Antiplasmodial and cytotoxic activities of secondary metabolites from the leaves of <i>Pleiocarpa bicarpellata</i> Stapf (Apocynaceae)

Abstract

Phytochemical studies of the leaves of <i>Pleiocarpa bicarpellata</i> led to the isolation of a new indole C-glycoside, Bicarpellatoside A (<b>1</b>), along with eight known compounds (<b>2-9</b>), including three indoles, two indolines, an iridoid monoterpenoid, a triterpenoid, and a phenolic acid. The structures of all isolated compounds were elucidated using NMR, MS, and IR spectroscopic data, in comparison with the literature. Compounds <b>1</b>, <b>3</b>, and <b>9</b> are reported in this genus for the first time. <i>In vitro</i> antiplasmodial activity tests were conducted against both chloroquine-sensitive (3D7) and chloroquine-resistant (Dd2) strains of <i>Plasmodium falciparum</i>, using the crude extract and isolated compounds <b>1-4</b>. The crude extract exhibited promising activity, with IC₅₀ values of 4.07 ± 0.78 μg/mL (Dd2) and 4.32 ± 0.42 μg/mL (3D7). Bicarpellatoside A (<b>1</b>) showed good activity, with IC₅₀ values of 2.24 ± 0.05 µM and 2.74 ± 0.05 µM against Dd2 and 3D7 strains of <i>P. falciparum</i>, respectively. Compound <b>4</b> showed moderate activity (IC₅₀ of 40.93 ± 3.39 µM and 48.13 ± 5.63 µM on Dd2 and 3D7 strains of <i>P. falciparum</i>, respectively, with a high selectivity index of 34.48, indicating potential for further development. Overall, these findings highlight and confirm the antiplasmodial potential of compounds from <i>P. bicarpellata</i>.