Assessment of the antioxidant and antimutagenic activity of extracts from goji berry of Greek cultivation

Abstract

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.

Keywords: ABTS•+, 2,2΄-Azino-bis-(3-ethyl-benzthiazoline-sulphonic acid; Antioxidant; DPPH•, 2,2-diphenyl-1-picrylhydrazyl; GSH, glutathione; Glutathione; Goji berry; Lipid peroxidation; Muscle cells; Polyphenols; Protein oxidation; ROS, reactive oxygen species; TBARS, thiobarbituric acid-reactive substances.

Graphical abstract

Fig. 1

Representative photo of the protective activity of extract 5 against ROO•- induced DNA damage. Lane 1, plasmid DNA without any treatment; lane 2, plasmid DNA exposed to AAPH; lanes 3–7, plasmid DNA exposed to AAPH in the presence of 0.06, 0.12, 0.24, 0.48 and 1.92 mg/ml of extract respectively; lane 8, plasmid DNA exposed to 1.92 mg/ml of extract alone.

Fig. 2

Cell viability of C2C12 cells after treatment with the goji berry extract. The results represent the mean ± SEM of three independent experiments carried out in triplicate. *p < .05: significantly different from the control value.

Fig. 3

Effects of the goji berry extract 5 after treatment for 24 h on oxidative stress markers in C2C12 cells. (a) The histograms of cell counts versus fluorescence of 10,000 cells analyzed using flow cytometer for the detection of GSH. The histograms represent the detection of fluorescence using 488 and 580 nm as the excitation and emission wavelengths, respectively. (b) The histograms show the cell counts versus fluorescence of 10,000 cells analyzed using flow cytometer for the detection of ROS. The histograms represent the detection of fluorescence using 488 and 530 nm as the excitation and emission wavelengths, respectively. For ROS and GSH measurement, C2C12 cells were incubated with 10 mM DCF-DA and 40 mM mercury orange respectively, for 30 min at 37 °C. The cells were then washed, suspended in PBS, and analyzed using flow cytometry, as described in Materials and methods section. (c) Effects of extract 5 on ROS, GSH, TBARS and CARB are shown. All values are presented as the mean ± SEM of three independent experiments. *p < 0.05: significantly different from the control value.