The influence of royal jelly and human interferon-alpha (HuIFN-αN3) on proliferation, glutathione level and lipid peroxidation in human colorectal adenocarcinoma cells in vitro

Abstract

Among royal jelly’s (RJ) various biological activities, its possible antitumor activity deserves particular attention. The purpose of this study was to investigate the influence of RJ and human interferon-alpha (HuIFN-αN3) on the proliferation of human colorectal adenocarcinoma cells (CaCo-2), and ascertain their effect on intracellular glutathione (GSH) level and lipid peroxidation. We studied the antiproliferative (AP) activity of RJ [(0.1 g/10 mL phosphate buffer saline (PBS)], HuIFN-αN3, (1000 I.U. mL^-1), 10-hydroxy-2-decenoic acid (10-HDA) at 100.0 μmol L^-1, and their different combinations, in the ratio 1:1, 1:2, and 2:1 on CaCo-2 cells. The GSH level was measured by glutathione assay. The lipid peroxidation was measured by malondialdehyde (MDA) assay. Single RJ had a low AP activity: 2.0 (0.5 mg mL^-1). HuIFN-αN3 had an AP activity of 2.5 (208.33 I.U. mL^-1), while 10-HDA had an AP activity of 1.5 (37.5 μmol mL^-1). The highest AP activity of 3.8 was obtained when RJ and HuIFN-αN3 were applied at the ratio 2:1. In that combination the level of GSH was 24.9±2.4 nmol g^-3 of proteins (vs. 70.2±3.2 nmol g^-3 in the control) and the level of MDA was 72.3±3.1 nmol g^-3 (vs. 23.6±9.1 nmol g^-3 in the control). It is assumed that 10-HDA, a major fatty acid component and important constituent of RJ, together with HuIFN-αN3, is responsible for the inhibition of CaCo-2 cells proliferation in vitro. In our study, RJ and HuIFN-αN3 applied at 2:1 decreased the level of GSH and significantly increased the lipid peroxidation via MDA in CaCo-2 cells. Future studies should show whether these GSH- and MDA-related activities of RJ, HuIFN-αN3, 10-HDA, and their combinations may decrease the tumorigenicity index and tumorigenic potential of various tumour cells in vitro