Plant extracts were prepared in accordance to the methods of
Basri and Fan with minor modifications [25]. Briefly, 150 g of
each powdered plant material was soaked in 500 mL of
ethanol for 24 h with shaking. The resultant extracts were
centrifuged at 3000 r/min for 5 min at 4 C. The supernatant
was filtered through Whatman filter paper No. 1 (Whatman,
UK), while the residues were used for a second extraction
with 300 mL of ethanol. After the second extraction, the
filtrates were concentrated under reduced pressure using a
rotary evaporator at 50 C. The crude extracts were collected
and allowed to dry at room temperature