Phytochemical properties, antioxidant activity and mineral content (Fe, Zn and Cu) in Iranian produced black tea, green tea and roselle calyces

In this study, aqueous and ethanol extracts of Iranian produced green tea, black tea and roselle calyces were considered for measurements with respect to their total phenol content (TPC), total flavonoids content (TFC), total tannin content (TTC), total anthocyanins content (TAC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. In addition, the concentrations of copper (Cu), iron (Fe), and zinc (Zn) were quantified. High-performance liquid chromatography (HPLC) analysis protocols were optimized for the quantification of 17 phenolic acids and flavonoids compounds. The highest TPC and TFC were observed in the ethanol extract of green tea. The aqueous extract of green tea showed the maximum TTC. The highest TAC was obtained in the aqueous and ethanol extracts of roselle calyces. HPLC analysis of the methanolic extract showed the presence of caffeic acid, quercetin, hesperidin and hesperetin in all of the studied samples. The minerals were present at concentrations well below the acceptable daily consumption level recommended by health limitation guidelines.