RESUMO
Three new compounds were isolated from a MeOH extract of the leaves of Syzygium samarangense, one new cyanogenic glucoside, taxiphyllin 6'-O-gallate (1), one new megastigmane glucoside, actinidioionoside 6'-O-gallate (2), and one new sulfated flavonoid rhamnoside, myricetrin 2â³-O-sulfate (3), together with 14 known compounds, lupeol (4), demethoxymatteucinol (5), cryptostrobin (6), betulinic acid (7), ß-sitosterol glucoside (8), 2R-prunasin (9), myrciaphenone A (10), 1-feruloyl-ß-D-glucopyranoside (11), (3S,5R,6R,7E,9S)-3,5,6,9-tetrahydroxymegastigman-7-ene (12), guaijaverin (13), myricetin 4'-methyl ether 3-O-α-L-rhamnopyranoside (14), myricetrin (15), gallic acid (16) and actinidioionoside (17). The structures of the new compounds were determined through a combination of spectroscopic, HPLC and chemical analyses.
Assuntos
Anti-Infecciosos/química , Antineoplásicos/química , Flavonoides/química , Nitrilas/química , Galato de Propila/análogos & derivados , Syzygium/química , Anti-Infecciosos/isolamento & purificação , Anti-Infecciosos/farmacologia , Antineoplásicos/isolamento & purificação , Antineoplásicos/toxicidade , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Flavonoides/isolamento & purificação , Flavonoides/farmacologia , Sequestradores de Radicais Livres/química , Humanos , Leishmania/efeitos dos fármacos , Espectroscopia de Ressonância Magnética , Metanol/química , Testes de Sensibilidade Microbiana , Conformação Molecular , Nitrilas/isolamento & purificação , Nitrilas/farmacologia , Folhas de Planta/química , Folhas de Planta/metabolismo , Galato de Propila/química , Galato de Propila/isolamento & purificação , Galato de Propila/farmacologia , Syzygium/metabolismoRESUMO
The cytotoxic effects of propyl gallate (PG), its related gallates and gallic acid have been studied in freshly isolated rat hepatocytes. Addition of PG (0.5-2.0 mM) to hepatocyte suspension elicited concentration-dependent cell death accompanied by losses of intracellular ATP, adenine nucleotide pools, glutathione (GSH) and protein thiols. The rapid loss of intracellular ATP preceded the onset of cell death caused by PG. In the comparative toxic effects of PG and related gallates at concentration of 1 mM, octyl gallate (OG), dodecyl gallate (DG) and butyl gallate (BG) elicited an abrupt depletion of ATP, followed by an acute cell death. These gallates were more toxic than PG; the toxic effects of PG were similar to those of methyl gallate (MG) and ethyl gallate (EG). In mitochondria isolated from rat liver, PG caused a concentration-dependent increase in the rate of state 4 oxygen consumption, indicating an uncoupling effect. The rate of state 3 oxygen consumption was inhibited by OG and DG. According to the respiratory control index, the order of impairment potency to mitochondria was OG > BG, DG > PG > EG, MG > gallic acid. These results indicate that PG and related gallates are toxic to hepatocytes and that the acute cytotoxicity may be due to mitochondrial dysfunction.