Structural perspective into thiazoles and other azole derivatives as anthelmintic agents

Helminths or worm-like parasites are common infectious pathogens that cause significant diseases and mortality in animals and humans. To be noted, nematodes or soil-transmitted helminths (STH) have been infected about 1.5 billion people according to the recent reports of world health organization (WHO). Helminths-based infections are a significant type of neglected tropical diseases (NTDs) that show higher occurrence in deprived regions of tropical and subtropical areas. Low-level sanitation and limited facilities increase the risk of affliction with these infectious diseases. Helminths infections are known to be associated with non-significant symptoms to heavier ones such as gastrointestinal (GI) manifestations, weakness, impaired growth, disturbed physical development and death on the basis of involved worm population. Despite the implementations of preventive and mass-treatment strategies, incomplete curative effects and drug-resistance potentiality inspires the discovery of new and potent anthelmintic agents. In this context, several efforts have been focused on the synthesis and biological evaluation of various heterocycles, and in particular azoles, as anthelmintic agents. Structural elucidations of the emerged anti-infective agents from the medicinal chemistry perspective is a rational way to tackle the burden of infections throughout development of new anthelmintic medications. In continuation to our previous contributions, privileged azole-based anthelmintic compounds that have been documented in the 2012-2023 period and their structure activity relationship (SAR), are going to be reviewed in this study.

Design, facile synthesis and anthelmintic activity of new O-substituted 6-methoxybenzothiazole-2-carbamates. Part II

In the framework of pursuing the design and synthesis of a new series of substituted 6-methoxybenzothiazole-2-carbamates as potential anthelmintics, and as a continuation of the expended efforts in part I, we have set out to develop novel compounds with enhanced anthelmintic activity by blocking the 6-position of benzothiazole with side chains of different polarities. Guided by the findings in part I, and reporting the paramphistomicidal activity of oxadiazoline derivatives V and VI, we aimed to synthesize target benzothiazoles designed to comprise some planar heterocyclic ring systems, namely, 1,3,4-oxadiazoles and 1,2,4-triazoles, bearing a variety of hydrophobic and hydrophilic components. The synthesis of the desired compounds was primarily achieved by cyclization of 6-acetohydrazide, 1. The in vitro paramphistomicidal activity of all synthesized carbamates was evaluated. Four synthesized carbamates exhibited notable activity. Compound 24, methyl 6-[(5-(4-bromophenacylsulfanyl)-[1,3,4]-oxadiazol-2-yl)methoxy]benzothiazole-2-carbamate, displayed an equipotent effect to the reference drug oxyclozanide at a concentration of 80 μg mL^-1; compounds 9, 10 and 23 showed high orders of anthelmintic effect. A structural computational study on the polar nature and hydrophilic-lipophilic properties of the synthesized carbamates was undertaken to discuss their structure-activity relationship (SAR). Besides, pharmacophore mapping was performed using eight active compounds as a training set. The generated pharmacophore model revealed five common features and was validated using fenbendazole, triclabendazole and triclabendazole sulfoxide.

Novel iron doped calcium oxalates as promising heterogeneous catalysts for one-pot multi-component synthesis of pyranopyrazoles

The co-precipitation method using a surface modifier, glutamic acid was employed in the design of iron doped calcium oxalates (Fe-CaOx).