Pyrimethanil targets multiple pathways in fungal pathogens. Its primary mechanism of action is inhibition of methionine biosynthesis in Botrytis cinerea. By blocking methionine and other amino acid synthesis, the compound disrupts protein synthesis and fungal growth. Pyrimethanil also inhibits fungal cell wall synthesis by targeting the enzyme chitin synthase, which is essential for cell wall integrity. This dual mechanism of action contributes to its broad-spectrum fungicidal activity. The compound is effective against Botrytis spp. and other ascomycetes. Its anilinopyrimidine structure is characteristic of this class of fungicides.

Pyrimethanil is a fungicide classified as anilinopyrimidines, specifically a strobilurin. After being exposed to two environmentally relevant concentrations of pyrimethanil for an extended period of time, the Italian tree frog H. intermedia's tissues may undergo histological changes and exhibit a variety of toxic reactions (5 and 50 µg/L)[2]. In the medium of three-day-old cultures, pyrimethanil reduces the activity of polygalacturonase, cellulase, proteinase, and laccase. For polygalacturonase, cellulase, and proteinase, the 50% reduction in total enzyme activity (IC50) caused by pyrimethanil is roughly 0.25 μM, and for laccase, it is approximately 1.0 μM[3].
In vitro, pyrimethanil has demonstrated potent antifungal activity against Botrytis cinerea and other fungal pathogens. The compound inhibits methionine and other amino acid biosynthesis in Botrytis cinerea. It also inhibits chitin synthase, affecting fungal cell wall synthesis. Pyrimethanil (5 and 50 µg/L) elicits a range of toxic responses and has the potential to induce histological alterations in tissues. Its antifungal activity is concentration-dependent, with effective concentrations typically in the low µg/L range. The compound's activity against Botrytis spp. has been demonstrated in various in vitro assays. Its broad-spectrum activity makes it effective against multiple fungal pathogens.

In vivo, pyrimethanil is used as a contact fungicide for the control of Botrytis spp. on a variety of crops including fruits, vegetables, and ornamental plants. It is applied as a foliar spray to prevent and treat fungal infections. The compound's efficacy against Botrytis cinerea has been demonstrated in field trials and agricultural applications. Pyrimethanil can be used for the research of fungal disease prevention on fruit, vegetable, and ornamental plants with mold infection. Its contact fungicide activity means it acts on the plant surface rather than being systemically absorbed. The compound's effectiveness against a variety of pathogens makes it valuable for crop protection research.

For in vitro biochemical assays, pyrimethanil is evaluated for its antifungal activity and effects on fungal metabolism. Minimum inhibitory concentration (MIC) and EC50 values are determined using agar dilution or broth microdilution methods against Botrytis cinerea and other fungi. Methionine biosynthesis inhibition is assessed by measuring methionine levels or by complementation studies with methionine. Chitin synthase inhibition is measured using enzyme activity assays with appropriate substrates. Fungal growth inhibition is assessed by measuring mycelial growth or spore germination. Resistance mechanism studies can be performed by isolating and characterizing resistant mutants. These assays help characterize the compound's antifungal activity and mechanism of action.

In vitro cellular assays for pyrimethanil are performed using fungal cultures. Botrytis cinerea and other fungal pathogens are cultured in appropriate media and treated with pyrimethanil at various concentrations. Fungal growth is monitored by measuring mycelial diameter, biomass, or spore germination. Methionine and amino acid levels are measured using HPLC or colorimetric assays. Chitin content is measured to assess effects on cell wall synthesis. Fungal viability is assessed using fluorescent dyes or by plating for colony counts. Gene expression of target enzymes is analyzed by qPCR. These cellular assays help validate the compound's antifungal activity and characterize its mechanism of action.

In vivo animal experiments with pyrimethanil are limited, as the compound is primarily used as an agricultural fungicide rather than a therapeutic agent. Toxicological studies in animals have been conducted to assess safety for agricultural workers and consumers. Rodent models are used for acute, subchronic, and chronic toxicity assessments. Parameters assessed include body weight, food consumption, clinical signs, hematology, clinical chemistry, organ weights, and histopathology. The compound's potential to induce histological alterations in tissues has been noted in some studies. Environmental toxicity studies assess effects on non-target organisms including aquatic species and beneficial insects. These studies help establish safe use guidelines for agricultural applications.

Absorption, Distribution and Excretion
In rats, absorption, metabolism, and excretion are rapid. Following a single oral administration, over 95% is eliminated within 6–8 hours. Metabolism/Metabolites Metabolism involves oxidation to hydroxylated derivatives, followed by conjugation reactions. …Metabolism is minimal in fruits.
Pharmacokinetic properties of pyrimethanil have been characterized in toxicological studies. As a contact fungicide, the compound is primarily applied to plant surfaces and has limited systemic absorption. When ingested, pyrimethanil is absorbed from the gastrointestinal tract and distributed to tissues. It is metabolized in the liver and eliminated primarily in urine and feces. The compound's half-life in mammals is relatively short. Detailed PK parameters such as half-life, Cmax, Tmax, AUC, volume of distribution, and clearance are available in the toxicological literature. The compound's pharmacokinetic properties are relevant for assessing human exposure risks in agricultural settings.

The toxicological profile of pyrimethanil has been characterized through extensive safety studies. The compound is classified as having low to moderate acute toxicity. Chronic exposure studies have identified potential target organs including the liver and kidneys. Pyrimethanil has been shown to elicit a range of toxic responses and has the potential to induce histological alterations in tissues. The compound's effects on reproduction and development have been evaluated. Genotoxicity studies have generally shown negative results. The compound is not considered a significant carcinogenic risk. Environmental toxicity assessments have been conducted to evaluate effects on aquatic organisms and other non-target species. Appropriate safety precautions should be followed when handling pyrimethanil.

[1]. Petr Masner, et al. Possible methionine biosynthesis inhibition by pyrimidinamine fungicides. Pesticide Science
[2]. L Kanetis, et al. Characterization of genetic and biochemical mechanisms of fludioxonil and pyrimethanil resistance in field isolates of Penicillium digitatum. Phytopathology
[3]. Richard J. Milling, et al. Mode of action of the anilino‐pyrimidine fungicide pyrimethanil. 2. Effects on enzyme secretion in Botrytis cinerea. Volume45, Issue1, September 1995.
[4]. Salvatore D'Aquino, et al. Residue levels and effectiveness of pyrimethanil vs imazalil when using heated postharvest dip treatments for control of Penicillium decay on citrus fruit. J Agric Food Chem. 2006 Jun 28;54(13):4721-6.

Azoxystrobin belongs to the aminopyrimidine class of compounds, with the structure N-phenylpyrimidine-2-amine, and two methyl substituents at the 4 and 6 positions respectively. It is a fungicide used to control gray mold on fruits, vegetables, and ornamental plants, as well as leaf spot on pome fruits. In addition, it is commonly used to control gray mold in grapes, grape juice, fermented grape juice, and winemaking processes. Azoxystrobin possesses multiple properties, including being an aromatic hydrocarbon receptor agonist, an environmental pollutant, an exogenous substance, and an antifungal pesticide. It is an aminopyrimidine compound, belonging to the secondary amino compounds and phenylpyrimidine fungicides.
Azoxystrobin has been reported to exist in Ganoderma lucidum, and relevant data are available.
Azoxystrobin is a fungicide used on grapevines.
See also: Cyproterin (note moved to).

---

Mechanism of Action
/Its mode of action is/inhibiting the secretion of fungal pathogenic enzymes. This study investigated the effects of pyraclostrobin on the levels of cell wall-degrading enzymes secreted by Botrytis cinerea in diseased plant tissues and liquid cultures. Three days after inoculation, the total protease activity isolated from infected carrot slices treated with 5.0 μM pyraclostrobin decreased by 76%. After three days of culture in a medium containing pyraclostrobin, the activities of polygalacturonase, cellulase, protease, and laccase were all reduced. The pyraclostrobin concentration (IC50) that resulted in a 50% reduction in total enzyme activity was approximately 0.25 μM for polygalacturonase, cellulase, and protease, and approximately 1.0 μM for laccase. No significant growth inhibition was observed at these pyraclostrobin concentrations. Pyraclostrobin neither directly inhibits these enzymes nor inhibits cytoplasmic protein synthesis. Therefore, it is hypothesized that this fungicide inhibits protein secretion at the post-translational stage of the secretion pathway. The effects of pyraclostrobin on the growth of Botrytis cinerea on liquid media and agar plates differed significantly depending on the composition of the medium. In liquid media with cellulose and protein as carbon and nitrogen sources, 5.0 μM pyraclostrobin inhibited fungal growth; however, no growth inhibition was observed at 50 μM pyraclostrobin in malt extract. Similarly, on potato dextrose agar (PDA) medium, 0.5 μM pyraclostrobin promoted fungal growth, but no fungal growth was observed at this concentration on agar media containing cellulose and protein. Therefore, pyraclostrobin appears to have the highest activity in media where fungi must utilize extracellular enzymes to mobilize the nutrients required for their growth.
Pyrimethanil is a valuable research tool for studying fungal diseases, particularly those caused by Botrytis spp.. It is used in agricultural research to develop effective fungicide strategies and to study fungicide resistance mechanisms. The compound's dual mechanism of action (inhibition of methionine biosynthesis and chitin synthase) makes it useful for studying fungal metabolism and cell wall synthesis. Pyrimethanil is also relevant for studying the environmental fate and impact of fungicides. Its anilinopyrimidine structure makes it an interesting model for studying structure-activity relationships in fungicide development. The compound is used in research on fungal disease prevention on fruits, vegetables, and ornamental plants.

C12H13N3

199.25

199.11

53112-28-0

Pyrimethanil-13C,15N2;Pyrimethanil-d5;2118244-83-8

91650

Colorless crystals

1.1±0.1 g/cm3

362.8±45.0 °C at 760 mmHg

96°C

173.2±28.7 °C

0.0±0.8 mmHg at 25°C

1.622

2.84

1

3

2

15

179

0

N([H])(C1C([H])=C([H])C([H])=C([H])C=1[H])C1=NC(C([H])([H])[H])=C([H])C(C([H])([H])[H])=N1

ZLIBICFPKPWGIZ-UHFFFAOYSA-N

InChI=1S/C12H13N3/c1-9-8-10(2)14-12(13-9)15-11-6-4-3-5-7-11/h3-8H,1-2H3,(H,13,14,15)

4,6-dimethyl-N-phenylpyrimidin-2-amine

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: This product requires protection from light (avoid light exposure) during transportation and storage.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : 130 mg/mL (652.45 mM)

Solubility in Formulation 1: ≥ 3.25 mg/mL (16.31 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 32.5 mg/mL clear DMSO stock solution to 400 μL of PEG300 and mix evenly; then add 50 μL of Tween-80 to the above solution and mix evenly; then add 450 μL of normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

---

Solubility in Formulation 2: 3.25 mg/mL (16.31 mM) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 32.5 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

---

View More

Solubility in Formulation 3: ≥ 3.25 mg/mL (16.31 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 32.5 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

---

 (Please use freshly prepared in vivo formulations for optimal results.)