Fig 1.
Diagram of the UAE system.
Table 1.
Variables and experimental design levels for RSM.
Fig 2.
Effects of different extraction parameters (ethanol concentration, %; ultrasonic intensity, W/cm2; particle diameter, mm; extraction temperature, °C; ultrasonic time, min; solid-liquid ratio, mg/mL and extraction cycle) on yield of total phenolics from the T. chebula fruits.
Values were expressed as mean ± SD (n = 3), and evaluated by one-way AVONA followed by the Tukey test. Different letter and same letter were considered to be statistically significant (p < 0.05) and statistically insignificant (p > 0.05), respectively.
Table 2.
The Box-Behnken experimental design with four independent variables.
Table 3.
ANOVA for response surface quadratic model analysis of variance table.
Fig 3.
Response surface (3D) and contour plots (2D) showing the effects of different extraction parameters (X1: ethanol concentration, %; X2: ultrasonic intensity, W/cm2; X3: solid-liquid ratio, mg/mL) added on the response Y.
Table 4.
Predicted and experimental values of the responses at optimum conditions.
Fig 4.
Antioxidant activities of the UAE extract, the CRE extract and Ascorbic acid.
(A) Reducing power, (B) FRAP, (C) DPPH radical-scavenging activity, (D) ABTS radical-scavenging activity and (E) superoxide radical-scavenging activity. Values were expressed as mean ± SD (n = 3), and evaluated by one-way AVONA followed by the Tukey test. Different letter and same letter were considered to be statistically significant (p < 0.05) and statistically insignificant (p > 0.05), respectively.
Fig 5.
The HPLC chromatogram (a), total ion chromatogram of mass spectrometer in negative ion mode (b) and positive ion mode (c) of the T. chebula fruits extract.
Fig 6.
The MS spectra in negative mode of seven representative compounds in the T. chebula fruits extract: shikimic acid (a), gallic acid (b), 5-O-galloylshikimic acid (c), corilagin (d), peak (e), 3,4,8,9,10-Pentahydroxydibenzo [b, d] pyran-6-one (f), ellagic acid (g).
Fig 7.
The MS spectra in postitive mode of seven representative compounds in the T. chebula fruits extract: gallic acid (a), 5-O-galloylshikimic acid (b), corilagin (c), 3,4,8,9,10-Pentahydroxydibenzo [b, d] pyran-6-one (d), ellagic acid (e).
Table 5.
HPLC-ESI-MS fragmentation (negative and positive ion mode) of the compounds detected in T. chebula fruit extract.