Inhibitory effects of amber extract on mast cell-mediated allergic reactions

Background and objectives: Amber is a fossilized tree resin and has been traced in traditional medicines used in Russia and China. In the recent studies, amber extract has been shown the potential to treat and prevent Alzheimer's disease, inflammation-related diseases, and obesity-related diseases. Allergic diseases are inflammatory diseases that have become a global clinical health problem. However, there is still a limited report about amber extract functionality on allergic diseases. Therefore, in this study we aim to evaluate the anti-allergy effects and investigate the mechanism of anti-allergy function of amber extract on RBL-2H3. Methods: The RBL-2H3 cells were treated with different type of concentration of amber extract. The toxicity of amber extract was conducted using MTT assay test. The RBL-2H3 cell were stimulated with the allergens, PMA/A23187. β-hexosaminidase is used as a marker to measure the efficacy amber extract in preventing mast cell activation and degranulation. ROS generation was also evaluated. The effect of amber extract on cytokines key mediators' production (IL-4, COX-2, p -38, Akt, and JNK) were also investigated. Results: The result showed that amber extract up to 50 µg/mL has no cytotoxic effect on the RBL-2H3 cells. Treatment with amber extract have significantly suppressed the release of β-hexosaminidase in the dose dependent manner especially at 50 µg/mL concentration. Furthermore, amber extract suppressed the significantly increased amount of intracellular ROS stimulated by PMA/A23187. We also found that amber extract inhibited the increase levels of allergy associated cytokines (IL-4 and COX-2) in a dose dependent manner. In addition, amber extract tends to inhibit the increase of p-38, Akt, and JNK production. Conclusion: Amber extract was found to suppress the release of β-hexosaminidase and the increased of ROS generation. Amber extract significantly inhibited the increase levels of allergy associated cytokines. Amber extract tends to inhibit the increase of p-38, Akt, and JNK production (MAPK's key mediator). MAPKs phosphorylation are also crucial events in the allergic inflammation response. Taken together, these results suggest that amber extract exerts anti-allergic effects by inhibition of MAPK phosphorylation. These results indicate that amber extract may be a promising new anti-allergic inflammatory agent