Absorption, Distribution and Excretion
…500 μg of 14C-labeled DB(a,i)P was dissolved in peanut oil and subcutaneously injected into C57BL/6 Jax mice. The distribution of radioactivity at the injection site and between organs was determined…85% of the carcinogen was cleared from the injection site, and…it was almost completely cleared within 10 weeks. Metabolism/Metabolites In liver homogenates and microsomes of 3-methylcholanthrene-pretreated rats, dibenzo[a,i]pyrene (10 μmol) was metabolized by mixed-function oxidases into partially identified phenols and dihydrodiols. It has been reported that 1,2- and 3,4-dihydrodiols are its metabolites after incubation of dibenzo[a,i]pyrene with rat liver preparations. 3,4-Dihydrodiol has been reported to be mutagenic to bacteria in the presence of an exogenous metabolic system; it is a tumor initiator on mouse skin and a tumorigenin in newborn mice.

Toxicity Summary
Identification and Uses: Dibenzo[a,i]pyrene (DB(a,i)P) forms yellowish-green needle-like, prismatic, or platy crystals. It has been used as an experimental carcinogen. Human Exposure and Toxicity: DB(a,i)P is reasonably expected to be a human carcinogen. In the presence of the mitochondrial post-formulation isolated from human liver, DB(a,i)P was mutagenic in the Ames assay. Animal Studies: Groups of 20 female mice received 10 dermal applications of DB(a,i)P (total doses of 100 μg and 500 μg, respectively). Ten days after initial treatment, all animals received a 2.5 μg application of 12-O-tetradecanoylphorbol-13-acetate (TPA) for 20 weeks. The incidence of skin tumors in mice treated with 100 μg DB(a,i)P was 40% (mean 0.5 skin tumors per mouse), while the incidence in mice treated with 500 μg DB(a,i)P was 85% (mean 5.8 skin tumors per mouse). One group of 20 female rats received intramammary injections of 4 μmol (1.2 mg)/mammary gland of DB(a,i)P, while the other group received no treatment. At the end of the study, 18 out of 19 rats in the DB(a,i)P-treated group developed fibrosarcoma (mean 2.4 tumors per rat), 11 developed mammary adenocarcinoma (mean 1.4 tumors per rat), and 1 developed mammary adenofibroma (2 tumors). In contrast, 2 out of 20 rats in the untreated group developed mammary epithelial tumors (1 adenofibroma and 1 adenocarcinoma), but no fibrosarcoma. Dermal exposure to DB(a,i)P caused benign or malignant skin tumors (papillomas or epitheliomas) in mice, while subcutaneous injection caused cancer (sarcomas) at the injection site in mice and hamsters. In the Ames assay, DB(a,i)P exhibited mutagenicity in the presence of the formulation in isolated liver mitochondria from mice, rats, hamsters, and pigs. In vitro studies showed that DB(a,i)P did not induce DNA damage in mammalian cells. Ecotoxicity studies: DB(a,i)P induced 7-ethoxyhalothrin-O-deethylase activity in rainbow trout hepatocyte cell lines.

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Interactions
Many documented cases of human carcinogen exposure involve complex mixtures of polycyclic aromatic hydrocarbons (PAHs). Although the biological properties of many pure PAHs have been studied, little is known about their effects when present as components of mixtures.
Since the ability to form DNA adducts in vivo is often an indicator of the carcinogenic activity of polycyclic aromatic hydrocarbons (PAHs), we determined the binding affinity of dibenzo[a,e]pyrene (DB(a,e)P), dibenzo[a,h]pyrene (DB(a,h)P), dibenzo[a,i]pyrene (DB(a,i)P), dibenzo[a,l]pyrene (DB(a,l)P), and benzo[a]pyrene (B(a)P), alone or in combination, to DNA after topical application to the skin of male Parkes mice. DNA isolated from the skin and lungs was analyzed using a 32P labeling post-analysis method. Each PAH-formed adduct exhibited significantly different chromatographic mobilities on polyethyleneimine-cellulose thin-layer chromatography plates. The relative binding efficiencies of these compounds in skin and lungs were: dibenzo[a,l]pyrene > dibenzo[a,i]pyrene > dibenzo[a,e]pyrene, which is consistent with their reported carcinogenicity in mouse skin. Most adducts were cleared from DNA within 21 days after treatment, but low levels of adducts were found in both tissues for at least 3 months. When dibenzo[a,l]pyrene, dibenzo[a,e]pyrene, and benzo[a]pyrene were applied simultaneously to mouse skin, the total binding was 31% lower than expected; while the mixture of dibenzo[a,e]pyrene and benzo[a]pyrene bound to skin DNA at levels 65% higher than expected when these carcinogens were applied alone. Other binary combinations of these three polycyclic aromatic hydrocarbons produced adduct levels similar to the sum of the binding levels when each component was applied alone. The results showed that the 32P-post-labeling method can be used to assess the DNA-binding capacity of polycyclic aromatic hydrocarbons in mouse tissues and to detect the interactions between components of a mixture of carcinogens. Ferulic acid, caffeic acid, chlorogenic acid, and ellagic acid, four natural plant phenolic compounds, were able to inhibit the mutagenicity and cytotoxicity of (+/-)-7β,8α-dihydroxy-9α,10α-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (B[a]P 7,8-diol-9,10-epoxide-2), while B[a]P 7,8-diol-9,10-epoxide-2 is currently the only known final carcinogenic metabolite of benzo[a]pyrene. In Salmonella typhimurium strain TA100, the mutagenicity of 0.05 nmol of benzo[a]pyrene-7,8-diol-9,10-epoxide-2 was inhibited by 50% by adding 150 nmol of ferulic acid, 75 nmol of caffeic acid, 50 nmol of chlorogenic acid, or most significantly, 1 nmol of ellagic acid to a 0.5 ml incubation mixture of the bacterium and diol epoxide. 3 nmol of ellagic acid inhibited 90% of the mutation induction. Ellagic acid is also a potent antagonist of benzo[a]pyrene-7,8-diol-9,10-epoxide-2 in Chinese hamster V79 cells. When the tissue culture medium contained 2 μM ellagic acid, the 8-azaguanine resistance mutation induced by 0.2 μM diol epoxide was reduced by 50%. Similar to the results in bacterial experiments, in mammalian cell experiments, ferulic acid, caffeic acid, and chlorogenic acid showed approximately two orders of magnitude lower activity than ellagic acid. The antimutagenic effects of plant phenolic compounds stem from their direct interaction with B[a]P 7,8-diol-9,10-epoxide-2, as all four phenolic compounds increased the rate of diol epoxide disappearance in a concentration-dependent manner in a 1:9 dioxane/water cell-free solution at pH 7.0. Consistent with mutagenicity studies, ellagic acid accelerated the disappearance of B[a]P 7,8-diol-9,10-epoxide-2 80–300 times more efficiently than other phenolic compounds. At pH 7.0, 10 μM ellagic acid resulted in approximately 20 times greater disappearance of B[a]P 7,8-diol-9,10-epoxide-2 than through spontaneous hydrolysis and hydride ion-catalyzed hydrolysis of the diol epoxide. Ellagic acid is a potent inhibitor of the mutagenic activity of bay diol epoxides of benzo[a]pyrene, dibenzo[a,h]pyrene, and dibenzo[a,i]pyrene, but higher concentrations are required to inhibit the mutagenic activity of bay diol epoxides of the less chemically reactive benzo[a]anthracene, chrysene, and benzo[c]phenanthrene. These studies demonstrate that ellagic acid is an effective antagonist of the adverse biological effects of various polycyclic aromatic hydrocarbon (PAH) final carcinogenic metabolites, and suggest that this commonly ingested natural plant phenol may inhibit the carcinogenicity of PAHs.

[1]. Quantitative Structure-Activity Relationship (QSAR) Analysis Using the Partial Least Squares (PLS) Method: The Binding of Polycyclic Aromatic Hydrocarbons (PAH) to the Rat Liver 2,3,7,8-Tetrachlorodibenzo-P-Dioxin (TCDD) Receptor. Quant. Struct.-Act. Relat. 8, 83-89 (1989).

According to an independent committee of scientific and health experts, dibenzo[a,i]pyrene is a possible carcinogen. Dibenzo[a,i]pyrene is a colorless solid, insoluble in water. It is a polycyclic aromatic hydrocarbon with ortho- and pericyclic fusion. Dibenzo[a,i]pyrene is an aromatic hydrocarbon composed of six fused rings, produced by the incomplete combustion of organic matter. It is primarily found in gasoline exhaust, tobacco smoke, and coal tar. Dibenzo[a,i]pyrene is reasonably expected to be a human carcinogen. (NCI05)

C24H14

302.38

302.109

189-55-9

Dibenzo(a,i)pyrene-d14;158776-07-9

9106

Light yellow to yellow solid powder

1.3±0.1 g/cm3

552.3±17.0 °C at 760 mmHg

283.6 °C

282.0±15.1 °C

0.0±0.7 mmHg at 25°C

1.913

7.63

0

0

0

24

436

0

TUGYIJVAYAHHHM-UHFFFAOYSA-N

InChI=1S/C24H14/c1-3-7-19-15(5-1)13-17-9-10-18-14-16-6-2-4-8-20(16)22-12-11-21(19)23(17)24(18)22/h1-14H

hexacyclo[10.10.2.02,7.09,23.014,19.020,24]tetracosa-1(23),2,4,6,8,10,12,14,16,18,20(24),21-dodecaene

Benzo(rst)pentaphene; DB(a,i)p; Dibenzo(a,i)pyrene

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.)