Cryptolepis sanguinolenta extracts are currently used by African herbalists to cure malaria but the compounds involved in its antimalarial activity have not been identified. Two alkaloids, cryptolepine and isocryptolepine, have been isolated from the roots of C. sanguinolenta and their antimalarial activity evaluated. Both alkaloids possess intrinsic inhibitory activity against the human malaria parasite, Plasmodium falciparum in vitro, whatever the chloroquine‐resistance status of the strains used. Cryptolepine was slightly more efficient for parasite killing with an IC50 in the range of 0.2 to 0.6 μMSC compared with an IC50 of about 0.8 μMSC for isocryptolepine. The antimalarial activity of cryptolepine was confirmed in vivo on the rodent malarial parasites Plasmodium vinckei petteri and Plasmodium berghei ANKA.

Cryptolepis sanguinolenta extracts are currently used by African herbalists to cure malaria but the compounds involved in its antimalarial activity have not been identified. Two alkaloids, cryptolepine and isocryptolepine, have been isolated from the roots of C. sunguinolenta and their antimalarial activity evaluated. Both alkaloids possess intrinsic inhibitory activity against the human malaria parasite, Plasmodium fakiparum in vitro, whatever the chloroquine-resistance status of the strains used. Cryptolepine was slightly more efficient for parasite killing with an ICs in the range of 0.2 to 0.6 p~ compared with an ICso of about 0.8 PM for isocryptolepine. The antimalarial activity of cryptolepine was confirmed in vivo on the rodent malarial parasites Plasmodium vinckei petleri and Plasmodium berghei ANKA.

The bisbenzylisoquinolines 7-O-demethyltetrandrine and limacine, respectively, isolated from Strychnopsis thouarsii Baill. and Spirospermum penduliflorum Thou. were evaluated for their intrinsic antimalarial activity in vitro and chloroquine potentiating action against the chloroquine-resistant Plasmodium falciparum FCM 29 originating from Cameroon. They both showed significant antiplasmodial potency in vitro with very similar IC50 values of respectively, 740 nM and 789 nM (IC50 = 214 nM for chloroquine used as standard drug), which demonstrated that the stereochemistry of the C-1 and C-1' configuration likely plays a role in the chloroquine potentiating effect of these drugs. If confirmed in vivo, these results may account for the traditional use of the two plants as antimalarials and adjuvant to chloroquine in Madagascan folklore remedies.

No abstract