Synthesis and anti-neuroinflammatory activity of N-heterocyclic analogs based on natural biphenyl-neolignan honokiol

[Display omitted] •Isoxazole and pyrazole analogs in B ring of honokiol.•Isoxazole and pyrazole were constructed by nitrile oxide cycloaddition and condensation of 4-chromone and alkylhydrazine.•Two pyrazole analogs strongly inhibit NO production in LPS-activated BV-2 cells by suppressing iNOS and COX-2 expression. Novel isoxazole and pyrazole analogs based on natural biphenyl-neolignan honokiol were synthesized and evaluated for their inhibitory activities against nitric oxide production in lipopolysaccharide-activated BV-2 microglial cells. The isoxazole skeleton was constructed via nitrile oxide cycloaddition from oxime 3 and pyrazole was generated by condensation of 4-chromone and alkylhydrazine. Among the analogs, 13b and 14a showed stronger inhibitory activities with IC50 values of 8.9 and 1.2 µM, respectively, than honokiol.