Browsing by Author "Rodriguez, Jaime A."

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    Gastroprotective Effect and Cytotoxicity of Labdeneamides with Amino Acids
    (GEORG THIEME VERLAG KG, 2011) Schmeda Hirschmann, Guillermo; Rodriguez, Jaime A.; Theoduloz, Cristina; Valderrama, Jaime A.
    Semisynthetic aromatic amides from Araucaria araucana diterpene acids have been shown to display a relevant gastroprotective effect with low cytotoxicity. The aim of this work was to assess the gastroprotective effect of amino acid amides from imbricatolic acid and its 8(9)-en isomer in the ethanol/HCl-induced gastric lesions model in mice as well as to determine the cytotoxicity of the obtained compounds on the following human cell lines: normal lung fibroblasts (MRC-5), gastric adenocarcinoma (AGS), and liver hepatocellular carcinoma (Hep G2). The diterpenes 15-acetoxyimbricatolic acid, its 8(9)-en isomer, 15-hydroxyimbricatolic acid, and the 8(9)-en derivative, bearing a COOH function at C-19, were used as starting compounds. New amides with C-protected amino acids were prepared. The study reports the effect of a single oral administration of either compound 50 min before the induction of gastric lesions by ethanol/HCl. Some 20 amino acid monoamides were obtained. Dose-response experiments on the glycyl derivatives showed that at a single oral dose of 100 mg/kg, the compounds presented an effect comparable to the reference drug lansoprazole at 20 mg/kg and at 50 mg/kg reduced gastric lesions by about 50%. All derivatives obtained in amounts >30 mg were compared at a single oral dose of 50 mg/kg. The best gastroprotective effect was observed for the exomethylene derivatives bearing a valine residue at C-19 either with an acetoxy or free hydroxy group at C-15. The tryptophanyl derivative from the acetate belonging to the 8,9-en series presented selective cytotoxicity against hepatocytes. The glycyl amide of 15-acetoxyimbricatolic acid was the most cytotoxic and less selective compound with IC50 values between 47 and 103 mu M for the studied cell lines. This is the first report on the obtention of semisynthetic amino acid amides from labdane diterpenes.
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    Inhibition of human topoisomerase I and activation of caspase-3 by aza-angucyclinones and arylaminopyrimido[4,5-c]isoquinoline-7,10-quinones
    (SPANDIDOS PUBL LTD, 2012) Monsalve, Francisco A.; Valderrama, Jaime A.; Vasquez, David; Ibacache, Andrea; Rodriguez, Jaime A.; Gonzalez, Daniel R.; Leiva, Elba; Gonzalez, Enrique
    Cancer is the second cause of death in the world after cardiovascular diseases. Cancer cells acquire capacities not present in normal cells, such as self-sufficiency, resistance to antiproliferative stimuli, evasion of apoptosis, unlimited replication, invasiveness and metastasis. Consequently, it is of major interest to explore and develop molecules with anticancer activity directed to specific targets. In this study, we aimed to evaluate two series of polycyclic quinones: aza-angucyclinone and arylaminopyrimido[4,5-c]isoquinoline-7,10-quinones, in their capacity to inhibit human topoisomerase I (TOP1) and to trigger apoptosis through activation of caspase-3. We evaluated the capacity of the two series of polycyclic quinones to inhibit TOP1, using a DNA supercoiled relaxation assay and their capacity to induce apoptosis through the activation of caspase-3 in HL60 cells. Both series of quinones inhibited TOP1 activity over 50%. When we evaluated the pro-apoptotic capacity of both series of quinones, at therapeutically relevant concentrations, the arylaminoquinones ADPA-ICC (methyl 7-(4-methoxyphenyl)amino-1,3-dimethyl-5,8-dioxo-5,8-dihydroisoquinoline-4-carboxylate), P4 (9-phenylamino-3,4-dihydrophenanthridine-1,7,10(2H)-trione) and the aza-angucyclinone OH-6H (8-hydroxy-2,4-dimethyl-2H,4H-benzo[g]pyrimido[4,5-c]isoquinoline-1,3,7,12-tetraone) increased the caspase-3 activity by approximately 2-fold over the control. The series of the arylaminoquinones and aza-angucyclinones showed differential antiproliferative capacity. We further identified a group of them that showed antiproliferative capacity possibly through inhibition of TOP1 and by activation of caspase-3. This group of molecules may represent a potential pharmacological tool in treatment against cancer.
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    Studies on quinones. Part 43: Synthesis and cytotoxic evaluation of polyoxyethylene-containing 1,4-naphthoquinones
    (PERGAMON-ELSEVIER SCIENCE LTD, 2008) Valderrama, Jaime A.; Leiva, Hilda; Rodriguez, Jaime A.; Theoduloz, Cristina; Schmeda Hirshmann, Guillermo
    A series of naphthoquinones 2,3-disubstituted with chlorine and oxyethylene groups have been prepared from 2,3-dichloro- and 2,3-dimethoxy-1,4-naphthoquinone. The members of these series were tested on normal human. broblasts and on a panel of four human cancer cell lines. Antitumor activities, which were in the range of IC50 1.3-89.5 mu M, discussed in terms of LUMO energy, lipophilicity and size of the polyoxyethylene moiety. (C) 2008 Elsevier Ltd. All rights reserved.
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    Studies on quinones. Part 44: Novel angucyclinone N-heterocyclic analogues endowed with antitumoral activity
    (PERGAMON-ELSEVIER SCIENCE LTD, 2008) Valderrama, Jaime A.; Colonelli, Pamela; Vasquez, David; Florencia Gonzalez, M.; Rodriguez, Jaime A.; Theoduloz, Cristina
    In the search for new potentially anticancer drugs, series of angucyclinone aza-analogues containing pyridine and pyridopyridazine rings have been designed and synthesized by a highly efficient sequence involving a one-pot step for the synthesis of tricyclic quinone intermediate and highly regiocontrolled cycloaddition reactions with polarized 1,3-dienes. The new N-heterocyclic angular quinones were evaluated in vitro on normal human. broblasts and on a panel of four distinct human cancer cell lines. All tested compounds showed high to moderate antitumor activity. Among the compounds, those with one and two pyridine moieties fused to the quinone system have shown the best effect. Structure-activity relationships established the main structural requirement for the activity of the new potential anticancer drugs. (C) 2008 Elsevier Ltd. All rights reserved.
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    Studies on quinones. Part 46. Synthesis and in vitro antitumor evaluation of aminopyrimidoisoquinolinequinones
    (ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER, 2010) Vasquez, David; Rodriguez, Jaime A.; Theoduloz, Cristina; Calderon, Pedro Buc; Valderrama, Jaime A.
    In the search of structure-activity relationship studies and to explore the antitumor effect associated with the pyrimidoisoquinolinequinone scaffold, several diversily substituted 8-aminopyrimido[4,5-c] isoquinolinequinones were regioselectively synthesized. Variation in the structure of the nitrogen substituent bonded to the 8-position of the pyrimidoisoquinolinequinone system led to a set of alkylamino-, phenylamino- and alkyphenylamino derivatives. The cytotoxic activity of the aminoquinone derivatives was evaluated in vitro using the MTT colorimetric method against one normal cell line (MRCS lung fibroblasts) and four human cancer cell lines (AGS human gastric adenocarcinoma; SK-MES-1 human lung cancer cells, and J82 human bladder carcinoma; HL-60 human leukemia) in 72-h drug exposure assays. Among the series, five compounds exhibited interesting antitumor activity against AGS human gastric adenocarcinoma and human lung cancer cells. The SAR studies revealed that both the nature of the nitrogen substituent into the quinone ring and the methyl group at the 6-position play key roles in the antitumor activity. (C) 2010 Elsevier Masson SAS. All rights reserved.
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    Studies on quinones. Part 47. Synthesis of novel phenylaminophenanthridinequinones as potential antitumor agents
    (ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER, 2011) Valderrama, Jaime A.; Ibacache, Andrea; Rodriguez, Jaime A.; Theoduloz, Cristina; Benites, Julio
    In our search for potential anticancer agents, a series of 8- and 9-phenylamino-3,4-tetrahydro-phenanthridine-1,7,10(2H)-triones with substituent variations at 6-, 8- and 9-positions were prepared using a highly efficient sequence involving: a) solar photoacylation reactions of benzoquinone with arylaldehydes, b) one-pot procedure for the synthesis of 3,4-dihydrophenanthridine-1,7,10(2H)-trione intermediates from acylhydroquinones and c) highly regiocontrolled acid-induced amination reaction of phenanthridinequinones with phenylamines. The members of this series were in vitro evaluated using the KIT colorimetric method against one normal cell line and three human cancer cell lines. The SAR analysis indicates that the location of nitrogen substituents on the quinone nucleus, the presence of methyl, phenyl, furyl and thienyl groups at the 6-position and the aromatization of the angular cyclo-aliphatic ring of the phenylamino-3,4-tetrahydrophenanthridine-1,7,10(2H)-trione pharmacophore play key roles in the antitumor activity. (C) 2011 Elsevier Masson SAS. All rights reserved.
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    Synthesis and antitumor evaluation of 8-phenylaminopyrimido[4,5-c]isoquinolinequinones
    (PERGAMON-ELSEVIER SCIENCE LTD, 2009) Vasquez, David; Rodriguez, Jaime A.; Theoduloz, Cristina; Verrax, Julien; Calderon, Pedro Buc; Valderrama, Jaime A.
    A series of 8-phenylaminopyrimido[4,5-c]isoquinoline-7,10-quinone derivatives were prepared by regioselective amination reaction of pyrimido[4,5-c] isoquinoline-7,10-quinones with arylamines in the presence of a Lewis acid catalyst. Preliminary evaluation of the members of the series against cancer cell lines and assays of activation of their cytotoxic activity on K562 cells with ascorbic acid are reported. (C) 2009 Elsevier Ltd. All rights reserved.