Thiosemicarbazones and 4-thiazolidinones indole-based derivatives: Synthesis, evaluation of antiproliferative activity, cell death mechanisms and topoisomerase inhibition assay

In this study, we report the synthesis of twenty new acridine–thiosemicarbazone derivatives and their antiproliferative activities. Mechanisms of action such as the inhibition of topoisomerase IIα and the interaction with DNA have been studied for some of the most active derivatives by means of both in silico and in vitro methods, and evaluations of the non-clinical toxicities (in vivo) in mice. In general, the compounds showed greater cytotoxicity against B16-F10 cells, with the highest potency for DL-08 (IC50 = 14.79 µM). Derivatives DL-01 (77%), DL-07 (74%) and DL-08 (79%) showed interesting inhibition of topoisomerase IIα when compared to amsacrine, at 100 µM. In silico studies proposed the way of bonding of these compounds and a possible stereoelectronic reason for the absence of enzymatic activity for CL-07 and DL-06. Interactions with DNA presented different spectroscopic effects and indicate that the compound CL-07 has higher affinity for DNA (Kb = 4.75 × 104 M−1; Ksv = 2.6 × 103 M−1). In addition, compounds selected for non-clinical toxicity testing did not show serious signs of toxicity at the dose of 2000 mg/kg in mice; cytotoxic tests performed on leukemic cells (K-562) and its resistant form (K-562 Lucena 1) identified moderate potency for DL-01 and DL-08, with IC50 between 11.45 and 17.32 µM.

Purpose : This study aimed to evaluate the possible cytotoxic activity of the essential oil of the Eugenia uniflora leaves on normal and tumoral human cells by colorimetric cell viability assay, based on the use of tetrazolium salt (XTT). Methods : To achieve the cytotoxicity it was used normal human lung fibroblast cell line GMO7492A and the evaluation of antiproliferative activity was performed on three tumor cell lines, as follows: human glioblastoma (MO59J), human cervical adenocarcinoma (HeLa) and human breast adenocarcinoma (MCF-7). For the determination of cytotoxic concentration to the normal line, 12 concentrations were evaluated being from 2.44 to 5000 µg/mL. In the evaluation of antiproliferative activity were tested 8 different concentrations of the extract (3.91 to 500 µg/mL). Results : The results in the normal line GM07492A showed that concentrations higher or equal to 39.1 µg/mL are significantly different of the negative control. In the evaluation of antiproliferative activity on tumor cell lines MO59J, HeLa and MCF-7 was observed that the concentration of 125 µg/mL showed a cytotoxic effect on these lines being significantly different from the negative control. The results from the evaluation of the antiproliferative activity in different tumor cell lines of E. uniflora oil was not selective for the tested cell types. Conclusion : E. uniflora oil did not show cytotoxic activity in concentrations lower than 39.1 µg/mL, however, the values found to IC 50 for tumor cells were superior, concluding that the oil has no selectivity for tumor cells tested.

Design, synthesis, and anticancer evaluation of new Quinazoline hybrids: DNA intercalation, topoisomerase IIα inhibition, and in silico studies.

Thiophene-2-carbohydrazide was used in this study to produce some thiophene-containing oxadiazole, triazole, and thiazolidinone derivatives through reactions with various carbon-centered electrophiles. Besides, the hydrazone obtained was allowed to react with mercaptoacetic acid and acetic anhydride to construct thiazolidinone and oxadiazole derivatives. The results of computational chemical study and outcomes of the experiments were in good agreement. The in vitro antiproliferative activity of the produced compounds was examined against two human cell lines namely, breast adenocarcinoma (MCF7) and colon cancer (HCT116) cell lines using doxorubicin as a reference anticancer agent. The produced hydrazones and spiro-indolin-oxadiazole derivatives were the most potent against the two cancer cell lines. The molecular docking was conducted to demonstrate the binding energies of produced substances toward human carbonic anhydrase IX (CA IX) protein. The binding energies of these ligands were near to that of the co-crystallized ligand (9FK). Compound 11b exhibits a binding energy of -5.5817 kcal mol-1, indicating tight binding to some key nucleobases and amino acids of CA IX protein, while compound 11a displays a higher binding energy compared to the reference ligand (9FK). This suggests that compounds 11b and 11a display a notably strong binding affinity towards the human carbonic anhydrase IX (CA IX) protein. ADME profiles of the potent compounds including physicochemical characteristics, lipophilicity, and drug-likeness were predicted.

In this paper, the asymmetric-Schiff base 2-(4-(2-hydroxybenzylideneamino)benzylideneamino)benzoic acid (SB-2) was newly synthesized and characterized by various spectroscopic methods. The interaction of SB-2 with calf thymus DNA was investigated by UV–vis, fluorescence spectroscopy and molecular docking methods. It was determined that SB-2 effectively binds to DNA via the intercalation mode. DNA electrophoretic mobility experiments displayed that topoisomerase IIα could not cleave pBR322 plasmid DNA in the presence of SB-2, confirming that the Schiff base acts as a topo II suppressor. In the molecular docking studies, SB-2 was found to show an affinity for both the DNA-topoisomerase IIα complex and the DNA. In vitro antiproliferative activity of SB-2 was screened against HT-29 (colorectal) and HeLa (cervical) human tumor cell lines by MTT assay. SB-2 diminished the cell viability in a concentration- and incubation time-dependent manner. The ability of SB-2 to measure DNA damage in tumor cells was evaluated with cytokinesis-block micronucleus assay after incubation 24 h and 48 h. Light and scanning electron microscopy experiments of tumor cells demonstrated an incubation time-dependent increase in the proportion of apoptotic cells (nuclear condensation and apoptotic bodies) suggesting that autophagy and apoptosis play a role in the death of cells. Based on the obtained results, it may be considered that SB-2 is a candidate for DNA-targeting antitumor drug. Communicated by Ramaswamy H. Sarma

Thimerosal is an organic mercury compound that is widely used as a preservative in vaccines and other solution formulations. The use of thimerosal has caused concern about its ability to cause neurological abnormalities due to mercury accumulation during a normal schedule of childhood vaccinations. While the chemistry and the biological effects of methylmercury have been well-studied, those of thimerosal have not. Thimerosal reacted rapidly with cysteine, GSH, human serum albumin, and single-stranded DNA to form ethylmercury adducts that were detectable by mass spectrometry. These results indicated that thimerosal would be quickly metabolized in vivo because of its reactions with protein and nonprotein thiols. Thimerosal also potently inhibited the decatenation activity of DNA topoisomerase II alpha, likely through reaction with critical free cysteine thiol groups. Thimerosal, however, did not act as a topoisomerase II poison and the lack of cross-resistance with a K562 cell line with a decreased level of topoisomerase II alpha (K/VP.5 cells) suggested that inhibition of topoisomerase II alpha was not a significant mechanism for the inhibition of cell growth. Depletion of intracellular GSH with buthionine sulfoximine treatment greatly increased the K562 cell growth inhibitory effects of thimerosal, which showed that intracellular glutathione had a major role in protecting cells from thimerosal. Pretreatment of thimerosal with glutathione did not, however, change its K562 cell growth inhibitory effects, a result consistent with the rapid exchange of the ethylmercury adduct among various thiol-containing cellular reactants. Thimerosal-induced single and double strand breaks in K562 cells were consistent with a rapid induction of apoptosis. In conclusion, these studies have elucidated some of the chemistry and biological activities of the interaction of thimerosal with topoisomerase II alpha and protein and nonprotein thiols and with DNA.

Flavonoids-compounds abundant in balanced daily diets-have been extensively investigated for biological activity. The pronounced antiproliferative effects of flavonoids have prompted studies to elucidate their mode of action against tumor cells. The anticancer properties of myricetin, a 3',4',5'-tri-hydroxylated flavonol, have been confirmed for a number of neoplasms, but myricitrin, its 3-O-rhamnoside derivative found in fruits and other parts of edible plants, has been scarcely investigated as a chemopreventive agent. This study evaluated the antiproliferative potential of myricitrin obtained from Combretum lanceolatum (Combretaceae) against MCF7 (breast), PC-3 (prostate), HT-29 (colon), 786-0 (kidney), and HL-60 (acute promyelocytic leukemia) cancer cell lines, using the sulforhodamine B and tetrazolium salt assays. Myricitrin proved most effective in inhibiting growth of HL-60 cells (GI50 = 53.4 μmol·L-1), yet showed weak antiproliferative activity against other cell lines. Possible cytotoxic mechanisms involving inhibition of topoisomerases I and IIα by myricitrin were also evaluated, revealing inhibitory activity only against topoisomerase IIα. The results suggested that topoisomerase IIα inhibition is the probable mechanism responsible for the antiproliferative activity of myricitrin. In vivo mutagenicity by myricitrin and its possible antimutagenic effect on doxorubicin-induced DNA damage were also investigated by performing the somatic mutation and recombination test (SMART) on Drosophila melanogaster. Myricitrin proved nonmutagenic to the offspring of standard (ST) and high-bioactivation (HB) crosses, while cotreatments with doxorubicin revealed the antimutagenic properties of myricitrin, even under conditions of high metabolic activation.

Cashew apple extract (CAE) is a product with intense yellow color obtained from residual fibers of juice processing. Although CAE is known to be rich in carotenoids and anacardic acids, the biological activities of this potential natural food colorant remain unexplored. The present study is the first to investigate the toxicity, antiproliferative and antimicrobial activities of the lyophilized CAE (L-CAE) and its encapsulated products, using maltodextrin (M-CAE) or cashew gum (CG-CAE) as carriers. In addition to their high carotenoid content, the phenolic contents in all materials was determined using UPLC-QTOF-MSE. The acute toxicity was performed using adult zebrafish (Danio rerio); antiproliferative activity was assessed using seven different human tumor cell lines [U-251 (glioblastoma), MCF-7 (breast, adenocarcinoma), NCI-ADR/RES (multidrug-resistant ovarian adenocarcinoma), NCI-H-460 (lung, large cell carcinoma), PC-3 (prostate, adenocarcinoma), OVCAR-3 (ovarian adenocarcinoma), and HT-29 (colon, adenocarcinoma)] and an immortalized human keratinocyte (HaCaT) while the antimicrobioal activity was evaluated on Staphylococcus aureus ATCC 25923, Listeria monocytogenes ATCC 19115, Escherichia coli ATCC 25922 and Salmonella Typhimurium ATCC 51812 microorganisms. Both lyophilized and encapsulated CAE samples did not exert acute toxicity against zebrafish neither antiproliferative effect against human tumor and non-tumor cell lines. Further, L-CAE showed potential antimicrobial activity against Listeria monocytogenes, which was confirmed using electron microscopy. The current findings demonstrated that CAE is a potential source of bioactive compounds to use as an additive in the food industry.

Synthesis, antiproliferative activity evaluation and structure–activity relationships of novel aromatic urea and amide analogues of N-phenyl- N′-(2-chloroethyl)ureas

In our continuing structure-activity relationship study of a new class of erythromycin A (EM-A) derivatives with antiproliferative activity, a new series of de(N-methyl) EM-A dimers jointed by a four-atom linker, -CH2CH = CHCH2-, were prepared and their antiproliferative activity against three human tumor cell lines was evaluated by MTT assay. The most active EM-A dimer, compound 1b, that carrying C6 methoxyl groups was further investigated and showed potent antiproliferative activity in six other human tumor cell lines. Flow cytometry analysis of 1b treated HeLa and MCF-7 cells indicated that the four-atom EM-A dimers induced the SubG1 phase cell cycle arrest and cell apoptosis, in time- and dose-dependent manners. Further experiments including morphologic observation, DNA agarose gel electrophoresis, mitochondrial potential alternation and western blot analysis revealed that the antiproliferative mechanism may involve the induction of apoptosis in activating the mitochondrial pathway, and regulation of apoptotic proteins.

This study was designed to investigate the antioxidant and antiproliferative activities of water and methanol extracts of endemic plant Gypsophila sphaerocephala subsp cappadocica in conjuction with phenolic profiles. Individual phenolics of the extracts were identified and quantified by RP-HPLC analysis. Antioxidant potentials of the extracts were evaluated by DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS [2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)] radical scavenging capacity tests, cupric ion reducing antioxidant capacity (CUPRAC) method and Fe2+ chelating assay. Antiproliferative activities of the extracts were tested against MCF-7 (breast adenocarcinoma), HT-29 (colorectal adenocarcinoma) and HepG2 (hepatocellular carcinoma) cell lines. RP-HPLC analysis showed that methanol extract was richer than water extract in terms of phenolic content. In parallel to the phenolic contents, methanol extract showed higher antioxidant activity than water extract by DPPH, CUPRAC and Fe2+ chelating tests while water extract exhibited higher activity by ABTS method. Moreover, methanol extract displayed 1.8-fold, 4.3-fold and 2.6-fold more antiproliferative activity than water extract against MCF-7 cells, HepG2 cells and HT-29 cells, respectively. However, both extracts were found to show moderate antioxidant and antiproliferative activity compared to positive controls. These results suggest that Gypsophila sphaerocephala may be used as a promising source for food and nutraceutical industries due to its considerable antioxidant and antiproliferative potentials together with its rich phenolic content.

Background/Objectives: In the current medical era, Topoisomerase II is recognized as an essential enzyme that regulates DNA topology during critical biological processes such as DNA replication, transcription, and repair. This study aimed to design, synthesize, and biologically evaluate a new series of pyrazolo[3,4-b]pyridines (8a–g, 10a–g, and 12) as potential anticancer agents and Topoisomerase II inhibitors. Methods: The synthesized compounds were subjected to in vitro anticancer screening at the National Cancer Institute (NCI, USA). Active derivatives were further evaluated through a five-dose screening to determine their antiproliferative potency. Selected compounds were examined for their effects on leukemia cell lines (K562 and MV4-11), and mechanistic studies were performed to assess DNA damage, cell cycle distribution, and apoptosis-related protein modulation. Additionally, enzyme inhibition assays were conducted to determine Topoisomerase IIα (TOPIIα) inhibition. Results: Initial single-dose screening identified several active compounds, notably 8b, 8c, 8e, 8f, 10b, 10c, 10e, and 10f. Among these, compound 8c exhibited potent and broad-spectrum antiproliferative activity across the NCI cancer cell line panel, with a GI50 MG-MID value of 1.33 µM (range: 0.54–2.08 µM). The synthesized molecules showed moderate to good anti-leukemic efficacy against K562 and MV4-11 cells. Mechanistic investigations revealed that compound 8c induced DNA damage and S-phase cell cycle arrest, leading to apoptosis as evidenced by the modulation of PARP-1, Bax, XIAP, and Caspases. Furthermore, target-based assays confirmed that compound 8c significantly inhibited the DNA relaxation activity of TOPIIα in a dose-dependent manner, comparable to etoposide. Conclusions: The study highlights compound 8c as a promising pyrazolo[3,4-b]pyridine derivative with potent antiproliferative activity and effective inhibition of Topoisomerase IIα. These findings suggest its potential as a lead scaffold for further optimization in anticancer drug development..

Novel derivatives of deoxycholic acid bearing aliphatic or cyclic diamine moieties at the C-3 position: Synthesis and evaluation of anti-proliferative activity

In continuation of our research to explore new antiproliferative agents, we report herein the synthesis and antiproliferative activity of two new series of N-(substituted phenyl)-5-aryl-1,3,4-oxadiazol-2-amine (4a–j) and N-{[5-aryl-1,3,4-oxadiazol-2-yl]methyl}-substituted aniline (4k–t) analogs. The antiproliferative activity of fifteen compounds (4a–h, and 4n) was tested against nine different panels of nearly 60 NCI human cancer cell lines. N-(2-Methoxyphenyl)-5-(4-chlorophenyl)-1,3,4-oxadiazol-2-amine (4b) and 4-{5-[(2-Methoxyphenyl)amino]-1,3,4-oxadiazol-2-yl}phenol (4c) showed maximum antiproliferative activity among the series with a mean growth percents (GPs) of 45.20 and 56.73, respectively. The compound 4b showed significant percent growth inhibitions (GIs) on nearly 47 cancer cell lines and were found to have higher sensitivity towards HL-60(TB), MDA-MB-435, OVCAR-3, and K-562 with percent GIs (GIs) of 109.62, 105.90, 91.94, and 88.30, respectively. Similarly the compound, 4c showed significant percent GIs on nearly 42 cancer cell lines and were found to have higher sensitivity towards UO-31, MDA-MB-435, KM12, and K-562 with %GIs of 84.31, 80.52, 78.65, and 77.06, respectively. Both the compounds 4b and 4c showed better antiproliferative activity than the standard drug Imatinib while the antiproliferative activity of compound 4b was found to be nearly comparable to the standard drug 5-flurouracil (5-FU). The antiproliferative activity of five compounds (4o-s) was tested against the breast cancer cell lines (MCF-7 and MDA-MB-231) as per Sulforhodamine B assay (SRB assay). N-{[5-(4-Methoxyphenyl)-1,3,4-oxadiazol-2-yl]methyl}-4-methylaniline (4p) was found to have significant antiproliferative activity against MCF-7 and MDA-MB-231 with GI50 of 12.9 and 59.3 µM, respectively. Further, the free radical scavenging activity results were significant for the most active compounds, 4b (IC50 = 21.07 µM) and 4c (IC50 = 15.58 µM). The docking studies was also carried against tubulin enzyme and the most active compound (4b) showed good interaction with the residues Lys254, Ala250, Cys241, Val318, Ala316, Asn258, and Lys352 present in the hydrophobic cavity of tubulin.

Discovery and optimization of 2-pyridones as dual h-DHFR/EGFRTK inhibitors with immunomodulatory potential; design, synthesis, anti-proliferative activity, and apoptosis inducer.