Determination of Oleanolic and Ursolic Acids in Hedyotis diffusa Using Hyphenated Ultrasound-Assisted Supercritical Carbon Dioxide Extraction and Chromatography

Table 1

Yields of the investigated components obtained through the heat-reflux extraction (HRE) method with various solvents (one extraction cycle) and the pure SC–CO₂ extraction method.

Methods/solvents	Extraction yield (mg/g)^a
	OA	UA
HRE^b
Nonpolar
Chloroform	0.582 ± 0.023	2.580 ± 0.105
-Hexane	Not detected	Not detected
polar
0% Ethanol (water)	Not detected	Not detected
10% Ethanol	Not detected	Not detected
20% Ethanol	Not detected	Not detected
30% Ethanol	Not detected	Not detected
40% Ethanol	Not detected	Not detected
50% Ethanol	Not detected	Not detected
60% Ethanol	0.544 ± 0.021	1.171 ± 0.045
70% Ethanol	0.661 ± 0.025	1.674 ± 0.060
80% Ethanol	0.650 ± 0.024	2.283 ± 0.082
90% Ethanol	0.629 ± 0.022	2.601 ± 0.093
95% Ethanol	0.623 ± 0.025	2.340 ± 0.092
99.5% Ethanol	0.599 ± 0.024	2.211 ± 0.081
Pure SC−	Not detected	Not detected

Values are mean ± SD of six replications and are calculated on plant dry weight basis (HD3).
^bThe experimental conditions are described in the experimental section.
^cPure SC−CO₂ conditions: extraction pressure at 10.4–30.0 MPa, extraction temperature at 40–70°C, a static extraction time of 30 min, a dynamic extraction time of 10–180 min, mean particle size at 0.096–0.925 mm, and CO₂ flow rate at 0.6–2.5 mL/min (STP).