The fresh leaf was split down the middle (along the vertical
axis) and each half was weighed and extracted at a ratio of
50 mL water to 1 g of leaf material after liquid nitrogen-aided
crushing. The first half was kept boiling under constant heat
for 60 min, while the other half of the leaf was suspended in
water at room temperature for 60 min to function as the
control. The same methodology was used for the preparation
of the infusion, but instead of boiling under constant heat for
60 min, boiling water was added instead and the sample was
left to stand for 15 min without any additional heating. The
control was the leaves suspended for 15 min in water at room
temperature. Methanolic extracts were prepared with 70 %
methanol, which was previously found to have the highest
extraction efficiency for phenolic compounds in a preliminary
study in our laboratory.