Ocimum tenuiflorum L. and Ocimum basilicum L., two spices of Lamiaceae family with bioactive essential oils

The present study provides new insights to the antifungal mechanism of action of the essential oils of Ocimum tenuiflorum L. and Ocimum basilicum L., namely inhibition of germ tube formation, inhibition of biofilm formation and preformed biofilm disruption. The essential oils were characterized by GC and GC–MS. The major compounds were methyl eugenol (84.7%) and β-caryophyllene (7.4%) for O. tenuiflorum and linalool (35.1%), eugenol (20.7%) and 1,8-cineole (9.9%) for O. basilicum. The essential oil from O. tenuiflorum showed a more preeminent effect against C. neoformans (0.16 μL/mL) and dermatophytes (0.32 μL/mL). The effect on the germ tube formation of both essential oils was described here for the first time showing that O. tenuiflorum decreases germ tube formation by more than 50% at values four times lower than MIC (Minimal Inhibitory Concentration) while O. basilicum is able to decrease at values eight times lower than MIC. Furthermore, O. basilicum showed a more preeminent effect both in inhibition of C. albicans biofilm formation as well as in disruption of preformed biofilm. The activity of all major compounds was also determined, and their activity was in general similar to that of the essential oils thus suggesting that those are the main active compounds. Overall, this study highlights the antifungal activity of two widely used spices and complies with the antifungal uses described in folk medicine. In addition, it shows that both essential oils are able to inhibit virulence factors of C. albicans associated with resistance to treatment and relapse cases. Both species are of industrial interest as shown by their use on food and cosmetic industries which was reinforced by the results presented herein.