Multifaceted antimalarial effects of curcumin: Targeting PfGSK3, cytokine modulation, and histological improvements.

Curcumin, a polyphenolic compound exhibits various bioactivities, including antimalarial and anti-inflammatory effects. This study investigated the long-term antimalarial effects of curcumin through in vivo experiments using Plasmodium berghei NK65-infected mice, complemented by in vitro and in silico analyses targeting the plasmodial GSK3 protein. Through in vitro, the antimalarial activity of curcumin was assessed on P. falciparum K1 (multi-drug resistant strain) and 3D7 (sensitive strain) as well as P. knowlesi A1H1 of Plasmodium lactate dehydrogenase (pLDH) assay, alongside cytotoxic effects on Vero cells using the MTT assay. Curcumin demonstrated its bioactivity to disrupt the parasite's growth and replication based on the effective inhibition on both P. falciparum (3D7 EC50=8.11 µM; K1 EC50=31.21 µM) and P. knowlesi (EC50=4.51 µM). Molecular docking studies explored curcumin's interaction with the ATP-binding pocket of P. falciparum glycogen synthase kinase-3 (PfGSK3) with favourable binding affinity (-8.72 kcal/mol), revealing it potential as a selective inhibitor. Further, in vivo experiments validated curcumin's immunomodulatory activities and therapeutic effects in P. berghei-infected mice. Prolonged curcumin treatment has shown to significantly reduce the parasitaemia compared to the controls. Cytokine profiling via ELISA showed enhanced levels of anti-inflammatory cytokines (IL-10, IL-4) and decreased pro-inflammatory markers (TNF-α, IFN-γ), mitigating systemic inflammation associated with malaria. Histopathological analysis revealed reduction of tissue damage in the curcumin-treated mice, including decreasing parasite sequestration, inflammatory cell infiltration, hepatocyte necrosis and hemorrhages. This study highlights curcumin's potentials in inhibiting PfGSK3, regulating immune responses, and attenuating tissue damage which support its therapeutic role against malarial infection.