Anti-asthmatic effects of type-A procyanidine polyphenols from cinnamon bark in ovalbumin-induced airway hyperresponsiveness in laboratory animals

Increased sensitivity to bronchoconstricting agents, airway inflammation and airflow obstruction are the characteristic feature of the asthma. The present study aimed to study the anti-asthmatic potential of type-A procyanidine polyphenols (TAPP) isolated from Cinnamon (Cinnamomum zeylanicum Syn C. verum, family: Lauraceae) bark against ovalbumin (OVA)-induced airway hyperresponsiveness (AHR) in laboratory animals. Preparation and characterization of TAPP from cinnamon bark was carried out. The AHR was induced in the male Wistar rats by intraperitoneal (i.p.) injection of OVA and boosted with an identical OVA solution (s.c.) on day 7. Rats received oral treatment of TAPP (10, 30 and 100 mg/kg) from day 7 to day 14. After completion of treatment, the rats were challenged with OVA-aerosol intranasal administration (i.n.). The behavioral (lung function test), biochemical (total and differential cell count, level of albumin, nitric oxide (NO) and total protein in serum, lungs and bronchalveolar lavage fluid, bronchoalveolar lavage fluid (BALF)) and histopathological (lung) assessments were performed. Characterization data (HPLC fingerprinting) showed the presence of pentameric procyanidine flavonoid in TAPP (purity – 75.9%). Treatment with TAPP (100 mg/kg) showed the significant decrease (P < 0.001) in breathing rate and PIF whereas the PEF and FEV expired in one second (FEV1) was significantly increased (P < 0.001) as compared to AHR control rats. TAPP also showed the significant increase (P < 0.01) in the level of hemoglobin, RBCs and WBCs. TAPP (100 mg/kg) treatment significantly (P < 0.001) reduced the elevated levels of total protein (lung and BALF), albumin (serum, BALF and lung), goblet cell hyperplasia and inflammatory cell infiltration in lung tissue in OVA-induced hyperresponsive rats. In conclusion, TAPP showed anti-asthmatic effects in OVA-induced hyperresponsive rat model and may have potential therapeutic value for the management of asthma.