In Vivo Anti-inflammatory and Analgesic Activities of a Purified Saponin Fraction Derived from the Root of Ilex pubescens

Abstract

The root of Ilex pubescens (Mao-Dong-Qing in Chinese, MDQ) has been commonly used for treatment of cardiovascular and inflammatory diseases in the Chinese medical system. The current studies aimed to investigate the anti-inflammatory and analgesic effects as well as the underlying mechanisms of a purified saponin fraction (PSF) derived from MDQ. PSF was found to significantly suppress the paw edema of rats induced by histamine given intraperitoneally at dosages ranging from 12.5-100 mg/kg. Meanwhile, PSF given orally at dosages of 200 and 100 mg/kg significantly inhibited acetic acid-induced abdominal writhing response of mice and prolonged the time required for mouse tail flick after exposure to a source of radiant heat. The mechanistic studies showed that cyclooxygenase-2 (COX-2) protein expression in carrageenan-injected paw tissues of rats was markedly attenuated by intraperitoneal injection of PSF at dosages of 12.5 to 100 mg/kg. PSF could also markedly inhibit production of proinflammatory cytokines, especially IL-1 beta, IL-6 and TNF-alpha, but enhance production of anti-inflammatory cytokines of IL-4 and IL-10 in the carrageenan-injected paw tissues in rats. These effects resulted in an overall attenuation of the ratio of proinflammatory/anti-inflammatory cytokines and, ultimately suppression of the paw edema. In conclusion, the current study has demonstrated the in vivo anti-inflammatory and analgesic effects of PSF, and suggested that the molecular mechanisms might be associated with inhibition of the elevated expression of COX-2 protein and the overproduction of the proinflammatory cytokines, as well as augmentation of the anti-inflammatory cytokines IL-4 and IL-10 in the carrageenan-injected paw tissues of rats.