbicides and activation processes.

those with an even number are degraded to herbicidally inactive phenols [21]. The occurrence of resistance in weeds to triallate has been attributed to reduced sulfoxidation, i.e., bioactivation, rates. The photosynthesis inhibitor *N,N*-dimethyl phenylurea diuron is converted into the corresponding *N*-methyl phenylurea DCPMU upon oxidative phosphorylation [22]. Dealkylation of the *N*,*N*,*N*\_,*N*\_-tetraethyl triazine derivative chlorazine to trietazine then to simazine increases the photosynthesis inhibitory activity by several orders of magnitude. For the rice herbicide thiobencarb (*S*-4-chlorobenzyl diethylthiocarbamate), reductive dehalogenation occurring in soil yields the *S*-benzyl derivative, believed to be responsible for phytotoxicity *in vivo.* These are meant for controlling weeds. Some of the proherbicides along with their active metabolites and activation processes are given in the **Table 3**.

**Author details**

Shaon Kumar Das<sup>1</sup>

**References**

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\* and Irani Mukherjee<sup>2</sup>

2 Division of Agricultural Chemicals, IARI, New Delhi, India

1 ICAR-National Organic farming Research Institute, Tadong, Gangtok, India

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[1] Das SK. Recent development and future of botanical pesticides in India. Popular Kheti.

Propesticides and Their Implications http://dx.doi.org/10.5772/intechopen.71532 115

[2] Kayser H, Eilinger P. Metabolism of diafenthiuron by microsomal oxidation: Procide activation and inactivation as mechanisms contributing to selectivity. Pest Management

[3] Das SK, Mukherjee I. Effect of light and pH on persistence of flubendiamide. Bulletin of

[4] Ohno I. Proinsecticide candidates *N*-(5-methyl-2-oxo-1,3-dioxol-4-yl)methyl derivatives of imidacloprid and 1-chlorothiazolylmethyl-2-nitroimino-imidazolidine. Bioorganic

[5] Das SK, Mukherjee I. Flubendiamide transport through packed soil columns. Bulletin of

[6] Chen L, Wang Q. Inseticidal benzoylphenylurea-s-carbamate: A new propesticide with two effects of both benzoylphenylureas and carbamates. Journal of Agriculture and

[7] Das SK, Avasthe RK, Singh R, Babu S. Biochar as carbon negative in carbon credit under

[8] Das SK, Mukherjee I. Influence of microbial community on degradation of flubendiamide in two Indian soils. Environmental Monitoring and Assessment. 2014;**186**:3213-3219 [9] Das SK, Mukherjee I. Effect of moisture and organic manure on persistence of flubendiamide in soil. Bulletin of Environmental Contamination and Toxicology. 2012;**88**:515-520

[10] Das SK. Role of micronutrient in rice cultivation and management strategy in organic agriculture—A reappraisal. Agricultural Sciences. 2014;**5**:65-769. DOI: 10.4236/as.2014.59080

[11] Das SK, Avasthe RK, Gopi R. Vermiwash: Use in organic agriculture for improved crop

\*Address all correspondence to: shaon.iari@gmail.com
