Novel chitosan/polyvinyl alcohol gel encapsulating ethanolic Centella asiatica extract for cosmeceutical applications

Abstract

Centella asiatica (C. asiatica) possesses various skin-beneficial properties such as antioxidants, anti-inflammatory, antibacterial, and wound healing activities. In this study, a novel approach has been conducted for the first time by incorporating C. asiatica extract into a peel-off gel of chitosan (CS) and polyvinyl alcohol (PVA) via a straightforward and eco-friendly blending process. This method reveals several advantages, including the simplicity of the formulation, the utilization of biodegradable ingredients, good gel stability, and ease of production. The total extraction yield of the C. asiatica extract is in the range of 22.5 ± 0.69%–33.5 ± 1.02%, along with total phenolic content (133.2 ± 4.1–221.0 ± 7.6 mg gallic acid/g extract), total flavonoid content (371.7 ± 3.6–423.5 ± 15.1 mg rutin/g extract), and total triterpenoid content (562.0 ± 23.5–869.5 ± 47.6 mg ursolic acid/g extract). Moreover, the C. asiatica extracts show moderate antibacterial activity against Cutibacterium acnes, Staphylococcus epidermidis, and Escherichia coli, but an effective antioxidant ability with an EC₅₀ value of 12.74 ± 0.13 (μg/mL) which is approx. 2.45 times lower than that of the extract obtained in the previous work. Regarding the synthesis of CS/PVA gel encapsulated in the extract, the formulation using 20% ethanol shows a smooth-surfaced and uniformly structure, natural hydrophilicity, a drying time within 25–30 min, a spreadability of 47.6–58.5 mm, and excellent swelling ratio of up to 4200%. The mechanical properties of the dried CS/PVA/extract gels, including elongation (100–199%), tensile strength (13–19.9 N/mm²), and folding endurance (more than 250 times), indicate that the developed gels own favorable qualities for facial mask applications.