Herbicidal agent

The commercial herbicide formulation Betanal® Expert and its active ingredients (a.i.s) ethofumesate, phenmedipham and desmedipham were focused in this study. Following questions yielding from a previous study, an in-depth analysis of the reproductive toxicity of the pesticide was made. Long-term exposures of Daphnia magna and Daphnia longispina to Betanal® Expert, to each a.i. and to a customised mixture matching the a.i.s ratio within the commercial formulation were carried out, and deleterious effects in the offspring were recorded. This intended to clarify whether (1) the tested compounds induce reproductive injury; (2) there is interspecific variation in daphnids tolerance to the compounds; (3) there is an interaction between chemicals in combined treatments; and (4) the so-called inert ingredients added to the commercial formulation contribute to the toxicity of the herbicide. Generally, developmental impair was observed in both species (egg abortion and release of undeveloped embryos or dead offspring) at concentrations of any of the a.i.s below 1 mg L(-1). Ethofumesate was invariably the least toxic pesticide, and D. magna tended to be of slightly higher sensitivity to the exposures compared to D. longispina. Joint exposures indicated that the a.i.s can interact, inducing more than and less than additive effects for Betanal® Expert and the customised a.i. mixture, respectively. This indicates that inert ingredients co-formulating the commercial pesticide (which are absent from the customised a.i. mixture) actually contribute to its overall toxicity. This study constitutes an add-on to the discussion on the ecotoxicological framework required for authorisation of pesticide trade and usage. The results support the need to consider test species, long-term hazardous potential and toxicity of commercial formulations rather than solely that of active ingredients, as relevant variables in pesticide regulation[1].

Absorption, Distribution and Excretion
Benzodipine is readily absorbed in rats, dogs, and humans. In rats, 99% of benzodipine is recovered in urine and feces 72 hours after oral administration. Urine is the primary route of excretion, with 80% excreted within the first 24 hours. Radiolabeled levels in the kidneys are extremely low, at 0.039 ppm, and levels in all other tissues are below this. It is absorbed through leaves, with minimal absorption through soil and roots. Metabolism/Metabolites Benzodipine is rapidly metabolized in rats. Metabolism… hydrolyzes to methyl N-(3-hydroxyphenol) carbamate (MHPC)… forms hydroxyphenyl carbamate… degrades to m-aminophenol, which is acetylated to… 3-hydroxyacetanilide. These metabolites are subsequently bound in the form of glucuronide and sulfate. Betaine…is rapidly metabolized in rats to the corresponding phenol…(60-70%) (partially bound) and m-hydroxyaniline, the latter being excreted as m-hydroxyacetaniline…(2%). Carbamates are enzymatically hydrolyzed in the liver; degradation products are excreted via the kidneys and liver. (L793)

Toxicity Summary
Benzodipine is a cholinesterase, or acetylcholinesterase (AChE) inhibitor. Carbamate compounds form unstable complexes with cholinesterase by carbamylation of the enzyme's active site. This inhibition is reversible. Cholinesterase inhibitors suppress the activity of acetylcholinesterase. Because acetylcholinesterase has important physiological functions, chemicals that interfere with its activity are potent neurotoxins, causing excessive salivation and lacrimation even at low doses. High-dose exposure typically results in symptoms such as headache, salivation, nausea, vomiting, abdominal pain, and diarrhea. Acetylcholinesterase breaks down the neurotransmitter acetylcholine, which is released at the neuromuscular junction, causing muscle or organ relaxation. Inhibition of acetylcholinesterase results in the accumulation and sustained action of acetylcholine, leading to persistent nerve impulse transmission and an inability to stop muscle contractions. Toxicity Summary
Benzodipine is a cholinesterase, or acetylcholinesterase (AChE) inhibitor. Carbamates form unstable complexes with cholinesterases by carbamylated at the enzyme's active site. This inhibition is reversible. Cholinesterase inhibitors inhibit the activity of acetylcholinesterase. Because acetylcholinesterase has important physiological functions, chemicals that interfere with its activity are potent neurotoxins, causing excessive salivation and lacrimation even at low doses. High-dose exposure typically causes headache, salivation, nausea, vomiting, abdominal pain, and diarrhea. Acetylcholinesterase breaks down the neurotransmitter acetylcholine, which is released at the neuromuscular junction, causing muscle or organ relaxation. Inhibition of acetylcholinesterase leads to the accumulation and sustained action of acetylcholine, resulting in the continuous transmission of nerve impulses and the inability to stop muscle contraction.

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Toxicity Data
LD50: >8000 mg/kg (rat, oral)
Treatment
If this compound is ingested, rapid gastric lavage with 5% sodium bicarbonate solution should be performed. If it comes into contact with skin, wash the skin with soap and water. If the compound gets into the eyes, flush with copious amounts of isotonic saline or water. In severe cases, atropine and/or pralidoxime should be used. Anticholinergic drugs work by counteracting excess acetylcholine and reactivating acetylcholinesterase. Atropine can be used in combination with the antidote pyridoxime or other pyridoximes (such as trimeoxime or olbioxime), but at least two meta-analyses have found no benefit and may even be harmful from the use of "oximes." Atropine is a muscarinic receptor antagonist and therefore blocks the peripheral effects of acetylcholine.

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Toxicity Data
LD50: >8000 mg/kg (rat, oral)

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Non-human Toxicity Values
LD50 Dog oral 4000 mg/kg
LD50 Guinea pig oral 4000 mg/kg
LD50 Chicken oral 3000 mg/kg
LD50 Rat dermal 4000 mg/kg
LD50 Rat oral >8000 mg/kg

[1]. Reproductive and Developmental Toxicity of the Herbicide Betanal® Expert and Corresponding Active Ingredients to Daphnia SPP. Environ Sci Pollut Res Int. 2016 Jul;23(13):13276-87.

Phenmedipham is a colorless crystal or white powder. (NTP, 1992)
Phenmedipham is a carbamate, a derivative of (3-methylphenyl)carbamic acid, in which the hydrogen on the hydroxyl group is replaced by 3-[(methoxycarbonyl)amino]phenyl]. It is both an environmental pollutant and an exogenous substance and herbicide.
Phenmedipham is a selective herbicide belonging to the carbamate and dicarbamate classes. Carbamate insecticides are derived from carbamic acid, and their insecticidal mechanism is similar to that of organophosphate insecticides. They are widely used in homes, gardens, and agriculture. The first carbamate insecticide, Sevin, was introduced in 1956, and its global usage exceeds that of all other carbamate insecticides combined. Due to its relatively low oral and dermal toxicity to mammals and its broad spectrum of control, Sevin is widely used in lawns and gardens. Most carbamate herbicides are highly toxic to hymenoptera; therefore, precautions must be taken to prevent contact with foraging insects such as bees or parasitic wasps. Some carbamate herbicides can be transported within plants, making them effective systemic herbicides. Phenmedipham was developed by Schering AG and approved for use in the United States in 1970. Today, approximately 100 tons of phenmedipham are used annually. It is commonly used on crops such as sugar beets, spinach, and strawberries to control weeds, often in combination with dexamethasone, traded under the names Betanal or Betamax. (L795)

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Mechanism of Action
Phenmedipham exerts its herbicidal effect by interfering with photochemical reactions.
The main changes involve phosphorylation and its associated non-cyclic electron transport.
Phenmedipham is a potent inhibitor of the Hill reaction in plants.
At concentrations close to 2 × 10⁻⁴ M, phenmedipham inhibits electron transport in the mitochondria of potatoes and mung beans. The inhibition appears to be localized to the flavoprotein region. It preferentially affects exogenous nicotinamide adenine dinucleotide (NADH) dehydrogenase in potato mitochondria. Succinate dehydrogenase is less inhibited. Bendimethalin at 2 × 10⁻⁷ M completely inhibits photosynthesis.

C16H16N2O4

300.31

300.11

C, 63.99; H, 5.37; N, 9.33; O, 21.31

13684-63-4

Phenmedipham-d3;1773497-41-8

24744

White to off-white solid powder

1.2±0.1 g/cm3

510.3±60.0 °C at 760 mmHg

140-144°C

262.4±32.9 °C

0.0±1.4 mmHg at 25°C

1.569

4.42

2

4

5

22

388

0

IDOWTHOLJBTAFI-UHFFFAOYSA-N

InChI=1S/C16H16N2O4/c1-11-5-3-6-12(9-11)18-16(20)22-14-8-4-7-13(10-14)17-15(19)21-2/h3-10H,1-2H3,(H,17,19)(H,18,20)

[3-(methoxycarbonylamino)phenyl] N-(3-methylphenyl)carbamate

HSDB 1402; Fenmedifam; Phenmedipham; 13684-63-4; 3-((Methoxycarbonyl)amino)phenyl m-tolylcarbamate; BETANAL; Fenmedifam; Spin-aid; Phenmediphame; Kemifam; Phenmedipham

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)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*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.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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