Hepatoprotective Effects of the Polysaccharide Isolated from Tarphochlamys affinis (Acanthaceae) against CCl4-Induced Hepatic Injury

This study was designed to investigate the protective effects of the polysaccharide isolated from Tarphochlamys affinis (PTA) against CCl4-induced hepatotoxicity in rats. Liver injury was induced in rats by the administration of CCl4 twice a week for 2 weeks. During the experiment, the model group received CCl4 only; the treatment groups received various drugs plus CCl4, whereas the normal control group received an equal volume of saline. Compared with the CCl4 group, PTA significantly decreased the activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) in the serum and increased the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx) in the liver. Moreover, the content of hepatic malondialdehyde (MDA) was reduced. Histological findings also confirmed the anti-hepatotoxic characterisation. In addition, PTA significantly inhibited the proinflammatory mediators, such as prostaglandin E2 (PGE2), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α) and myeloperoxidase (MPO). Further investigation showed that the inhibitory effect of PTA on the pro-inflammatory cytokines was associated with the down-regulation of nuclear factor-kappa B (NF-κB). In brief, our results show that the protective effect of PTA against CCl4-induced hepatic injury may rely on its ability to reduce oxidative stress and suppress inflammatory responses.