Template:Short description Template:Use dmy dates Template:Cs1 config Template:Chembox Zinc pyrithione (or pyrithione zinc) is a coordination complex of zinc. It has fungistatic (inhibiting the division of fungal cells) and bacteriostatic (inhibiting bacterial cell division) properties and is used in the treatment of seborrhoeic dermatitis<ref name="MD">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> and dandruff.

Structure of the compoundEdit

The pyrithione ligands, which are formally monoanions, are chelated to Zn2+ via oxygen and sulfur centers. In the crystalline state, zinc pyrithione exists as a centrosymmetric dimer (see figure), where each zinc is bonded to two sulfur and three oxygen centers.<ref>Template:Cite journal</ref> In solution, however, the dimers dissociate via scission of one Zn-O bond.Template:Citation needed

This compound was first described in the 1930s.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Pyrithione is the conjugate base derived from 2-mercaptopyridine-N-oxide (CAS# 1121-31-9), a derivative of pyridine-N-oxide.Template:Citation needed

UsesEdit

MedicineEdit

Zinc pyrithione can be used to treat dandruff and seborrhoeic dermatitis.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> It also has antibacterial properties and is effective against many pathogens from the Streptococcus and Staphylococcus genera.<ref name="American Chem Soc">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Its other medical applications include treatments of psoriasis, eczema, ringworm, fungus, athletes foot, dry skin, atopic dermatitis, tinea versicolor,<ref>Template:Cite journal</ref><ref name="American Chem Soc" /> and vitiligo.Template:Medical citation needed

PaintEdit

Because of its low solubility in water (8 ppm at neutral pH), zinc pyrithione is suitable for use in outdoor paints and other products that protect against mildew and algae. It is an algaecide. It is chemically incompatible with paints relying on metal carboxylate curing agents. When it is used in latex paints with water containing much iron, a sequestering agent that preferentially binds the iron ions is needed. It is decomposed by ultraviolet light slowly, providing years of protection in direct sunlight.Template:Citation needed

SpongesEdit

Zinc pyrithione is an antibacterial treatment for household sponges, as used by the 3M Corporation.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>Template:Cite journal</ref>

ClothingEdit

A process to apply zinc pyrithione to cotton with washable results was patented in the United States in 1984.<ref>Template:Cite patent</ref> Zinc pyrithione is used to prevent microbe growth in polyester.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Textiles with applied zinc pyrithione protect against odor-causing microorganisms. Export of antimicrobial textiles reached US$497.4 million in 2015.<ref>Template:Cite journal</ref>

Mechanism of actionEdit

Antibacterial effectEdit

Zinc pyrithione is known to exhibit antibacterial activity by disrupting cell membrane integrity and essential metabolic functions in bacteria.<ref>Template:Cite journal</ref>

Antifungal effectEdit

Its antifungal effect is thought to derive from its ability to disrupt membrane transport by blocking the proton pump that energizes the transport mechanism.<ref>Template:Cite journal</ref> A study from 2011 showed that antifungal effects of Zinc pyrithione work by copper toxicity mechanism that targets critical iron–sulphur proteins.<ref>Template:Cite journal</ref>

Health effectsEdit

Zinc pyrithione is approved for over-the-counter topical use in the United States as a treatment for dandruff and is the active ingredient in several anti-dandruff shampoos and body wash gels. In its industrial forms and strengths, it may be harmful by contact or ingestion. Zinc pyrithione can in the laboratory setting trigger a variety of responses, such as DNA damage in skin cells.<ref>Leading references: Template:Cite journal</ref>

Legal statusEdit

European UnionEdit

Use of zinc pyrithione is prohibited within cosmetic products in the European Union since December 2021.<ref name="EU Commission Regulation-2021">Template:Citation</ref> The substance was considered safe for use in rinse-off and leave-in products of different tested concentrations, but due to potential environmental toxicity consideration of the use of zinc pyrithione was made against potential alternative substance ingredients. Due to no industry submission to the regulators supporting the continued use of zinc pyrithione and/or an absence of indications that there were no suitable alternatives to the substance: the use of zinc pyrithione became automatically prohibited within cosmetic products as an intended ingredient. This was as a consequence of zinc pyrithione addition to the Cosmetic Product Regulation (EC) No 1223/2009 Annex II list.<ref name="EU Commission Regulation-2021" />

United StatesEdit

Zinc pyrithione concentration of up to 2% is allowed for products when they are formulated to be applied and then washed off after brief exposure. Alternatively, up to 0.25 percent when formulated to be left on the skin or scalp <ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Environmental concernsEdit

A large Swedish study shows that it is broken down in wastewater plants and does not release into waterways.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> A Danish study shows that it biodegrades quickly, but that a risk of continuous leaching from boat paint may cause environmental toxicity.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

See alsoEdit

ReferencesEdit

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