Design, synthesis and biological evaluation of several aromatic substituted chalcones as antimalarial agents

Malaria is a communicable disease which is caused by protozoan's mainly Plasmodium species (P. falciparum, P. ovale, P. vivax, P. malariae and P. knowlesi). The increasing resistance of Plasmodium to available malarial drugs poses a great responsibility for the researchers in the field of malaria. To overcome this problem of resistance, this study aimed to design and synthesize a new class of antimalarial agent with chalcone as the main moiety. Chalcones, a member of flavanoid family, consist of two aromatic rings of 1,3-diphenyl-2-propen-1-one linked by a three carbon α,β-unsaturated carbonyl system. Five derivatives were designed and among them one was selected. The CC2 was then synthesized by esterification of Para amino acetophenone followed by treatment with hydrazide to form 2-(4 acetylphenoxy)acetohydrazide. This was then coupled with 2-Bromo substituted Diazotized esterified anilines, which was finally linked with substituted benzaldehyde to yield CC2. These were then structurally verified by Infra Red (IR) and Nuclear Magnetic Resonance (NMR) spectroscopy. The chalcone was then tested for in vitro growth inhibition assays using SYBR GREEN-1 Based assay and IC₅₀ values were identified. The compound CC2 showed quite promising antimalarial activity by inhibiting cysteine protease enzyme. The acute toxicity studies of the compound were carried out as per OECD guideline 425 and the results showed no toxic signs and symptoms indicating CC2 as a safe and less toxic compound.