Acceleration of the alcohol oxidation rate in rats with aloin, a quinone derivative of Aloe

Abstract

Aloe contains abundant aloin, a C-glycoside derivative of anthraquinone. Based on recent reports indicating that the water extract of Aloe enhances the ethanol oxidation rate and also that quinones, in general, have a functional role in elevating the alcohol oxidation rate in vivo, we have attempted to identify the quinone derivative contained in Aloe that could increase the alcohol oxidation rate. Upon oral administration of aloin (300 mg/kg) given 12 hr prior to the administration of alcohol (3.0 g/kg), the blood alcohol area under the curve (AUC) was found to be decreased significantly (by 40%). This was supported by increases in the rates of blood alcohol elimination and the disappearance of alcohol from the body by 45 and 50%, respectively. Analysis of hepatic triglyceride (TG) levels revealed that both the ethanol and the aloin treatment alone significantly increased the TG levels in a comparable manner; however, the level obtained by the combined treatment of aloin and ethanol was not statistically different from that produced by either treatment alone. The levels of serum L-aspartate:2-oxoglutarate aminotransferase (AST) and L-alanine:2-oxoglutarate aminotransferase (ALT) activities were not increased by acute alcohol intoxication, aloin alone, or by the combined treatment of alcohol and aloin. Pretreatments with aloe-emodin, the anthraquinone aglycone of aloin, resulted in a significantly decreased blood alcohol AUC and an increase in the rate of ethanol disappearance. These results suggested that when the aloin localized primarily in the skin of Aloe is ingested, aloe-emodin (the quinone aglycone) may be released, and the released quinone may produce acceleration of the ethanol metabolism rate in vivo.