A 1.5 g sample was homogenized with 20 mL of methanol in an Ultra-Turrax homogenizer
(IKA, Ultra-Turrax T25 digital, Germany) for 2 min and
centrifuged (3000 g for 20 min, Sigma, model 4K15, England) at
4 C. A 250 mL aliquot of the supernatant was diluted in 4 mL of
distilled water. The control was prepared using 250 mL of methanol.