The aim of the research was to investigate the antiendotoxin effects of Sinomenine, Fangchinoline, Stachydrine, Chuanxionggzine, Oxymartrine and Evodiamine. Endothelial cells were challenged with 1 μg/mL LPS for 3 h then treated respectively with six alkaloids at three concentrations (1, 5 and 10 μg/mL). The cells were incubated at 37°C in a cell incubator for 21 h. The supernatants were collected and analyzed the levels of interleukin-1α (IL-1α), thromboxane B(2) (TXB(2)), endothelin-1 (ET-1) and E-selectin by ELISA kits. The results revealed that Sinomenine, Oxymartrine and Evodiamine inhibited the production of IL-1α; Stachydrine, Chuanxionggzine and Evodiamine inhibited the secretion of TXB(2); Sinomenine and Oxymartrine down-regulated ET-1 expression; Fangchinoline and Evodiamine decreased the level of E-selectin. All these changes were significant. Taken together, the data suggested that six alkaloids may effectively reduce inflammatory response via these cytokines.