342 R. Helal and M. F. Melzig: release of lysozyme activity, respectively. Lower concentrations of 50µg/ml and 25µg/ml had no significant results on lysozyme secretion. Hederacosid C was the only saponin with no statistically significant effects on the release of lysozyme activity regardless of the saponin concentration used (Data not shown). The exceptional saponin tended to inhibit lysozyme activity release was aescin. However, this inhibitory effect was particularly significant at the non-toxic concentration of 50µg/ml, whereas higher concentrations of this saponin had no significant effects on lysozyme secretion. Fig. 2. Percent change in the secreted lysozyme activity of 0.5×10+6 cells/ml HT-29 cell cultures treated with various saponins for 1 hour using sensitive fluorescence- based lysozyme activity assay. Control cultures without saponin addition were considered to have 100% lysozyme activity. All points were measured in triplicate, and each column is representative of average value of six separate experiments. Values with asterisk are significantly different (P<0.05, Mann- Whitney U test) from values of control cultures. Synthesis & secretion of lysozyme activity in cell cultures after long-term treatment with saponins Lysozyme activity levels in HT-29 cultures supplemented with different saponins were measured at various incubation time points of up to 72 hours. Contrary to the tendency towards increased lysozyme secretion observed with the short- term treatment with saponins, epithelial cells treated with saponins for 24 hours showed tendency to decrease in the secretion and the expression of lysozyme activity in the examined cultures. However, this inhibitory effect was mostly associated with toxic effects of the saponins to cells. Sci Pharm. 2011; 79: 337–349