Armillariella mellea shows anti-inflammatory activity by inhibiting the expression of NO, iNOS, COX-2 and cytokines in THP-1 cells.

Armillariella mellea (AM), also known as Mi-Huan-Ku, a popular medicinal fungus used in the traditional Chinese medicine for treating headache, neurasthenia and insomnia. In the present study, our aim was to determine the effects of aqueous (AAM) and ethanol (EAM) extracts of A. mellea on lipopolysaccharide (LPS)-induced inflammatory response by measuring the inducible nitric oxide synthase (iNOS), cyclooxygenase-1 and -2 (COX-1 and COX-2) protein expression, cytokines (TNF-alpha, IL-4 and IL-8) formation, nitric oxide (NO) release and prostaglandin (PGE(2)) production in human monocytic (THP-1) cells. At concentration of 100 microg/ml, EAM, but not AAM, effectively protected against LPS-induced cell death in THP-1 cells. At concentrations of 10 approximately 100 microg/ml, EAM showed a potent anti-inflammatory activity as demonstrated by a dose-dependent inhibition of LPS (1 microg/ml)-induced release of NO and PGE(2), and significantly decreased the transcription of proinflammatory cytokines. EAM at 100 mug/ml significantly blocked the LPS induction of iNOS and COX-2 expression, but not COX-1. Therefore, the protective effect of EAM against LPS-induced inflammatory mediators release could explain, at least in part, its effectiveness in alleviating certain inflammatory related diseases.