Proliferative responses of human lymphocytes to cultured allogeneic HeLa cells and to PHA were employed as in vitro cellular immune systems to investigate effects of mercuric chloride on the both proliferative responses. When stimulator HeLa cells were pretreated with mercury, proliferative response of lymphocytes to HeLa cells in the mixed cell culture was suppressed dose-dependently. The response of lymphocytes treated with mercury to HeLa cells was suppressed markedly, even at 15-min exposure to 1×10-5 M HgCl2. The response of lymphocytes to PHA as well as that to HeLa cells was suppressed by mercury treatment, even at 15-min exposure. A possible mechanism for the suppressive effect of mercury on the mixed cell reaction was discussed; mercury modification of molecules at the cell surface of the stimulator cells or responder cells and effects of mercury on macrophages.
To investigate the mechanism by which various biological action of licorice root are brought about, the effects of echinatin as a small constituent of Glycyrrhiza echinata and several related compounds on mitochondrial energy transfer reactions were examined. The results obtained were as follows: 1) Echinatin, 4'-hydroxychalcone, chalcone and 3, 4'-dihydroxychalcone at a low concentration cause deterioration of respiratory control and oxidative phosphorylation of isolated rat liver mitochondria. 2) Chalcone and 4'-hydroxychalcone stimulate both latent and DNP-ATPase activity of mitochondria. Echinatin inhibits DNP-ATPase activity while stimulating range latent ATPase activity in the low concentration. 3) Chalcone and 4'-hydroxychalcone induce a rapid potassium release from mitochondrial vesicles, while echinatin and 3, 4'-dihydroxychalcone have lesser effect than the former two substances. From these results, it can be concluded that echinatin and several related compounds disturb the mitochondrial energy transfer reactions and membrane permeability.
The mutagenicity of kojic acid was studied by means of reversion mutation test in bacteria (Ames test), forward mutation test in cultured Chinese hamster cells and dominant lethal test in mice. A positive result was obtained only in Ames test (TA 98, 1535 and 100) which was not modified by the presence of S-9 fraction. Thus, it is concluded that although kojic acid is a weak mutagen in bacteria, it is nonmutagenic in eukaryotic systems either in vivo or in vitro.