Plasmodium berghei: Antiparasitic effects of orally administered Hypoestoxide in mice

Hypoestoxide (HE) is a diterpene isolated from Hypoestes rosea (Acanthaceae), a plant indigenous to Nigeria. Previous studies demonstrated that HE exhibited potent anti-inflammatory and anti-cancer activities in well established animal models but weak in vitro activities in both the anti-inflammation and anti-cancer in vitro screening systems. We now report a similar observation in the in vitro and in vivo screening systems for antimalarial activity. The results indicate that while HE exhibits a relatively weak in vitro activity (IC50 = 10 μM versus 0.11 μM for chloroquine) against different strains of cultured P. falciparum parasites, the dose of HE required to reduce parasitemia by 90% in Plasmodium berghei-infected mice, is much lower than standard antimalaria drugs (SD90 = 250 μg/kg versus 5 mg/kg for chloroquine). Furthermore, lower doses of HE were much more effective than higher doses in inhibiting parasite development. The implications of these findings are discussed.