Biological Activities of NHC–Pd(II) Complexes Based on Benzimidazolylidene N-heterocyclic Carbene (NHC) Ligands Bearing Aryl Substituents

Ibrahim Al Nasr,Waleed Koko,Tariq Khan,Sedat Yaşar,Ismail Özdemir,Naceur Hamdi,Nedra Touj

doi:10.3390/catal10101190

Abstract

N-heterocyclic carbene (NHC) precursors (2a–i), their pyridine-enhanced precatalyst preparation stabilization and initiation (PEPPSI)-themed palladium N-heterocyclic carbene complexes (3a–i) and palladium N-heterocyclic triphenylphosphines complexes (4a–i) were synthesized and characterized by elemental analysis and 1H NMR, 13C NMR, IR, and LC–MS spectroscopic techniques. The (NHC)Pd(II) complexes 3–4 were tested against MCF7 and MDA-MB-231 cancer cells, Escherichia coli, methicillin-resistant Staphylococcus aureus (MRSA), Candida albicans microorganisms, Leishmania major promastigotes and amastigotes, Toxoplasma gondii parasites, and Vero cells in vitro. The biological assays indicated that all compounds are highly active against cancer cells, with an IC50 < 1.5 µg mL−1. Eight compounds proved antibacterial and antileishmanial activities, while only three compounds had strong antifungal activities against C. albicans. In our conclusion, compounds 3 (b, f, g, and h) and 4b are the most suitable drug candidates for anticancer, antimicrobial, and antiparasitical.

Highlights

Since the discovery of N-heterocyclic carbenes (NHCs) [1], NHCs have emerged as efficient ligands, and their transition metal complexes have been widely applied as organometallic catalysts [2,3,4,5,6,7,8].In particular, NHC–Pd complexes have been utilized in coupling reactions [2,3,4]
We found the structure of Ag(I)–NHC compounds and respective benzimidazolium recent results, we found the structure of Ag(I)–NHC compounds and respective benzimidazolium salt salt to be of potent antitumor property [36,37]
The aim of this work was to study the activities against cancer cells, Escherichia coli, methicillinThe aim of this work was to study the activities against cancer cells, Escherichia coli, resistant Staphylococcus aureus (MRSA), Candida albicans, Leishmania major, Toxoplasma gondii of novel methicillin-resistant Staphylococcus aureus (MRSA), Candida albicans, Leishmania major, Toxoplasma gondii benzimidazolium salts 2a-i, precatalyst preparation stabilization and initiation (PEPPSI)-type N-functionalized N-heterocyclic carbene complexes 3 and of novel benzimidazolium salts 2a-i, PEPPSI-type N-functionalized N-heterocyclic carbene complexes palladium N-heterocyclic triphenylphosphine complexes 4

Summary

Introduction

NHC–Pd complexes have been utilized in coupling reactions [2,3,4]. A series of well-defined NHC–Pd complexes were developed, and their catalytic activities were fully evaluated in organic transformations [13,14,15,16,17,18,19,20,21,22,23,24,25,26]. 22 of of 11 organic reactions [27,28,29]. They are promising candidates with diverse bioassays properties

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Conclusion