Evaluation of inhibition of cancer cell proliferation in vitro with different berries and correlation with their antioxidant levels by advanced analytical methods

Dimethylsulfoxide extracts of Chilean berries [Myrteola nummularia, 'Murtilla-like'] vs. well known 'Murtilla', Chilean and Polish blueberries, and Chilean raspberries were investigated for their antioxidant, quenching and antiproliferative activities. The significantly highest levels of polyphenols, flavonoids, flavanols and their antioxidant activities were estimated in 'Murtilla' (MT) berries (P<0.05), than in other investigated samples. DPPH kinetic measurements were calculated to compare, distinguish and discriminate the antiradical activity among berry extracts by multivariate analysis. The lowest IC(50) values, 751 and 858 μg/ml, were obtained for MT extract on colon cancer cell lines HT-29 and SW48. HT-29 cells treated with MT extract showed a decrease in G1 phase cells from 77% to 56% (P<0.05). At the highest concentration of 2000 μg/ml MT extract caused 90-100% cell growth inhibition. Percentage of death cells treated with MT extract was 80.1% and 72.5% for SW48 and HT-29 cells, respectively. The inhibition of cancer cell proliferation highly correlated with the levels of polyphenols, flavonoids and their antioxidant activities. The interaction between drugs and serum albumin plays an important role in the distribution and metabolism of drugs, therefore the complexation reaction between flavonoids, and berries extracts, and bovine serum albumin (BSA) was investigated by 3-D fluorescence and FTIR spectroscopy. The results indicated that flavonoids and polyphenol extracts have strong ability to quench the intrinsic fluorescence of BSA by forming complexes. A shift in the maximum of amides FTIR-bands appeared. In conclusion, these findings suggest that the intake of a new kind of berry, as a source of natural antioxidants, may reduce colon cancer risk.