Oxovanadium(IV) complexes with Knoevenagel Schiff base condensate as impending chemotherapeutic agents: Synthesis,characterization, biological screening and anti-proliferative assay

Two novel oxovanadium(IV) complexes [VOL1]SO₄ (1) and [VOL2]SO₄ (2) containing Knoevenagel condensate Schiff base ligand (L1/L2) have been synthesized and characterized by physical, spectral and analytical methods. These complexes are reported as ionic in nature on the basis of elemental composition and molar conductance, and possess square pyramidal geometry around the central metal ions. The binding interactions of (1) and (2) with calf thymus DNA (CT DNA) were explored by absorption spectrophotometric titration, cyclic voltammetry data and viscosity measurements. The calculated intrinsic binding constant values (K_b) for (1) and (2) obtained from UV–Vis absorption studies are 0.4 × 10⁵ and 5.6 × 10⁵ (M⁻¹) respectively. These experimental results indicate that (1) and (2) are intercalative binders and avid binder to CT DNA with different affinities. These complexes exhibit significant oxidative cleavage of supercoiled plasmid (pUC18) DNA in the presence of activators. In particular, the in vitro antimicrobial efficacy of oxovanadium(IV) complexes reveal that they are more active than free ligands. Besides, the in vitro cytotoxic effect of the titled complexes were examined on a bundle of human tumor cell lines such as MCF-7 and HeLa cancerous cell lines by the MTT method. Interestingly, complex (2) exhibits more potent cytotoxic activity than the other complex and standard drug (cisplatin). The mode of cell death was assessed by Hoechst 33258 staining morphological studies.     

Trans-Pd/Pt(II) saccharinate complexes with a phosphine ligand: Synthesis,cytotoxicity and structure-activity relationship

New trans-[Pd(sac)₂(PPhMe₂)(DMSO)]·H₂O (Pd) and trans-[Pt(sac)₂(PPhMe₂)₂]·H₂O (Pt) complexes (sac = saccharinate and PPhMe₂ = dimethylphenylphosphine) were synthesized and characterized by elemental analysis, IR, NMR, ESI-MS spectral analyses and X-ray diffraction. The complexes were evaluated for their in vitro cytotoxicity against breast (MCF-7), colon (HCT116) and lung (A549) human cancer cell lines. The ATP viability assay displayed that Pd was biologically inactive, but Pt showed significant anticancer potency on MCF-7 cancer cells, similar to cisplatin. The results suggested that Pt targeted DNA, whereas Pd displayed higher binding affinity towards human serum albumin (HSA). Mechanism of action studies of Pt suggested apoptotic cell death due to significant increase in intracellular ROS (reactive oxygen species) levels, mitochondrial damage and formation of DNA double-strand breaks. Finally, this work represents a new example of potent transplatin anticancer complexes.     

Design,synthesis, molecular modeling and biological evaluation of novel 1H-pyrazolo[3,4-b]pyridine derivatives as potential anticancer agents

In trying to develop new anticancer agents, a series of 1H-pyrazolo[3,4-b]pyridine derivatives was designed and synthesized. Fifteen compounds were evaluated in vitro for their anti-proliferative activity against HePG-2, MCF-7, HCT-116, and PC-3 cell lines. Additionally, DNA binding affinity of the synthesized derivatives was investigated as a potential mechanism for the anticancer activity using DNA/methyl green assay and association constants assay. Compounds 19, 20, 21, 24 and 25 exhibited good activity against the four cancer cells comparable to that of doxorubicin. Interestingly, DNA binding assay results were in agreement with that of the cytotoxicity assays where the most potent anticancer compounds showed good DNA binding affinity comparable to that of doxorubicin and daunorubicin. Furthermore, a molecular docking of the tested compounds was carried out to investigate their binding pattern with the prospective target, DNA (PDB-code: 152d).     

Anticancer and DNA binding studies of potential amino acids based quinazolinone analogs: Synthesis,SAR and molecular docking

A novel series of amino acids conjugated quinazolinone-Schiff’s bases were synthesized and screened for their in vitro anticancer activity and validated by molecular docking and DNA binding studies. In the present investigations, compounds 32, 33, 34, 41, 42 and 43 showed most potent anticancer activity against tested cancer cell lines and DNA binding study using methyl green comparing to doxorubicin and ethidium bromide as a positive control respectively. The structure-activity relationship (SAR) revealed that the tryptophan and phenylalanine derived electron donating groups (OH and OCH₃) favored DNA binding studies and anticancer activity whereas; electron withdrawing groups (Cl, NO₂, and F) showed least anticancer activity. The molecular docking study, binding interactions of the most active compounds 33, 34, 42 and 43 stacked with A–T rich regions of the DNA minor groove by surface binding interactions were confirmed.     

Palladium(II) binding to N(7) of acyclovir: DNA interaction and herpes simplex virus (HSV-1) inhibitory activity

Cytotoxicity and herpes simplex virus (HSV-1) inhibitory activity of acyclovir (ACV), 9-[(2-hydroxyethoxy)methyl]guanine, and the palladium(II) coordination complex cis-[PdCl₂(H₂O)(N7-ACV)] · ACV · xH₂O have been tested in African green monkey kidney (Vero line) epithelial cell cultures. The N(7) position of ACV represents the preferred binding site to afford a pseudo-chelate N7/O6 Pd(II) complex involving H-bonds with the cis H₂O molecule. The Pd(II)-ACV complex has been structurally characterized by FTIR and ¹H NMR spectroscopy techniques, chemical composition was measured by elemental analysis, and the thermoanalytical study was performed by TG/DTA. The recognition of secondary ACV molecules by the Pd(II) derivative promotes cooperatively potent HSV-1 inhibitory activity which, in turn, strongly depends on concentration conditions. At the optimal concentration of 10 μM, this complex exhibits antiviral efficiency in vitro, approximately hundred-fold (ca. 1.87 log₁₀) more effective in herpes-infected cells when compared with that of the parent ACV molecules. The molecular-level observation of noticeable modifications caused by the complex on the morphology of the plasmid pBR322 DNA was monitored by AFM, whose mutual interaction evolves to eventually afford DNA condensates upon increasing the period of incubation.     

Facile synthesis of fluoro,methoxy, and methyl substituted ferrocene-based urea complexes as potential therapeutic agents

In the present work, the synthesis, characterization (FT-IR, multinuclear (¹H and ¹³C) NMR, AAS, Raman, and elemental analysis), DNA binding (cyclic voltammetry, UV–Vis spectroscopy and viscometry), and in vitro biological assessment of nine new ferrocene-based ureas are reported. The desulphurization of ferrocenyl thioureas to the corresponding oxo analogues using aqueous sodium hydroxide and mercuric chloride led to the ferrocenyl ureas (F1–F9) in high yields. The DNA binding studies performed by cyclic voltammetry and UV–Vis spectroscopy produced results that are in close agreement with one another for the binding constants (K) and an electrostatic mode of interaction was observed. The nature and the extent of interaction with DNA was further investigated by viscometry. The DFT/B3LYP method was used to determine the charge distribution and HOMO/LUMO energies of the optimized structure. The DFT calculated HOMO and LUMO energies correlate well with the experimentally determined redox potential values. The synthesized ferrocenyl derivatives exhibited good scavenging activity against 1,1-diphenyl-2-picrylhydrazyl radical (DPPH). These complexes were also scanned for their in vitro cytotoxicity against human carcinoma cell line THP-1 (leukemia cells). The results showed a moderate level of cytotoxicity against the subjected cancer cell line as compared with the standard chemotherapeutic drug (cisplatin).     

Design,synthesis and biological evaluation of certain CDK2 inhibitors based on pyrazole and pyrazolo[1,5-a] pyrimidine scaffold with apoptotic activity

Different series of novel pyrazole and pyrazolo[1,5-a] pyrimidine derivatives (2a-g), (3a-c), (7a-d) and (10a-e) were designed, synthesized and evaluated for their ability to inhibit CDK2/cyclin A2 enzyme in vitro. In addition, the cytotoxicity of the newly synthesized compounds was screened against four different human cancer cell lines. The CDK2/cyclin A2 enzyme inhibitory activity revealed that compounds (2d) and (2 g) are among the most active with inhibitory activity values of 60% and 40%, respectively, while compounds (7d) and (10b) exhibited the highest activity among the newly synthesized derivatives against four tumor cell lines (HepG2, MCF-7, A549 and Caco2) with IC50 values 24.24, 14.12, 30.03 and 29.27 μM and 17.12, 10.05, 29.95 and 25.24 μM, respectively. Flow cytometry cell cycle assay was carried for compounds (7d) and (10b) to investigate their apoptotic activity. The obtained results revealed that they induced cell-cycle arrest in the G0-G1phase and reinforced apoptotic DNA fragmentation. Molecular modeling studies have been carried out to gain further understanding the binding mode of the target compounds together with field alignment to define the similar field properties.     

Probing the antibacterial and anticancer potential of tryptamine based mixed ligand Schiff base Ruthenium(III) complexes

Development of new chemotherapeutic agents to treat microbial infections and recurrent cancers is of pivotal importance. Metal based drugs particularly ruthenium complexes have the uniqueness and desired properties that make them suitable candidates for the search of potential chemotherapeutic agents. In this study, two mixed ligand Ru(III) complexes [Ru(Cl)₂(SB)(Phen] (RC-1) and [Ru(Cl)₂(SB)(Bipy)] (RC-2) were synthesised and characterized by elemental analysis, IR, UV–Vis, ¹H, ¹³C NMR spectroscopic techniques and their molecular structure was confirmed by X-ray crystallography. Antibacterial activity evaluation against two Gram-positive (S. pneumonia and E. faecalis) and four Gram-negative strains (P. aurogenosa, K. pneumoniae, S. enterica, and E. coli) revealed their moderate antibacterial activity with MIC value of ≥250 μg/mL. Anticancer activity evaluation against a non-small lung cancer cell line (H1299) revealed the tremendous anticancer activity of these complexes which was further validated by DNA binding and docking results. DNA binding profile of the complexes studied by UV–Visible and fluorescence spectroscopy showed an intercalative binding mode with CT-DNA and an intrinsic binding constant in the range of 3.481–1.015× 10⁵ M⁻¹. Both the complexes were also found to exert weak toxicity to human erythrocytes by haemolytic assay compared to cisplatin. Potential of these complexes as anticancer agents will be further delineated by in vivo studies.     

Synthesis, structural characteristics, DNA binding properties and cytotoxicity studies of a series of Ru(III) complexes

Four related ruthenium(III) complexes, with the formula mer-[RuCl₃(dmso)(N−N)] (dmso = dimethyl sulfoxide; N−N = 2,2′-bipyridine (1), 1,10-phenantroline (2), dipyrido[3,2-f:2′,3′-h]quinoxaline (3) and dipyrido[3,2-a:2′,3′-c]phenazine (4)), have been reported. Complexes 3 and 4 are newly synthesized and characterized by X-ray diffraction. The hydrolysis process of 1-4 has been studied by UV-vis measurement, and it has been found that the extension of the N−N ligands can increase the stability of the complexes. The binding of these complexes with DNA has been investigated by plasmid cleavage assay, competitive binding with ethidium bromide (EB), DNA melting experiments and viscosity measurements. The DNA binding affinity is increased with the extension of the planar area of the N−N ligands, and complex 4 shows an intercalative mode of interaction with DNA. The in vitro anticancer activities of these compounds are moderate on the five human cancer cell lines screened.     

Lignans from the fruit of Schisandra sphenanthera,and their inhibition of HSV-2 and adenovirus

The systematic isolation of the EtOAc extract from Schisandra sphenanthera fruit was performed during a search for HSV-2 and adenovirus inhibitors. Sixteen lignans were obtained, with compound 1 representing a new and rare type of lignan in the genus Schisandra. Their structures were elucidated by spectroscopy and comparison with literature data. Among all the lignans tested for their antiviral activities, compound 14 was the most active against HSV-2 with a selectivity index value up to 29.83. Moreover, the new compound 1, and the known ones (4, 6, 7, 10 and 14) also exhibited moderate inhibition of HSV-2 and adenovirus. To the best of our knowledge, this is the first report that these lignans from Schisandra genus were shown to have modest activity against HSV-2 and adenovirus. Meanwhile, structure–activity relationships of some lignans for the inhibitory activity against HSV-2 and adenovirus were discussed in this study.     

Synthesis and anticancer activity of new thiazolo[3,2-a]pyrimidines: DNA binding and molecular modeling study

A novel series of nitrogenous heterocycles starting from chalcones including thiazolo[3,2-a]pyrimidines (20–67), were synthesized. Structure elucidation of the synthesized compounds was attained by the use of ¹H NMR, ¹³CC NMR, and Mass spectrometry. The obtained compounds were evaluated for their in vitro anticancer activity at the National Cancer Institute (NCI) 60 cell lines panel assay. Three cell lines, non-small cell lung cancer Hop-92, ovarian cancer IGROV1, and melanoma SK-MEL-2, exhibited some sensitivity against most of the tested compounds. Six compounds have passed the 5-log dose level NCI assay. Compounds 34 and 24 proved to be the most active derivatives with GI₅₀, TGI, LC₅₀ of 5.89, 20.0, 66.1% and 5.0, 19.5, 52.5% respectively. Compounds 36, 39, 63 showed lesser activity with GI₅₀, TGI, LC₅₀ 3.2, 11.8, 38.9%, 3.4, 16.6, 60.3%, 3.5, 17.8, 66.1% respectively. DNA binding assay of synthesized compound were performed. Molecular docking showed that compounds 34, 42, and 60 could effectively fit into the minor groove and selectively bind with AT base pairs. The results could confer the anticancer activity of compounds 24, 34, 36, and 39 in vitro to their abilities to bind at DNA minor groove.     

Synthesis, DNA binding, photo-induced DNA cleavage, cytotoxicity and apoptosis studies of copper(II) complexes

Two new Cu(II) complexes, [Cu(acac)(dpq)Cl] () and [Cu(acac)(dppz)Cl] () (acac = acetylacetonate, dpq = dipyrido[3,2-d:20,30-f]quinoxaline, dppz = dipyrido[3,2-a:20,30-c] phenazine), have been synthesized and their DNA binding, photo-induced DNA cleavage activity and cell cytotoxicity are studied. The complexes show good binding propensity to calf thymus DNA in the order: 2(dppz) > 1(dpq). Furthermore, two complexes exhibit efficient DNA cleavage activity on natural light or UV-A (365 nm) irradiation via a mechanistic pathway involving formation of singlet oxygen as the reactive species. The photo-induced DNA cleavage activity of the dppz complex 2 is found to be more efficient than its dpq analogue. In vitro study of the photocytotoxicity of two complexes on HeLa cells indicate that both of them have the potential to act as effective anticancer drugs, with IC₅₀ values of 5.25 ± 0.83 μM (1) and 4.40 ± 0.52 μM (2) in the natural light, and 2.57 ± 0.92 μM (1) and 2.18 ± 0.52 μM (2) in UV-A light. In addition, to detect an apoptotic HeLa body, cells were stained with Hoechst 33342 dye.     

New bio-sensitive and biologically active single crystal of pyrimidine scaffold ligand and its gold and platinum complexes: DFT,antimicrobial, antioxidant,DNA interaction,molecular docking with DNA/BSA and anticancer studies

Novel gold and platinum complexes [AuL₂]·Cl, 1 and [PtL₂]·2Cl, 2 with ligand, 2-methoxy-6-((2-(4-(trifluoromethyl)pyrimidin-2-yl)hydrazono)methyl)phenol (HL) have been synthesized and screened for their antimicrobial, antioxidant, DNA binding and anticancer (in vitro) activities. The single crystal of ligand HL was obtained by slow evaporation technique. The molecular structure of HL was confirmed from single crystal X-ray technique. Density functional theory calculations have been performed to gain insights into the electronic structure of these metal complexes. Antimicrobial result shows that, HL and complexes (1 and 2) have good antimicrobial agents against E. coli (bacteria) and C. albicans (fungi) than others bacterial and fungal strains. Antioxidant assay results suggest that, HL and complexes (1 and 2) possess good radical scavenging activity against diverse free radicals (DPPH, SOD, NO and H₂O₂). The intercalative interactions of HL and complexes (1 and 2) with CT-DNA were confirmed from spectroscopic titrations and viscometric measurements. Furthermore, the interactions of prepared compounds with DNA were confirmed by molecular docking analysis. In order to understand the nature of interactions between these metal complexes and BSA protein results clearly shows that complex 1 binds better than that of complex 2. The antitumor activities of prepared products were tested against single normal and different tumor cell lines by MTT assay. These results reveal that prepared complexes (1 and 2) have significant cytotoxic effect against tumor cell lines.     

Synthesis, structural characterization and biological studies of novel mixed ligand Ag(I) complexes with triphenylphosphine and aspirin or salicylic acid

Two new mixed ligand silver(I) complexes of formulae {[Ag(tpp)₃(asp)](dmf)} (1) (aspH = o-acetylsalicylic acid and tpp = triphenylphosphine) and [Ag(tpp)₂(o-Hbza)] (2) (o-HbzaH = o-hydroxy-benzoic acid) were synthesized and characterized by elemental analyses, spectroscopic techniques and X-ray crystallography at ambient conditions. Three phosphorus and one carboxylic oxygen atoms from a de-protonated aspirin ligand in complex 1 and two phosphorus and two carboxylic oxygen atoms from a chelating o-Hbza anion in complex 2 form a tetrahedral geometry around Ag(I) ions in both complexes.Complexes 1 and 2 and the silver(I) nitrate, tpp, aspNa and o-HbzaH were tested for their in vitro cytotoxic activity against leiomyosarcoma cells (LMS), human breast adenocarcinoma cells (MCF-7) and normal human fetal lung fibroblasts (MRC-5) cells with Thiazolyl Blue Tetrazolium Bromide (MTT) assay. For both cell lines 1 and 2 were found to be more active than cisplatin. Additionally, 1 and 2 exhibit lower activity on cell growth proliferation of MRC-5 cells. The type of LMS cell death caused by 1 and 2 were evaluated in vitro by use of flow cytometry assay. The results show that at concentrations of 1.5 and 1.9 μΜ of complex 1, 44.1% and 69.4%, respectively of LMS cells undergo programmed cell death (apoptosis). When LMS cells were treated with 1.6 and 2.3 μM of 2, LMS cells death was by 29.6% and 81.3%, respectively apoptotic. Finally, the influence of the complexes 1 and 2, upon the catalytic peroxidation of linoleic acid to hydroperoxylinoleic acid by the enzyme lipoxygenase (LOX) was kinetically and theoretically studied. The binding of 1 and 2 towards LOX was also investigated by Saturation Transfer Difference (STD) ¹H NMR experiments.     

Leishmanicidal effect of LLD-3 (1), a nor-triterpene isolated from Lophanthera lactescens

Leishmanicidal activity of 6α, 7α, 15β, 16β, 24-pentacetoxy-22α-carbometoxy-21β,22β-epoxy-18β−hydroxy-27,30-bisnor-3,4-secofriedela-1,20 (29)-dien-3,4 R-olide (LLD-3 (1)) isolated from Lophanthera lactescens Ducke, a member of the Malpighiaceae, was demonstrated against intramacrophage amastigote forms (IC₅₀ of 0.41 μg/mL). The in vitro leishmanicidal effect of Glucantime, the first choice drug for leishmaniasis treatment, was increased by LLD-3 (1) association. The leishmanicidal effect of LLD-3 (1) was not due to stimulation of nitric oxide production by macrophages. LLD-3 (1) was also not cytotoxic for mouse peritoneal macrophages or B cells as assessed by the XTT and Trypan blue exclusion assays. LLD-3 (1) was unable to affect proliferation of naïve or activated B and T cells, as well as the B cells immunoglobulin synthesis. Cellularity of different tissues, liver and kidney functions were not altered in mice treated with LLD-3 (1), as well as the histology pattern of different organs. Our results add LLD-3 (1) as a potential drug candidate for treatment of leishmaniasis.     

Targeting hepatocellular carcinoma: Synthesis of new pyrazole-based derivatives,biological evaluation,DNA binding,and molecular modeling studies

A new series of pyrazole derivatives was prepared in this work, including pyrazolopyrimidines, pyrazolotriazines, pyrazolylthienopyridines, and 2-(pyrazolylamino)thiazol-4-ones, utilizing 3-amino-5-methyl-1H-pyrazole as a synthetic precursor. Their in vitro anticancer activity was tested on hepatocellular carcinoma cell line, HepG2. The results revealed that the pyrazolylhydrazonoyl cyanide 8, the pyrazolopyrimidine 3, and the pyrazolylaminothiazolone 17 were the most active with IC₅₀ values of 2, 7, and 7 µM respectively in comparison with 5.5 µM for cisplatin as a reference drug. Interestingly, all the synthesized compounds showed higher selectivity index than cisplatin. DNA binding assay was also carried out for the synthesized compounds to rationalize their mechanism of action. Molecular modeling studies, including docking into DNA minor groove, flexible alignment, and surface mapping, were conducted. Results obtained proved the superior DNA-binding affinity of the most active anticancer compounds.     

Quinic acid derivatives and coumarin glycoside from the roots and stems of Erycibe obtusifolia

A new quinic acid derivative (1) and a new coumarin glycoside (8), together with six known compounds (2–7) were isolated from the roots and stems of Erycibe obtusifolia. The structures of the new compounds were elucidated by spectroscopic and chemical analyses. The in vitro antiviral activity against the respiratory syncytial virus (RSV) of seven quinic acid derivatives was evaluated by cytopathic effect (CPE) reduction assay. Among them, the dicaffeoylquinic acids (6 and 7) displayed potent in vitro anti-RSV activity.     

Synthesis,antimicrobial, cytotoxic and E. coli DNA gyrase inhibitory activities of coumarinyl amino alcohols

Here we report the in vitro antimicrobial activity (minimum inhibitory concentration) of fourteen coumarinyl amino alcohols 2–16 against eight bacterial strains and two fungi. Among these compounds 4, 8, 12, 15 and 16 showed moderate to good microbial inhibition with MIC values varied from 6.25 to 25 μg/mL. The most promising compounds were also evaluated for their in vitro cytotoxic and E. coli DNA gyrase inhibitory activities along with the two 7-oxy-4-methyl coumarinyl amino alcohol derivatives 17 and 18, which were found to be the most potent in in vitro antimicrobial screening in our previous study. All the active compounds, including 17 and 18, were also docked into the E. coli DNA gyrase ATP binding site (PDB ID: 1KZN) to investigate their binding interactions. Of these compound 17 has shown maximum binding energy value of −6.13 kcal/mol.     

Discovery of a novel DNA binding agent via design and synthesis of new thiazole hybrids and fused 1,2,4-triazines as potential antitumor agents: Computational,spectrometric and in silico studies

New series of furan–thiazole hybrids (3a-f), thiazolo[2,3-c]-1,2,4-triazines (4a-f), their bioisosteres 1,3,4-thiadiazolo[2,3-c]-1,2,4-triazines (8a-d) and 1,2,4-triazino[4,3-b]-1,2,4-triazines (13a-e) were designed, synthesized and evaluated for their in vitro antitumor activities at the National Cancer Institute (NCI, USA). Among the synthesized compounds, 3d was found to exhibit promising broad spectrum antitumor activity (GI₅₀ MG-MID = 14.22 µM) in a five-dose assay against the full panel NCI-cancer cell lines. 3d displayed higher antitumor activity against most tested cancer cell lines than 5-FU as reference. COMPARE analysis and molecular electrostatic potential computational study revealed that 3d probably exerts its antitumor properties through DNA binding similar to Clomesone. Further DNA binding studies using fluorescent terbium (Tb⁺³) probe revealed increased fluroresence of DNA-3d-Tb⁺³ mixture due to damage of the double-stranded DNA. Also, UV–vis absorption study was conducted which showed hyperchromic shift in DNA absorption confirming 3d-induced DNA damage. The assessed potency of 3d-induced DNA damage of calf thymus DNA showed a concentration as low as 2.04 ng/mL for a detectable DNA damage. Moreover, in silico calculation of physicochemical properties and druglikeness were in compliance to Lipinski’s rule.