Effect of flavonoids from Prosthechea michuacana on carbon tetrachloride induced acute hepatotoxicity in mice

Context: Prosthechea michuacana W. E. Higgins (LaLlave & Lex) (Orchidaceae) is an orchid that has been used in traditional medicine for the treatment of inflammation, diabetes, wound, and liver disorders. Therefore, we thought it would be worthwhile to study the effect of this orchid on liver damage using mice as model. Objective: The present study investigates the effect of flavonoids isolated from methanol extract of P. michuacana on carbon tetrachloride (CCl4)-induced liver damage in mice. Materials and methods: The methanol extract was purified by repeated column chromatography, resulting in the identification of five metabolites whose hepatoprotective effects were evaluated by measuring aspartate transaminase, alanine transaminase, alkaline phosphatase, glutamate, total bilirubin level, lactate dehydrogenase, total serum protein, and lipid peroxidation (thiobarbituric acid reactive substances assay) in CCl4-induced hepatic injury in mice. Results: From the bulbs of P. michuacana, four known flavonoids were isolated (scutellarein 6-methyl ether, dihydroquercetin, apigenin 7-O-glucoside, and apigenin-7-neohesperidoside), together with the new flavonol glycoside apigenin-6-O-beta-D-glucopyranosil-3-O-alpha-L-rhamnopyranoside. Their structures were characterized by 1D and 2D nuclear magnetic resonance experiments. Treatment with flavonoids significantly prevented the biochemical measurable changes induced by CCl4 in the liver. Compounds 1, 4, and 5 were found to exhibit good hepatoprotective effect. These effects were comparable to that of the standard drug silymarin, a well-known hepatoprotective agent. Discussion: These results demonstrate that flavonoids contained in the bulbs of P. michuacana contribute to the hepatoprotective activity attributed to the plant.