Inhibitory effect of Ferula asafoetida L. (Umbelliferae) on Blastocystis sp. subtype 3 growth in vitro

Asafoetida is an oleo-gum-resin obtained from many Ferula species and frequently used in traditional medicine. The current study aimed to evaluate the activity of asafoetida against the in vitro growth of Blastocystis sp. Asafoetida as powder-form (Ap) and oil-form (Ao) extracts at concentrations of 2, 4, 8, 16, and 20 mg/ml and 5, 10, 25, 40, and 50 mg/ml, respectively were incubated with isolates of Blastocystis sp. subtype 3 for 24, 72, and 144 h and compared to the reference antiprotozoan drug metronidazole at concentrations of 10, 100, and 500 μg/ml. Asafoetida either as Ap or Ao decreased counts and viability of all tested isolates of Blastocystis sp. subtype 3 which was confirmed by microscopy. The degree of the inhibitory effect was dependent on the concentration, form, as well as the time of incubation with asafoetida extracts. The lowest concentrations of Ap and Ao that caused complete (100 %) inhibition of Blastocystis growth and highest (100 %) percentage inhibition of multiplication was 16 and 40 mg/ml, respectively; mean counts at these concentrations either did not differ or decreased significantly when compared to metronidazole control (p < 0.05). Also, the parasites did not resume growth after re-cultivation in asafoetida-free medium when examined further after 48, 72, and 144 h of cultivation. These findings demonstrate the potential of phytomedicine asafoetida as a potent natural alternative for treatment of Blastocystis sp.infection.