Antibacterial and Antioxidant Properties of Methanolic Extracts of Apple (Malus pumila), Grape (Vitis vinifera), Pomegranate (Punica granatum L.) and Common Fig (Ficus carica L.) Fruits

As people demand to consume natural foods due to health concerns, the investigation of natural compounds for the discovery of new constituents with antibacterial and antioxidant properties is increasing. The aim of the present study was to evaluate antioxidant and antibacterial activities of some fruits including apple (Malus pumila), grape (Vitis vinifera), pomegranate (Punica granatum L.) and common fig (Ficus carica L.) produced in Kermanshah, west of Iran.
The antibacterial activity of fruit extracts were examined by broth micro-dilution and agar disk diffusion methods. Their antioxidant activity were measured using 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing antioxidant power, β-carotene/linoleic acid bleaching and thiobarbituric acid (TBA) methods. The contents of total phenolic (TP) and total flavonoid (TF) of extracts were determined using Folin Ciocalteu and colorimetric methods, respectively.
The highest and lowest antibacterial effects were found for P. granatum and F. carica extracts, respectively. The most antibacterial effect was observed against Bacillus subtilis, followed by B. cereus and Staphylococcus aureus, respectively. The similar sensitivity was observed for Listeria monocytogenes, Salmonella typhimurium and Escherichia coli O157:H7. P. granatum extract had a significant higher DPPH radical scavenging (0.16 ± 0.07 mg/ml), ability to prevent the bleaching of β-carotene (0.09 ± 0.01 mg/ml), ferric reducing power (0.33 ± 0.03 mg/ml) and TBA (0.27 ± 0.01 Meq malondialdehyde/g) values. The highest TP and TF were found in P. granatum, followed by V. vinifera, M. pumila, and F. carica, respectively, which were in consistent with the results of antioxidant and antibacterial properties.
The strong in vitro antioxidant activities of investigated fruit extracts support their traditional application in the treatment and/or prevention of different diseases.