Synthesis and Evaluation of N-(3-Trifluoroacetyl-indol-7-yl) Acetamides for Potential In Vitro Antiplasmodial Properties

New structural classes of antimalarials

Malaria remains a major vector borne disease claiming millions of lives worldwide due to infections caused by Plasmodium sp. Discovery and development of antimalarial drugs have previously been dominated majorly by single drug therapy. The malaria parasite has developed resistance against first line and second line antimalarial drugs used in the single drug therapy. This has drawn attention to find ways to alleviate the disease burden supplanted by combination therapy with multiple drugs to overcome drug resistance. Emergence of resistant strains even against the combination therapy has now mandated the revision of the current antimalarial pharmacotherapy. Research efforts of the past decade led to the discovery and identification of several new structural classes of antimalarial agents with improved biological attributes over the older ones. The following is a comprehensive review, addressed to the new structural classes of heterocyclic and natural compounds that have been identified during the last decade as antimalarial agents. Some of the classes included herein contain one or more pharmacophores amalgamated into a single bioactive scaffold as antimalarial agents, which act upon the conventional and novel targets.

Crystal structure of 1-(5-bromo-2-(4-methoxyphenyl)-1H-indol-7-yl)ethanone oxime, C17H15BrN2O2

C17H15BrN2O2, monoclinic, P21/c, a = 14.4197(9) Å, b = 7.5423(5) Å, c = 14.9602(9) Å, β = 114.665(2)°, V = 1478.59(16) Å3, Z = 4, R gt(F) = 0.0196, wR ref(F 2) = 0.0526, T = 173(2) K.

Synthesis, Evaluation of Cytotoxicity and Molecular Docking Studies of the 7-Acetamido Substituted 2-Aryl-5-bromo-3-trifluoroacetylindoles as Potential Inhibitors of Tubulin Polymerization

The 3-trifluoroacetyl⁻substituted 7-acetamido-2-aryl-5-bromoindoles 5a⁻h were prepared and evaluated for potential antigrowth effect in vitro against human lung cancer (A549) and cervical cancer (HeLa) cells and for the potential to inhibit tubulin polymerization. The corresponding intermediates, namely, the 3-unsubstituted 7-acetyl-2-aryl-5-bromoindole 2a⁻d and 7-acetamido-2-aryl-5-bromoindole 4a⁻d were included in the assays in order to correlate both structural variations and cytotoxicity. No cytotoxicity was observed for compounds 2a⁻d and their 3-trifluoroacetyl⁻substituted derivatives 5a⁻d against both cell lines. The 7-acetamido derivatives 4⁻d exhibited modest cytotoxicity against both cell lines. All of the 3-trifluoroacetyl⁻substituted 7-acetamido-2-aryl-5-bromoindoles 5e⁻h were found to be more active against both cell lines when compared to the chemotherapeutic drug, Melphalan. The most active compound, 5g, induced programmed cell death (apoptosis) in a caspase-dependent manner for both A549 and HeLa cells. Compounds 5e⁻h were found to significantly inhibit tubulin polymerization against indole-3-carbinol and colchicine as reference standards. Molecular docking of 5g into the colchicine-binding site suggests that the compounds bind to tubulin by different type of interactions including pi-alkyl, amide-pi stacked and alkyl interactions as well as hydrogen bonding with the protein residues to elicit anticancer activity.