The total phenolic content (TPC) of each extract was assessed
using the Folin–Ciocalteu phenol reagent method (Singleton and
Rossi, 1965). The spectrophotometer used was a UV/VIS spectrophotometer
(Lambda Bio20, Perkin-Elmer, Waltham, MA). The
TPC was expressed as gallic acid equivalents (GAE) in mg per root
g FW.