Investigation of antioxidant capacity, bioaccessibility and LC-MS/MS phenolic profile of Turkish propolis.

Propolis is a resinous bee hive product that has many biological activities. In this study, a total of 11 raw propolis samples were collected from various geographical areas in Turkey. Phenolic compounds were extracted from all samples and analyses of total phenolics and flavonoids and total antioxidant capacities were performed. All the samples showed high total phenolic and flavonoid contents and antioxidant capacities. Moreover, the in vitro bioaccessibility of Turkish propolis samples were investigated according to simulated in vitro gastrointestinal digestion method. Bioaccessibility was increased through the gastric and intestinal phases. Furthermore, the composition of polyphenols (phenolic acids and flavonoids) in Turkish propolis extracts was investigated by LC-MS/MS method. A total of 32 phenolic compounds, including Caffeic acid phenylethyl ester (CAPE) which was observed in all samples, were identified in the samples. Higher CAPE contents were determined in the samples from the Marmara region which is in line with its higher antioxidant capacity values. As a conclusion, propolis samples collected from different geographical locations differ for their phenolic and flavonoid contents, individual phenolic profile and bioaccessibility.