The metabolism of 9-chloro-ß-lapachone and its effects in isolated hepatocytes. The involvement of NAD(P)H:quinone oxidoreductase 1 (NQO1).

A ß-lapachone analogue (3,4-dihydro-2,2-dimethyl-9-chloro-2H-naphtho[1,2b]pyran-5,6-dione) (9-chloro ß-lapachone), named CGQ, with antitumoral, antiviral and antitrypanocidal activities was assayed for cytotoxic effects on isolated rat hepatocytes. The incubation of hepatocytes with this o-naphthoquinone showed (a) decreased adenylate energy charge, as a result of a decrease in ATP, and an increase in AMP levels; (b) increased NADP(+) content, with a concomitant decrease of NADPH, NADH and NAD(+) content; (c) decreased GSH content, accompanied by an increase in GSSG formation; (d) stimulated oxygen uptake as well as increased superoxide anion production and hydrogen peroxide formation; (e) inhibited lipid peroxidation; (f) hepatocyte viability was not reduced unless the NQO1 inhibitor dicoumarol was present. We hypothesize that the cytotoxicity of CGQ in dicoumarol-treated hepatocytes was the result of inhibition of the NQO1 detoxification pathway, thus allowing more quinone to be metabolized towards the one-electron pathway to form reactive semiquinones and/or reactive oxygen species. The results obtained indicate a protective role of NQO1 in preventing CGQ cytotoxicity in isolated rat hepatocytes.

Apoptogenic effect of the lipophilic o-naphthoquinone CG 10-248 on rat hepatocytes: light and electron microscopy studies.

CG 10-248 (3,4-dihydro-2,2-dimethyl-9-chloro-2H-naphtho[1,2b]pyran-5,6-dione; CG-NQ), a beta-lapachone analogue, modified the ultrastructure of rat hepatocytes, as demonstrated by light and electron microscopy. After 4 h incubation with 100 microM CG-NQ, the following effects were observed: (a) nuclear chromatin condensation; (b) chromatin fragmentation; (c) displacement of mitochondria, concentrated around the nucleus; (d) disruption or expansion of mitochondrial outer or inner membranes, respectively; (e) displacement and alteration of endoplasmic reticulum (rough and smooth); (f) decrease of microvilli; (g) blebbing of plasma membrane and production of apoptotic bodies formed by folding of plasma membrane fragments around mitochondria or peroxysomes; and (h) production of hydrogen peroxide. Expression of such effects varied according to hepatocyte samples and taken together strongly support an apoptotic action of CG-NQ dependent on "reactive oxygen species".

Apoptogenic effect of the lipophilic o-naphthoquinone CG 10-248 on rat hepatocytes: light and electron microscopy studies.

CG 10-248 (3,4-dihydro-2,2-dimethyl-9-chloro-2H-naphtho[1,2b]pyran-5,6-dione; CG-NQ), a beta-lapachone analogue, modified the ultrastructure of rat hepatocytes, as demonstrated by light and electron microscopy. After 4 h incubation with 100 microM CG-NQ, the following effects were observed: (a) nuclear chromatin condensation; (b) chromatin fragmentation; (c) displacement of mitochondria, concentrated around the nucleus; (d) disruption or expansion of mitochondrial outer or inner membranes, respectively; (e) displacement and alteration of endoplasmic reticulum (rough and smooth); (f) decrease of microvilli; (g) blebbing of plasma membrane and production of apoptotic bodies formed by folding of plasma membrane fragments around mitochondria or peroxysomes; and (h) production of hydrogen peroxide. Expression of such effects varied according to hepatocyte samples and taken together strongly support an apoptotic action of CG-NQ dependent on [quot ]reactive oxygen species[quot ].

Effect of the lipophilic o-naphthoquinone CG 10-248 on rat liver mitochondria structure and function.

CG 10-248 (3,4-dihydro-2,2 dimethyl-9-chloro-2H-naphtho[1,2b]pyran-5,6-dione), a beta-lapachone analogue, modified the ultrastructure of rat liver mitochondria in vitro, in the absence of added oxidizable substrates. The condensed mitochondrial state was replaced by the orthodox or swollen state to a significant degree. The number of modified mitochondria depended on incubation time and quinone concentration, in the 25-100 microM range. Under the same experimental conditions, mitochondrial respiration was uncoupled as indicated by the increase in the rate of succinate oxidation by controlled mitochondria in metabolic state "4" (not in state "3"), and by the activation of latent F0F1-ATP synthase. Taking into account structural similarities, the results reported here may be valid for other o-naphthoquinones, such as beta-lapachone.

Effect of the lipophilic o-naphthoquinone CG 10-248 on rat liver mitochondria structure and function

CG 10-248 (3,4-dihydro-2,2 dimethyl-9-chloro-2H-naphtho[1,2b]pyran-5,6-dione), a beta-lapachone analogue, modified the ultrastructure of rat liver mitochondria in vitro, in the absence of added oxidizable substrates. The condensed mitochondrial state was replaced by the orthodox or swollen state to a significant degree. The number of modified mitochondria depended on incubation time and quinone concentration, in the 25-100 microM range. Under the same experimental conditions, mitochondrial respiration was uncoupled as indicated by the increase in the rate of succinate oxidation by controlled mitochondria in metabolic state "4" (not in state "3"), and by the activation of latent F0F1-ATP synthase. Taking into account structural similarities, the results reported here may be valid for other o-naphthoquinones, such as beta-lapachone.

Effect of the lipophilic o-naphthoquinone CG 10-248 on rat liver mitochondria structure and function

CG 10-248 (3,4-dihydro-2,2 dimethyl-9-chloro-2H-naphtho[1,2b]pyran-5,6-dione), a beta-lapachone analogue, modified the ultrastructure of rat liver mitochondria in vitro, in the absence of added oxidizable substrates. The condensed mitochondrial state was replaced by the orthodox or swollen state to a significant degree. The number of modified mitochondria depended on incubation time and quinone concentration, in the 25-100 microM range. Under the same experimental conditions, mitochondrial respiration was uncoupled as indicated by the increase in the rate of succinate oxidation by controlled mitochondria in metabolic state "4" (not in state "3"), and by the activation of latent F0F1-ATP synthase. Taking into account structural similarities, the results reported here may be valid for other o-naphthoquinones, such as beta-lapachone.(AU)

Effect of the lipophilic o-naphthoquinone CG 10-248 on rat liver mitochondria structure and function.

CG 10-248 (3,4-dihydro-2,2 dimethyl-9-chloro-2H-naphtho[1,2b]pyran-5,6-dione), a beta-lapachone analogue, modified the ultrastructure of rat liver mitochondria in vitro, in the absence of added oxidizable substrates. The condensed mitochondrial state was replaced by the orthodox or swollen state to a significant degree. The number of modified mitochondria depended on incubation time and quinone concentration, in the 25-100 microM range. Under the same experimental conditions, mitochondrial respiration was uncoupled as indicated by the increase in the rate of succinate oxidation by controlled mitochondria in metabolic state [quot ]4[quot ] (not in state [quot ]3[quot ]), and by the activation of latent F0F1-ATP synthase. Taking into account structural similarities, the results reported here may be valid for other o-naphthoquinones, such as beta-lapachone.

Efectos fisiopatologicos del oxido nitrico y su relacion con el estres oxidativo / Psysiopathologic effects of nitric oxide and its relationship with oxidative stress

El óxido nítrico (NO.) es producido por la oxidación de la arginina a citrulina, una reacción catalizada por las enzimas óxido nítrico sintasas (NOS). Se acepta que esa reacción es la única capaz de producir NO en los sistemas biológicos, en condiciones normales o patológicas. El NO regula diferentes funciones en células y tejidos de mamíferos, tales como: (a) el control de la presión sanguínea; (b) la relajación del tono del músculo liso arterial; (c) la agregación y adhesión plaquetaria; (d) la neurotransmisión; (e) la función neuro-endócrina. El NO. también participa en la destrucción de microorganismos patógenos y de células tumorales por leucocitos y macrófagos. La producción de anión superóxido (O2-) y NO. ha sido asociada al desarrollo de muchas patologías, pero recientemente se ha comprobado que la interacción de esas moléculas genera el ión peroxintrito (ONOO-), lo que constituye un importante mecanismo fisiopatológico pues, como oxidante, el ONOO- ataca un gran número de blancos biológicos. Por su influencia sobre la producción de ONOO-, el balance entre la producción de NO y O2- es crítico en la etiología de procesos como hipertensión, ateroesclerosis, enfermedades neurodegenerativas, infecciones virales, daño por isquemia-reperfusión y cáncer.

Efectos fisiopatologicos del oxido nitrico y su relacion con el estres oxidativo / Psysiopathologic effects of nitric oxide and its relationship with oxidative stress

El óxido nítrico (NO.) es producido por la oxidación de la arginina a citrulina, una reacción catalizada por las enzimas óxido nítrico sintasas (NOS). Se acepta que esa reacción es la única capaz de producir NO en los sistemas biológicos, en condiciones normales o patológicas. El NO regula diferentes funciones en células y tejidos de mamíferos, tales como: (a) el control de la presión sanguínea; (b) la relajación del tono del músculo liso arterial; (c) la agregación y adhesión plaquetaria; (d) la neurotransmisión; (e) la función neuro-endócrina. El NO. también participa en la destrucción de microorganismos patógenos y de células tumorales por leucocitos y macrófagos. La producción de anión superóxido (O2-) y NO. ha sido asociada al desarrollo de muchas patologías, pero recientemente se ha comprobado que la interacción de esas moléculas genera el ión peroxintrito (ONOO-), lo que constituye un importante mecanismo fisiopatológico pues, como oxidante, el ONOO- ataca un gran número de blancos biológicos. Por su influencia sobre la producción de ONOO-, el balance entre la producción de NO y O2- es crítico en la etiología de procesos como hipertensión, ateroesclerosis, enfermedades neurodegenerativas, infecciones virales, daño por isquemia-reperfusión y cáncer. (AU)