Abstract
Purpose: This study aimed to determine the total antioxidant capacity (TAC), total oxidant capacity (TOC) and the oxidative stress index (OSI) of ethanolic extracts of some selected red fruit/vegetables; it also aimed to evaluate the antimicrobial effect of this extracts.
Materials and Methods: The fruit/vegetables were extracted with ethanol (EtOH) using a Soxhlet device. TAC, TOC and OSI were determined using Rel Assay kits. The antimicrobial activity of the extracts was screened against two Gram-positive (Staphylococcus aureus, Bacillus subtilis), one Gram-negative bacteria (Escherichia coli) and one fungi (Candida albicans) strains using the agar diffusion method.
Results: The highest TAC (8.407±0.399 mmol/L), TOC (7.277±0.244 µmol/L) and OSI (0.157±0.019) values were determined in red cabbage, red onion, and red radish, respectively. The lowest TAC (3.668±0.437), TOC (3.769±0.568) and OSI (0.058±0.002) values were obtained in red radish, red pomegranate, and red carrot, respectively. Red beets and cabbage showed no antimicrobial activity. Pomegranate extract selectively inhibited the growth of Gram-negative bacteria and fungi, being E. coli the most susceptible one with 21 mm of inhibition zone. Carrot, onion and radish extracts gave similar results on B. subtilis (12-13mm) and E. coli (12-13mm). Onions and radishes extracts do not show anti-fungal activity.
Conclusion: It can be said that the antioxidant potential of red cabbage is very high. In addition, low oxidative stress index of pomegranate and red carrot have shown that endogenous antioxidants in the plant significantly inhibit endogenous oxidants. Pomegranate has been found to be as antimicrobial as antibiotics, even more than some.