Anti-allergic activity of compounds from Boesenbergia thorelii

Boesenbergia thorelii extract of rhizomes and its compounds were investigated for anti-allergic activities using antigen-induced β-hexosaminidase release in RBL-2H3 cells. From bioassay-guided fractionation, the chloroform fraction was separated to afford four compounds: asaronaldehyde (1), β-sitosterol-D-glucoside (2), protocatechuic acid methyl ester (3) and 2-hydroxy-1-(3, 4-dimethoxyphenyl) ethanols (4). Their structures were elucidated on the basis of UV, IR and NMR spectroscopic data. Of these, compound 1 (asaronaldehyde) was the most active with an IC50 value of 24.3 μM, followed by 2 (IC50 = 63.3 μM) and 4 (IC50 = 72.6 μM), respectively; whereas compound 3 was inactive (IC50 > 100 μM). Anti-allergic effect of 1 (IC50 = 24.3 μM) was higher than that of ketotifen fumarate (IC50 = 41.1 μM), the positive control. This study may support the use of B. thorelii for treatment of allergy-related diseases. Moreover, this is the first report on biological study and chemical constituents of B. thorelii.