In Vitro Anti-Leishmanial Activity of Essential Oils Extracted from Vietnamese Plants

Leishmania mexicana is one of the pathogens causing cutaneous leishmaniasis which is associated with patient morbidity. In our researches for new safe and effective treatments, thirty-seven essential oils (EOs) extracted from Vietnamese plants were screened in vitro for the first time on Leishmania mexicana mexicana(Lmm) promastigotes at the maximum concentration of 50 nL/mL. Active EOs were also analyzed for cytotoxicity on mammalian cell lines (WI38, J774) and their selectivity indices (SI) were calculated. Their composition was determined by GC-MS and GC-FID. Our results indicated that EOs extracted from Cinnamomum cassia, Zingiber zerumbet, Elsholtzia ciliata and Amomum aromaticum, possessed a moderate anti-leishmanial activity, with IC₅₀ values of 2.92 ± 0.08, 3.34 ± 0.34, 8.49 ± 0.32 and 9.25 ± 0.64 nL/mL respectively. However, they also showed cytotoxicity with SI < 10. The most promising EO was extracted from Ocimum gratissimum, displaying an IC₅₀ of 4.85 ± 1.65 nL/mL and SI > 10. It contained 86.5% eugenol, which was demonstrated to be effective on Lmm with IC₅₀ of 2.57 ± 0.57 nL/mL and not toxic on mammalian cells, explaining the observed activity.