The fresh leaves of G. procumbens were collected in March 2013
from Khon Kaen Province, Thailand. Fresh leaves (5 kg) were
washed to remove surface pollutants and dried under hot air
at 60 °C for 48 h, according to our pre-experiments, in which
the temperature range of 30–90 °C was considered and we found
that the contents of total phenolics and flavonoids increased
up to a maximum at 60 °C and decreased afterwards during
the drying process. After drying, the sample was ground into
a fine powder, passed through a 60 mesh sieve to obtain a particle
size of approximately 210 _m (moisture content of 7% dry
basis) and then stored at room temperature in desiccators until
further analysis within 24 h.