Pharmacological Studies on Certain Mushrooms from China

This article focuses mainly on biopharmacological studies of selected Chinese medicinal mushrooms, namely the immunomodulation and antitumor activity of Tricholoma giganteum Massee, blood pressure lowering action and mechanism of Volvariella volvacea (Bull.: Fr.) Sing., and the liver protective effect of Trametes versicolor (L.: Fr.) Lloyd. A polysaccharide-protein complex (PSPC) isolated from the culture filtrates of T. giganteum inhibited the growth of solid Sarcoma 180 in mice, with no sign of toxicity. PSPC showed immunomodulating action in vivo. It restored and increased phagocytic function of peritoneal exudate cells (macrophages) of the tumor-bearing mice. It also exhibited indirect cytotoxicity against P815 and L929 by activating macrophages to release the mediators, such as nitric oxide (NO) and tumor necrosis factor-α (TNF-α). The direct cytotoxicity of PSPC was observed in PU5-1.8, H3B, HL-60, and melanoma cell lines. The antiproliferative activity against PU5-1.8 cells was strong at a dose of 60 μg/ml of PSPC. Therefore, the antitumor activity of PSPC might be due to both host-mediated immunomodulating action and direct cytotoxicity to cancer cells. A fraction isolated from the fruiting bodies of Volvariella volvacea (VE), with a molecular mass of about 10 kDa, was heat stable and resistant to trypsin digestion. The blood pressure changes produced by the extract alone or in the presence of various specific agonists or antagonists were investigated. An intravenous injection of VE produced a hypotensive effect in normotensive rats with an ED50 of 25 mg dry weight/kg body weight. This hypotensive effect of VE was attenuated or blunted in the presence of hexamethonium, phentolamine, pyrilamine, and cimetidine suggesting the involvement of the α-adrenergic component of the autonomic system and/or histaminergic stimulation. The contractile response could be inhibited by the antagonists of serotonin and α-adrenoceptor, ketanserin, and phentolamine, respectively. It is likely that VE contained serotonin-like substances because the mechanism of action of VE was similar to that of serotonin. The protective effects of polysaccharide peptide (PSP) of Trametes versicolor on hepatotoxicity were investigated using carbon tetrachloride (CCl4)-induced and paracetamol (APAP)-induced liver injury in the rat as the chemical hepatitis models. A toxic dose of CCl4 (1.25 ml/kg) raised the levels of serum glutamic pyruvic transaminase (SGPT) and that of glutamic oxaloacetic transaminase (SGOT) in the experimental rats. PSP significantly reduced the elevated levels of both the SGPT and SGOT in rats exposed to CCl4. Similarly, a single oral dose of 1.0 g/kg of APAP was able to produce significantly elevated levels of SGPT and SGOT. Intraperitoneal administration of 300 mg/kg of PSP could significantly reduce the APAP-induced acute elevation in the levels of SGPT and SGOT in rats. PSP probably acts to prevent the fall of hepatic reduced glutathione (GSH) through some GSH-dependent enzymes and preserve the structural integrity of the cellular membrane of hepatocytes, or probably protect paracetamol-induced liver injury through their antioxidant properties acting as a scavenger of free radicals even at low levels of GSH.