The Ethanol Extract of Polish Propolis Exhibits Anti-Proliferative and/or Pro-Apoptotic Effect on HCT 116 Colon Cancer and Me45 Malignant Melanoma Cells In Vitro Conditions

Background. Propolis is a natural product widely consumed in folk medicine. Different biological activities, such as anticancer, antioxidant, anti-inflammatory, antibiotic and antifungal effects have been reported for propolis and its constituents. Objectives. An in vitro study focused on an evaluation of the biological activity of EEPP, including its anti-proliferative influence on selected neoplastic cells, considering qualitative-quantitative chemical characterization of Polish propolis. Material and Methods. Cytotoxicity was evaluated by means of the MTT and LDH assays. The apoptosis was determined using fluorescence microscopy with annexin V-FITC. Additional EEPP composition was analyzed by a High Performance Liquid Chromatography (HPLC) method. The antimicrobial activity was evaluated by minimal inhibitory concentrations (MIC) against Streptococcus aureus, Enetecoccus faecalis, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. Results. The total content of flavonoids per quercetin in the examined propolis extract amounted to 0.442 +/- 0.091 mg/mL. The flavonoid compounds identified in Polish propolis included flavones, flavonones, flavonolols, flavonols and phenolic acids. The multi-directional interactions among the various chemical compounds in propolis seem to be the essential biological activities when considering its anticancer effects. The results showed that in case of Me45 and HCT 116 cell lines, the ethanol extract of propolis could inhibit cell growth as well as cell size reduction. Regarding antimicrobial activity, EEPP showed MICs ranging from 0.39 to 6.25 mg/mL. Conclusions. Ethanol extract of propolis from Poland obtained in the study exhibits anti-proliferative activity in different carcinoma cells