Anti-endotoxic effects of syringic acid of Radix Isatidis.

The anti-endotoxic effect of syringic acid (SA) isolated from Radix Isatidis (Banlangen, BLG) was studied. SA was extracted and isolated from BLG and diluted into 1% solution. The content of SA-pretreated endotoxin (ET) was quantitatively determined using Limulus test. The ability of fever induction of ET pretreated with SA was measured using endotoxin-induced fever test in rabbits. The LPS-induced death in mice pretreated with and without SA was compared. Results showed that after pretreatment with SA, 83.16% of ET was destroyed, the ET-induced fever in rabbits relieved markedly and the LPS-induced death rate in mice dropped from 68% to 20%. It was concluded that SA isolated from BLG had anti-endotoxic effects.