RESUMEN
8-Acetyl-5,7-diemthoxy-4-phenylcoumarin at concentrations 0.03 to 0.3 mM uncoupled oxidative phosphorylation, in vitro, in rat liver mitochondria. Preincubation of mitochondria with the compound enhanced this effct. Similar uncoupling was observed with 5,7-dihydroxy-4phenylcoumarin; 7-acetonyloxycoumarin; 6,7-dimethyl-4-phenylcoumarin and 4-phenyldaphentin also. All these compounds stimulated mitochondrial ATPase activity three- to eight-fold. However, coumarin, the paretn substance of all these compounds had no effect on oxidative phosphorylation in mitochondria.
Asunto(s)
Cumarinas/farmacología , Mitocondrias Hepáticas/metabolismo , Fosforilación Oxidativa/efectos de los fármacos , Desacopladores/farmacología , Adenosina Difosfato/metabolismo , Adenosina Trifosfatasas/metabolismo , Animales , Técnicas In Vitro , Mitocondrias Hepáticas/enzimología , Consumo de Oxígeno/efectos de los fármacos , Ratas , Estimulación QuímicaRESUMEN
The in vitro effect of aflatoxins M1, B1 and G1 on oxidative phosphorylation by rat liver mitochondria with succinate as substrate has been studied. All these toxins inhibit the electron transport chain at a 1-10-4 M concentration and the site of inhibition is between cytochrome b and cytochrome c or c1. Aflatoxin M1 (AFM1) uncouples oxidative phosphorylation at a concentration of 1-10-6 M and reduces the ADP:O ratio, whereas aflatoxin B1 (AFB1) at 1-10-6 M concentration uncouples oxidative phosphorulation but does not affect the ADP:O ratio. At a concentration of 1-10-5 M, AFB1 also decreases the ADP:O ratio along with the uncoupling of oxidative phosphorylation. Aflatoxin G1 (AFG1) acts as an uncoupler at a relatively higher concentration of 1-10-4 M. Preincubation of mitochondria with these aflatoxins resulted in inhibition of respiration and uncoupling of rat liver mitochondria.
Asunto(s)
Aflatoxinas/farmacología , Mitocondrias Hepáticas/efectos de los fármacos , Mitocondrias Hepáticas/metabolismo , Fosforilación Oxidativa/efectos de los fármacos , Desacopladores , Adenosina Difosfato/metabolismo , Animales , Transporte de Electrón , Cinética , Consumo de Oxígeno/efectos de los fármacos , Ratas , Factores de TiempoRESUMEN
Radiorespirometric studies using glucose labelled at 1, 2, 3-4, and 6 positions and enzymatic studies were conducted to determine the primary pathways of glucose dissimilation in Mycobacterium tuberculosis H37Rv. The pattern of 14CO2 recovery was C3-4 greater than C1 greater than C6 = C2. The Embden-Meyerhof pathway was found to be the predominant pathway for glucose oxidation, operative to the extent of 94%. The pentose phosphate pathway accounted for the remaining 6%. Maximum incorporation of 14C into cellular components was from C2 and C6 labelled glucose.