Effect of gelling agents on properties of coumestrol-loaded nanoemulsions – Formulation, skin retention/permeation, antioxidant and skin photoprotective activities

• Published in: Journal of drug delivery science and technology Vol. 98; p. 105834
• Main Authors: Oliveira, Laura Karsburg, Argenta, Débora Fretes, Balestrin, Lucélia Albarello, Medeiros-Neves, Bruna, Fachel, Flávia Nathiely Silveira, Mautone, Henrique, Moreira, José Cláudio, Koester, Letícia Scherer, Bassani, Valquiria Linck, Simões, Claudia Maria Oliveira, Teixeira, Helder Ferreira
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-09-2024
• Subjects: Antioxidant; Hydrogel; Isoflavonoids; Nanoestructures; Topical formulations; UV radiation; UV radiation; Isoflavonoids; Topical formulations; Nanoestructures; Hydrogel; Antioxidant
• ISSN: 1773-2247
• DOI: 10.1016/j.jddst.2024.105834

Coumestrol is an isoflavonoid that exhibits antioxidant activity. In this study, hydrogels containing coumestrol-loaded nanoemulsions were designed to protect the skin against UVA/UVB light. The systems investigated were coumestrol-loaded nanoemulsions obtained by spontaneous emulsification procedure formulated in semisolid hydrogels composed of ionic (Carbopol 940®), cationic (chitosan) or non-ionic (hydroxyethylcellulose) gelling materials. Transmission electron microscopy images of formulations showed oil droplets exhibiting 200–300 nm. Hydrogels displayed non-Newtonian shear-thinning behavior. Coumestrol content in formulations remained close to 100 % (1 mg/mL) over time (up to 90 days). Regardless of the gelling material used, a lowering of coumestrol release rate was observed, in comparison with the release from nanoemulsion. The permeation and retention of coumestrol in porcine ear skin was evaluated using Franz-type diffusion cells. A higher retention of coumestrol in the epidermis was noticed (20 μg/g) from Carbopol 940-based formulation after 8 h of kinetics. No histological evidence of tissue damage was observed. The nanoemulsion containing coumestrol thickened with Carbopol 940® was selected for further studies. The formulation exhibited antioxidant potential as estimated by TRAP and TAR assays. The skin photoprotective effect was evidenced by means of TBARS, protein carbonylation, and protein thiol content experiments. Overall, our research suggests that the formulation is promising to protect skin against oxidative damage from UVA/UVB light.
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