[Search for TNF-alpha sensitivity degradation principles from medicinal foods-hepatoprotective amide constituents from Thai natural medicine Piper chaba].

Eighty percent (80%) aqueous acetone extract from fruit of Piper chaba (Piperaceae) was found to have a hepatoprotective effect on D-galactosamine (D-GalN)/lipopolysaccharide (LPS)-induced liver injury in mice. Among the isolates, several amide constituents inhibited D-GalN/tumor necrosis factor-alpha (TNF-alpha)-induced death of hepatocytes, and the following structural requirements were suggested: i) the amide moiety was essential for strong activity; ii) the 1,9-decadiene structure between the benzene ring and the amide moiety tended to enhance the activity. Moreover, a principal constituent, piperine, exhibited strong in vivo hepatoprotective effect at a dose of 5 mg/kg, p.o. and its mode of action was suggested to depend on the reduced sensitivity of hepatocytes to TNF-alpha.