Context: The fruit of Lycium barbarum L. (Solanaceae), known as goji berry, has been exploited for a long time in traditional Chinese medicine. In recent decades, it has received much attention as one of the trendiest functional foods with a wide array of pharmacological activities in Western diets.
Objective: In this study the phenolic profile and potential antioxidant capacity of Lycium barbarum cultivated in Crete (Greece) were investigated.
Materials and methods: The berries were defatted with hexane and then extracted with dichloromethane and methanol using a Soxhlet apparatus. Furthermore, the methanol extract was fractionated with ethyl acetate and butanol. All fractions/extracts were tested for their antioxidant activity (DPPH, FRAP, chemiluminescence). Folin-Ciocalteu and LC-DAD-MS analyses were utilized for the identification of the phenolic compounds.
Results: The total phenolic content ranged from 14.13 ± 0.40 (water fraction) to 109.72 ± 4.09 (ethyl acetate fraction) mg gallic acid equivalent/g dry extract. Ethyl acetate extract exhibited the highest scavenging activities determined as EC50 (4.73 ± 0.20 mg/mL) and IC50 (0.47 ± 0.001 mg/mL) using DPPH and chemiluminescence assays. Seventeen phenolic compounds, including cinnamoylquinic acids and derivatives, hydrocinnamic acids and flavonoid derivatives, were tentatively identified. To the best of our knowledge, quercetin 3-O-hexose coumaric ester and quercetin 3-O-hexose-O-hexose-O-rhamnose are reported for the first time in goji berry fruits.
Discussion and conclusion: The results of this study suggest that consumption of goji berry fruits could serve as a potential source of natural antioxidant compounds and that goji berry phenolic extracts could be exploited for nutritional pharmaceutical purposes.
Keywords: Goji berry; LC-DAD-MS (ESI+); chemiluminescence; polyphenols.