Enhancing the efficacy of Arrabidaea chica extract release from polysaccharide-based films: The impact of cashew gum and cross-linking process

Polysaccharide films containing plant-derived bioactive agents have emerged as alternatives for the treatment of mucosal lesions. Herein, polysaccharide films composed of chitosan (CH), alginate (AL), and cashew gum (CG, an exudate of Anacardium occidentale L.) containing the standardized Arrabidaea chica Verlot (synonym Fridericia chica L) (Ac) plant extract, as a bioactive agent, were produced. The properties of the films, such as morphology, thickness, mechanical properties, swelling, contact angle, and the plant extract release kinetics were evaluated. Moreover, the influence of the cross-linking process with calcium ions on these properties was also analyzed. Transparent, reddish films with lamellar cross-sections and thickness values varying from 63.5 to 123.7 mu m were produced, with Ac incorporation efficiency varying from 79 to 93 %, being higher for CH-AL films. The addition of Ac to CH-AL films reduced their tensile strength, but when Ac was added to the CH-AL-CG formulation, no significant variation was observed in this property, showing that CG and Ac may interact in a positive manner towards the tensile strength. The presence of CG increased the structural stability of the CH-AL films in simulated saliva, from 300 min to more than 500 min. Besides that, the addition of CG changed the impact of Ac extract diffusion and matrix erosion on the Ac release mechanism, but did not lead to significant changes in the mechanical properties of the films. Although the least cross-linked film exhibited only about half the swelling degree (around 5.4 g/g) when compared to the other formulations, it displayed the highest extract release ratio (45 mg of Ac extract per gram of film), showing an anomalous diffusion mechanism, which may indicate that a balance between erosion and diffusion phenomena is fundamental for efficient Ac extract release.