Geniposide from Gardeniae Fructus exerts antipyretic effect in febrile rats through modulating the TLR4/NF-κB signaling pathway

The desiccative ripe fruits of Gardenia (Gardenia jasminoides Ellis) (called Zhizi in China) are known with cold character and the effects of reducing fire except vexed, clearing away heat evil, and cooling blood and eliminating stasis. Zhizi is often clinical formulated to treat various types of fever. Fever is a sign of inflammation and, geniposide from Zhizi has been proved with anti-inflammatory in various inflammatory models. The aim of this study was to investigate the antipyretic role of geniposide with three classical inflammatory fever models and explore the underlying mechanisms. Water extract (WE), high polar part (HP), iridoid glycoside part (IG), and gardenia yellow pigment part (GYP) from Gardeniae Fructus (GF) were obtained from Zhizi. The antipyretic activities of these composes were tested with dry yeast induced fever rats. Geniposide was further purified from IG and the antipyretic activity was evaluated by gavage, intraperitoneal injection, and caudal intravenous injection to rats of fever induced by dry yeast, lipopolysaccharide (LPS), and 2, 4-dinitrophenol (DNP) in rats. Then, the mechanism of geniposide by intragastric administration was studied. The contents of thermoregulatory mediators and inflammatory factors relating to TLR4/NF-κB pathway in serum were determined by ELISA and Western blot, and the pathological changes of the hypothalamus were observed by HE staining. The temperature was decreased by geniposide in the three fever model rats. Geniposide can not only inhibit the increase of inflammatory factors in serum but also protect the hypothalamus from fever pathological damage in the three fever models. Western blot showed that geniposide could inhibit the TLR4/NF-κB pathway. Geniposide exerts antipyretic effect in febrile rats through modulating the TLR4/NF-κB signaling pathway.