Inhibition of tumor necrosis factor-alpha production by orally administering a perilla leaf extract

The overproduction of tumor necrosis factor-alpha (TNF-alpha) was suppressed by orally administering a perilla leaf extract (PLE). When mice were successively injected with OK-432, severe TNF-alpha was induced in the serum, but this elevated TNF-alpha level was reduced after an oral administration of PLE (400 microliters/mouse). Oral administration of PLE also inhibited TNF-alpha production that was induced by muramyl dipeptide (500 micrograms/mouse) and OK-432 (3 KE/mouse). These characteristics were obtained from all strains of perilla. The inhibitory activity against TNF-alpha production was heat-stable, and the existence of several active molecules was suggested. When PLE was passed through an ultrafilter, the inhibitory activity against TNF-alpha production was collected in those fractions with a mass of 0.5 to 1 kDa and more than 10 kDa. When PLE was solvent-extracted, the strongest activity was recognized with aqueous preparation, although significant activity was also detected in preparations extracted with n-hexane and ethyl acetate. These findings suggest that the daily use of certain functional foods may be useful for controlling the host defense system.