Tandem Mass Spectrometry and Bio‐Guided Isolation of Secondary Metabolites With Antiplasmodial Activity From Dalbergia miscolobium Bark

Strategies have been employed to address antimalarial drug resistance, including the exploration of new therapeutic targets. In this study, the stem bark of Dalbergia miscolobium was investigated using in vitro assays against Plasmodium falciparum and pyruvate kinase II (PyrKII), an essential enzyme for parasite development. Compounds were dereplicated from ethanolic extract (IC 50 3D7 = 9 µg/mL) using LC‐HRMS, revealing active constituents: procyanidin A1 ( 2 ), biochanin ( 5 ) and formononetin ( 7 ). Bio‐guided fractionation of the ethyl acetate active fraction (IC 50 3D7 = 8.4 µg/mL) led to the isolation of compounds with antiplasmodial potential, identified by 1D/2D NMR as procyanidin A1 ( 2 ) (IC 50 3D7 = 42 µM), epicatechin ( 9 ) (IC 50 3D7 > 50 µM), lupenone ( 10 ) (IC 50 3D7 = 27 µM) and lupeol ( 11 ) (IC 50 3D7 = 33 µM). In addition, procyanidin A1 exhibited 90% inhibition of PyrKII catalytic activity at 200 µg/mL. These findings pave the way for the discovery of novel antiplasmodial inhibitors from D. miscolobium .