In vitro Effects of Saponins on Lysozyme Activity of Human Cells 341 Aescin and Quillaja saponaria saponins had statistically significant inhibitory effects on the total lysozyme activity synthesized by THP-1 cells as well as on the release of lysozyme in cell cultures treated with each of these two saponins for 24 hours and for 48 hours, whereas Hydrocotyle vulgaris and Gypsophila paniculata saponins (Saponinum album) had significant inhibitory effects on both total and secreted lysozyme activity only after 48 hours treatment (Tab. 1). On the other hand, primulic acid (6.25µg/ml) and glycyrrhizinic acid (25µg/ml) caused about 18% significant decrease in the total lysozyme activity expressed by THP-1 cells after 24 hours treatment, while this inhibitory activity disap- peared after 48 hours treatment. Another group of saponins showed no influences on total and secreted lysozyme activity of monocytes after long-term treatment, including ginsenosid-Rd, hederacosid C and saponins from Helianthus annuus marginal flowers. Furthermore, no significant differences were found when these saponins were used at different end-concentrations up to 25µg/ml. Human colon epithelial cells HT-29 Secretion of lysozyme activity in cell cultures after short-term treatment with saponins Majority of the examined saponins stimulated lysozyme secretion after one hour incubation with epithelial cells (Fig. 2). Saponins of Quillaja saponaria, primulic acid and saponinum album stimulated the release of lysozyme activity with no clear dose-effect relationship. Quillaja saponaria saponins at non-toxic concentrations of 3.125µg/ml and 100µg/ml induced significant increases of 54% and 46% in the secreted lysozyme activity respectively, while 12.5µg/ml of this saponin caused less but significant increase of 12%. Primulic acid caused a significant increase of 26% at a concentration of 25µg/ml, while lower concentration of 12.5µg/ml led to more significant increase of 37%. However, primulic acid at 25µg/ml exhibited slight toxicity to cells that was statistically non-significant after one hour treatment, while lower concentrations showed no cytotoxicity. Saponins from Gypsophila paniculata (Saponinum album) caused slight but significant rise of about 18% in the release of lysozyme activity, with no significant difference when two non-toxic concentrations of 12.5µg/ml and 50µg/ml of the saponin were used. A direct dose-effect relationship could be found to some extent with saponins from Hydrocotyle vulgaris, ginsenosid-Rd, glycyrrhizinic acid and Helianthus annuus saponins. Hydrocotyle vulgaris saponins at 12.5µg/ml induced a significant increase of 37% in the secreted lysozyme, while lower doses of 3.125µg/ml and 6.25µg/ml of this saponin had no significant effects. A point to be considered that 12.5µg/ml of Hydrocotyle saponins showed slight toxic effects to the epithelial cells that were statistically non-significant, whereas lower concentrations were non-toxic. Ginsenosid-Rd, glycyrrhizinic and acid Helianthus annuus saponins at the non-toxic concentration of 100µg/ml resulted in significant increases of 37%, 24% and 26% in the Sci Pharm. 2011; 79: 337–349