Evaluation of radical scavenging and anti-tyrosinase activity of some Citrus fruits cultivated in Turkey via in vitro methods and high-performance thin-layer chromatography-effect-directed analysis

In the present study, the fresh fruit peels of some species of the genus Citrus L. cultivated in Turkey were prepared with 80% methanol using maceration and accelerated solvent extraction. The obtained extracts were compared to spectrophotometric methods due to the total phenolic and flavonoid contents, DPPH radical scavenging activities, and tyrosinase inhibition properties. Moreover, the correlation between the phenolic/flavonoid contents and radical scavenging/anti-tyrosinase activities were evaluated. The fingerprint analysis of the extracts was evaluated by high-performance thin-layer chromatography (HPTLC). Radical scavenging and tyrosinase inhibition properties were also examined via HPTLC-effect-directed analysis to assess the effective components of the extracts. The bioactive unknown zones were isolated from HPTLC plates and analyzed by mass spectrometry. In the extracts, naringin which is responsible for the anti-tyrosinase activity, hesperidin, and neoeriocitrin, which are responsible for the antioxidant activity, were identified tentatively.