Contribution to the In Vitro Study of the Antioxidant and Antimicrobial Activities of Urtica dioica L. Extracts from the Mostaganem Region for Cosmeceutical Applications.

Abstract

This study aims to enhance the value of Urtica dioica by evaluating its biological properties, particularly its antioxidant and antibacterial activities, as well as its potential use in the preparation of natural cosmetic products. The study includes a theoretical part, presenting the main botanical, chemical, and pharmacological characteristics of this plant. The practical part involved the extraction of active compounds using both maceration and Soxhlet methods, followed by physical, chemical, and biological analyses. This experimental work focused on assessing the biological properties of Urtica dioica extracts obtained through two methanolic extraction methods: Soxhlet extraction (ES) and maceration (EM). The study covered the identification of bioactive compounds, the evaluation of antioxidant and antibacterial activities, and the formulation of natural cosmetics based on the plant extracts. The results showed that the Soxhlet method yielded a slightly higher extract percentage than maceration (51% vs. 50%), reflecting the influence of the extraction method on the amount of compounds obtained. Phytochemical screening confirmed the presence of secondary metabolites such as phenols, flavonoids, alkaloids, tannins, and coumarins. Thin-layer chromatography (TLC) further confirmed these findings, revealing variations in compound composition depending on the extraction method. Regarding antioxidant activity, the DPPH assay showed that the EM extract exhibited stronger activity compared to the ES extract. The IC50 value was 27.35 mg/ml for EM versus 52.8 mg/ml for ES, indicating a higher free radical scavenging capacity in the macerated extract. Concerning antibacterial activity, the results showed that the extracts were effective against some bacterial strains, particularly Bacillus cereus, which was the most susceptible, while other strains, such as Escherichia coli, showed significant resistance. These results were explained by the characteristics of the bacterial cell wall and the varying ability of plant compounds to penetrate it. Finally, this work culminated in the development of two natural cosmetic products: a soap and a skin cream formulated with Urtica dioica extract. Preliminary tests showed acceptable properties in terms of stability, pH, foaming, and texture, enhancing their potential for use in biocosmetics.