Nascent pharmacological advancement in adamantane derivatives

The adamantane moiety has attracted significant attention since its discovery in 1933 due to its remarkable structural, chemical, and medicinal properties. This molecule has a notable impact in the therapeutic field because of its "add-on" lipophilicity to any pharmacophoric moieties. As in the case of molecular hybridization, in which one pharmacophore is attached to another one(s) with a probability of increasing the biological activity, adding an adamantane unit improves the absorption distribution, metabolism and excretion properties of the resultant hybrid molecule. This review summarizes various reports highlighting the biological activities of adamantane-based synthetic compounds and their structure-activity relationship study. The information presented in this review may open up possible dimensions for adamantane-based drug development and discovery in the pharmaceutical industry after proper structural modifications.

Identification of (E)-1-((1H-indol-3-yl)methylene)-4-substitute-thiosemicarbazones as potential anti-hepatic fibrosis agents

Liver fibrosis remains a global health challenge due to its rapidly rising prevalence and limited treatment options. The orphan nuclear receptor Nur77 has been implicated in regulation of autophagy and liver fibrosis. Targeting Nur77-mediated autophagic flux may thus be a new promising strategy against hepatic fibrosis. In this study, we synthesized four types of Nur77-based thiourea derivatives to determine their anti-hepatic fibrosis activity. Among the synthesized thiourea derivatives, 9e was the most potent inhibitor of hepatic stellate cells (HSCs) proliferation and activation. This compound could directly bind to Nur77 and inhibit TGF-β1-induced α-SMA and COLA1 expression in a Nur77-dependent manner. In vivo, 9e significantly reduced CCl4-mediated hepatic inflammation response and extracellular matrix (ECM) production, revealing that 9e is capable of blocking the progression of hepatic fibrosis. Mechanistically, 9e induced Nur77 expression and enhanced autophagic flux by inhibiting the mTORC1 signaling pathway in vitro and in vivo. Thus, the Nur77-targeted lead 9e may serve as a promising candidate for treatment of chronic liver fibrosis.

High-yielding synthesis of cyclometallated iridium complexes with hydrogen bond-rich ligands

A library of cyclometallated iridium(III) complexes with a strong H-bonding motif in their ancillary ligand was synthesized, characterized and their photophysical properties measured. Demonstrated herein is a general synthetic high yield procedure for these compounds. We ascribe these yields to the use of an intermediary primer ligand. This de novo strategy circumnavigates the standard synthetic issues of H-bond rich ligand precursors (self-aggregation and poor solubility in organic solvents).

Multicomponent synthesis of chromophores – The one-pot approach to functional π-systems

Multicomponent reactions, conducted in a domino, sequential or consecutive fashion, have not only considerably enhanced synthetic efficiency as one-pot methodology, but they have also become an enabling tool for interdisciplinary research. The highly diversity-oriented nature of the synthetic concept allows accessing huge structural and functional space. Already some decades ago this has been recognized for life sciences, in particular, lead finding and exploration in pharma and agricultural chemistry. The quest for novel functional materials has also opened the field for diversity-oriented syntheses of functional π-systems, i.e. dyes for photonic and electronic applications based on their electronic properties. This review summarizes recent developments in MCR syntheses of functional chromophores highlighting syntheses following either the framework forming scaffold approach by establishing connectivity between chromophores or the chromogenic chromophore approach by de novo formation of chromophore of interest. Both approaches warrant rapid access to molecular functional π-systems, i.e. chromophores, fluorophores, and electrophores for various applications.

Screening of in vitro and in silico effect of Fluorophenylthiourea compounds on glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase enzymes

Inhibition studies of enzymes in the pentose phosphate pathway (PPP) have recently emerged as a promising technique for pharmacological intervention in several illnesses. Glucose 6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) are the most important enzymes of the PPP. For this purpose, in the current study, we examined the effect of some fluorophenylthiourea on G6PD and 6PGD enzyme activity. These compounds exhibited moderate inhibitory activity against G6PD and 6PGD with K_I values ranging from 21.60 ± 8.42 to 39.70 ± 11.26 μM, and 15.82 ± 1.54 to 29.97 ± 5.72 μM, respectively. 2,6-difluorophenylthiourea displayed the most potent inhibitory effect for G6PD, and 2-fluorophenylthiourea demonstrated the most substantial inhibitory effect for 6PGD. Furthermore, the molecular docking analyses of the fluorophenylthioureas, competitive inhibitors, were performed to understand the binding interactions at the enzymes' binding site.

Synthesis and Biological Evaluation of 1-(2-(6-Methoxynaphthalen-2-yl)-6-methylnicotinoyl)-4-Substituted Semicarbazides/Thiosemicarbazides as Anti-Tumor Nur77 Modulators

Nur77 is an orphan nuclear receptor that participates in the occurrence and development of a variety of tumors. Many agonists of Nur77 have been reported to have significant anticancer effects. Our previous studies have found that the introduction of bicyclic aromatic rings, such as naphthalyl and quinoline groups, into the N'-methylene position of indoles' Nur77 modulators can effectively improve the anti-tumor activity of the target compounds. Following our previous studies, a series of novel 1-(2-(6-methoxynaphthalen-2-yl)-6-methylnicotinoyl)-4-substituted semicarbazide/thiosemicarbazide derivatives 9a-9w were designed and synthesized in four steps from 6-methoxy-2-acetonaphthone and N-dimethylformamide dimethylacetal. All compounds were characterized by 1H-NMR, 13C-NMR and HRMS, and their anti-tumor activity on various cancer cell lines such as A549, HepG2, HGC-27, MCF-7 and HeLa are also evaluated. From the series of compounds, 9h exhibited the most potent anti-proliferative activity against several cancer cells. Colony formation and cell cycle experiments showed that compound 9h inhibited cell growth and arrested the cell cycle. Additionally, 9h leads to the cleavage of PARP. We initially explored the mechanism of 9h-induced apoptosis and found that compound 9h can upregulate Nur77 expression and triggered Nur77 nuclear export, indicating the occurrence of Nur77-mediated apoptosis. These results suggested that 9h may be a promising anti-tumor leading compound for the further research.

Synthesis of New Thiourea-Metal Complexes with Promising Anticancer Properties

In this work, two thiourea ligands bearing a phosphine group in one arm and in the other a phenyl group (T2) or 3,5-di-CF₃ substituted phenyl ring (T1) have been prepared and their coordination to Au and Ag has been studied. A different behavior is observed for gold complexes, a linear geometry with coordination only to the phosphorus atom or an equilibrium between the linear and three-coordinated species is present, whereas for silver complexes the coordination of the ligand as P^S chelate is found. The thiourea ligands and their complexes were explored against different cancer cell lines (HeLa, A549, and Jurkat). The thiourea ligands do not exhibit relevant cytotoxicity in the tested cell lines and the coordination of a metal triggers excellent cytotoxic values in all cases. In general, data showed that gold complexes are more cytotoxic than the silver compounds with T1, in particular the complexes [AuT1(PPh₃)]OTf, the bis(thiourea) [Au(T1)₂]OTf and the gold-thiolate species [Au(SR)T1]. In contrast, with T2 better results are obtained with silver species [AgT1(PPh₃)]OTf and the [Ag(T1)₂]OTf. The role played by the ancillary ligand bound to the metal is important since it strongly affects the cytotoxic activity, being the bis(thiourea) complex the most active species. This study demonstrates that metal complexes derived from thiourea can be biologically active and these compounds are promising leads for further development as potential anticancer agents.

Crystallographic and Theoretical Exploration of Weak Hydrogen Bonds in Arylmethyl N'-(adamantan-1-yl)piperidine-1-carbothioimidates and Molecular Docking Analysis

Crystal structures of two potential chemotherapeutic agents, namely 4-nitrobenzyl N'-(adamantan-1-yl)piperidine-1-carbothioimidate 1 and 4-bromobenzyl N'-(adamantan-1-yl)piperidine-1-carbothioimidate 2, have been analyzed in detail. X-ray analysis reveals that the molecular conformations of these compounds are strikingly different. These two structures are compared with two of their closely related structures. In the related structures, morpholine replaces piperidine. Based on the Hirshfeld surface analysis and two-dimensional (2D) fingerprint plots, we describe the effects of piperidine/morpholine and Br/NO2 groups on the intermolecular interactions. An analysis of the CLP-PIXEL energy provides insight into the energetics of the dimers observed in the title compounds and their related structures. Compound 1 stabilizes with bifurcated C-H···S, C-H···O, and O(lp)···C(π) interactions, whereas compound 2 stabilizes with C-H···N, C-H···Br, and C-H···C interactions. The energy frameworks for the crystal structures of the title compounds reveal differences. The atoms-in-molecules (AIM) analysis was performed to confirm the intermolecular interactions found in the crystal structures of 1 and 2. Additionally, docking analysis suggests that the title compounds bind at the active site of human sphingosine kinase 1, a well-known cancer target.

Complexes of 1,3-Diisobutyl Thiourea with Copper(I), Zinc(II) and Mercury(II): Their Antioxidant and Antibacterial Evaluation

The reaction of 1,3-Diisobutyl thiourea (Tu) with metal salts, {[CuX (X = Cl, I)], [ZnCl2] and [HgI2] in an appropriate stoichiometric ratio afforded the corresponding metal complexes [Tu2CuCl] (1), [Tu3CuI] (2), [Tu2ZnCl2] (3) and [Tu2HgI2] (4) in good yields. The FT-IR data show typically broad signals (3278–3288 cm−1) attributed to the involvement of NH bonds in extensive hydrogen bonding. The structures of complexes were proposed based on a spectroscopic data set. Compounds 1 and 2 were additionally characterized by single-crystal X-ray analysis. Complexes 1–4 were tested for their free radical scavenging efficiency using 2,2-diphenyl-1-picrylhydrazyl free radical (hereafter abbreviated as DPPH). The free radical scavenging activity was a function of decrease in the resultant absorption of DPPH solution after the mixing of an appropriate concentration of the respective complex. The activity of complexes was determined to be dose dependent and increased concentration of the complex resulted in improved antioxidant activity. Compound 1 was found to be the most efficient, with 79.9% free radical scavenging activity. Complexes were also tested for their efficiency against selected strains of bacteria (E. coli, S. flexneri, S. typhi, and P. aeruginosa) and the activities were compared to commercially available standard drug cephradine. Compound 1 was more active against P.aeruginosa (ZI 13.25), while compound 4 was found to be more active against E. coli (ZI 11.0), S. flexneri (ZI 11.2), and S. typhi (ZI 10.5).

Synthesis, antioxidant activity and bioinformatics studies of L-3-hydroxytyrosine templated N-alkyl/aryl substituted urea/thioureas

A new series of urea/thiourea derivatives have been efficiently synthesized from the reaction of L-3-hydroxytyrosine with selective isocyanates/isothiocyanates and characterized by Infra-red, proton & carbon-13 nuclear magnetic resonance spectral and mass spectrometry studies. All the synthesized compounds have been screened for their antioxidant activity by 1,1-diphenyl1-2-picrylhydrazyl radical assay, ferric reducing antioxidant power assay and also studied their molecular docking interaction profiles against 1N8Q and 3NRZ enzymatic proteins. The in vitro antioxidant activity has further supported by quantitative structure activity relationship, absorption, distribution, metabolism, and excretion & toxicity studies, bioactivity studies & enzyme inhibition assay and identified that they were potentially bound to ASP490 & ASP361 aminoacid residue in chain A of 1N8Q protein and GLN1194 aminoacid residue in chain L of 3NRZ protein and are responsible for potential antioxidant activity. It is proved that urea derivatives linked with 4-fluoro & 4-nitro and thiourea derivatives linked with 3-chloro & 4-fluoro have exhibited promising antioxidant activity. In eventual synthesized compounds have been identified as potential blood-brain barrier penetrable compounds and proficient central nervous system active neuro-protective antioxidant agents as they have envisaged as easily penetrable to blood-brain barrier thresholds, a neuroprotective property.

Probing the Effect of Halogen Substituents (Br, Cl, and F) on the Non-covalent Interactions in 1-(Adamantan-1-yl)-3-arylthiourea Derivatives: A Theoretical Study

The effect of halogen substituents (X = Br, Cl, and F) on the crystal packing and intra- and intermolecular interactions in four adamantane-thiourea hybrid derivatives is investigated using different theoretical tools. The bromo and chloro derivatives exhibit 3D isostructurality as evident from lattice parameters, molecular conformation, and crystal packing. The density functional theory study suggests that the molecular conformation of the parent (unsubstituted) and fluoro derivatives exhibits a stable low energy anti-syn conformation. In contrast, bromo and chloro derivatives adopt stable and relatively high energy minima on their potential energy surfaces. Hirshfeld surface analysis reveals the effect of halogen substituents on the intermolecular contacts. The halogen atoms mainly reduce the contribution of H···H contacts toward crystal packing. PIXEL energy analysis indicates the strong dimer formed by N-H···S hydrogen bonds in all four structures. It also revealed that a vast number of H···H contacts observed in different dimers of these structures either presented along with other conventional interactions or solely stabilize the dimeric topology. The topological parameters for intermolecular interactions in these structures suggest an intermediate bonding character between shared and closed-shell interactions for N-H···S hydrogen bonds in the parent and chloro derivatives. In contrast, the N-H···S hydrogen bond in other structures is of a closed-shell interaction. Among four derivatives, the fluoro derivative is weakly packed in the solid state based on the PIXEL method's lattice energy calculation.

X-ray and theoretical investigation of (Z)-3-(adamantan-1-yl)-1-(phenyl or 3-chlorophenyl)-S-(4-bromobenzyl)isothioureas: an exploration involving weak non-covalent interactions, chemotherapeutic activities and QM/MM binding energy

A detailed exploration of crystal packing of two adamantane-isothiourea hybrid derivatives along with a known closely related structure has been performed to delineate the effect of halogen substituents and the role of weak intermolecular interactions in their supramolecular architectures. The adamantane-isothiourea hybrid derivatives used in the present study are (Z)-3-(Adamantan-1-yl)-S-(4-bromobenzyl)-1-phenylisothiourea (1), C₂₄H₂₇BrN₂S and (Z)-3-(Adamantan-1-yl)-S-(4-bromobenzyl)-1-(3-chlorophenyl)isothiourea (2), C₂₄H₂₆BrClN₂S, characterized by X-ray crystallography. The X-ray structures revealed that the molecular conformation of 1 and 2 are different and stabilized by intramolecular C-H···N interactions. In addition, a short intramolecular H···H contact is formed in 2. The Hirshfeld surface analysis was used to delineate the nature of different intermolecular interactions and their contributions toward crystal packing. The quantitative analysis of strengths of molecular dimers existed in 1 and 2 has been performed using the PIXEL method. The electrostatic potential map clearly revealed nature and strength of σ-holes at Br and Cl atoms. The topological analysis was used to characterize the nature and the strength of various intermolecular interactions including the type I Br···Br contact. Interestingly, all the H-H bonding observed in 1 and 2 show closed-shell in nature. Further, an in-vitro antimicrobial activity studies suggest that the title compounds exhibited potent antibacterial activity against all the tested Gram-positive bacterial strains and Gram-negative Escherichia coli. Compound 2 showed marked anti-proliferative activity against MCF-7 and HeLa cell lines.Communicated by Ramaswamy H. Sarma.

Synthesis of Some Benzimidazole-derived Molecules and their Effects on PARP-1 Activity and MDA-MB-231, MDA-MB-436, MDA-MB-468 Breast Cancer Cell Viability

Background:

Poly (ADP-ribosyl) polymerase-1 (PARP-1) inhibitors are compounds that are used to treat cancers, which are defective in DNA-repair and DNA Damage-Response (DDR) pathways.

Objective:

In this study, a series of potential PARP-1 inhibitor substituted (piperazine-1-carbonyl)phenyl)-1Hbenzo[ d]imidazole-4-carboxamide compounds were synthesised and tested for their PARP-1 inhibitory and anticancer activities.

Methods:

Compounds were tested by cell-free colorimetric PARP-1 activity and MTT assay in MDA-MB-231, MDA-MB-436, MDA-MB-468 breast cancer, and L929 fibroblast cell lines.

Results:

Our results showed that compound 6a inhibited viability in MDA-MB-231 and MDA-MB-468 cells whereas 8a inhibited viability in MDA-MB-468 cells. Compound 6b significantly inhibited cell viability in tested cancer cells. However, 6b exhibited toxicity in L929 cells, whereas 6a and 8a were found to be non-toxic for L929 cells. Compounds 6a, 6b and 8a exhibited significant inhibition of PARP-1 activity.

Conclusion:

These three compounds exhibited PARP-1 inhibitory activities and anticancer effects on breast cancer cells, and further research will enlighten the underlying mechanisms of their effects.

Synthesis and Biological Activity of 2-Arylidene-N-(quinolin-6-yl)hydrazine-1-carboxamides

A series of 2-arylidene-N-(quinolin-6-yl)hydrazine-1-carboxamides 5a–5o were synthesized and characterized. The synthesized compounds (5a–5o) were screened in vitro against three breast cancer cell lines: SKBR3, MDA-MB-231, and MCF-7 cancer cell lines by the MTT assay. According to MTT results, compounds 5k and 5l showed better antiproliferative activities over MCF-7 cell lines with IC50 values of 8.50 and 12.51 μM. Colony formation assay indicated 5k/5l treatment obviously inhibited the growth of MCF-7 cells and 5k/5l-induced cell cycle was arrested in the G2-M phase. Moreover, 5k/5l significantly increased the level of cleaved PARP and induced the apoptosis in MCF-7 cells. In addition, compared to Hela cells, MCF-7 cells were more sensitive to 5k/5l treatment.

Design, synthesis, and biological evaluation of 5-((8-methoxy-2-methylquinolin-4-yl)amino)-1H-indole-2-carbohydrazide derivatives as novel Nur77 modulators

Nur77 is a potential target for the treatment of cancer such as HCC. Herein, we detailed the discovery of a novel series of 5-((8-methoxy-2-methylquinolin-4-yl)amino)-1H-indole-2-carbohydrazide derivatives as potential Nur77 modulators. The studies of antiproliferative activity and Nur77-binding affinity of target compounds resulted in the discovery of a lead candidate (10g), which was a good Nur77 binder (K_D = 3.58 ± 0.16 μM) with a broad-spectrum antiproliferative activity against all tested hepatoma cells (IC₅₀ < 2.0 μM) and was low toxic to normal LO2 cells. 10g could up-regulate Nur77 expression and mediate sub-cellular localization of Nur77 to induce apoptosis in hepatocellular carcinoma cell lines, which relied on 10g inducing Nur77-dependent autophagy and endoplasmic reticulum stress as the upstream of apoptosis. Moreover, the in vivo assays verified that 10g significantly inhibited xenograft tumor growth. These results indicate that 10g has the potential to be developed as a novel Nur77-targeting anti-hepatoma drug.

Multiple molecular targets mediated antioxidant activity, molecular docking, ADMET, QSAR and bioactivity studies of halo substituted urea derivatives of α-Methyl-l-DOPA

A series of novel α-methyl-l-DOPA urea derivatives viz., 3-(3,4-dihydroxyphenyl)-2-methyl-2-(3-halo/trifluoromethyl substituted phenyl ureido)propanoic acids (6a-e) have been synthesized from the reaction of α-methyl-l-DOPA (3) with various aryl isocyanates (4a-e) by using triethylamine (5, TEA) as a base catalyst in THF at reflux conditions. The synthesized compounds are structurally characterized by spectral (IR, ¹H &¹³C NMR and MASS) and elemental analysis studies and screened for their in-vitro antioxidant activity against DPPH, NO and H₂O₂ free radical scavenging assays and identified compounds 6c &6d as potential antioxidants. The acquired in vitro results were correlated with the results of molecular docking, ADMET, QSAR and bioactivity studies performed for them and predicted that the recorded in silico binding affinities are in good correlation with the in vitro antioxidant activity results. The molecular docking analysis has comprehended the strong hydrogen bonding interactions of 6a-e with 1CB4, 1N8Q, 3MNG, 1OG5, 1DNU, 3NRZ, 2CDU, 1HD2 and 2HCK proteins of their respective SOD, LO, PRXS5, CP450, MP, XO, NO, PRY5 and HCK enzymes. This has sustained the effective binding of 6a-e and resulted in functional inhibition of selective aminoacid residues to be pronounced as multiple molecular targets mediated antioxidant potent compounds. In addition, the evaluated toxicology risks of 6a-e are identified with in the potential limits of drug candidates. The conformational analysis of 6c & 6d prominently infers that urea moiety uniting α-methyl-l-DOPA with halo substituted aryl units into a distinctive orientation to comply good structure-activity to inhibit the proliferation of reactive oxygen species in vivo.

Substituent effect on the packing architecture of adamantane and memantine derivatives of sulfonamide molecular crystals

A specific number of structures described in this paper with adamantane and memantine fragments have been synthesised and characterised.

Hunig's base catalyzed synthesis of new 1-(2,3-dihydro-1H-inden-1-yl)-3-aryl urea/thiourea derivatives as potent antioxidants and 2HCK enzyme growth inhibitors

A series of 1-(2,3-dihydro-1H-indan-1-yl)-3-aryl urea/thiourea derivatives (4a-j) have been synthesized from the reaction of 2,3-dihydro-1H-inden-1-amine (2) with various aryl isocyanates/isothiocyanates (3a-j) by using N,N-DIPEA base (Hunig's base) catalyst in THF at reflux conditions. All of them are structurally confirmed by spectral (IR, ¹H &¹³C NMR and MASS) and elemental analysis and screened for their in-vitro antioxidant activity against DPPH and NO free radicals and found that compounds 4b, 4i, 4h &4g are potential antioxidants. The obtained in vitro results were compared with the molecular docking, ADMET, QSAR and bioactivity study results performed for them and identified that the recorded in silico binding affinities were observed in good correlation with the in vitro antioxidant results. The Molecular docking analysis had unveiled the strong hydrogen bonding interactions of synthesized ligands with ARG 160 residue of protein tyrosine kinase (2HCK) enzyme and plays an effective role in its inhibition. Toxicology studies have assessed the potential risks of 4a-j and inferred that all of them were in the limits of potential drugs. The conformational analysis of 4a-j inferred that the urea/thiourea spacer linking 2,3-dihydro-1H-inden-1-amino and substituted aryl units has facilitated all these molecules to effectively bind with ARG 160 amino acid residue present on the α-helix of the protein tyrosine kinase (2HCK) enzyme specifically on chain A of hemopoetic cell kinase. Collectively this study has established a relationship between the antioxidant potentiality and ligands binding with ARG 160 amino acid residue of chain A of 2HCK enzyme to inhibit its growth as well as proliferation of reactive oxygen species in vivo.

Design and synthesis of phenylpiperazine derivatives as potent anticancer agents for prostate cancer

Novel thiourea (5a, 5b) and thiazolidinone derivatives (6a, 6b) were synthesized by hybridizing molecules starting from the compound 6-(4-phenylpiperazin-1-yl)pyridin-3-amine (4) which is known to show anticancer activity. The synthesis of the leading compound was carried out by using 1-(5-nitropyridin-2-yl)-4-phenylpiperazine (3) which was obtained by a novel method of the reaction of 2-chloro-5-nitropyridine (1) and N-phenylpiperazine (2). The structures of the compounds were confirmed using FTIR, ¹ H NMR, ¹³ C NMR, HRMS spectroscopic methods and elemental analysis. The organic molecules were tested for their anticancer activities against prostate cancer (PC) cell lines: DU 145, PC-3 and LNCaP. As the compound 5a exerted the highest cytotoxic activity, IC₅₀ concentrations of compound 5a were further investigated in terms of morphology, colony-forming ability, RNA expression, fragmented DNA and cell cycle distributions of PC cell lines. Overall data revealed that compound 5a treatment induces apoptosis and DNA fragmentation in PC cell lines and inhibits cell cycle progression resulting in the accumulation of cells in either the G1 or the S phases.