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Preservative Resistance
Published in Philip A. Geis, Cosmetic Microbiology, 2020
Enzymatic mechanisms of microorganisms are better understood than any other mechanism of preservative resistance. For example, it was reported in 1985 that five strains of Pseudomonas isolated from contaminated cosmetic products were resistant to high concentrations of imidazolidinyl urea (5). In each of these contaminated products, imidazolidinyl urea had been metabolized to formaldehyde which in turn was metabolized to a UV-absorbing lutidine derivative. In addition to imidazolidinyl urea, Pseudomonas aeruginosa isolates have also been found to be resistant to the antimicrobial activity of DMDM hydantoin, another formaldehyde-releasing preservative. These resistant isolates were found to have typical patterns of outer membrane proteins (8). It was determined that the development of these Pseudomonas aeruginosa-resistant strains was not due to a reduced permeation of DMDM hydantoin or other formaldehyde-releasing preservative across the outer membrane of the bacterial cell, but due to the enzyme formaldehyde dehydrogenase that is able to metabolize formaldehyde to formic acid that is ineffective as a cosmetic/personal care preservative (15,16).
Proteins for Conditioning Hair and Skin
Published in Randy Schueller, Perry Romanowski, Conditioning Agents for Hair and Skin, 2020
Proteins are components of every living thing, attesting to the broad-based compatibility of their monomers, the amino acids. It should thus not be surprising that proteins and their hydrolyzates and derivatives are readily biodegradable. A suitable preservation system must thus be incorporated in products containing both water and protein-based material. The protein products sold as aqueous solutions utilize a variety of preservation systems. Most frequently employed are the parabens (methyl- and propylparaben, in particular). Finished products containing proteins in their native states (generally present to make use of their enzymatic activities) require preservatives which have very low reactivity toward the protein and so do not appreciably modify the conformation of the protein. A combination of parabens and phenoxyethanol at a level of up to 1% by weight of the formulation may be employed. When hydrolyzates and their derivatives are utilized, more reactive (and more cost-effective) preservatives can be utilized. Such agents may include quaternium-15, imidazolidinyl urea, diazolidinyl urea, DMDM hydantoin, and methyl[chloro]isothiazolinone, with or without parabens. Specific preservation systems are referenced by some manufacturers (16,17). Certain preservatives are incompatible with proteinaceous matter, particularly at high concentration. A striking example is the firm gel produced after overnight storage at room temperature of a solution of approximately equal proportions of 37% formaldehyde and 55% hydrolyzed collagen (2000 Da).
Chemical Compounds as Trigger Factors of Immediate Contact Skin Reactions
Published in Ana M. Giménez-Arnau, Howard I. Maibach, Contact Urticaria Syndrome, 2014
In the case of free formaldehyde, for which bactericidal and fungicidal properties confer it a place of choice for preservation of cosmetics, its use has been reduced because of the bad press it has received as an irritant, sensitizer, and potential carcinogen.[27] Formaldehyde is known to be a strong, ubiquitous skin sensitizer, including from noncosmetic sources of contact. Because of this, exposure to formaldehyde in the European Union is subject to restrictions. Free formaldehyde may be used as a preservative in all cosmetic products (maximum authorized concentration 0.2%, except 0.1% in products for oral hygiene) except aerosol cosmetics. Annex VI of the Cosmetics Directive 76/768 EEC further stipulates that all finished products containing formaldehyde or substances that release formaldehyde must be labeled with the warning “contains formaldehyde” if the concentration of free formaldehyde in the finished product exceeds 0.05%.[28] As an alternative, chemical compounds that slowly release formaldehyde in the presence of water and under usage conditions, the so-called formaldehyde releasers, are commonly employed as preservatives in cosmetics (water-based preparations) instead of free formaldehyde. Examples are bronopol and imidazolidinyl urea. Unfortunately, many formaldehyde releasers used in cosmetics are also skin sensitizers because of released formaldehyde but also to reactive intermediates other than formaldehyde that could be involved in the formation of the hapten-protein antigenic complex, a key step of the sensitization process, and thus explaining their sensitizing potential per se.[29] Even if it is a strong sensitizer, reported immediate reactions to formaldehyde are mainly classified as NICoU because they seem not to be mediated by IgE.[30] However, there is still no consensus in the reports that have appeared as to whether the mechanism is immunological or nonimmunological.[31]
Development of a nanotechnological hydrogel containing desonide nanocapsules in association with acai oil: design and in vivo evaluation
Published in Pharmaceutical Development and Technology, 2022
Priscila Rosa, Mariane Lago Friedrich, Juliana dos Santos, Natháli Schopf Pegoraro, Camila Camponogara, Sara Marchesan Oliveira, Cristiane de Bona da Silva, Andréa Inês Horn Adams
Desonide (DES) (97.42%) was purchased from Fagron (São Paulo, Brazil). The açai oil (AO) was donated by Beraca Ingredientes Naturais SA (Ananindeua, Brazil). Medium chain tryglicerides (MCT) were bought from Delaware (Porto Alegre, Brazil), polysorbate 80, sorbitan monooleate, methanol and acetonitrile from Sigma Aldrich (St Louis, USA). Eudragit® RL 100 was bought from Evonik (Essen, Germany) and Amigel® (Sclerotium gum) from PharmaSpecial (Itapevi, Brazil). Imidazolidinyl urea was acquired from All Chemistry (São Paulo, Brazil). Commercial gel cream (CG-C, Adinos® desonide 0.05%, lot 1709428 Aché, Garulhos, Brazil) was acquired locally. For the in vivo evaluation, ketamine (Dopalen®) and xylazine (Anasedan®) were acquired from Ceva (Paulínia, Brazil), croton oil from Sigma Chemical Co. (St. Louis, USA), hematoxylin-eosin and paraffin from Merck (Darmstadt, Germany). Acetone, formaldehyde, ethanol and acetic acid were purchased from Vetec (Rio de Janeiro, Brazil).
Undeclared formaldehyde levels in patient consumer products: formaldehyde test kit utility
Published in Cutaneous and Ocular Toxicology, 2019
Jason E. Ham, Paul D. Siegel, Howard Maibach
Several studies have identified additional hydrolysis products from formaldehyde releasers. (4-hydroxymethyl-2,5-dioxo-imidazolidine-4-yl)-urea (HU), (3,4-bis-hydroxymethyl-2,5-dioxo-imidazolidine-4-yl)-urea (BHU) were as major decomposition products in cosmetics from both diazolidinyl urea and imidazolidinyl urea11,12. The authors suggested that patch testing with HU and BHU should be performed, but provided no data with respect to the allergenicity of these compounds. Kireche et al. (2010) reported that DMDM hydantoin was directly reactive toward amino acids, while the bronopol and methenamine breakdown products, bromoethanol and diaminomethane, respectively, were amino acid reactive13. Bronopol is a known contact allergen14, and while we found no reports of diaminomethane allergy, diaminoethane (ethylenediamine) is a known contact allergen15. This suggest potential non-formaldehyde protein haptenation/allergic contact dermatitis products containing these formaldehyde releasers.
Accelerated infected wound healing by topical application of encapsulated Rosemary essential oil into nanostructured lipid carriers
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2019
Keyvan Khezri, Mohammad Reza Farahpour, Shokoofeh Mounesi Rad
Gels were prepared as described by others [3]. In summary, the rheological additive (0.8% w/w) was included and dispersed in the aqueous phase, under mild agitation. In order to solubilize the REO, a solubilizing compound was added to the REO to obtain aqueous gels containing different percentages of EO. All gel formulations were produced by deionized water having 0.35% w/w imidazolidinyl urea, 0.05% w/w methylchloroisothiazolinone and methylisothiazolinone as preservatives.