Purpose Polyphenols possess anti-allergic activities. Catechin is one of the polyphenols that are abundantly present in the Acacia catechu. In this study, the authors investigated the effect of catechin isolated from A. catechu in an experimental mouse model of ovalbumin (OVA)-induced allergic asthma. Design/methodology/approach Catechin was isolated from A. catechu, and phytochemical analysis was carried out by ultraviolet visible and thin-layer chromatography (TLC), high pressure thin-layer chromatography was used for the determination of an amount of catechin present. In a first set of an experiment, the authors have carried out dose-dependent evaluation of catechin on histamine synthesis in normal rats. In another study, allergic asthma was induced in BALB/c mice by intraperitoneal injection of 50 mg OVA dissolved in 4 mg aluminum hydroxide dissolved in 0.2 ml saline on Days 0 and 14. Catechin was given orally at the dose of 100 mg/kg, once a day from Day 1 to Day 35 and after which various respiratory parameters such as tidal volume, respiratory rate and airflow rate, biochemical parameters such as histamine release from mast cells, bronchoalveolar (BAL) lavage fluid analysis and histopathology of lungs were carried out. Findings Catechin showed significant (p < 0.05) improvement in respiratory parameters such as tidal volume, respiratory rate and airflow rate, as well as biochemical and hematological parameters such as blood histamine, serum bicarbonate and nitric oxide levels as compared to the disease control group. The treatment also showed inhibitory effects on histamine synthesis in rat peritoneal as well as BAL mast cells. Also, a significant (p < 0.05) improvement in lung histopathology was observed with catechin. Originality/value From the present study, the authors can conclude that catechin exhibited potent anti-allergic activity by inhibition of histamine synthesis by inhibition of histidine decarboxylase enzyme. The study suggests that catechin has therapeutic potential for the treatment of allergic inflammatory disease in humans.

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Background: Arthritis is a joint disorder that involves inflammation and immune response in joints due to release of various inflammatory mediators. Objective: The objective of present study was to investigate anti-arthritis activity of catechin on complete Freund's adjuvant induced arthritis models in rats. Materials and methods: Rheumatoid arthritis was induced by sub plantar injection of the left hind paw with 0.1ml of complete Freund's adjuvant. Catechin was given orally once a day from day 1 to day 21 at the dose of 100mg/kg, p.o. and after which physical parameters like arthritic index, paw edema, paw thickness, splenomegaly and thymus index, biochemical and hematological parameters like C-reactive protein, serum rheumatoid factor, erythrocyte sedimentation rate and % hemoglobin and histopathology of ankle joints were carried out. Results: Treatment of catechin to freund's adjuvant induced arthritis showed significant improvement in physical parameters like arthritic index, paw edema, paw thickness, splenomegaly and thymus index as well as reduction of inflammatory markers like C-reactive protein, serum rheumatoid factor, erythrocyte sedimentation rate and hemoglobin % as compared to disease control group. Furthermore, in the disease control group protective effect of catechin was observed in hyperplasia of synovium, pannus formation and destruction of the joint space. Conclusion: From the present study we can conclude that catechin exhibited ameliorative effect by acting on immune system in experimental models of adjuvant induced arthritis.