2.2. Preparation of Plant Extracts. Leaves and rhizomes of 23
plants were collected locally from Mahasarakham province
in the Northeast of Thailand (Table 1). Plant materials were
cut into small pieces and dried in hot air oven at 45◦C for 3
days.
The dried plants were separately ground into powders
using a small grinder and stored at 4◦C in polypropylene
bags. For extraction, 100 g of each powdered plant materials
and 300mL of 80% ethyl alcohol were added into sterile 2L
Erlenmeyer flask, and the flask was agitated at 100 rpm for
24 h. After filtering through a Buchner funnel andWhatman
No. 1 filter paper, the extracts were concentrated under low
pressure using rotary evaporator. The crude extracts were
reconstituted to have the concentration of 20% (w/v) using
80% ethyl alcohol (v/v, in distilled water) and stored at 4◦C
in glass vials to be used as stock plant extracts. For the tests,
these stock plant extracts were dissolved in distilled water
containing 0.05% Tween 80 to have the concentration of 5%
(w/v).
experiments.
2.2.