ABSTRACT
OBJECTIVE: To investigate and compare the hepatoprotective effects of six different polysaccharides from Dendrobium huoshanense (DHP), D. officinale (DOP'), D. fimbriatum (DFP), D. chrysotoxum (DCP), D. nobile (DNF) and D. moniliforme (DMP) against alcohol-induced subacute liver injury in mice. METHODS: The mice were randomized into the normal control, alcohol control, positive control and Dendrobium treatment groups. Dendrobium treatment groups were divided into different sub-groups, which were intragastrically administered with high(200 mg · kg-1), middle(100 mg · kg-1) and low(50 mg · kg-1) dosages of six Dendrobium polysaccharides for 30 d, respectively. The positive control group were orally administrated with Lyceum barbarum polysaccharides (200 mg · kg-1 b. w) for 30 d. The normal control and alcohol control groups were fed with distilled water at the same volume as polysaccharide for 30 d. On the 16th day, the mice in all groups except the normal control group were intragastrically administered with alcohol(30%, V/V, 10 mL · kg-1) once a day for 14 d to induce subacute liver injury. After the last administration, the mice were fasted for 4 h and euthanized with pentobarbital solution for body weight measurement, blood sampling from abdominal aorta and liver tissue sampling. Then, serum biochemical parameters including alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total bilirubin (TBIL), total cholesterol (TC), triglycerides (TG), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol(HDL-C) were analyzed and hepatic biochemical parameters including TC, TG, alcohol dehydrogenase (ADH), aldehyde dehydrogenase (ALDH), antioxidant enzymes (SOD, CAT, GSH-PX, GR, GST), glutathione(GSH) and malondialdehyde(MDA) were determined. Meanwhile, the histopathological changes in liver tissues were observed and the mRNA expression of hepatic CYP2E1, TNF-α and IL-1β in mice were measured. RESULTS: Compared with the alcohol control group, different polysaccharides from six Dendrobium species showed different hepatoprotective effects against alcohol-induced liver injury. Among all tested polysaccharides, DHP and DOP possessed the highest potential for protecting the liver from hepatotoxicity caused by alcohol intake, which was evidenced by the decreased levels of ALT, AST, ALP, TBIL, TC, TG and LDL-C in serum and TC, TG, MDA, CYP2E1, TNF-α and IL-1β in hepatic tissues, the increased levels of HDL-C in serum and SOD, CAT, GSH-PX, GR, GST, GSH, ADH and ALDH in hepatic tissues, and the ameliorated histopathological changes of hepatic tissues. CONCLUSION: DHP and DOP can protect against hepatotoxicity caused by alcohol intake in mice by inhibition of hepatic oxidative damage and inflammatory damage. The differences of hepatoprotective effects between different Dendrobium polysaccharides might be related to their differences in chemical structures including molecular weight, monosaccharide compositions and glycosidic linkages.