Purpose: To investigate the in vivo antimalarial effect of Eryngium thorifolium, an endemic plant in Turkey.

Methods: The methanol and water extracts were prepared and phytochemical analysis conducted on the extracts. Twenty four healthy Balb/c male mice, divided into 4 groups (n = 6), were infected intravenously with Plasmodium berghei and 100 - 250 mg/kg plant extracts administered orally in a single dose per day for 5 days. The untreated group of mice received normal saline solution and chloroquine (standard drug) served as reference drug.

Results: The water extract group (250 mg/kg) prolonged the survival of the mice by 6 days compared with the untreated mice while the mice that received choloroquine treatment remained alive at the end of the study of the mice. In the untreated control group, maximum parasitaemia was observed on the 10th day of infection whereas The water extract exhibited some degree of antiplasmodial activity compared to untreated control group. The mice of chloroquine treated group remained alive at the end of the study with 100 % chemosuppression (p < 0.05). In the untreated control group, maximum parasitaemia was observed on the 10th day of infection whereas in the water extract group maximum parasitaemia was attained on the 16th day of infection. The water extract of the plant showed 45.85 % chemosuppression. Phytochemical screening of the water and methanol extracts revealed the presence of flavonoids, terpenoids and tannins. Anthraquinones were positive for water extract.

Conclusions: The possible active compounds responsible for the observed chemosupression may be flavonoids, terpeneoids and anthraquinones which are present in the extract. This is the first report on the in vivo antimalarial activity of E. thorifolium.