Artigos
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11800
Navegar
9 resultados
Resultados da Pesquisa
Item Síntese de 2-( 2- piridil) quinolinas promovida por micro- ondas e suas atividades antifúngicas(Química Nova, 2017-09) Borel, Carmindo R.; Barbosa, Luiz C. A.; Maltha, Célia R. A.; Fernandes, Sergio A.; Santos, Larissa B.; Takahashi, Jacqueline A.In this work a series of 2-(2- pyridyl)quinolines were prepared via a Povarov reaction between anilines, 2-pyridinocarbadehyde and ethyl vinyl ether under microwaves heating conditions. The optimized conditions herein reported allowed the preparation of several pyridylquinolines in yields in the range of 30-83%, some of them not previously accessible by this multicomponent process. The reported methodology has advantage over previous report due to its larger scope and short reaction time (2 hours). All quinolines obtained were assayed against five species of clinically important yeasts Candida sp and against Cryptococcus neoformans. Some of them possessed a broad spectrum of action including 2-(2-pyridyl)quinoline (20) and 6,8-dimethoxy-2-(pyridin-2-yl)quinolone (22) that were highly effective in inhibiting Candida species (IC50 < 1.95 µg/mL against C. tropicalis and C. krusei). Some compounds were more potent than commercial drugs Nistatin and Miconazole.Item Síntese e avaliação da atividade antimicrobiana de furanonas halogenadas e de compostos análogos aos nostoclídeos(Química Nova, 2010) Barbosa, Luiz C. A.; Maltha, Célia R. A.; Demuner, Antônio J.; Pinheiro, Patrícia F.; Varejão, Jodieh O. S.; Montanari, Ricardo M.; Andrade, Nélio J.Considering the broad spectrum of biological activity of gamma-butyrolactone derivatives, we presented the synthesis of 3,4-dihalo-5-arylidenefuran-2(5H)-ones (17-21) and analogues (24-28) of the natural product nostoclide (7,8). Furanones 17-21 were synthesized from the condensation of aromatic aldehydes with lactones 14 and 15, that were obtained from mucobromic and mucochloric acids. Lactone 15 was converted into the intermediate 23 in 36% overall yield. Compound 23 was then transformed into the nostoclide analogues 24-28. Some of the compounds prepared showed antimicrobial activities against Escherichia coli, Staphylococcus aureus and Bacillus cereus comparable to commercial antibiotics.Item Hederagenin amide derivatives as potential antiproliferative agents(European Journal of Medicinal Chemistry, 2019-04-15) Barbosa, Luiz C. A.; Demuner, Antonio J.; Rodríguez-Hernández, Diego; Martins, João Paulo Ataide; Csuk, René; Fischer (nee Heller), LucieIn this study, a series of C-28 amides derivatives of hederagenin with or without the presence of an acetyl group at positions 3 and 23 in ring A, were synthetized aiming to develop potent cytotoxic agents. Their structures were confirmed by MS, IR, 1H NMR and 13C NMR spectroscopic analyses and their cytotoxic activities were screened in SRB assays using a panel of six human cancer cell lines. The majority of the amide derivatives were cytotoxic for a variety of human tumor cell lines. In general, the hydroxylated derivatives (1a-1d; EC50 in the range 1.2–22.5 μM) were less active than the acetylated derivatives (2a-2n; EC50 in the range 0.4–9.0 μM). Hydroxylated derivative bearing pyrrolidinyl substituent 1c, was the most active for HT29 human line cells (EC50 = 1.2 μM), however their acetylated derivative 2c was the most potent and selective against A2780, FaDu, SW1736 cells, showing EC50 values between 0.4 and 1.7 μM and SI between 5.6 and 24. Staining experiments combined with fluorescence microscopy indicate that the cell membrane became permeable, and finally a process of secondary necrosis was observed. In addition, the docking results showed that acetylated compounds display more affinity to HER2 than to USP7, indicating that HER2 is a most probable receptor, both proteins found in tumor cell line A2780.Item Synthesis and evaluation of cadiolide analogues as inhibitors of bacterial biofilm formation(Medicinal Chemistry Research, 2018-12) Mairink, Simone Z.; Barbosa, Luiz C. A.; Boukouvalas, John; Pedroso, Silvia H. S. P.; Magalhães, Paula P.; Farias, Luiz M.; Santos, Simone G.Bacterial biofilm infections pose a major clinical challenge due to the ability of biofilms to resist high levels of conventional antibiotics. In the present study, we describe the synthesis and biofilm inhibiting properties of nine new butenolides related to the cadiolide family of marine antibiotics. Eight new cadiolide analogues were synthesized using oxazole−ynone Diels−Alder cycloaddition/cycloreversion as the key step. Their effects on bacterial growth and biofilm formation were investigated against a range of Gram-positive and Gram-negative bacteria, namely Staphylococcus aureus, Enterococcus faecalis, Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa. The cadiolide analogues strongly inhibited biofilm formation of the two Gram-positive bacteria (S. aureus and E. faecalis) at concentrations as low as 0.3 μg mL−1 and 0.5 μg mL−1, respectively. The identification of synthetic cadiolides with potent biofilm-inhibiting capabilities opens a new avenue for therapeutic interventions and highlights the potential of this class of compounds for antimicrobial drug development.Item Synthesis, molecular properties and DFT studies of new phosphoramidates as potential urease inhibitors(Medicinal Chemistry Research, 2014-06-28) Oliveira, Fabricio M.; Barbosa, Luiz C. A.; Demuner, Antônio J.; Maltha, Célia R. A.; Pereira, Silvana R.; Horta, Lı́via P.; Modolo, Luzia V.In this work, new phosphoramidates were prepared and screened for their putative urease inhibitory activity. The importance of this class of compounds is related to the wide range of biological activities which they exhibit. Consequently, higher activity shown by phosphoramidates 3a, 4b, 5a, 5b, 5c, and 9a suggests that they could serve as lead substances for the development of novel synthetic compounds with enhanced inhibitory ureolitic activity. Their predicted ADMET properties are also in accordance with the general requirements for drug-like compounds. Structure–activity relationship analyses suggest that the presence of cyclohexylamine group is an important structural feature associated with enhanced activities. DFT calculations were performed to obtain the energy values of HOMO and LUMO, and dipole moment.Item Thiobarbiturates as potential antifungal agents to control human infections caused by Candida and Cryptococcus species(Medicinal Chemistry Research, 2018-01-08) Shabeer, Muhammad; Barbosa, Luiz C. A.; Karak, Milandip; Coelho, Amanda C. S.; Takahashi, Jacqueline A.Hospitalized patients can suffer from Candida and Crytptococcus infections, aggravating underlying health conditions. Due to the development of drug-resistant microorganisms, we report here on the potential of some arylidene-thiobarbiturate to control five Candida spp. and one Cryptococcus species of medical interest. Initially, a bismuth nitrate catalyzed Knoevenagel condensation with thiobarbituric acid and aromatic aldehydes was developed. This new procedure generated seven new and thirteen known arylidene-thiobarbiturate derivatives (1–20) with excellent yields (81–95%), with a reaction time within 20 min. The antimicrobial activities of all compounds were evaluated against Candida albicans, C. tropicalis, C. parapsilosis, C. lusitaniae, C. dubliniensis, and Cryptococcus neoformans. Several compounds were as active as the commercially available drugs (IC50 < 1.95 µg mL−1) towards at least one microbial strain. The results suggest that some of the new compounds can serve as leads for new antimicrobial agents for the treatment of human fungal infections.Item Chemical composition and histochemistry of Sphagneticola trilobata essential oil(Revista Brasileira de Farmacognosia, 2012-01-17) Silva, Cleber José da; Barbosa, Luiz C. A.; Demuner, Antonio J.; Montanari, Ricardo M.; Francino, Dayana; Meira, Renata M. S. A.; Souza, Ana Olívia deAnatomical and histochemical investigations of Sphagneticola trilobata (L.) Pruski, Asteraceae, secretory structures in leaves and stems and the seasonal variation of essential oils were carried out. Histochemical techniques enabled the specific location of the essential oil accumulation in the internal (canals) and external structures (trichomes). Histochemical analysis showed that the secretory trichomes produced steroids. The highest yield was obtained from plants collected in winter, when it was registered low temperature and precipitation. The essential oil was characterized by high percentage of hydrocarbon sesquiterpenes, hydrocarbon monoterpenes and low levels of oxygenated sesquiterpenes. The major components were germacrene D (11.9-35.8%), α-phellandrene (1.4-28.5%), α-pinene (7.3-23.8%), E-caryophyllene (4.6-19.0%), bicyclogermacrene (6.0-17.0%), limonene (1.8-15.1%) and α-humulene (4.0-11.6%). The percentage of most of the individual constituents present in S. trilobata essential oil changed significantly during the months.Item Tailoring natural abenquines to inhibit the photosynthetic electron transport through interaction with the D1 protein in photosystem II(Journal of Agricultural and Food Chemistry, 2017-12-01) Nain-Perez, Amalyn; Barbosa, Luiz C. A.; Maltha, Celia R. A.; Giberti, Samuele; Forlani, GiuseppeAbenquines are natural N-acetylaminobenzoquinones bearing amino acid residues, which act as weak inhibitors of the photosynthetic electron transport chain. Aiming to exploit the abenquine scaffold as a model for the synthesis of new herbicides targeting photosynthesis, 14 new analogues were prepared by replacing the amino acid residue with benzylamines and the acetyl with different acyl groups. The synthesis was accomplished in three steps with a 68−95% overall yield from readily available 2,5-dimethoxyaniline, acyl chlorides, and benzyl amines. Key steps include (i) acylation of the aniline, (ii) oxidation, and (iii) oxidative addition of the benzylamino moiety. The compounds were assayed for their activity as Hill inhibitors, under basal, uncoupled, or phosphorylating conditions, or excluding photosystem I. Four analogues showed high effectiveness (IC 50 = 0.1− 0.4 μM), comparable with the commercial herbicide diuron (IC 50 = 0.3 μM). The data suggest that this class of compounds interfere at the reducing side of photosystem II, having protein D1 as the most probable target. Molecular docking studies with the plastoquinone binding site of Spinacia oleracea further strengthened this proposal.Item Chemical composition and antibacterial activity of essential oils from verbenaceae species: alternative sources of (E)-caryophyllene and germacrene-D(Química Nova, 2011-05-04) Montanari, Ricardo M.; Barbosa, Luiz C. A.; Demuner, Antonio J.; Silva, Cleber J.; Carvalho, Larissa S.; Andrade, Nélio J.Volatile oils from the leaves of Verbenaceae species Aloysia virgata, Lantana camara, Lantana trifolia, Lantana montevidensis, Lippia brasiliensis and Lippia sericea were investigated for its chemical composition and antibacterial activity. The volatile oils were characterized by a high content of sesquiterpenes of which (E)-caryophyllene (10-35%), germacrene-D (5-46%) and bicyclogermacrene (7-17%) were the major components for all studied species. For the flowers, a higher concentration of monoterpenes was observed for the species L. camara, L. trifolia and L. brasiliensis. These compounds probably act as attractive to specific pollinators. The volatile oils from A. virgata was the most active, exhibiting moderate antimicrobial activity against the bacteria Staphylococcus aureus, Bacillus cereus and Escherichia coli.