Armeniacae semen has been used in traditional medicine for the treatment of pain and inflammatory diseases. Amygdalin is the major compound of Armeniacae semen, and it is used for treatment of pain and cancers. In the present study, we compared the effects of aqueous extract of Armeniacae semen and a solution of amygdalin extracted from Armeniacae semen on the lipopolysaccharide (LPS)-stimulated cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) mRNA expressions in mouse BV₂ microglial cells. We also compared the effects of these compounds on the prostaglandin E₂ synthesis and the nitric oxide production in mouse BV₂ microglial cells. In the present results, Armeniacae semen and amygdalin suppressed prostaglandin E₂ synthesis and nitric oxide production by inhibiting the LPS-induced enhancement of COX-2 mRNA and iNOS mRNA expressions in mouse BV₂ cells. For the COX-1 expression, Armeniacae semen showed more potent suppression effect compared to the amygdalin. However, amygdalin more potently suppressed the LPS-induced COX-2 mRNA expression compared to aqueous extract of Armeniacae semen. In the case of iNOS mRNA expression, Armeniacae semen and amygdalin showed similar suppressing effects. For the LPS-induced PGE₂ synthesis, amygdalin showed more potent suppressing effect, meanwhile, Armeniacae semen and amygdalin showed similar suppressing effect on NO production. Based on the present results, amygdalin may exert anti-inflammatory and analgesic effect though mainly the inhibition of COX-2 pathway, in contrast Armeniacae semen may exert such effect though both the inhibition of COX-2 and iNOS pathways.

Keywords: amygdalin, Armeniacae semen, cyclooxygenase, inducible nitric oxide synthase, prostaglandin E₂, nitric oxide