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- Trisubstituted barbiturates and thiobarbiturates: Synthesis and biological evaluation as xanthine oxidase inhibitors, antioxidants, antibacterial and anti-proliferative agentsPublication . Figueiredo, Joana; Serrano, João L.; Cavalheiro, Eunice Cerdeira Soares; Keurulainen, Leena Maria; Yli-Kauhaluoma, Jari Tapani; Moreira, Vânia M; Ferreira, Susana; Domingues, F.C.; Silvestre, Samuel; Almeida, PauloBarbituric and thiobarbituric acid derivatives have become progressively attractive to medicinal chemists due to their wide range of biological activities. Herein, different series of 1,3,5-trisubstituted barbiturates and thiobarbiturates were prepared in moderate to excellent yields and their activity as xanthine oxidase inhibitors, antioxidants, antibacterial agents and as anti-proliferative compounds was evaluated in vitro. Interesting bioactive barbiturates were found namely, 1,3-dimethyl-5-[1-(2-phenylhydrazinyl)ethylidene]pyrimidine-2,4,6(1H,3H,5H)-trione (6c) and 1,3-dimethyl-5-[1-[2-(4-nitrophenyl)hydrazinyl]ethylidene]pyrimidine-2,4,6(1H,3H,5H)-trione (6e), which showed concomitant xanthine oxidase inhibitory effect (IC50 values of 24.3 and 27.9 μM, respectively), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (IC50 values of 18.8 and 23.8 μM, respectively). In addition, 5-[1-(2-phenylhydrazinyl)ethylidene]pyrimidine-2,4,6(1H,3H,5H)-trione (6d) also revealed DPPH radical scavenger effect, with an IC50 value of 20.4 μM. Moreover, relevant cytotoxicity against MCF-7 cells (IC50 = 13.3 μM) was observed with 5-[[(2-chloro-4-nitrophenyl)amino]methylene]-2-thioxodihydropyrimidine-4,6(1H,5H)-dione (7d). Finally, different 5-hydrazinylethylidenepyrimidines revealed antibacterial activity against Acinetobacter baumannii (MIC values between 12.5 and 25.0 μM) which paves the way for developing new treatments for infections caused by this Gram-negative coccobacillus bacterium, known to be an opportunistic pathogen in humans with high relevance in multidrug-resistant nosocomial infections. The most promising bioactive barbiturates were studied in silico with emphasis on compliance with the Lipinski's rule of five as well as several pharmacokinetics and toxicity parameters.
- 5-Hydrazinylethylidenepyrimidines effective against multidrug-resistant Acinetobacter baumannii: Synthesis and in vitro biological evaluation of antibacterial, radical scavenging and cytotoxic activitiesPublication . Figueiredo, Joana; Serrano, João L.; Soares, MN; Ferreira, Susana; Domingues, F.C.; Almeida, Paulo; Silvestre, SamuelAcinetobacter baumannii has emerged as an important nosocomial pathogen in recent years, with infectious outbreaks caused by multidrug-resistant strains increasing worldwide. Thus, new antibacterial treatments for multidrug-resistant A. baumannii strains are needed. In this work, a series of 5-hydrazinylethylidenepyrimidines were synthesized and in vitro evaluated against two multidrug-resistant A. baumannii strains (AcB 13/10 and AcB 73/10). Minimum inhibitory concentration results demonstrated that generally the compounds in study presented values in a low micromolar range. In the determination of in vitro bacterial growth at 24 h, it was observed that the pyrimidines 3a and 3c, with an unsubstituted hydrazinylphenyl, have bacteriostatic activity in both multidrug-resistant A. baumannii strains, with a concentration-dependent action. In general, an additive effect occurred in the combination of these compounds with gentamicin, rifampicin and polymyxin B, for both strains. Furthermore, all 5-hydrazinylethylidenepyrimidines under study presented a good 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity, generally low xanthine oxidase inhibition and low cytotoxicity in normal human dermal fibroblasts as well as potential favorable drug-likeness properties. Thus, these molecules can be considered attractive for the future development of antibacterial agents against multidrug-resistant A. baumannii.
- Effect of Diosgenin in Suppressing Viability and Promoting Apoptosis of Human Prostate Cancer Cells: An Interplay with the G Protein-Coupled Oestrogen Receptor?Publication . Figueira, Marília I; Marques, Ricardo; Cardoso, Henrique J.; Fonseca, Lara R. S.; Duarte, Ana Paula; Silvestre, Samuel; Socorro, SílviaDiosgenin is a phytosteroid sapogenin with reported antitumoral activity. Despite the evidence indicating a lower incidence of prostate cancer (PCa) associated with a higher consumption of phytosteroids and the beneficial role of these compounds, only a few studies have investigated the effects of diosgenin in PCa, and its mechanisms of action remain to be disclosed. The present study investigated the effect of diosgenin in modulating PCa cell fate and glycolytic metabolism and explored its potential interplay with G protein-coupled oestrogen receptor (GPER). Non-neoplastic (PNT1A) and neoplastic (LNCaP, DU145, and PC3) human prostate cell lines were stimulated with diosgenin in the presence or absence of the GPER agonist G1 and upon GPER knockdown. Diosgenin decreased the cell viability, as indicated by the MTT assay results, which also demonstrated that castrate-resistant PCa cells were the most sensitive to treatment (PC3 > DU145 > LNCaP > PNT1A; IC50 values of 14.02, 23.21, 56.12, and 66.10 µM, respectively). Apoptosis was enhanced in diosgenin-treated cells, based on the increased caspase-3-like activity, underpinned by the altered expression of apoptosis regulators evaluated by Western blot analysis, which indicated the activation of the extrinsic pathway. Exposure to diosgenin also altered glucose metabolism. Overall, the effects of diosgenin were potentiated in the presence of G1. Moreover, diosgenin treatment augmented GPER expression, and the knockdown of the GPER gene suppressed the proapoptotic effects of diosgenin in PC3 cells. Our results support the antitumorigenic role of diosgenin and its interest in PCa therapy, alone or in combination with G1, mainly targeting the more aggressive stages of the disease.
- Antimicrobial and antitumor activity of S-methyl dithiocarbazate Schiff base zinc(II) complexesPublication . Gomes, Filipa Ramilo; Addis, Yemataw; Tekamo, Israel; Cavaco, Isabel; Campos, Débora L.; Pavan, Fernando R.; Gomes, Clara S.B.; Brito, Vanessa; Santos, Adriana O.; Domingues, F.C.; Luís, Ângelo; Marques, M. Matilde; Pessoa, João Costa; Ferreira, Susana; Silvestre, Samuel; Correia, IsabelSchiff bases (SB) obtained from S-methyl dithiocarbazate and aromatic aldehydes: salicylaldehyde (H2L1), o-vanillin (H2L2), pyridoxal (H2L3) and 2,6-diformyl-4-methylphenol (H3L4), and their corresponding Zn(II)-complexes (1-4), are synthesized. All compounds are characterized by elemental analyses, infrared, UV-Vis, nuclear magnetic resonance spectroscopy and mass spectrometry. The structures of H2L2 and [Zn2(L1)2(H2O)(DMF)] (1a) (DMF = dimethylformamide) are solved by single crystal X-ray diffraction. The SB coordinates the metal center through the Ophenolate, Nimine and Sthiolate atoms. The radical scavenging activity is tested using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, with all ligand precursors showing IC50 values ~40 μM. Cytotoxicity studies with several tumor cell lines (PC-3, MCF-7 and Caco-2) as well as a non-tumoral cell line (NHDF) are reported. Interestingly, 1 has relevant and selective antiproliferative effect against Caco-2 cells (IC50 = 9.1 μM). Their antimicrobial activity is evaluated in five bacterial strains (Klebsiella pneumoniae, Acinetobacter baumannii, Listeria monocytogenes, Pseudomonas aeruginosa and Staphylococcus aureus) and two yeast strains (Candida albicans and Candida tropicalis) with some compounds showing bacteriostatic and fungicidal activity. The minimal inhibitory concentration (MIC90) of HnL against Mycobacterium tuberculosis is also reported, with H2L2 and H3L4 showing very high activity (MIC90 < 0.6 μg/mL). The ability of the compounds to bind bovine serum albumin (BSA) and DNA is evaluated for H3L4 and [Zn2(L4)(CH3COO)] (4), both showing high binding constants to BSA (ca. 106 M-1) and ability to bind DNA. Overall, the reported compounds show relevant antitumor and antimicrobial properties, our data indicating they may be promising compounds in several fields of medicinal chemistry.