Dose-Dependent Cytotoxicity of Calendula officinalis Oil on Human Nasal Epithelial Cells.

[OBJECTIVES] The effects of Calendula officinalis oil on human nasal epithelial cells were investigated in this study.

[METHODS] The authors obtained nasal epithelial specimens from clinically healthy tissue, as is standard practice in septorhinoplasty. After immersion in a sterile solution containing 2% antibiotic-antimycotic, the tissues were washed 3 times before being transferred to sterile tubes. After each wash, samples were centrifuged at 4 °C for 5 minutes at 300g. The nonadherent epithelial cell fraction was collected and seeded onto new culture plates. The plates contained DMEM/F-12 supplemented with fetal bovine serum, epidermal growth factor, insulin-transferrin-selenium, nonessential amino acids, and L-glutamine. After ∼7 days at 37 °C in a humidified atmosphere with 5% CO2, the cultures reached confluence. The day after seeding, cells were incubated continuously for 24 hours with C. officinalis oil (TABIMER) at doses of 1, 5, 15, 25, 50, 75, and 150 µL. Cell metabolic activity was measured using the MTT colorimetric assay.

[RESULTS] Analyzing the dose-response curve for C. officinalis oil showed that cell viability was strongly inversely related to oil concentration. The logIC50 value was 2.085, and the computed IC50 value was 121.7 µL. Regression analysis indicated the strong reliability of the dose-response relationship, showing that the nonlinear model fit the experimental data well (R3=0.9771). Compared with the negative control, quantitative analysis showed a dose-dependent decrease in cell viability. Statistical comparisons among the treatment groups showed that the negative control, lower-dose groups, and groups treated with higher concentrations of C. officinalis oil all had significantly decreased cell viability. Taken together, these results show that the cytotoxic effects of C. officinalis oil are dose-dependent, with effects becoming more pronounced at higher concentrations.

[CONCLUSION] Viability and proliferation of nasal epithelial cells are reduced in a dose-dependent manner by direct exposure to C. officinalis oil. Given its antibacterial and anti-inflammatory properties and its ability to reduce cell proliferation, it may be used topically on hyperkeratotic areas that develop during skin healing or on infected areas; this is particularly true in rhinoplasty patients. Animal experiments should be conducted initially on this matter.