Ethnopharmacological relevance: The isolation of D-pinitol (or 3-O-methyl-D-chiro-inositol) from an aqueous decoction of Desmodium adscendens (Fabaceae) leaves and twigs is reported. The protective and curative effect of this decoction, in which d-pinitol was quantified, and of pure D-pinitol, against chemically-induced liver damage in rats has been evaluated.
Materials and methods: Enzyme levels of aspartate transaminase (AST), alanine transaminase (ALT) and alkaline phosphatase (ALP), which are among the usual biomarkers for liver damage, were determined in serum samples of experimental animals. The protective effects against D-galactosamine-induced and ethanol-induced liver damage of a decoction of D. adscendens, quantified on its main constituent D-pinitol, was investigated in rats. In addition, the curative effects of pure D-pinitol and D. adscendens against chronic D-galactosamine-induced and acute acetaminophen-induced hepatotoxicity in rats was studied. Silymarin was used as positive control.
Results: In a first experiment evaluating the protective effect against acute D-galactosamine-induced liver damage in rats, a significant decrease of AST and ALT was observed for the D. adscendens decoction at a dose equivalent to 5 mg/kg/day and 20 mg/kg/day D-pinitol, as well as 20 mg/kg/day pure D-pinitol. With respect to chronic ethanol-induced liver damage in rats, the protective effects of D. adscendens at doses equivalent to 2 mg/kg/day and 10 mg/kg/day D-pinitol, were not observed for serum AST and ALT levels. However, with respect to reduced mortality of animals, statistical analysis showed a trend towards significance for the Desmodium group receiving a dose equivalent to 10 mg/kg/day D-pinitol, versus the untreated hepatotoxic animals. Additional experiments in rat models of acute acetaminophen-induced and chronic D-galactosamine-induced liver damage indicated that D. adscendens decoction and pure D-pinitol had no curative effect when given in a dose equivalent to 10 mg/kg/day D-pinitol, or up to 20 mg/kg/day as a pure compound daily, respectively.
Conclusions: The aqueous decoction of D. adscendens showed a protective effect in rats against liver damage induced by D-galactosamine and ethanol, and this effect is at least in part due to the presence of D-pinitol. However, no curative effect of D. adscendens decoction or D-pinitol on liver damage induced by the tested chemicals could be demonstrated.
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