RESUMO

New molecular hybrids were synthesized by combining tetrahydroquinoline (THQ) and isoxazole (ISX) scaffolds, in search for chemical structures with improved pharmacological properties. Our tetrahydroquinoline (THQ) and isoxazole (ISX) hybrids differ in the X and Y substituents: FM53 (X = H; Y= H), FM49 (X = CH3; Y= OCH3), FM50 (X = Cl; Y= H) and FM48 (X = Cl; Y= OCH3). Aiming at exploring their bioactivity in liver cancer cells, in this paper we report the effect of four THQ-ISX hybrids on viability, respiration and oxidative stress in Hep-G2 human hepatoma cells. In addition, we measured the alterations induced by these compounds on oxygen uptake and respiratory chain enzymes in isolated mitochondria. Cell viability assay indicated that these THQ-ISX hybrids displayed antiproliferative activity on Hep-G2 cells. Among these, FM50 (IC50 = 5.2 ±â€¯1.9 µM) and FM53 (IC50 = 6.8 ±â€¯0.7 µM) had the highest cytotoxicity. These four hybrids also inhibited the Hep-G2 cells respiration in the uncoupled state, with FM50 decreasing all respiratory states (basal, leak, uncoupled). While only FM49 and FM53 altered the Hep-G2 cells redox function. In terms of mitochondrial bioenergetics, THQ-ISX hybrids decreased the oxygen consumption in state 3 (via complex I and II), and also inhibited NADH oxidase and NADH cytochrome c reductase enzyme activities. In these experiments, the structural homologues FM50 and FM53 had a remarkable inhibitory effect (~50%) with respect to FM49 and FM48. These results show that THQ-ISX hybrids are promising compounds for hepatoma cancer treatment and that the phenyl substituent (Y= H) in the ISX scaffold intensifies both, the cytotoxicity in Hep-G2 cells and, inhibition of electron transport through complex I of the mitochondrial respiratory chain.

Assuntos

Metabolismo Energético/efeitos dos fármacos , Isoxazóis/química , Mitocôndrias Hepáticas/metabolismo , Quinolinas/química , Animais , Antineoplásicos/química , Antineoplásicos/metabolismo , Antineoplásicos/farmacologia , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/patologia , Sobrevivência Celular/efeitos dos fármacos , Células Hep G2 , Humanos , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patologia , Masculino , Complexos Multienzimáticos/metabolismo , NADH NADPH Oxirredutases/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Ratos , Ratos Wistar

RESUMO

Antecedentes: El linalool (2,6-dimetil-2,7-octadien-6-ol) es un monoterpeno presente en más de 200 tipos de plantas, y constituye el componente mayoritario de varios aceites esenciales. El linalool posee una amplia variedad de potenciales propiedades farmacológicas; que van desde propiedades antisépticas, ansiolíticas, anti-inflamatorias, antifúngicas, antimicrobianas y proapotóticas en diferentes líneas de células tumorales. Sin embargo, su principal uso está relacionado como una molécula odorante o fragancia en productos de uso tópico en productos cosméticos y en la industria del perfume. Objetivo: En este estudio se evaluó el efecto del linalool sobre la bioenergética de mitocondrias aisladas de hígado de rata. Métodos: El linalool en concentraciones entre (5-100µg/mL) fue evaluado en mitocondrias aisladas de ratas machos albinas raza Wistar, de acuerdo al método descrito por Voss et al (1961). Inicialmente, se determinó el consumo de oxígeno en mitocondrias intactas mediante un método polarográfico por medio de un oxígrafo. Posteriormente, se determinó el efecto del compuesto sobre las enzimas de la cadena respiratoria mitocondrial usando métodos polarográficos y espectrofotométricos. Resultados: Los resultados obtenidos indican que el linalool en las concentraciones de 5, 10, 50 y 100µg/mL, afecta la velocidad de consumo de oxígeno en el estado 3 y 4 de mitocondrias energizadas con glutamato-malato y succinato. Sin embargo, el efecto inhibitorio es mayor al usar glutamato-malato como sustrato. Por su parte, el análisis de la actividad de las enzimas de la cadena respiratoria mitocondrial mostró que el linalool (50µg/mL) inhibe los complejos I, III y la actividad ATPasa. Conclusiones: El linalool inhibe el complejo I, complejo III y la ATPasa, esta inhibición podría aumentar la generación de especies reactivas de oxígeno.

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Background: The linalool (2,6-dimethyl-2 ,7-octadiene-6-ol) is a monoterpene present in more than 200 types of plants, and it is the major component of several essential oils. The linalool has a wide range of potential pharmacological properties, such as antiseptic, anxiolytic, anti-inflammatory, antifungal, antimicrobial and proapoptotic in different tumor cell lines. However, its primary use is associated as an odorant molecule or fragrance in topical products, in cosmetics products and fragrance industry. Objective: In this study the effect of linalool on the bioenergetics of isolated rat liver mitochondria was evaluated. Methods: Linalool in concentrations between (5-100µg/mL) was evaluated in isolated mitochondria of male albino Wistar rats, according to the method described by Voss et al (1961). Initially, the oxygen consumption by intact mitochondria was determined by polarographic method using an oxygraph. Subsequently, the effect of the compound on mitochondrial respiratory chain enzymes was evaluated, by using polarographic and spectrophotometric methods. Results: The results obtained indicated that linalool, at concentrations of 5, 10, 50 and 100µg/mL, affects the rate of oxygen consumption in state 3 and 4 of mitochondria energized with glutamate-malate and succinate. However, the inhibitory effect was greater when using glutamate-malate as substrate. For its part, the analysis of the enzyme activities of the mitochondrial respiratory chain showed that linalool (50µg/mL) inhibits complex I, III, and ATPase activity. Conclusions: linalool inhibits complex I, complex III and ATPase, this inhibition could increase the generation of reactive oxygen species.

Assuntos

Humanos , Metabolismo Energético , Mitocôndrias , Consumo de Oxigênio , Ratos Wistar , Enzimas