Antihistaminic and antianaphylactic activity of HK-07, a herbal formulation

Objective: To study the antianaphylactic, antihistaminic and mast cell stabilization activity of HK-07 in experimental animals. Materials and Methods: HK-07 is a polyherbal formulation containing extracts of various plant constituents. The compound HK-07 was evaluated using Wistar rats and Duncan Hartley guinea pigs. The antianaphylactic activity was investigated in rats using the active anaphylaxis model. The effect on mast cell stabilization was performed by ex vivo challenge of antigen in sensitized rat intestinal mesenteries. Antihistaminic activity was studied in guinea pigs using histamine-induced bronchospasm where preconvulsive dyspnea was used as an end point following exposure to histamine aerosol. Dose response studies of HK-07 were conducted at 125, 250, and 500 mg/kg, p.o. in anaphylactic shock-induced bronchospasm in rats. The optimal dose level was used for the remaining experimental models. Results: Treatment with HK-07 at 125, 250, and 500 mg/kg, p.o. showed significant reduction in signs and severity of symptoms (P <0.05), onset (P <0.001) and mortality rate (P <0.05) following anaphylactic shock-induced bronchospasm. HK-07 also significantly reduced the serum IgE levels (P <0.001) in animals compared to untreated controls. Treatment of sensitized animals with HK-07 at 500 mg/kg, p.o. for 2 weeks resulted in a significant reduction in the number of disrupted mast cells (P <0.001) when challenged with an antigen (horse serum). HK-07 significantly prolonged the latent period of convulsion (P <0.008) as compared to control following exposure of guinea pigs to histamine aerosol. Conclusion: The findings from various studies reveal that the antihistaminic and antianaphylactic activity of HK-07 may be due to the mast cell stabilizing potential, suppression of IgE, and inhibition of release of inflammatory mediators.