Abstract
Background: Melanins are high molecular weight pigments responsible for the mammalian skin and hair colour and play a key role in skin protection from UV radiation; however, their overproduction and excessive accumulation lead to pigmentation problems including melasma, freckles, uneven colouring, and age spots. Therefore, the modulation of melanin synthesis represents a critical issue in medicine and cosmetology. In the present study, an innovative polymeric antioxidant to be used as skin whitening agent is developed by the conjugation of dextran with rosmarinic acid. Methods: Dextran-rosmarinic acid conjugates (DEX-RA) were synthesized in a one-pot method starting from Origanum vulgare aqueous leaf extract and dextran. The total polyphenol content and the antioxidant activity were assessed by Folin-Ciocalteau assay and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) and bleaching tests, respectively. The efficacy of DEX-RA was evaluated by inhibition of tyrosinase activity, in vitro diffusion and stability studies and in vivo studies. The biocompatibility of the conjugates was investigated by 3-[4,5-Dimethylthiaoly]-2,5-diphenyltetrazoliumbromide (MTT) and EPISKIN™ model. Results: Efficacy and safety studies confirmed the antioxidant and tyrosinase inhibitory activities and the biocompatibility of the synthesized conjugates. Conclusion: The polymeric conjugates, comparing to the free antioxidant, show a long-lasting efficacy combined to an enhanced stability resulting in an improved performance of the cosmetic formulations prepared using this innovative whitening agent as a bioactive ingredient.
Highlights
Melanins are coloured polymorphous biopolymers, which represent the main determinant of mammalian skin and hair colour [1]
Dextran is a natural hydrophilic, biodegradable, and biocompatible polysaccharide mainly based on α-1-6-linked d-glucose units and produced from Leuconostoc, Lactobacillus, Streptococcus, and Weissella species [39]
The reaction mechanism consists of the oxidation of ascorbic acid by H2 O2 with the formation of hydroxyl radicals, which attack the hydrogen atoms in the α-methylene and hydroxyl positions of the polymeric backbone leading to the formation of reactive sites involved in the reaction for rosmarinic acid insertion [40]
Summary
Melanins are coloured polymorphous biopolymers, which represent the main determinant of mammalian skin and hair colour [1] These pigments are synthesized within melanosomes by a combination of chemical and enzyme-catalysed reactions involving the amino acid L-tyrosine and called melanogenesis [2]. Several tyrosinase inhibitors, including hydroquinone [13], kojic acid [14], azelaic acid [15], and arbutin [16], have been employed for cosmetic purposes These compounds present topical as well as systemic side effects consisting of irritant dermatitis, leukoderma, ochronosis, post-inflammatory hyperpigmentation and kidney and liver diseases [17,18]. An innovative polymeric antioxidant to be used as skin whitening agent is developed by the conjugation of dextran with rosmarinic acid
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
