A novel compound having an excellent NFκB inhibitory effect is provided and specifically disclosed is a compound represented by the following formula (1) or a salt thereof:wherein, R1 represents a hydrogen atom, a lower alkyl group, a lower alkyloxy group, or a halogen atom;R2 represents a hydroxyl group, or a lower alkyloxy group;R3 represents a hydrogen atom, a lower alkyl group, or a halogen atom;R4 represents a hydrogen atom or a lower alkyloxy group;R5 represents a hydrogen atom, a lower alkyloxy group, a halogen atom, a hydroxyl group, or a methylenedioxy group formed together with R6 or an isopropylidenedioxy group formed together with R6;R6 represents a hydrogen atom, a lower alkyloxy group, or a methylenedioxy group formed together with R5 or an isopropylidenedioxy group formed together with R5;R7 represents a hydrogen atom or a lower alkyl group; andR8 represents a hydrogen atom, a hydroxyl group, an amino group, or a lower alkylcarbonyloxy group (excluding the case where R1, R3, R4 and R7 are hydrogen atoms, R2 and R8 are hydroxyl groups, and R5 and R6 are methoxy groups).