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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).
Household and Personal Care Products: Cleaning up and Looking Good
Published in Richard J. Sundberg, The Chemical Century, 2017
Many cosmetics and similar personal care products contain preservatives to control bacterial growth. Some of these have become controversial. One group is called parabens and are alkyl esters of para-hydroxybenzoic acid. The parabens have been considered to possibly be exogenous estrogens and endocrine disruptors, based mainly on in vitro studies28 (see Section 9.7). Another type that has elicited concern are formaldehyde generators such as 1,3-bis-(hydroxymethyl)-5,5-dimethyl hydantoin (DMDM hydantoin), quaternium-15, and imidazolidinyl urea. The structures are given in Scheme 6.4. Also used is a mixture of methylisothiazoline and methylchloroisothiazolidine. These compounds have some potential for allergenic sensitization. The incidence of sensitivity to the parabens is <0.5% and for the formaldehyde-release agents it ranges around 1–2%. Both the United States and EU require that the preservatives be listed and there are maximum concentrations that are permitted. New preservatives must be approved by appropriate safety committees. In the United States, this is done through the Cosmetic Ingredient Review process, which includes representatives of the industry, government, and consumers.
Improved transdermal delivery of valsartan using combinatorial approach of polymeric transdermal hydrogels and solid microneedles: an ex vivo proof of concept investigation
Published in Journal of Biomaterials Science, Polymer Edition, 2023
Cindy Kristina Enggi, Mega Tri Satria, Nirmayanti Nirmayanti, Jesscia Theodor Usman, Julika Fajrika Nur, Rangga Meidianto Asri, Nana Juniarti Natsir Djide, Andi Dian Permana
VAL (purity: >98.0% T) (HPLC) was obtained from Tokyo Chemical Industry (Tokyo, Japan). Carbopol 940 and DMDM Hydantoin were purchased from Sigma-Aldrich Pte Ltd. (Singapore, Singapore). SMNs (Dermarollers®) were obtained from SQY® (Guangdong, China). Other materials were analytical grade