In vitro, ex vivo, and in silico studies of phytochemicals from the stem bark of Bischofia javanica.

The stem bark extract of Bischofia javanica, used in traditional Kenyan medicine afforded nine compounds named, santin (1), ermanin (2), rhamnocitrin (3), kumatakenin (4), abyssinone V-4'-methyl ether (5), β-sitosterol (6), betulinic acid (7), friedelin (8) and 1-methyl-1,10-phenanthrolin-1-ium (9). Structural elucidation was performed based on spectroscopic and spectrometric analyses, and the data were compared with those reported in the literature. The natural origin of 1-methyl-1,10-phenanthrolin-1-ium (9) in the plant kingdom is reported here for the first time. Ermanin (2) showed selective in vitro antiplasmodial activity with IC50 = 0.05 μM, while 1-methyl-1,10-phenanthrolinium (9) exhibited potent antiplasmodial activity with IC50 values of 1.56 μM (in vitro), and 1.20 μM (ex vivo). Furthermore, molecular docking studies revealed that 1-methyl-1,10-phenanthrolinium (9) could be considered a potential lead compound for future antimalarial drugs.