Antifungal and Cytocompatible Properties of Juglans regia Extract for Dental Applications: A Novel Approach Against Oral Candida Infections

Oral Candida infections result from the overgrowth of this opportunistic fungus in the oral mucosa. Risk factors include immunosuppression, antibiotic or corticosteroid use, xerostomia, and conditions such as diabetes mellitus. Fungal resistance in Candida spp. has become a significant challenge, especially due to the excessive use of conventional antifungals such as azoles, echinocandins, and polyenes. Therefore, this study aims to determine the spectrum of antifungal activity of Juglans regia and assess its cytotoxicity on hepatocytes. Thus, a broth microdilution test was conducted according to the CLSI (M27-A3) guidelines. After initial screening, biofilm tests were conducted using the crystal violet (CV) and metabolic activity assays (MTT). Cytotoxicity was evaluated on human hepatocytes (HEPG2). The J. regia extract showed dose-dependent antifungal activity. At a concentration of 200 mg/mL, inhibition was greater according to the CV test in Candida albicans (31%) and Candida tropicalis (30.4%), while the MTT assay indicated a greater reduction in viability in C. albicans (61%) and C. glabrata (53.5%). At 100 mg/mL, C. albicans remained sensitive (37.7% CV; 71.6% MTT), while C. krusei and C. dubliniensis showed low viability by MTT (18.4% and 11.8%, respectively). At 50 mg/mL, C. albicans remained affected (74.3% MTT), but C. krusei, C. dubliniensis, and C. guilliermondii showed the lowest viability values (≤19.4% MTT), suggesting greater sensitivity to lower concentrations. These results indicate variation in susceptibility between species, with C. albicans being consistently inhibited, while C. krusei and C. dubliniensis responded better to lower doses. The extract showed cytocompatibility when applied to human hepatoma cells (HEPG2) and therefore holds significant potential for developing a new therapeutic approach.