Antioxidant, antiproliferative and antimicrobial activity of freeze-dried raspberry

Abstract

The main chemical composition, i.e. the total content of bioactive compounds (phenolics 2209.86 ± 70.32 mg GAE/100g FDR, flavonoids 831.87 ± 12.61 mg R/100g FDR and anthocyanins 144.55 ± 0.39 mg CGE/100g FDR), in freeze-dried raspberry (FDR) was evaluated spectrophotometrically. Vitamin C content was determined by HPLC analysis (88.81 ± 4.38 mg vit C/100g FDR). Antioxidant activities of FDR extract were evaluated spectrophotometrically on stable 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals and by electron spin resonance spectroscopy (ESR) method on hydroxyl radicals (• OH). EC50 values were evaluated. EC50DPPH• • was 0.127 ± 0.013 mg/ml, while EC50•OH was 1.366 ± 0.026 mg/ml. Antiproliferative activity of the FDR extract was evaluated in vitro in three human cell lines by colorimetric sulphorhodamine B (SRB) assay. The most pronounced effects were obtained in the breast adenocarcinoma cell line (MCF7). EC50 value was 395.07 ± 96.38 μg/ml. Antimicrobial activity was determined by disk diffusion method. The FDR extract produced a clear inhibition zone (without visible colonies) only toward Staphylococcus aureus. The minimal inhibitory (MIC) and minimal bactericidal (MBC) concentrations of FDR extract were evaluated. The values MIC were in the range of 4.7 - 100 mg/ml, and of MBC in the range of 6.3 - > 100 mg/ml.