Terbutryn targets the photosystem II complex in plants. It binds to the D1 protein (QB) in the thylakoid membrane, inhibiting photosynthetic electron transport. This disruption blocks the conversion of light energy into chemical energy, leading to inhibition of plant growth and development. The compound's mechanism is similar to that of other triazine herbicides such as atrazine.

In vitro, Terbutryn inhibits photosystem II activity in isolated chloroplasts or thylakoid membranes. The inhibition of electron transport is measured by monitoring the reduction of an artificial electron acceptor (e.g., DCPIP) spectrophotometrically. The IC50 for inhibition of photosystem II is determined from dose-response curves.

Terbutryn is used as a herbicide for pre- and post-emergence control of weeds. It is applied to soil or foliage and is absorbed by plant roots and leaves. It is effective against a wide range of annual broad-leaved weeds and grasses.

The activity of Terbutryn is assessed using cell-free assays that measure its inhibition of photosynthetic electron transport. Chloroplasts or thylakoid membranes are isolated from plant tissues and incubated with varying concentrations of Terbutryn. The rate of electron transport is measured by monitoring the reduction of DCPIP. The IC50 for inhibition of photosystem II is determined.

Absorption, Distribution and Excretion
They are efficiently absorbed by the intestines and are presumably also absorbed through the skin and lungs. /Urea, uracil, and triazine herbicides/
They can be absorbed through leaves and roots. They appear to penetrate leaves rapidly, minimizing the amount washed away by rainwater. It is transported upwards from roots and leaves through the xylem and accumulates in the apical meristem.
In mammals, 73-85% of the drug is excreted in feces as a metabolic form within 24 hours after oral administration.

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Metabolism/Metabolites
Tetrabutanone…After a single oral administration in rats and goats, it can be metabolized via one or more of the following pathways: S-demethylation, conversion of thiomethyl to hydroxyl, N-deethylation, oxidation of the ethyl terminal carbon to a carboxylic acid, oxidation of the tert-butyl terminal carbon to an alcohol or carboxylic acid, or conjugation with glucuronic acid.
Carbon-labeled tert-butanone was administered to rats and goats in a single oral dose. Urine was collected at regular intervals for 72 hours and then analyzed… Glucuronides were separated and analyzed by chromatography. The five conjugates isolated and identified were: 2-amino-4-(tert-butylamino)-6-(S-glucuronyl)-triazine; 2-(tert-butylamino)-4-ethylamino-6-(S-glucuronyl)-triazine; 2-ethylamino-(2-methyl)glucuronylpropyl)amino-6-(S-methylthio)-triazine; 2-amino-4-(2-(1-glucuronyl-2-methylpropyl)amino)-6-methylthio-triazine; 2-ethylamino-4-(2-(2-methylprop-1-ol)amino)-6-(S-glucuronyl)-triazine.
Urinary metabolites observed in rats after administration of tert-butyl ketone included: 2-hydroxytert-butyl ketone; 2-amino-4-hydroxy-6-tert-butylamino-triazine; 2-amino-4-tert-butylamino-6-mercapto-triazine; two S-glucuronides; and two tert-butyl-O-glucuronides. Other metabolites were formed by one or more of the following reactions: N-alkyl oxidation to alcohols or acids; S-demethylation; N-deethylation; and disulfide bond formation.
Microsomes were prepared from the livers of patients aged 30 to 70 years who underwent hepatectomy and incubated with 6.3 to 1000 μM of atrazine, tert-butyl ketone, tert-butylamine, or atrazine. The metabolites in the incubation mixture were then analyzed. These compounds produced a variety of metabolites, indicating that S-oxidation, N-dealkylation, and side-chain C-oxidation occurred. The formation of these metabolites exhibits biphasic kinetics, with Michaelis constants of 1.4–20 μM for the first phase and 54–530 μM for the second phase. Atrazine, Terbutryn, atrazine, or Terbutryn at a concentration of 25 μM were incubated with human liver microsomes containing isoenzyme substrates of cytochrome P4501A2 (CYP1A2), cytochrome P4502A6, cytochrome P4502D6, cytochrome P4502C9, cytochrome P4502C19, cytochrome P4502E1, or cytochrome P4503A4 (CYP3A4). Other microsomal formulations were incubated with 25 or 600 μM of S-triazine compounds with or without α-naphthylflavonoid (aNF), furazolidone, quinidine, sulfadiazine, diethyldithiocarbamate, pregnadienone, or ketoconazole (inhibitors of various specific cytochrome P450 (P450) isoenzymes at concentrations 5 to 10 times their inhibition constant). Microsomal formulations containing CYP1A2 and CYP3A4 substrates showed the best correlation with the metabolic rate of S-triazine compounds. Only the CYP1A2 inhibitors aNF and furazolidone inhibited the metabolism of S-triazine compounds. Human liver microsomal formulations with high levels of flavin monooxygenase (FMO) activity and purified recombinant human FMO-3 were incubated with atrazine and Terbutryn. The degree of sulfoxideization of the two compounds was determined. No significant sulfoxide metabolite formation was detected, indicating that the FMO system is not involved in the metabolism of S-triazine by human liver microsomes. The authors conclude that these results clearly demonstrate that CYP1A2 is the major phase I P450 isoenzyme involved in the metabolism of S-triazine by human liver microsomes. For more complete metabolite/metabolite data on tert-butyl ketone (7 metabolites), please visit the HSDB record page. Known metabolites of tert-butyl ketone include tert-butyl ketone sulfoxide, tert-butylhydroxytert-butyl ketone, and 2-hydroxyethyltert-butyl ketone.
Terbutryn has a molecular formula of C10H19N5S and a molecular weight of 241.36 g/mol. Its CAS number is 886-50-0. It is a white to off-white crystalline powder. It is soluble in organic solvents and has limited solubility in water. Standard storage conditions for chemical reagents apply.

Toxicity Data
LC50 (Rat) > 8,000 mg/m³/4h

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2,000 mg/kg
LD50 Rat Oral Administration 2450-2500 mg/kg
LD50 Rat Oral Administration 2045 mg/kg
LC50 Rat Inhalation Administration > 8 mg/L/4 hr /80% Formulation/ For more complete non-human toxicity data on Terbutryn (8 items), please visit the HSDB records page.
Terbutryn is a herbicide and can be toxic to non-target organisms. It may cause skin and eye irritation. Appropriate safety precautions should be taken when handling Terbutryn, including the use of personal protective equipment. It is not intended for human consumption.

Environ Sci Technol. 2014;48(1):244-54.

Terbutryn is a methylthio-1,3,5-triazine compound with the structure 2-(methylthio)-1,3,5-triazine, substituted at positions 2 and 4 with tert-butylamino and ethylamino groups, respectively. It can be used as a herbicide, exogenous substance, and environmental pollutant. It is a methylthio-1,3,5-triazine compound and also a diamino-1,3,5-triazine compound.

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Mechanism of Action
...Their main mechanism of action appears to be related to carbohydrate metabolism. Chlorotriazine compounds inhibit starch accumulation by blocking sugar production. Methoxy and methylthiotriazine compounds also exhibit similar effects. S-triazine herbicides have been reported to affect the tricarboxylic acid cycle by activating phosphophenylpyruvate carboxylase, leading to the consumption of sucrose and glyceric acid, and the production of aspartic acid and malic acid. /s-triazines/
The mechanism of action of 1,3,5-triazine herbicides is to inhibit photosynthesis by disrupting the light reaction and blocking electron transport. /1,3,5-Triazines, from Table/
The effects of certain s-triazine herbicides on acid phosphatase and phosphodiesterase in maize (Zea mays) roots were investigated. Terbutryn stimulated the activity of both phosphatases, while pymetrozine stimulated only phosphodiesterase activity. Atrazine, dexamethasone, pymetrozine, and simazine inhibited acid phosphatase activity. Atrazine had no effect. Enzyme activity assays and kinetic parameters indicated that the observed interference was due to an effect on the synthesis of one or both enzymes, rather than on the enzymatic reaction itself. The type of N-alkyl and chlorine substituents in the tested triazine structures appeared to be crucial in determining the degree of interference.
Terbutryn is a triazine herbicide used for weed control. It inhibits photosystem II in plants, blocking photosynthetic electron transport. It is a research tool for studying herbicide mechanisms and plant physiology.

C10H19N5S

241.35636

241.136

886-50-0

Terbutryn-d5;1219804-47-3

13450

WHITE, CRYSTALLINE
White powder

1.45

154-160°C

104-105°C

2 °C

1.55

2.381

2

6

5

16

206

0

N1C(NCC)=NC(NC(C)(C)C)=NC=1SC

IROINLKCQGIITA-UHFFFAOYSA-N

InChI=1S/C10H19N5S/c1-6-11-7-12-8(15-10(2,3)4)14-9(13-7)16-5/h6H2,1-5H3,(H2,11,12,13,14,15)

2-N-tert-butyl-4-N-ethyl-6-methylsulfanyl-1,3,5-triazine-2,4-diamine

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

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

DMSO : ≥ 100 mg/mL (~414.32 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (10.36 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 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL 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.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (10.36 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in 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 25.0 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.

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