ABSTRACT
ObjectiveLipopolysaccharide （LPS）-induced zebrafish inflammation model was used to evaluate the anti-inflammatory activity of different extracts from Lianggesan （LGS） and its component Glycyrrhiza Radix et Rhizoma. MethodDifferent polar fractions of LGS and Glycyrrhiza Radix et Rhizoma were obtained by the principle of similar miscibility. For toxicity observation， the zebrafish （3 day-post-fertilization） was exposed to different concentrations of extracts for 24， 48 and 72 h. The yolk sac of the zebrafish was microinjected with 0.5 g·L-1 LPS to establish the inflammation model， and then the embryos were soaked with different concentrations of extracts to observe their survival status at 72 h and the aggregation of neutrophils in yolk sac at 12 h after treatment. Hematoxylin-eosin staining was used to analyze the yolk sac of the zebrafish microinjected with LPS. Quantitative Real-time polymerase chain reaction （Real-time PCR） was performed to further investigate the anti-inflammatory effects and mechanisms of LGS and Glycyrrhiza Radix et Rhizoma. ResultThe toxicity of LGS and Glycyrrhiza Radix et Rhizoma was decreased with the increase of polarity， and the descending order was petroleum ether>ethyl acetate>n-butanol>water. Compared with model group， the extracts from different fractions of LGS and Glycyrrhiza Radix et Rhizoma prolonged the survival time of the zebrafish， and inhibited the recruitment and aggregation of neutrophils and decreased the infiltration of inflammatory cells in the yolk sac， among which the water fraction of LGS and the ethyl acetate fraction of Glycyrrhiza Radix et Rhizoma had the most significant effect （P<0.01）. In addition， compared with model group， the water fraction of LGS and the ethyl acetate fraction of Glycyrrhiza Radix et Rhizoma down-regulated the mRNA expression of interleukin-6 （IL-6） and tumor necrosis factor-α （TNF-α）， and suppressed the expression of toll like receptor 4 （TLR4） and nuclear factor kappa-B （NF-κB） in LPS-stimulated zebrafish （P<0.01）. ConclusionThe extracts from different fractions of LGS and Glycyrrhiza Radix et Rhizoma exerted protective effects in LPS-induced zebrafish by inhibiting the TLR4 and NF-κB signaling pathways. Moreover， in zebrafish model， the method of administration by soaking was applicable to the high-throughput screening of anti-inflammatory Chinese medicine， which was suitable for the evaluation of anti-LPS activity of Chinese medicine and the different extracts.