Diphenyl ether does not have a single specific molecular target but interacts with multiple cellular components. Its antimicrobial activity is attributed to disruption of microbial cell membranes and inhibition of key metabolic enzymes. In fungi, it interferes with ergosterol biosynthesis and mitochondrial function. In insects, it acts as a neurotoxin by modulating sodium channels and GABA receptors. Some studies suggest that diphenyl ether derivatives can inhibit cytochrome P450 enzymes, particularly CYP1A and CYP3A isoforms, affecting xenobiotic metabolism. The compound may also interact with aryl hydrocarbon receptor (AhR) and nuclear hormone receptors, though with relatively low affinity compared to its halogenated derivatives. Overall, diphenyl ether exhibits promiscuous binding to hydrophobic protein pockets and lipid bilayers, contributing to its broad-spectrum biological effects without high specificity for a single receptor or enzyme target.

utilized in chemical synthesis as well as a heat-transfer medium

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Diphenyl ether demonstrates moderate antimicrobial activity against Gram-positive bacteria such as Staphylococcus aureus and Bacillus subtilis with MIC values ranging from 50-200 μg/mL. Activity against Gram-negative bacteria is generally weaker due to the outer membrane permeability barrier. Antifungal activity is observed against Candida albicans and Aspergillus niger with MIC values of 100-250 μg/mL. In cell-free systems, diphenyl ether inhibits oxygen consumption and ATP synthesis in mitochondria, suggesting interference with electron transport chain components. It also shows moderate inhibition of acetylcholinesterase (IC50 ~150 μM) and tyrosinase (IC50 ~200 μM). In human cancer cell lines, diphenyl ether exhibits weak cytotoxic effects with IC50 values >100 μM, indicating low potency. Structure-activity relationship studies show that halogenation significantly enhances biological activity, while the parent compound remains relatively inactive in many pharmacological assays.

In vivo studies of diphenyl ether are limited due to its primary use as an industrial chemical rather than a therapeutic agent. In rodent models, acute oral administration exhibits low toxicity with LD50 values of approximately 3,000-5,000 mg/kg in rats. Subchronic exposure studies show that diphenyl ether accumulates in adipose tissue and liver, with minimal systemic effects at low doses. In zebrafish embryo toxicity assays, the compound causes developmental abnormalities at concentrations above 10 mg/L. Insecticidal activity has been demonstrated in topical application studies against houseflies and mosquitoes with LD50 values in the range of 50-200 μg/insect. No significant analgesic, anti-inflammatory, or CNS activity has been observed in standard rodent models at non-toxic doses. Pharmacokinetic studies in rats indicate rapid absorption and distribution to lipid-rich tissues, with slow elimination via biliary excretion and minimal urinary excretion of the parent compound.

For in vitro enzyme binding assays, diphenyl ether is typically dissolved in DMSO or ethanol and diluted in assay buffer. Cytochrome P450 inhibition assays are performed using human liver microsomes (0.5 mg/mL protein) with NADPH-regenerating system and probe substrates such as ethoxyresorufin for CYP1A. Test compound is pre-incubated with microsomes for 15 minutes at 37°C, followed by addition of substrate and NADPH. After 30 minutes, reactions are terminated with acetonitrile, and metabolite formation is quantified by LC-MS/MS. IC50 values are determined from 8-point concentration-response curves (0.1-500 μM). For acetylcholinesterase inhibition, Ellman's method is used with acetylthiocholine substrate and DTNB detection at 412 nm. Compounds are incubated with enzyme (0.1 U/mL) for 20 minutes, then substrate is added and absorbance monitored for 5 minutes. For antimicrobial assays, broth microdilution following CLSI guidelines determines MIC values against bacterial and fungal strains.

For in vitro cell-based assays, diphenyl ether is evaluated in mammalian cell lines including HepG2, HEK293, and Caco-2 cells. Cells are cultured in DMEM or MEM supplemented with 10% FBS, 2 mM glutamine, and 1% penicillin-streptomycin at 37°C in 5% CO2. Cytotoxicity is assessed using MTT or resazurin reduction assays after 24-72 hours of exposure to diphenyl ether (0.1-500 μM) dissolved in DMSO (final DMSO concentration ≤0.1%). Cell viability is calculated relative to vehicle-treated controls. For mitochondrial function assessment, JC-1 dye is used to measure membrane potential changes, and ATP levels are quantified using luciferase-based assays. Intracellular reactive oxygen species (ROS) generation is measured using DCFH-DA fluorescence. In bacterial cell assays, minimum bactericidal concentration (MBC) is determined by plating treated cultures on agar plates. For antifungal testing, broth microdilution in RPMI-1640 medium is used with Candida albicans and Aspergillus species.

For in vivo animal studies, diphenyl ether is typically administered orally or intraperitoneally in rodents. Acute toxicity studies follow OECD Guideline 423, where female Sprague-Dawley rats (n=3 per dose) receive single oral gavage doses of 300, 1,000, or 2,000 mg/kg in corn oil. Animals are observed for 14 days with daily clinical assessments, body weight measurements, and necropsy at study termination. For subchronic studies, rats receive daily oral doses of 10, 50, or 250 mg/kg for 28-90 days, with blood collection at specified intervals for hematology, clinical chemistry, and histopathology of major organs. For insecticidal testing, houseflies (Musca domestica) or mosquitoes (Aedes aegypti) are topically treated with acetone solutions of diphenyl ether (0.1-10 μg/insect) using a microapplicator, and mortality is recorded at 24, 48, and 72 hours. For zebrafish assays, embryos at 24 hours post-fertilization are exposed to diphenyl ether (0.1-50 mg/L) in embryo medium for 72 hours, with observations of developmental endpoints.

Absorption, Distribution and Excretion
Diphenyl ether exhibits up to 90% absorption in rats and rabbits after oral administration, regardless of dose. Data regarding skin absorption are contradictory. In rats, after a semi-occlusive application of 10-1000 mg/kg diphenyl ether to shaved skin, nearly 20% of the dose was absorbed, as determined by urinary excretion. However, in in vitro diffusion experiments, only 0.3% (rat skin) or 0.2% (human skin) of diphenyl ether permeated the skin. The higher absorption rate in in vivo may be due to the excipient (diethyl phthalate) and partial oral absorption after removal of the occlusive agent. In rats, after intraperitoneal injection of diphenyl ether, it was distributed to all organs and tissues within 1 hour, with the highest concentrations in the liver, lungs, kidneys, and spleen. …In rabbits, diphenyl ether was excreted in the urine as p-hydroxyphenylphenyl ether, not as the original ether form. (Pathway not specified)

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Metabolism/Metabolites
...In rabbits, the ether bonds of phenyl ethers did not break. The main metabolite was p-hydroxylated ether, excreted in free form (15%) and in combination with glucuronic acid (63%) and sulfuric acid (12%). Another metabolite was also isolated from rabbit urine and was predominantly identified as di(p-hydroxyphenyl) ether.
Subcellular fractions of trout liver homogenate primarily metabolized diphenyl ether to 4-hydroxy derivatives and contained trace amounts of other compounds, including 3-hydroxy derivatives and possibly 4,4'-dihydroxy derivatives.
Sphingomonas SS3 strain, which uses diphenyl ether as both a carbon and energy source, was enriched from soil samples from industrial waste dumps. In batch culture experiments, phenol and catechol were produced as intermediates during the degradation of diphenyl ether, which subsequently entered the 3-oxoadipic acid pathway. The initial steps of degradation follow a recently discovered 1,2-dioxygenation mechanism, which generates an unstable phenolic hemiacetal from the diphenyl ether structure. Screening of selected fungi showed that Cunninghamella echinulata was best suited for studies on the hydroxylation of diphenyl ethers. The process, depending on culture conditions, yielded up to 76% 4-hydroxybiphenyl oxide and approximately 6% 4,4'-dihydroxybiphenyl oxide.

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Diphenyl ether shows moderate oral absorption with bioavailability estimated at 40-60% in rats due to first-pass metabolism. Peak plasma concentrations occur 2-4 hours after oral administration. Volume of distribution is large (>10 L/kg), indicating extensive tissue binding and accumulation in lipid-rich compartments such as adipose tissue and liver. Plasma protein binding is approximately 90-95%, primarily to albumin and lipoproteins. Metabolism occurs predominantly in the liver via cytochrome P450-mediated hydroxylation at the para position, followed by glucuronidation and sulfation. Major metabolites include 4-hydroxydiphenyl ether and 4,4'-dihydroxydiphenyl ether, which are excreted in bile and urine. Elimination half-life ranges from 24-72 hours in rodents, with prolonged clearance in high-fat diets. In humans, predicted half-life is estimated at 5-10 days based on physiologically-based pharmacokinetic modeling. Minimal urinary excretion of parent compound (less than 1% of dose) is observed, with fecal excretion being the primary elimination pathway.

Toxicity Summary
Identification and Uses: Diphenyl ether is a colorless crystalline solid or liquid with an unpleasant odor. It is insoluble in water but soluble in ether, benzene, and acetic acid. Its odor is extremely unpleasant. Diphenyl ether is widely used in soaps and fragrances, primarily as a heat transfer medium (forming a eutectic mixture with diphenyl ether) and as a chemical intermediate in halogenation, acylation, and alkylation reactions; it can also be used as a dye carrier. Furthermore, it can be used as a processing aid in polyester production. Human Exposure and Toxicity: Exposure to commercial products containing diphenyl ether can cause burning eyes, respiratory irritation, severe nausea, and skin irritation. Ingestion of commercial products containing this chemical can cause severe degenerative changes in the liver and kidneys. Prolonged skin contact with the liquid can cause skin redness and irritation. Occupational exposure to diphenyl ether occurs through skin contact and inhalation of vapors. Diphenyl ether is widely used in various soap, detergent, cream, lotion, and perfume formulations, leading to general exposure to diphenyl ether through inhalation and skin contact. Diphenyl ether has been detected in collected complex adipose tissue. Animal studies: Acute oral administration of diphenyl ether to rats resulted in liver, spleen, kidney, thyroid, and intestinal damage. Undiluted diphenyl ether is irritating to rabbit skin, causing erythema and desquamation.

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Non-Human Toxicity Values
The oral LD50 in rats was 2830 mg/kg body weight (95% confidence interval: 2490–3210 mg/kg). The oral LD50 in rats was 3.99 g/kg. The oral LD50 in guinea pigs was 4.0 g/kg (all mice died). The oral LD50 in guinea pigs was 1.0 g/kg (all mice survived).

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Diphenyl ether exhibits relatively low acute oral toxicity with LD50 of 3,000-5,000 mg/kg in rats and mice. Dermal LD50 in rabbits exceeds 2,000 mg/kg. Inhalation LC50 in rats is >1,000 mg/m³ (4-hour exposure). Eye contact causes mild irritation, while skin exposure may produce slight irritation in sensitive individuals. Repeated dose toxicity studies in rats at doses of 250 mg/kg/day for 90 days show no significant adverse effects on body weight, organ weights, or histopathology, with a NOAEL of 100 mg/kg/day. Genotoxicity assays (Ames test, in vitro chromosomal aberration, and in vivo micronucleus) are negative, indicating no mutagenic potential. Developmental toxicity studies in rats at doses up to 500 mg/kg/day show no teratogenic effects, though slight fetotoxicity is observed at maternal toxic doses. Chronic toxicity studies in rodents reveal no carcinogenic potential at dietary concentrations up to 2,500 ppm. In aquatic organisms, LC50 values range from 1-10 mg/L for fish and daphnia.

Diphenyl ether is a colorless liquid with a slightly pleasant odor. It may float or sink in water. Its freezing point is 81°F (27°C). (US Coast Guard, 1999)
Diphenyl ether is an aromatic ether in which an oxygen atom is attached to two phenyl substituents. It is found in muscat grapes and vanilla. It is a plant metabolite.
Diphenyl ether has been reported in European grapes (Vitis vinifera) and mangoes (Mangifera indica), and there is relevant data.

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Diphenyl ether is primarily used as a chemical intermediate and industrial solvent rather than a pharmaceutical agent. Its biological activities have been studied extensively for environmental and toxicological purposes due to the widespread use of its halogenated derivatives as flame retardants. The compound is listed in various chemical inventories including TSCA, EINECS, and DSL. In perfumery, it is valued for its persistent floral-geranium odor and is used in soaps, detergents, and cosmetics at concentrations typically below 1%. As a heat transfer fluid, it is often combined with biphenyl in eutectic mixtures. Environmental persistence is moderate, with biodegradation occurring through microbial oxidation in soil and water. Bioaccumulation potential is moderate (log Kow 4.2), leading to some accumulation in aquatic organisms. Regulatory agencies have established acceptable daily intake levels of 0-0.1 mg/kg body weight for food contact applications. No human clinical trials have been conducted for therapeutic applications.

C12H10O

170.21

170.073

101-84-8

Diphenyl ether-d10;93952-05-7

7583

Colorless crystals or liquid
Colorless, crystalline solid or liquid (above 82 degrees F)

1.073

259 ºC

80.3 °F (NTP, 1992) ; 26.865 °C ; 37 - 39 °C ; 28 °C ; 82 °F ; 82 °F

115 ºC

0.0±0.5 mmHg at 25°C

1.5795-1.5815

4.21

0

1

2

13

116

0

O(C1C([H])=C([H])C([H])=C([H])C=1[H])C1C([H])=C([H])C([H])=C([H])C=1[H]

USIUVYZYUHIAEV-UHFFFAOYSA-N

InChI=1S/C12H10O/c1-3-7-11(8-4-1)13-12-9-5-2-6-10-12/h1-10H

phenoxybenzene

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.)