Ensulizole does not have a classical pharmacological target. It acts as a physical and chemical UV filter, absorbing ultraviolet radiation and preventing it from reaching the skin. It is a sulfonated benzimidazole derivative that is widely used in sunscreen products for its photoprotective properties.

Four0.0 μM parent PBSA may be entirely removed and TOC can be reduced by 25% with 190 minutes of UV irradiation at 4.0 mM [H2O2]0 [1].
Ensulizole is evaluated in vitro for its UV absorption properties. The compound's absorbance spectrum is measured using UV-Vis spectrophotometry. Its photostability is assessed by exposing the compound to UV radiation and measuring changes in absorbance over time. Its ability to protect cells from UV-induced damage can be assessed using cell-based assays.

In vivo, Ensulizole is used topically as a sunscreen agent. It is applied to the skin to absorb UV radiation and prevent sunburn and skin damage. Its efficacy is assessed in human volunteers by measuring the sun protection factor (SPF). It is also used as a pharmaceutical reference standard for the determination of the analyte in sunscreen formulations by HPLC.

In vitro assays for Ensulizole typically involve UV absorption spectroscopy. The compound is dissolved in an appropriate solvent, and its absorbance spectrum is measured from 290-400 nm. Photostability studies involve exposing the compound to UV radiation and monitoring absorbance changes. The compound's ability to protect cells from UV-induced damage can be assessed using cell-based assays with appropriate endpoints.

For in vitro cell-based assays, skin cells (e.g., keratinocytes, fibroblasts) are cultured and treated with Ensulizole prior to UV irradiation. Cell viability is assessed by MTT or other standard assays. DNA damage is assessed by measuring cyclobutane pyrimidine dimers (CPDs) or other UV-induced DNA lesions. The compound's photoprotective effects are evaluated by comparing UV-irradiated cells with and without compound treatment.

In vivo animal studies with Ensulizole are typically conducted in the context of sunscreen efficacy testing. Animal models (e.g., hairless mice) are exposed to UV radiation with or without topical application of the compound. Skin erythema, edema, and histological changes are assessed. The compound's ability to prevent UV-induced skin damage is evaluated. Human clinical studies are also conducted for SPF determination.

Ensulizole (CAS: 27503-81-7) has a molecular weight of 274.29 g/mol and a molecular formula of C13H10N2O3S. It is also known as 2-Phenylbenzimidazole-5-sulfonic acid. Appearance: white to off-white powder. Solubility: water-soluble. Storage: room temperature. It is a pharmaceutical secondary standard for quality control applications.

Ensulizole is generally recognized as safe for use in sunscreen products at concentrations up to 4%. It has a low potential for skin irritation and sensitization. Systemic absorption is minimal after topical application. It is not intended for oral use. It is an approved sunscreen ingredient in many countries, including the US and EU.

[1]. Abdelraheem WH, et al. Degradation and mineralization of organic UV absorber compound 2-phenylbenzimidazole-5-sulfonic acid (PBSA) using UV-254nm/H2O2. J Hazard Mater. 2015 Jan 23;282:233-40.

Ensulazole belongs to the benzimidazole class of compounds. Ensulazole, also known as 2-phenylbenzimidazole-5-sulfonic acid, is a water-soluble sunscreen agent with strong absorption of UV-B wavelengths. Due to its limited protection against UV-A wavelengths, it is often used in combination with other UV filters in cosmetic and sunscreen formulations. Because of its water solubility, ensulazole is commonly used in lightweight, non-greasy product formulations. Studies have shown that ensulazole treatment can prevent the formation of cyclobutanepyrimidine dimers and can photosensitize the formation of oxidized guanine bases after UV-A or UV-B irradiation. According to the U.S. Food and Drug Administration (FDA), the maximum approved concentration of ensulazole is 148 mM, but the concentration range of ensulazole in commercially available sunscreens is 74 to 148 mM. See also: Enshurizol; Titanium dioxide (ingredient); Enshurizol; Octyl salicylate (ingredient); Enshurizol; Octyl methoxycinnamate (ingredient)...View more...

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Drug Indications
Suitable for use as a UV-B absorbing molecule in sunscreen formulations.

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Mechanism of Action
Enshurizol strongly absorbs UV-B wavelengths. It prevents the formation of UV-B-induced cyclobutanepyrimidine dimers. Based on in vitro and cellular experiments, enshurizol induces DNA damage, leading to DNA strand breaks, and photosensitizes the formation of oxidized guanine after UV-A or UV-B irradiation via type I and type II photosensitization mechanisms following exposure. Enshurizol can generate reactive oxygen species, including singlet oxygen, upon photoexcitation.

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Pharmacodynamics
Enshurizol is a selective UV-B filter with very low activity against UV-A wavelengths. In vitro, ensolazole oxidizes guanine bases under UV-B light excitation and may cause photodamage to DNA, proteins, and lipids in the cellular environment.
Ensulizole (2-Phenylbenzimidazole-5-sulfonic acid) is a sulfonated UV absorber used as a sunscreen agent. It provides intense UVB and partial UVA absorption. It is used in cosmetic and pharmaceutical sunscreen formulations and as a pharmaceutical reference standard. It is an approved sunscreen ingredient in many countries.

C₁₃H₁₀N₂O₃S

274.30

274.041

27503-81-7

33919

White to yellow solid powder

1.5±0.1 g/cm3

300 °C

>100ºC

1.704

1.5

2

4

2

19

414

0

O=S(C1=CC=C2C(NC(C3=CC=CC=C3)=N2)=C1)(O)=O

UVCJGUGAGLDPAA-UHFFFAOYSA-N

InChI=1S/C13H10N2O3S/c16-19(17,18)10-6-7-11-12(8-10)15-13(14-11)9-4-2-1-3-5-9/h1-8H,(H,14,15)(H,16,17,18)

2-phenyl-3H-benzimidazole-5-sulfonic acid

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)

0.1 M NaOH : ~10 mg/mL (~36.46 mM)
DMSO : ~8.33 mg/mL (~30.37 mM)

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.)