Thai red rice extract provides liver protection in paracetamol-treated mice by restoring the glutathione system.

BACKGROUND

The incidence of drug-induced liver disease associated with oxidant-antioxidant imbalance is increasing. Colored rice can potentially improve these hepatic disorders through antioxidative and glutathione-restoring effects.

OBJECTIVE

The objective of this study is to determine the in vitro antioxidant properties of extracts from red (Hom-Dang and Hom-Kularb-Dang) and black (Hom-Dum-Sukhothai and Kum-Doi-Saket) Thai rice cultivars [Oryza sativa L. (Poaceae)] and to examine the in vivo hepatoprotective potential of Hom-Dang extract in paracetamol-treated mice.

METHODS

The in vitro antioxidant properties of the extracts were determined by ABTS, [Formula: see text], [Formula: see text], metal chelating capacity, and lipid peroxidation assays. To investigate hepatoprotective effects in vivo, mice administered 60 mg/kg/d paracetamol were given Hom-Dang extract (128, 256, and 512 mg/kg/d) and/or control antioxidant N-acetyl-cysteine (NAC, 150 mg/kg/d) for 7 and 30 d. Liver health was ascertained by measuring levels of hepatic transaminases (GPT/GOT), determining the glutathione profile (GSH/GSSG ratio), and histomorphological examination of liver tissue.

RESULTS

Hom-Dang extract showed the highest in vitro antioxidant potency (an IC50 value of 36.50 ± 0.46, 12.98 ± 0.23, 21.83 ± 2.58, 15.87 ± 0.30, and 86.21 ± 2.45 mg/mL for ABTS, OH(•), [Formula: see text], metal chelating, and lipid peroxidation, respectively). Mice administered paracetamol exhibited increases in GPT/GOT with decreases in GSH and GSH/GSSG ratio followed by histomorphological signs of liver injury. In the presence of the Hom-Dang extract, the GPT/GOT values were normalized, GSH production was induced, and the GSH/GSSG ratio was increased.

CONCLUSIONS

Thai colored rice cultivars, especially the Hom-Dang variety, are promising candidates for health supplements due to their antioxidative and hepatoprotective properties.