Sci Research article Pharm www.scipharm.at Open Access In vitro Effects of Selected Saponins on the Production and Release of Lysozyme Activity of Human Monocytic and Epithelial Cell Lines Racha HELAL, Matthias F. MELZIG * Institute of Pharmacy, Freie Universität Berlin, Königin-Luise-Str. 2+4, 14195, Berlin, Germany * Corresponding author. E-mail: melzig@zedat.fu-berlin.de (M. F. Melzig) Sci Pharm. 2011; 79: 337–349 Published: Accepted: April 18th 2011 April 18th 2011 doi:10.3797/scipharm.1012-15 Received: December 14th 2010 This article is available from: http://dx.doi.org/10.3797/scipharm.1012-15 © Helal and Melzig; licensee Österreichische Apotheker-Verlagsgesellschaft m. b. H., Vienna, Austria. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Lysozyme is one of the most important factors of innate immunity and a unique enzybiotic in that it exerts not only antibacterial activity, but also antiviral, anti- inflammatory, anticancer and immunomodulatory activities. The purpose of the present study was to investigate whether in vitro exposure to saponins can affect the release and production of lysozyme activity in human monocytic cells THP-1, and in human epithelial cells HT-29. Lysozyme activity levels in cell culture fluids were measured using highly sensitive fluorescence-based lysozyme activity assay. Majority of the examined saponins were demonstrated to stimulate significantly the release of lysozyme activity of monocytes and epithelial cells after one hour treatment at non-toxic concentrations. On the contrary, cells treated with saponins for longer periods up to 72 hours showed tendency to decrease in the secretion and production of lysozyme activity. However, these inhibitory effects of saponins observed with long-term treatment periods were mostly associated with toxic effects of saponins to cells. The results suggested positive contribution of some saponins to lysozyme release of monocytes and epithelial cells upon short exposure. Furthermore, demonstrated ability of these saponins to enhance the release of lysozyme activity can present a new mechanism contribute to explaining important biological characteristics of saponins, including the antibacterial, antiviral, anti- inflammatory or immune-stimulating properties. Keywords Lysozyme activity • Saponins • THP-1 • HT-29 • Fluorescence-based assay