Background

Propolis is a complex resinous sticky substance that honeybees collect from buds and exudates of various plants. Due to propolis versatile biological and pharmacological activities, it is widely used in medicine, cosmetics and food industry. The aim of this study was to evaluate cytotoxic and antioxidative effects of various ethanolic extracts of propolis (EEP) on human colon cancer cell line (HCT-116) and compare it with their composition. HPLC-DAD method was used to determine the chemical composition of propolis samples. 
Results

The most abundant flavonoids in all samples were chrysin, pinocembrin and galangin (12.697- 40.811 µg mg-1). On the other hand, main phenolic acids were caffeic, ferulic and isoferulic acid. Dose and time-dependent inhibition of cell growth of HCT-116 cells was observed in all propolis samples, with IC50 values ranging from 26.33 to 143.09 µg mL-1. Differences in cytotoxic activity of propolis samples were associated with differences in their composition. Our results showed that all EEP samples reduced both superoxide anion radical and nitrite levels and also had strong DPPH scavenging activity.

Conclusion

All tested propolis samples had pronounced cytotoxic and antioxidative activities.