The anti-endotoxic effect of o-aminobenzoic acid from Radix Isatidis

Aim: To study the anti-endotoxic effect of o-aminobenzoic acid (OABA) isolated from Banlangen(BLG). Methods: OA-BA was extracted and isolated from BLG and diluted into 0.5% solution. The concentration of endotoxin (ET) pretreated with OABA was quantitatively detected using Limulus test. The inhibition of ET induced fever by OABA was measured in rabbits. The rates of lipopolysaccharides (LPS)-induced death in mice pretreated with or without OABA were then compared. The influence of OABA on the release of TNF-alpha and NO from macrophages induced by LPS was examined in mice. Results: After pretreatment with OABA, 84.4% of ET was destroyed. The ET-induced fever in rabbits decreased significantly and the rate of LPS-induced death in mice dropped from 70% to 20%. The release of TNF-a and NO induced by LPS in mice was inhibited dose-dependently when the concentration of OABA was between 0.125% and 0.5%. Conclusion: OABA isolated from BLG has an anti-endotoxic effect.