Leaves of Cratoxylum formosum ssp. formosum
(Cff) contain high amounts of phenolic compounds with potential
anti-oxidant properties. In this study, the effects of the extraction
method on the recovery of phenolic compounds from Cff leaves were
investigated. Response surface methodology (RSM) was used to optimize
the extraction conditions based on the simultaneous maximization of
yields of total phenolics, chlorogenic acid, and antioxidant activity.
The extraction conditions were investigated using a central-composite
rotatable design of response surface methodology (RSM-CCRD). The
independent variables used were ethanol concentration, extraction
temperature, and time. The experimental results fitted the model well
and the investigated variability was explained. Maximal yields of total
phenolics, chlorogenic acid, and the extract with good antioxidant
activity were achieved by using an ethanol concentration of 38.83 %v/v,
temperature of 59.76 °C, and time of 5.50 h. These conditions gave the
extraction yields of total phenolics, chlorogenic acid, and anti-oxidant
activity of 43.52 ± 3.66 mg gallic acid equivalent (GAE)/g,
119.36 ± 6.34 mg/g, and 0.82 ± 0.08 mmol trolox equivalents (TE)/g dry
powder of plant leaves. The experimental values agreed with those
predicted within a 95 % confidence interval, thus indicating the
suitability of RSM in optimizing the extraction of phenolics from Cff.