Subcritical Water Extraction of Ursolic Acid from Hedyotis diffusa

Abstract

An efficient and environmental-friendly extraction method has been developed for extraction of ursolic acid (UA) from Hedyotis diffusa by using subcritical water extraction (SWE). The experiments were carried out at different particle sizes (20-100 mesh), extraction temperature (120-200 • C), extraction time (10-50 min), solvent/solid ratio (20-40 mL/g), and extraction pressure (0.6-3.0 MPa). Response surface methodology (RSM) was employed to optimize SWE conditions, and the maximum UA yield was 6.45 mg/g material. Optimal conditions are as follows: Particle size of 80 mesh, extraction temperature at 157 • C and a solvent/solid ratio of 30 mL/g. The model of experimental response was proved to predict the experimental results very well and demonstrated that UA yield was mainly depended on solvent/solid ratio, followed by particle size and temperature. The purified extract was analyzed by electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS). The acquired precursor ion was m/z 455.3532, which is consistent with calculated value of UA. Furthermore, different extraction methods, including maceration extraction, heat reflux extraction, ultrasonic extraction, microwave-assisted extraction, and SWE were comparatively analyzed, which indicated that SWE was a time-saving, cost-saving and environment-friendly extraction technology for extraction of UA from Hedyotis diffusa.

Extraction of Polysaccharide from Dendrobium nobile Lindl. by Subcritical Water Extraction

“…It is also observed in the SWE of other natural product. 58,59 The effect of the solvent/solid ratio on the polysaccharide yield was explored from 15:1 to 55:1 (mL/g) with an extraction temperature of 140 °C, extraction time at 12.5 min, and extraction pressure at 0.5 MPa. As shown in Figure 2B, the increased solvent/solid ratio had no obvious effect on polysaccharides yield.…”

Subcritical Water Extraction of Natural Products

“…For example, the whole plants of Hedyotis diffusa Willd. [ 13 ] and Centella asiatica L. [ 14 ] have medicinal values and the leaves, nodes, petioles, and roots of these two herbs were grounded before SBWE. Stems and leaves of ginseng [ 15 ], root of Sophora flavescens Ait.…”

“…A comparison of SBWE with traditional extraction technologies (Soxhlet, UAE, and SFE) showed that subcritical water could be a green and efficient substitution for the extraction of sesquiterpene lactones from I. racemose. Xiao et al [ 13 ] developed SBWE for extraction of ursolic acid from Hedyotis diffusa . The RSM model proved to predict the experimental results very well and demonstrated that UA yield was mainly dependent on solvent/solid ratio, followed by particle size and temperature.…”

Gold Nanoparticles from Plant Materials: Green Extraction, Biological Synthesis and Its Beneficials Properties for Cosmeceutical Applications

“…Pressure and temperature play the main roles in SWE, as at ambient condition, water is extremely polar, meanwhile, as the conditions vary, the polarity of water could change, depending on its dielectric constant values [1], [15]. In the subcritical water extraction, factors that may affect the research procedure are pressure, temperature, time, solid to solvent ratio, and particle size depending on the plant chosen as raw materials [14], [16]- [19]. There is research conducted in the optimization Salvia Officinalis L. using SWE [20].…”