Cells (2 105 cell/ml) were seeded onto 96-well plates with
100 ll of medium per well and cultured to sub-confluent for 2 h
(HL-60), or 24 h (MCF-7 and Caco-2). The cells were treated with
various concentrations of the extracts, in triplicate, at 37 C for
24, 48 and 72 h. After incubation, the supernatant was replaced
with 100 ll of medium containing 10% of 5 mg/ml MTT (Sigma)
solution and incubated for an additional 4 h. The supernatant
was removed and 100 ll of solubilising solution (1% Triton X-
100, 0.1 N HCl in isopropanol) was added. The absorbance at
570 nm was measured by ELISA reader with a reference wavelength
at 690 nm. All experiments were performed in triplicate.