LDT-623

LDT-623 is a novel, side-chain-modified 4-aminoquinoline (4-AQ) small molecule compound developed as a multistage antimalarial agent. Identified through a QSAR-based virtual screening strategy as a structural analog of LDT-611, LDT-623 exhibits potent in vitro activity against both chloroquine-sensitive (3D7) and multidrug-resistant (Dd2) strains of *Plasmodium falciparum* asexual blood stages. Unlike traditional 4-aminoquinolines such as chloroquine and piperaquine, LDT-623 displays unusual dual-stage activity, inhibiting multiple stages of the *Plasmodium* life cycle, including asexual blood stages, liver schizonts, stage IV-V gametocytes, and ookinetes. Its mechanism of action involves the inhibition of hemozoin (β-hematin) formation within the parasite's digestive vacuole and interaction with PfCRT-mediated transport. It demonstrates a high barrier to resistance and minimal cross-resistance with existing mutant *pfcrt* or *pfmdr1* lines.