Development of a standardized Centella asiatica (L.) Urb. Oral ulcer patches utilizing natural polymer xyloglucan derived from Tamarindus indica L. seed powder

Abstract

This study aimed to develop xyloglucan-based oral patches incorporating a pentacyclic triterpene-rich extract of Centella asiatica (L.) Urb. (PRE) for the management of aphthous stomatitis. PRE was prepared using microwave-assisted extraction followed by resin purification, while xyloglucan was extracted from Tamarindus indica L. seed powder. To identify the most suitable formulation, three fabrication approaches were evaluated, xerogel-based patches, crosslinked films, and non-crosslinked films. The prepared patches were characterized for physicochemical properties, including mechanical strength, pH, swelling behavior, erosion percentage, contact angle, morphology, and active ingredient release, together with in vitro biological activities such as nitric oxide inhibition, gingival fibroblast proliferation, antimicrobial activity, and stability. Physicochemical characterization demonstrated that the non-crosslinked film formulation provided the most suitable attributes for oral mucosal application, including appropriate mechanical strength, surface pH, high swelling capacity, and low erosion (suggesting better water resistance). The PRE-loaded non-crosslinked film patches exhibited superior biological performance, significantly enhancing gingival fibroblast proliferation and demonstrating antimicrobial growth inhibition against Staphylococcus aureus and Streptococcus mutans (MIC/MBC values of 16/32 mg/mL and 8/16 mg/mL, respectively). Drug release studies confirmed complete release of major triterpenes within 60 min. Stability evaluation revealed that the PRE-loaded non-crosslinked film patches maintained physical integrity after five freeze-thaw cycles and retained acceptable mechanical and disintegration properties during 10-week room-temperature storage. Overall, the PRE-loaded non-crosslinked film patches showed the greatest potential as a natural polymer-based oral delivery system; however, further in vivo and clinical investigation is warranted to confirm therapeutic efficacy and patient acceptability.