Plant polyphenols are secondary metabolites characterized by one or more hydroxyl groups binding to one or more aromatic rings

The aim of the present study was to examine the antioxidant and antibacterial activity of 21 types of honey derived from Mount Olympus (Mt. Olympus), a region with great plant biodiversity. The antibacterial activity was examined against the growth of Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) by the agar well diffusion assay and the determination of the minimum inhibitory concentration (MIC). The antioxidant activity was assessed by using the 2,2‑diphenyl‑1‑picrylhydrazyl (DPPH) and 2,2'‑azino‑bis(3‑ethylbenzothiazoline‑6‑sulphonic acid (ABTS•+) free radical scavenging assays. These activities were compared to Manuka honey which is used as an alternative medicine. The results revealed that all tested honey types exhibited antibacterial activity against S. aureus and P. aeruginosa. The MIC of the tested honey types against S. aureus ranged from 3.125 to 12.5% (v/v), while MIC of Manuka honey was determined to be 6.25% (v/v). The MIC values of the tested honey types against P. aeruginosa ranged from 6.25 to 12.5% (v/v) and the MIC of Manuka honey was determined at 12.5% (v/v). Moreover, the results suggested that the presence of hydrogen peroxide and proteinaceous compounds in the honey types accounted, at least in part, for the antibacterial activity. In addition, the total polyphenolic content (TPC) of the honey types seemed to contribute to the antibacterial activity against P. aeruginosa. Furthermore, some of the tested honey types exhibited potent free radical scavenging activity against DPPH and ABTS•+ radicals, which was greater than that of Manuka honey. The results indicated that not only the quantity, but also the quality of the polyphenols were responsible for the antioxidant activity. Moreover, four honey types exhibiting great antioxidant activity were converted to powder using a freeze drying method. The results indicated that following conversion to powder all honey types, apart from one, retained their antioxidant activity, although their TPC was reduced. On the whole, and at least to the best of our knowledge, the present study is the first that extensively examined the bioactivities of different types of honey derived from Mt. Olympus.

The aim of this study was to assess the antioxidant and antimutagenic activities of ultrasound assisted aqueous extracts from dry goji berry fruits cultivated in Greece. The extracts' free radical scavenging activity was assessed by the DPPH• and ABTS•+ assays. The results from both assays demonstrated that the extracts exhibited strong radical scavenging activity with IC50 values ranging from 1.29 to 3.00 mg/ml for DPPH• and from 0.39 to 1.10 mg/mL for ABTS•+ assay. The investigated extracts also inhibited free radical-induced DNA damage induced by peroxyl (ROO•) radicals with IC50 ranging from 0.69 to 6.90 mg/mL. Τhe antioxidant activity of the goji berry extract exhibited the highest potency in the above assays was also examined in muscle cells. In particular, muscle C2C12 cells were treated with the selected extract at non cytotoxic concentrations for 24 h and four oxidative stress markers were measured: total reactive oxygen species (ROS), glutathione (GSH), lipid peroxidation and protein carbonyl levels. The results showed that the extract at 25 and 100 μg/mL increased GSH levels up to 189.5% and decreased lipid peroxidation and protein carbonyls by 21.8 and 29.1% respectively. The present study was the first on the antioxidant effects of ultrasound assisted aqueous extracts from goji berry fruits in muscle cells.