Malaria is a life-threatening disease caused by different species of the protozoan parasitePlasmodium, withP. falciparumbeing the deadliest. Increasing parasitic resistance to existing antimalarials makes the necessity of novel avenues to treat this disease an urgent priority. The enzymes responsible for the synthesis of phosphatidylcholine and phosphatidylethanolamine are attractive drug targets to treat malaria as their selective inhibition leads to an arrest of the parasite’s growth and cures malaria in a mouse model. We present here a detailed study that reveals a mode of action for twoP. falciparumcholine kinase inhibitors bothin vitroandin vivo. The compounds present distinct binding modes to the choline/ethanolamine-binding site ofP. falciparumcholine kinase, reflecting different types of inhibition. Strikingly, these compounds primarily inhibit the ethanolamine kinase activity of theP. falciparumcholine kinase, leading to a severe decrease in the phosphatidylethanolamine levels withinP. falciparum,which explains the resulting growth phenotype and the parasites death. These studies provide an understanding of the mode of action, and act as a springboard for continued antimalarial development efforts selectively targetingP. falciparumcholine kinase.

Hyaluronic acid (HA) plays a crucial role in tumor growth and invasion through its interaction with cluster of differentiation 44 (CD44), a non-kinase transmembrane glycoprotein, among other hyaladherins. CD44 expression is elevated in many solid tumors, and its interaction with HA is associated with cancer and angiogenesis. Despite efforts to inhibit HA-CD44 interaction, there has been limited progress in the development of small molecule inhibitors. As a contribution to this endeavour, we designed and synthesized a series of N-aryltetrahydroisoquinoline derivatives based on existing crystallographic data available for CD44 and HA. Hit 2e was identified within these structures for its antiproliferative effect against two CD44⁺ cancer cell lines, and two new analogs (5 and 6) were then synthesized and evaluated as CD44-HA inhibitors by applying computational and cell-based CD44 binding studies. Compound 2-(3,4,5-trimethoxybenzyl)-1,2,3,4-tetrahydroisoquinolin-5-ol (5) has an EC₅₀ value of 0.59 μM against MDA-MB-231 cells and is effective to disrupt the integrity of cancer spheroids and reduce the viability of MDA-MB-231 cells in a dose-dependent manner. These results suggest lead 5 as a promising candidate for further investigation in cancer treatment.

Hyaluronic acid (HA), through its interactions with the cluster of differentiation 44 (CD44), acts as a potent modulator of the tumor microenvironment, creating a wide range of extracellular stimuli for tumor growth, angiogenesis, invasion, and metastasis. An innovative antitumor treatment strategy based on the development of a nanodevice for selective release of an inhibitor of the HA-CD44 interaction is presented. Computational analysis was performed to evaluate the interaction of the designed tetrahydroisoquinoline-ketone derivative (JE22) with CD44 binding site. Cell viability, efficiency, and selectivity of drug release under acidic conditions together with CD44 binding capacity, effect on cell migration, and apoptotic activity were successfully evaluated. Remarkably, the conjugation of this CD44 inhibitor to the nanodevice generated a reduction of the dosis required to achieve a significant therapeutic effect.

A series of 11 new substituted 1,5-dihydro-4,1-benzoxazepine derivatives was synthesised to study the influence of the methyl group in the 1-(benzenesulphonyl) moiety, the replacement of the purine by the benzotriazole bioisosteric analogue, and the introduction of a bulky substituent at position 6 of the purine, on the biological effects. Their inhibition against isolated HER2 was studied and the structure–activity relationships have been confirmed by molecular modelling studies. The most potent compound against isolated HER2 is 9a with an IC₅₀ of 7.31 µM. We have investigated the effects of the target compounds on cell proliferation. The most active compound (7c) against all the tumour cell lines studied (IC₅₀ 0.42–0.86 µM) does not produce any modification in the expression of pro-caspase 3, but increases the caspase 1 expression, and promotes pyroptosis. Graphical Abstract