Total phenolic content was measured in triplicate according to the method described by Singleton, Joseph, and Rossi (1965), with a minor modification. 0.2 N Folin Ciocalteu's phenol reagent (0.1 mL) was added to an aliquot (1.0 mL) of the TK extract and left at room temperature for 3 min. Then, 1.0 mL of 7.5% Na2CO3 solution was applied and maintained in the dark for 1 h. As a blank, the test was repeated using distilled water instead of sample. The absorbance was measured at 765 nm using a spectrophotometer (Pharmacia Biotech Ultrospec 1000, Cambridge, UK). The result was expressed as μg gallic acid per g of extract.