Antiparasitic compounds from Cornus florida L. with activities against Plasmodium falciparum and Leishmania tarentolae

Aim of the study: The objective of this study was to identify the antiplasmodial constituents from the bark of Cornus florida L., a plant traditionally used in North America for the treatment of malaria. Methods and materials: Dried and powdered bark was extracted with 95% ethanol. The resultant extract was subjected to in vitro antiplasmodial-guided fractionation against Plasmodium falciparum (D10 strain). Antiplasmodial IC ₅₀ values were calculated for pure compounds. Compounds were also assayed against Leishmania tarentolae, and rat skeletal myoblast L6 cells to assess antileishmanial activity and cytotoxicity, respectively. Results: Antiplasmodial-guided fractionation afforded 8 compounds: betulinic acid (1), ursolic acid (2), β-sitosterol (3), ergosta-4,6,8,22-tetraene-3-one (4), 3β-O-acetyl betulinic acid (5), 3-epideoxyflindissol (6), 3β-O-cis-coumaroyl betulinic acid (7), 3β-O-trans-coumaroyl betulinic acid (8), of which, (6) is for the first time here isolated from a natural product and (4), (7) and (8) are reported for the first time from this genus. In vitro IC ₅₀ values against P. falciparum for (4) (61.0 μM) (6) (128.0 μM), (7) (10.4 μM), (8) (15.3 μM) are reported for the first time. Antileishmanial IC ₅₀ values are reported here for the first time for (4) (11.5 μM), (6) (1.8 μM), (7) (8.3 μM) and (8) (2.2 μM). Cytotoxicity against L6 cells is reported for all compounds. Conclusions: The compounds isolated in this study, while displaying moderate in vitro antiplasmodial activity, do not fully support the historical importance of C. florida as an antimalarial remedy in North America. The traditional remedy may exert its well documented effects by mechanisms unrelated to direct antiplasmodial action. While not traditionally used to treat Leishmania, this work shows that several constituents of C. florida possess promising in vitro antileishmanial activity.