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CAS Number: 7681-93-8 (also 1396-30-1 for natamycin hydrate)
Synonyms: Pimaricin, E235, Natacyn, Delvocid, Delvopos, antibiotic E-235, tennecetin, pimaricin (former name)
Physical Properties: White to cream-colored crystalline powder, almost odorless and tasteless. Very slightly soluble in water (0.04–0.10 g/L at 25°C); slightly soluble in methanol and DMSO; practically insoluble in ethanol. Melting point 290°C (decomposes). Strong UV absorption at 303 nm (conjugated tetraene chromophore). Unstable to light (photolabile), heat (decomposes above 100°C), and oxidizing agents. Stable at pH 3–9 in the dark. Log P = 1.3. Molecular weight 665.73 g/mol.
Applications: Surface treatment of soft cheeses (Camembert, Brie, Gouda, Edam, Havarti, Roquefort, blue cheese). Dry and fermented sausages (salami, chorizo, pepperoni). Bakery products (cakes, pastries, bread, tortillas, pita). Yogurt and sour cream. Fruit juices and apple cider. Cooked meat and poultry (ham, turkey breast). Ophthalmic suspension (Natacyn 5%) for fungal keratitis. Topical antifungal for cutaneous infections. Coating of catheters and contact lenses. Post-harvest dip for fruits (citrus, apples, pears, strawberries). Animal feed and silage preservative.
Description:
Natamycin (E235) is a naturally occurring polyene macrolide antifungal compound produced by fermentation of Streptomyces natalensis (also S. chattanoogensis and S. gilvosporeus). It belongs to the tetraene subgroup, meaning it contains four conjugated double bonds in the macrolide ring, and it is structurally distinct from nystatin (also a tetraene) and amphotericin B (a heptaene). The molecular structure includes a large lactone ring with a conjugated chromophore that absorbs UV light at 303 nm.
The mechanism of action involves selective, high-affinity binding to ergosterol, the principal sterol in fungal cell membranes. Unlike nystatin and amphotericin B, which form large pores leading to cell lysis, natamycin acts primarily as a fungistatic agent: it binds to ergosterol and disrupts membrane fluidity, inhibits ergosterol biosynthesis, and blocks membrane transport systems without causing immediate leakage. This prevents fungal growth and sporulation without rapidly killing the cells, making it ideally suited for surface preservation where fungal contamination occurs from the environment during ripening, such as in cheese caves.
Natamycin is remarkably specific for fungi (both yeasts and molds) and shows negligible activity against bacteria (both Gram-positive and Gram-negative), viruses, protozoa, and mammalian cells. This selective toxicity occurs because mammalian cell membranes contain cholesterol instead of ergosterol, and natamycin binds to cholesterol with much lower affinity. This explains the excellent safety profile of natamycin. Toxicologically, less than one percent of ingested natamycin is absorbed from the gastrointestinal tract, and any absorbed fraction is rapidly metabolized by the liver and excreted in feces. No systemic toxicity, genotoxicity, carcinogenicity, or reproductive toxicity has been observed at dietary exposure levels, and JECFA has set an ADI of 0.3 mg per kilogram of body weight per day.
The primary limitation of natamycin is photodegradation: exposure to sunlight or ultraviolet light causes isomerization and oxidation of the conjugated tetraene chromophore, turning the solution yellow or brown and inactivating the compound. Therefore, in cheese production, it is applied only to surfaces that are not exposed to light, typically wrapped in opaque film. Natamycin does not penetrate deeply into food; it remains on the surface where over 90 percent of contamination occurs. This surface-only action is beneficial because it preserves the natural microbial flora, including bacterial starter cultures and cheese rind microflora, while eliminating spoilage fungi.
In the United States, natamycin is approved as a direct food additive under 21 CFR 172.155 only for cheese including processed cheese and for treating meats and poultry as a secondary additive. The European Union permits E235 in all surface treatment applications. Unlike sorbic acid or propionates, natamycin is effective at very low concentrations of 1 to 10 parts per million and does not alter the taste, odor, color, or texture of the product. Resistance is rare due to the essentiality of ergosterol for fungal survival; mutations in ergosterol synthesis are often lethal or severely reduce viability, although some resistance mechanisms such as overexpression of efflux pumps and altered sterol composition have been reported. In ophthalmology, natamycin remains a first-line treatment for fungal keratitis, a severe corneal infection often following plant matter injury.
SAFETY INFORMATION ABOUT E235 – NATAMYCIN
First aid measures:
Description of first aid measures:
General advice:
Consult a physician.
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
If inhaled:
If breathed in, move person into fresh air.
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off contaminated clothing and shoes immediately.
Wash off with soap and plenty of water.
Consult a physician.
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
If swallowed:
Do NOT induce vomiting.
Never give anything by mouth to an unconscious person.
Rinse mouth with water.
Consult a physician.
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment.
Avoid breathing vapours, mist or gas.
Evacuate personnel to safe areas.
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste.
Keep in suitable, closed containers for disposal.
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place.
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles.
Faceshield (8-inch minimum).
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
Skin protection:
Handle with gloves.
Gloves must be inspected prior to use.
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product.
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices.
Wash and dry hands.
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls.
If the respirator is the sole means of protection, use a full-face supplied air respirator.
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions.
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company.
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product
