The aim of this study was to evaluate the antifungal activity of essential oils (EOs) of Citrus sinensis (C. sinensis) and Citrus latifolia (C. latifolia) against five Candida species: Candida albicans, Candida tropicalis, Candida glabrata, Candida lusitaniae and Candida guilliermondii; and perform its genotoxic evaluation. The EOs of C. sinensis and C. latifolia were obtained from the peel by hydro-distillation. The major components determined by GC-MS were in C. sinensis, d-limonene (96%) and α-myrcene (2.79%); and in C. latifolia, d-limonene (51.64%), β-thujene (14.85%), β-pinene (12.79%) and γ-terpinene (12.8%). Antifungal properties were studied by agar diffusion method, where C. sinensis presented low activity and C. latifolia essential oil was effective to inhibit growing of C. lusitaniae and C. guilliermondii with IC50 of 6.90 and 2.92 μg respectively. The minimum inhibitory concentrations (MIC) for C. sinensis were in a range of 0.42–3.71 μg and for C. latifolia of 0.22–1.30 μg. Genotoxic evaluation was done by Ames test where none of the oils induced point mutations. Flow cytometry was used to measure toxicity in human oral epithelial cells, C. sinensis was not cytotoxic and C. latifolia was toxic at 21.8 μg. These properties might bestow different odontological applications to each essential oil.

The essential oils of Citrus sinensis and Citrus latifolia showed antimycotic activity against Candida spp. isolated from the oral cavity; they are neither mutagenic on the Ames test nor cytotoxic. Their main components are R-(+)-limonene, β-thujene, α-myrcene and γ-terpinene. The aim of this work was to evaluate their antimutagenic and antioxidant capacities. Antimutagenic properties were evaluated against MNNG and ENNG on S. typhimurium TA100; against 2AA on strain TA98 and in front of 4NQO and NOR on strain TA102. Both were antimutagenic against MNNG (p < 0.001) but only C. latifolia was antimutagenic against ENNG (p < 0.001). Both presented antimutagenic activity against 2AA (p < 0.001). They were antioxidant against the ROS-generating compound 4NQO (p < 0.001) and the antibiotic NOR (p < 0.001). In the antioxidant evaluation, the activity in DPPH assay was in a range of 6–23% for C. sinensis and of 22–71% for C. latifolia. Both were antioxidant compared with BHT in β-carotene bleaching assay and were able to decreased apoptosis in HaCat cells stimulated with H2O2. The levels of intracellular superoxide ion were lower in the presence of both oils. In conclusion, the essential oils of C. sinensis and C. latifolia are antimutagenic against at least three types of mutagens and have antioxidants properties.

Within the context of the COVID-19 pandemic, there is currently an epidemiological alert in health care services due to outbreaks of Candida auris , Candida glabrata , and other fungal species multiresistant to conventional antifungals. Therefore, it is important to propose alternative molecular targets, as well as new antifungals.