Essential oils from Smyrnium olusatrum L. (Apiaceae) as a potential source of trypanocidal compounds

Plant-borne sesquiterpenes are considered as promising natural inhibitors against bloodstream forms of Trypanosoma brucei, the protozoan parasite causing the human African trypanosomiasis (HAT). Smyrnium olusatrum L. (Apiaceae), also known as Alexanders or wild celery, is an overlooked vegetable characterized by oxygenated sesquiterpenes1. Among them, isofuranodiene, germacrone and β-acetoxyfuranoeudesm-4(15)-ene are the most abundant in the plant essential oil. In the present work, we investigated the antitrypanosomal activity of S. olusatrum essential oils obtained from different parts and the isolated sesquiterpenes, namely isofuranodiene, germacrone and β-acetoxyfuranoeudesm-4(15)-ene. The quali-quantitative composition of essential oils was investigated by gas chromatography coupled to mass-spectrometry (GC-MS). All essential oils reduced the growth of T. brucei with IC50 values of 1.9-4.0 g/ml. Among the isolated compounds, isofuranodiene showed a significant and selective inhibitory effect against T. brucei (IC50 of 0.6 g/ml, SI = 30), with β-acetoxyfuranoeudesm-4(15)-ene giving a moderate synergistic effect2. These results, albeit preliminary, shed light on the potential application of isofuranodiene as antitrypanosomal drug to be used for prophylactic and curative purposes against HAT.