Phenolics

Dimethylsulphoxide (DMSO), RPMI-1640 medium, trypan blue, fetal bovine serum, penicillin/streptomycin antibiotic, Trypsin-EDTA, Folin-Ciocalteau, DPPH and phenolics standards were purchased from Sigma Aldrich Chemical Co. (St. Louis, Mo, USA).de Man Rogosa and Sharpe (MRS) medium was obtained from Merck (Darmstadt, Germany). The commercial minced date fruit (Phoenix dactylifera L. var. Siwi) was purchased from the local market and reserved at room temperature. Human tumor carcinoma cell lines (human colon cancer, Caco-2) and (human larynx carcinoma, Hep-2) that used in this study were obtained from the American Type Culture Collection (ATCC, Manassas, VA, USA). Cell lines were maintained by sub-culturing at the National Cancer Institute, Cairo, Egypt.
Two probiotic lactic acid bacteria (LAB) strains were used in this study i.e. Lactobacillus acidophilus La5 and Lactobacillus sakei NRRL 1917. They supplied from Chr. Hansen (Horsholm, Denmark) and the US Department of Agriculture, Northern Regional Research Laboratories (NRRL), respectively. LAB stock cultures were stored frozen at -20 °C in MRS medium (with 20% glycerol) and activated at 37 °C in MRS medium before use. The numeration of the LAB cells after fermentation and during cold storage was performed by the standard plate count method with MRS agar after a proper dilution and expressed as log CFU/mL.