Effect of aqueous extracts of <em>Enicostema axillare</em> and <em>Toddalia asiatica</em> on complement system alternative pathway activity

Abstract

Complement system, precisely, the Alternative complement pathway (AP) is the first line of defence against microbial infection. Herbal extracts are known to suppress as well as boost these pathways and have applications accordingly. Here, we explored the effect of aqueous extracts of two commonly used medicinal plants <em>Enicostema axillare</em> (Poir. ex Lam.) A.Raynal (AEEA) and <em>Toddalia asiatica </em> (L.) Lam. (AETA), on <em>in vitro</em> and <em>in vivo</em> AP activity and also compared factor B activity with that of the known immunostimulant levamisole. The <em>in vitro</em> results revealed a concentration dependent increase in the AP for levamisole, AEEA and AETA. The <em>in vivo</em> AP and factor B were studied using rat animal model. The studies were carried out independently using Veronal Buffer Saline (VBS)-AP buffer and Triethanolamine (TEA)-AP buffer to compare the suitability of TEA buffer. The AP activity in terms of concentration of the sample required to cause 50 % hemolysis (APC50) and factor B activity of AEEA and AETA treated animals were significantly (<em>P</em> < 0.05) higher than control. However, AP 50 was significantly (<em>P</em> <0.05) higher for levamisole when compared with that of AEEA or AETA. Significant increase in Factor B activity was observed for AETA, AEEA and levamisole when compared with that of control. Factor B activity of AETA was comparable with that of levamisole (<em>P</em> < 0.05) where as factor B activity of AEEA treated animal was significantly less than levamisole (<em>P</em> < 0.05). The results sugggest VBS buffer to be more sensitive than TEA buffer.