Anti-allergic and antioxidative activities of some compounds from Thai medicinal plants

Evaluation of the anti-allergic and antioxidative activities of compounds from Thai medicinal plants demonstrated that lawsone methyl ether significantly exhibited the inhibitory effect on degranulation in RBL-2H3 cells with an EC50 Of 26.71 muM, while quercetin, a standard control, had an EC50 of 10.02 muM. Other compounds from Thai medicinal plants including lucidin-omega-methyl ether, bergenin, homorapanone, strictosidinic acid and barakol, had no effect on the degranulation assay. In a DPPH radical scavenging assay, strictosidinic acid and barakol were more potent than the positive control, BHT. The EC50 values of strictosidinic acid and barakol were 27.68 and 39.62 muM, respectively. Other tested compounds, including lawsone methyl ether, bergenin, homorapanone and lucidin-omega-methyl ether, had weak antioxidative activities or no activity. In a nitrite assay, only lawsone methyl ether reduced nitrite production with an EC50 of 10.27 muM in RAW 264.7 cells. In conclusion, lawsone methyl ether suppresses degranulation in RBL-2H3 cells and reduces nitrite production in RAW 264.7 cells whereas strictosidinic acid and barakol have an antiradical action against DPPH.