Anti­inflammatory effects of dihydromyricetin in a mouse model of asthma.

Dihydromyricetin (DHM) is a plant flavonoid and is the primary active ingredient isolated from the medicinal herb, Ampelopsis grossedentata. DHM has been shown to possess various pharmacological activities, including anti­inflammatory effects. However, the possible role of DHM in asthma treatment remains to be elucidated. The present study aimed to investigate its anti­inflammatory properties in mice with symptoms of allergic asthma. The C57BL/6 mice were sensitized and challenged with ovalbumin (OVA) to induce asthma. DHM or phosphate­buffered saline treatment was administered 1 h prior to the OVA challenge. The levels of interleukin (IL)­4, IL­5 and IL­13 in the bronchoalveolar lavage (BAL) fluid were measured by enzyme­linked immunosorbent assay (ELISA), and OVA­specific serum IgE and IgG1 levels were also determined by ELISA. Histopathological staining was performed to evaluate the infiltration of inflammatory cells into the BAL fluid, lung tissues and goblet cell hyperplasia. DHM treatment significantly reduced the total number of inflammatory cells, including eosinophils, neutrophils, lymphocytes and macrophages, in the BAL fluid. DHM also reduced the levels of IL­4, IL­5 and IL­13 in the BAL fluid, and reduced the secretion of OVA­specific IgE and IgG1 in the serum. The histological staining demonstrated that DHM treatment effectively suppressed the OVA­induced inflammatory cells in the lung tissues and in the mucus hypersecreted by goblet cells in the airway. These results showed that DHM had a potent anti­inflammatory effect in an OVA­induced mouse model of asthma, offering potential as an anti­inflammatory agent for the treatment of asthma.