Oral mucosa and subacute systemic toxicity of anacardic acid loaded-zein nanoparticles

Abstract Anacardic acid, a bioactive phytochemical extracted from cashew shell liquid of Anacardium occidentale, is a promising oral antimicrobial agent, lacking complete toxicity evaluation. This study aimed to evaluate the oral mucosal and systemic toxicity of zein nanoparticles containing anacardic acid in vivo. Oral (gavage) and topical administration on oral mucosa were performed in mice (female c57bl/6j) over 30 days, distributed in four groups: Negative control - sterile saline solution 0.89%; Standard Group – chlorhexidine gluconate 0.12%; Group AaZNp – anacardic acid loaded-zein nanoparticles (9.337 µg/mL) and Group BZNp – blank zein nanoparticles. Weight variation, relative organs weight, and thickness of target organs were analyzed. Subepithelial inflammation frequency (%) was determined. ANOVA/Tukey test and chi-square/Fisher’s exact tests were used (p < 0.05). Groups AaZNp (-4.2 ± 1.49 g) and BZNp (-4.00 ± 1.30 g) showed the highest weight loss; although without significant difference in kidneys, lungs, liver, and spleen weights. Groups AaZNp (0.16 ± 0.01 g) and BZNp (0.16 ± 0.02 g) presented lower cardiac mass than the negative (0.21 ± 0.01 g) and standard (0.22 ± 0.02 g) (p = 0.045) groups. Ventral tongue epithelium thickness of the negative control (3250 ± 439 µm) was significantly lower than BZNp treated (8650 ± 1079 µm) (p = 0.001); Jugal epithelial thickness was lower in AaZNp and BZNp than Standard Group (p < 0.001), while the thickness of gingival epithelium was lower in the negative control (134 ± 13 µm) than the other groups (p = 0.001). There were no significant signs of inflammatory infiltrate. The administration of AaZNp and BZNp caused a reduction in the cardiac mass without showing other signs of oral mucosal or systemic toxicity.