Isophorone can be selectively oxidized to 4-hydroxyphorone, a synthetic intermediary for pigments and medicinal compounds as well as a significant flavor and aroma component. It is a good target for oxidation via biocatalysis [1].

Absorption, Distribution and Excretion
The demonstrated toxicity of isophorone by oral, inhalation, and dermal exposures indicates that it is capable of passage across epithelial membranes.
Rabbits and rats treated orally with isophorone excreted unchanged isophorone in the expired air and in the urine.
Preliminary results of a pharmacokinetic study indicate that rats treated orally with 14C-isophorone excreted 93% of the radiolabel in the urine, expired air & feces in 24 hr. The majority was found in the urine indicating that isophorone was well absorbed. The wide distribution of isophorone in the organs of rats & a rabbit 1-5 hr after dosing by gavage with 4000 mg/kg indicates rapid GI absorption. In two rabbits given a gavage dose of 1000 mg/kg isophorone, a blood level of isophorone of 102 ug/L was found within 10 min. The level increased to 141 ug/L in 30 min & declined to < or = 0.05 ug/L in 21 hr. The results indicate rapid absorption & elimination. The detection of unchanged isophorone & its metabolites in the urine & the observations of systemic toxicity & carcinogenicity in animals exposed orally to isophorone provide qualitative evidence that isophorone is absorbed after oral exposure.
In rats exposed to 400 ppm isophorone for 4 hr & sacrificed immediately after exposure or 1.5 or 3 hr after exposure, levels of isophorone were highest in all tissues examined (brain, lungs, heart, stomach, liver, spleen, pancreas, kidney, adrenals, testicles, & ovaries) immediately after exposure. Levels ranged from 1.5-74 ug/g tissue wet weight. The levels declined rapidly in males but declined very little in females by 3 hr after exposure.
Radiolabel was widely distributed in male rats 24 hr after an oral dose of 14C-isophorone in corn oil, with highest levels in the liver, kidney, preputial gland, testes, brain, & lungs. Isophorone was widely distributed to the tissues of rats & a rabbit following treatment with isophorone at a gavage dose of 4000 mg/kg. The rats died within 1-5 hr & the rabbit died within an hr after dosing at which times the tissues were sampled for analysis. in rats, tissue levels of isophorone in ug/g tissue wet weight were as follows: stomach-6213, pancreas-2388, adrenals-1513, spleen-1038, liver-613, brain-378, lung-383, heart-387, kidney-465, testes-275, & ovaries-471. In the rabbit, tissue levels were as follows: stomach-5395, adrenals-1145, ovaries-3000, spleen-545, liver-515, kidney-295, heart-260, & lungs-50.

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Metabolism / Metabolites
... ISOPHORONE IS METABOLIZED IN RABBITS INTO 5,5-DIMETHYLCYCLOHEX-1-EN-3-ONE-1-CARBOXYLIC ACID, WHICH IS EXCRETED IN URINE AS ESTER GLUCURONIDE.
AFTER ORAL ADMIN OF 1 G/KG ALPHA-ISOPHORONE, RABBIT & RAT URINE CONTAINED ALPHA-ISOPHORONE, ISOPHOROL, CIS-3,5,5-TRIMETHYLCYCLOHEXANOL, TRANS-3,5,5-TRIMETHYLCYCLOHEXANOL, DIHYDROISOPHORONE, 5,5-DIMETHYLCYCLOHEX-1-EN-3-ONE-1-CARBOXYLIC ACID, & DIHYDROISOPHORONE GLUCURONIDE.
The allylic methyl group of isophorone was oxidized to a carboxylic acid group when industrial isophorone was administered orally to rabbits. The product was detected in urine and no other products were identified.
Rabbits & rats treated orally with isophorone excreted unchanged isophorone in the expired air & in the urine. The urine also contained 3-carboxy-5,5-dimethyl-2-cyclohexene-1-one & glucuronic conjugates of 3,3,5-trimethyl-2-cyclohexene-1-ol (isophorol), 3,5,5,-trimethylcyclohexanone (dihydroisophorone), & cis- & trans-3,5,5-trimethylcyclohexanols. Rat urine contained more dihydroisophorone & less isophorol than did rabbit urine. ... /It was/ proposed that metab of isophorone involves methyloxidation to 3-carboxy-5,5-dimethyl-2-cyclohexene-1-one, reduction of the ketone group to isophorol, reduction of the ring double bond to dihydroisophorone, & dismutation of dihydroisophorone to cis- & trans-3,5,5-trimethylcyclohexanols.

Toxicity Summary
IDENTIFICATION: Isophorone is a colorless liquid with a peppermint like odor. It is soluble in water and miscible with most organic solvents. HUMAN EXPOSURE: The odor of isophorone can be detected at low concentrations. Eye, nose and throat irritation has been observed along with nausea, headache, dizziness, faintness and inebriation. Dermal and inhalation exposure may occur along with oral exposure from drinking water. ANIMAL STUDIES: Distribution studies in rats using (14)C isophorone showed that 93% of orally administered radioactivity appeared mainly in the urine and expired air within 24 hr. The tissues retaining the highest concentration after this period were the liver, kidney and preputial glands. The metabolites from oral administration of isophorone identified in rabbit urine resulted from the oxidation of the 3-methyl group, reduction of the keto group and hydrogenation of the double bond of the cyclohexene ring, and were eliminated as such or as glucuronide derivatives in the case of the alcohols. In animal studies, data indicate that isophorone is rapidly absorbed through the skin. Acute effects from dermal exposure in rats and rabbits ranged from mild erythema to scabs. Conjunctivitis and corneal damage have been reported following direct application to the eye or exposure to high concentrations of isophorone. In acute and short-term oral studies on rodents at high doses degenerative effects were seen in the liver and CNS depression and some deaths. In a 90 day oral study in beagle dogs (with limited numbers) no effects were seen at doses up to 150 mg/kg body weight per day. Isophorone does not induce gene mutations in bacteria, chromosomal aberrations in vitro, DNA repair in primary rat hepatocytes, or bone marrow micronuclei in mice. Positive effects were observed only in the absence of an exogenous metabolic system in L5178YTK +/- mouse mutagenesis assays as well as in a sister chromatid exchange assay. Isophorone induced morphological transformation in vitro in the absence of an exogenous metabolism system. It did not induce sex linked recessive lethal mutations in Drosophilia. In long term oral toxicity studies in mice and rats, male rats showed several lesions of the kidney, including nephropathy, tubular cell hyperplasia and low incidence of tubular cell adenomas and adenocarcinomas. Isophorone exposure was associated with some neoplastic lesions of the liver, and the integumentary and lymphoreticular systems of male mice, as well non-neoplastic liver and adrenal cortex lesions, but this was not observed in female mice. In /one/ long term inhalation study in rats and rabbits, irritation to eye and nasal mucosa, and lung and liver changes were observed. Very limited studies in rats and mice indicate that isophorone does not affect fertility nor does it cause developmental toxicity in experimental animals. The fact that central nervous system depression occurs in experimental animals could indicate a positive neurotoxic effect. Isophorone also elicited a positive effect in the behavioral despair swimming test. No data on terrestrial animals were available. The available data suggest that isophorone has a low toxicity to aquatic organisms.

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Toxicity Data
LC50 (rat) = 7,000 mg/m3/4h

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Interactions
Joint toxic action of isophorone with 26 industrial liquid chemicals was examined based on acute LD50 data from oral intubations of female albino rats. ... LD50s were determined for each of the cmpds. Based on the assumption of simple similar action, isophorone exhibited >additive toxicity in combination with 9 cmpds & additive toxicity. An equitoxic mixture was defined as a mixture of chemicals in volumes directly proportional to their respective rat oral LD50 values, so that each component contributed the same degree of toxicity to the mixture.
... /It was/ reported that inhalation of isophorone for 4 hr by mice increased the threshold for onset of seizures produced by iv admin of pentrazole ... .

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Non-Human Toxicity Values
LD50 Rat oral 1000-3450 mg/kg.
LC50 Rabbit dermal 1380 mg/kg
LC50 Rat inhalation 7000 mg/cu m/4 hr
LD50 Mouse oral 2.0 g/kg
For more Non-Human Toxicity Values (Complete) data for ISOPHORONE (10 total), please visit the HSDB record page.

[1]. Stereoselective hydroxylation of isophorone by variants of the cytochromes P450 CYP102A1 and CYP101A1. Enzyme Microb Technol. 2018 Apr;111:29-37.

Isophorone is a clear liquid that smells like peppermint. It can be dissolved in water and evaporates somewhat faster than water. It is an industrial chemical used as a solvent in some printing inks, paints, lacquers, and adhesives. It is also used as an intermediate in the production of certain chemicals. Although isophorone is an industrial chemical, it also occurs naturally in cranberries.
Isophorone appears as a clear colorless liquid, with a camphor-like odor. Less dense than water and insoluble in water. Boiling point 420 °F. Flash point near 200 °F. Contact irritates skin and eyes. Toxic by ingestion. Used as a solvent and in pesticides.
Isophorone is a cyclic ketone, the structure of which is that of cyclohex-2-en-1-one substituted by methyl groups at positions 3, 5 and 5. It has a role as a solvent and a plant metabolite. It is a cyclic ketone and an enone.
Isophorone is a widely used solvent and chemical intermediate. The acute (short-term) effects of isophorone in humans from inhalation exposure include eye, nose, and throat irritation. Chronic (long- term) exposure to isophorone in humans can cause dizziness, fatigue, and depression. Animal studies indicate that long-term inhalation of high concentrations of isophorone causes central nervous system effects. Limited evidence in animal studies suggests that isophorone may cause birth defects such as fetal malformations and growth retardation from inhalation exposure to isophorone during pregnancy. No information is available on the reproductive, developmental, or carcinogenic effects of isophorone in humans. EPA has classified isophorone as a Group C, possible human carcinogen.
Isophorone has been reported in Artemisia judaica, Vaccinium macrocarpon, and other organisms with data available.

C9H14O

138.21

138.104

78-59-1

Isophorone-d5;1262769-87-8;Isophorone-d8;14397-59-2

6544

Colorless to light yellow liquid

0.9±0.1 g/cm3

215.2±0.0 °C at 760 mmHg

−8 °C(lit.)

84.4±0.0 °C

0.2±0.4 mmHg at 25°C

1.455

2.07

0

1

0

10

187

0

O=C1C([H])=C(C([H])([H])[H])C([H])([H])C(C([H])([H])[H])(C([H])([H])[H])C1([H])[H]

HJOVHMDZYOCNQW-UHFFFAOYSA-N

InChI=1S/C9H14O/c1-7-4-8(10)6-9(2,3)5-7/h4H,5-6H2,1-3H3

3,5,5-trimethylcyclohex-2-en-1-one

NSC-403657; NSC 403657; Isophorone

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 (~723.54 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (18.09 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 (18.09 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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Solubility in Formulation 3: ≥ 2.5 mg/mL (18.09 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 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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