An overlooked horticultural crop, Smyrnium olusatrum, as a potential source of compounds effective against African trypanosomiasis

Among natural products, sesquiterpenes have showed promising inhibitory effects against bloodstream forms of Trypanosoma brucei, the protozoan parasite causing the human African trypanosomiasis (HAT). Smyrnium olusatrum (Apiaceae), also known as Alexanders or wild celery, is a neglected horticultural crop characterized by oxygenated sesquiterpenes containing a furan ring. In the present work we explored the potential of its essential oils obtained from different organs and the main oxygenated sesquiterpenes, namely isofuranodiene, germacrone and β-acetoxyfuranoeudesm-4(15)-ene, as inhibitors of Trypanosoma brucei. All essential oils effectively inhibited the growth of parasite showing IC50 values of 1.9-4.0 g/mL. Among the main essential oil constituents, isofuranodiene exhibited a significant and selective inhibitory activity against T. brucei (IC50 of 0.6 g/mL, SI = 30), with β-acetoxyfuranoeudesm-4(15)-ene giving a moderate potentiating effect. These results, albeit preliminary, shed light into the possible application of isofuranodiene as anti-protozoal agent to be included in combination treatments aimed not only at curing patients but also at preventing the diffusion of this HAT.