Azolium mediated N Heterocyclic carbene selenium adducts: Synthesis, cytotoxicity and molecular docking studies

Synthesis of N-heterocyclic carbene‑selenium complexes modulating apoptosis and autophagy in cancer cells: Probing the interactions with biomolecules and enzymes

Growing cancer resistance is a global threat that calls for development of newer chemotherapeutic analogues especially targeted based therapy to enhance efficacy and selectivity. In this contribution, herein, we report synthesis of selenium incorporated N-heterocyclic carbene (NHC) compounds to explore their potential cytotoxicity against HeLa cells. Test compounds were assured for suitability as drug candidates through physiochemical properties that showed lipophilicity logP 0.85-1.45 for C1-C3 and found stable in biological media (DMEM), whereas, least reactive with N-acetyl cysteine (NAC) and L-glutathione. All the studied compounds showed good cytotoxicity against various cancer strains while compound C1 [3,3-(hexane-1,6-diyl)bis(1-phenethyl-1H-imidazole-2(3H)-selenone)] and C2 [3,3-(hexane-1,6-diyl)bis(1-decyl-1H-imidazole-2(3H)-selenone)] showed promising results with IC50 values of 14.65 ± 0.66 and 8.05 ± 0.35 μg/mL respectively as compared to positive control 21.5 ± 0.05 μg/mL against HeLa cell lines. These compounds showed six-fold higher apoptosis than control with higher accumulation of Ca+ ions intracellularly that alters the expression level of autophagy proteins and increased capase-9 activity. Cell cycle analysis indicated an arrest of cycle in G1 phase of HeLa cells when treated with C1 & C2. Test compounds showed prominent affinity for binding with DNA and inhibiting thioredoxin reductase enzymes in time dependent manners. These findings indicate that Selenium NHC compounds are promising drug candidates to induce cytotoxicity via apoptosis, autophagy and mitochondrial membrane disruptions to manage tumor growth.

Synthesis, Characterization, and DFT Studies of NHC-Derived Amide-Functionalized Organoselenium Compounds

The NHC-Se scaffold has emerged as an intriguing target, opening new avenues for discovering compounds that could significantly improve public health. Recently, extensive efforts have been made to synthesize NHC-Se-based organic compounds for various biomedical applications. Herein, we disclose a straightforward method to access a series of new N-heterocyclic carbene (NHC)-derived organoselenium molecules functionalized with an amide moiety. The parent NHC-Se adduct with a pendent ester moiety is sufficiently activated to facilitate a base- and additive-free ester-to-amide bond transformation. Furthermore, the use of PEG 3550, a biocompatible solvent, enhances reaction efficiency and simplifies the workup. This approach employs a broad spectrum of aliphatic amines with good functional group tolerance, offering a versatile and ecofriendly method for extending chemical space around organoselenium compounds. Additionally, density functional theory (DFT) calculations provide insights into the electronic properties, stability, and reactivity profiles of the synthesized compounds, suggesting their promising potential for applications in biomedical fields.

The first evaluation of the in vitro effects of silver(I)-N-heterocyclic carbene complexes on Encephalitozoon intestinalis and Leishmania major promastigotes

Encephalitozoon intestinalis is an opportunistic microsporidian parasite that primarily infects immunocompromised individuals, such as those with HIV/AIDS or undergoing organ transplantation. Leishmaniasis is responsible for parasitic infections, particularly in developing countries. The disease has not been effectively controlled due to the lack of an effective vaccine and affordable treatment options. Current treatment options for E. intestinalis infection and leishmaniasis are limited and often associated with adverse side effects. There is no previous study in the literature on the antimicrosporidial activities of Ag(I)-N-heterocyclic carbene compounds. In this study, the in vitro antimicrosporidial activities of previously synthesized Ag(I)-N-heterocyclic carbene complexes were evaluated using E. intestinalis spores cultured in human renal epithelial cell lines (HEK-293). Inhibition of microsporidian replication was determined by spore counting. In addition, the effects of the compounds on Leishmania major promastigotes were assessed by measuring metabolic activity or cell viability using a tetrazolium reaction. Statistical analysis was performed to determine significant differences between treated and control groups. Our results showed that the growth of E. intestinalis and L. major promastigotes was inhibited by the tested compounds in a concentration-dependent manner. A significant decrease in parasite viability was observed at the highest concentrations. These results suggest that the compounds have potential anti-microsporidial and anti-leishmanial activity. Further research is required to elucidate the underlying mechanisms of action and to evaluate the efficacy of the compounds in animal models or clinical trials.

Synthesis and physical properties of tunable aryl alkyl ionic liquids based on 1-aryl-4,5-dimethylimidazolium cations

We present a new class of tunable aryl alkyl ionic liquids (TAAILs) based on 1-aryl-4,5-dimethylimidazolium cations with electron-withdrawing and -donating substituents in different positions of the phenyl ring and the bis(trifluoromethylsulfonyl)imide (NTf2) anion. We investigated the effect of additional methyl groups in the backbone of the imidazolium core on the physical properties regarding viscosity, conductivity and electrochemical window. With an electrochemical window of up to 6.3 V, which is unprecedented for TAAILs with an NTf2 anion, this new class of TAAILs demonstrates the opportunities that arise from modifications in the backbone of the imidazolium cation.

N-heterocyclic carbene based Bi-nuclear organoselenium compounds impart a mild biocidal potential compared to their ligands: Synthesis, characterization, computational studies

N-heterocyclic carbene (NHC) based compounds are remarkably known for astonishing biological potentials. Coordination of metal center with these compounds can substantially improve the biological potential for better efficacy. In this context, three binuclear azolium salts (L1-L3) and subsequent selenium adducts L1Se-L3Se were synthesized and assured through analytical techniques. Synthesized compounds were also simulated through computational approach and results were compared with experimental observations that also relatable with biological potentials. Synthesized compounds were screened against bacterial strains and interestingly, the studied compounds showed good antimicrobial potential with MIC values of 7.01, 10.7 and 10.5 µM for S. Aureus (gram positive bacteria) while 12.5, 11.75 and 14.5 µM against E. Coli (gram negative bacteria). The studied compounds showed good antioxidant activity to scavenge DPPH free radicals among which azolium salts were found better in antioxidant potential (IC50 5.75-6.55 µg/mL) than their respective selenium compounds (IC50 9.50-12.75 µg/mL). The hemolytic assay against red blood cells showed that ligands are least toxic comparative to their Se-adducts and can be further trialed for In Vivo studies.

Synthesis, Characterization, and Evaluation of Antifungal Activity of 1-Butyl-3-hexyl-1H-imidazol-2(3H)-selenone by Surface-Enhanced Raman Spectroscopy

In the present research work, a selenium N-heterocyclic carbene (Se-NHC) complex/adduct was synthesized and characterized by using different analytical methods including FT-IR, 1HNMR, and 13CNMR. The antifungal activity of the Se-NHC complex against Aspergillus flavus (A. flavus) fungus was investigated with disc diffusion assay. Moreover, the biochemical changes occurring in this fungus due to exposure of different concentrations of the in-house synthesized compound are characterized by surface-enhanced Raman spectroscopy (SERS) and are illustrated in the form of SERS spectral peaks. SERS analysis yields valuable information about the probable mechanisms responsible for the antifungal effects of the Se-NHC complex. As demonstrated by the SERS spectra, this Se-NHC complex caused denaturation and conformational changes in the proteins as well as decomposition of the fungal cell membrane. The SERS spectra were analyzed using two chemometric tools such as principal component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA). The fungal samples' SERS spectra were differentiated using PCA, while various groups of spectra were discriminated with ultrahigh sensitivity (98%), high specificity (99.7%), accuracy (100%), and area under the receiver operating characteristic curve (87%) using PLS-DA.

Design, DFT studies, antimicrobial and antioxidant potential of Binuclear N-heterocyclic Carbene (NHCs) complexes, Probing the aspect of DNA interaction through In-vitro and In-silico approach

N-heterocyclic carbene (NHC) adducts have shown remarkable biological potential for numerous medical applications. With an aim to improve biological potential of benzimidazolium salts, newer analogues of benzimidazole and their silver complexes were synthesized and characterized. Synthesized salts (L₁-L₂) and silver complexes (C₁-C₂) were confirmed through elemental analysis, UV-visible spectroscopy, FTIR, ¹H NMR & ¹³C NMR spectroscopy. The compounds C1 & C2 were found stable in solution form for studied time period when examined spectroscopically and showed optimum lipophilicity when measured for their partition coefficient through flask shake method. Synthesized compounds showed good antimicrobial potential against gram positive bacterial strain S. Aureus with IC₅₀ 2.02±0.12 and 2.11±0.13 µM respectively while 2.11±0.1 and 2.28±0.17 µM against gram negative bacterial strain E. Coli for C1 and C2 respectively. The interaction study of the related compounds with DNA was predicted by molecular docking study, which confirmed that the studied compound C1 (-8.04 kcal/mol) has a higher binding energy than compound C2 (-4.23 kcal/mol); Also, the compound C1 exhibits a better affinity against to DNA than Ethidium bromide (-7.68 kcal/mol) and cisplatin (-6.21 kcal/mol).The claim was practically assured through spectroscopic and viscometeric method which confirmed that compounds have good affinity for DNA with binding constant kb, 5.78×10⁴ M^-1 and 6.84×10⁴ M^-1 for C1 and C2 respectively.