| Natural plant contains a diverse group of bioactive substances with a broad range of applications in medicine, healthcare product and cosmetic. China is rich in medical herb resources, but has a weak market share (less than 5%) for plant extract in the world market. Past methods for extracting these bioactive compounds from complex plant matrixes have varied from traditional solvent extractions to more modern techniques such as supercritical fluid extractions, pressurized fluids extraction, microwave-assisted extraction, and ultrasound-assisted extraction. But there are many limitations of the present extraction technology: usage of organic solvents, often toxic and high flammable, low yields of an extraction for one stage of processing, as a corollary one multiple repetition of the extraction. The utilization of great quantities of organic solvents makes the technology very expensive, fire hazard and ecologically dangerous. Therefore, environmental friendly and industry-ready technique with low cost and enhanced efficiency is required in order to accelerate the development of herb extract industry in China.The present study was focused on the pressure-shear induced chemical transitions(PICT) assisted extraction of andrographolide from Andrographis paniculata, total triterpene acid from fir needles and syringin Eleutherococcus senticosus with water as solvent. First, the chemical reagent was selected according to the yield of target compounds by PICT assisted extraction; Second, a preliminary investigation was conducted on the interaction of the target compound-chemical reagent. Different pretreatment was compared with respect to their effects on the plant material morphology as well as the target compound yield. Finally, the PICT process was optimized based on both orthogonal and one-factor experiment, and was compared with conventional heat reflux extraction.Preliminary investigation showed that andrographolide could possibly be neutralized by Na2CO3, and certain complexes may have been formed between andrographolide and hydroxypropyl-β-cyclodextrin (HP-β-CD) after the solid grinding process; total triterpene acid could possibly be neutralized by Na2CO3; certain complexes may have been formed between syringin and HP-β-CD after the solid grinding process. The yield of PICT treated samples (extracting with water) was significantly improved (P <0.05) comparing with physical mixing and superfine grinding samples. Both particle analysis and scanning electron micrographs suggested that the plant cell wall could be broken up after the mechanochemcal treatment.The optimum parameters for PICT assisted extraction of andrographolide were as follows: (1) alkali reagent. Na2CO3 content, 3% (w/w); milling period, 45min (particle size, D95≤37μm); extraction solvent, water; liquid/solid ratio, 1:60 g:ml. (2) HP-β-CD reagent. HP-β-CD content, 13% (w/w); circulating water temperature, 70℃; milling period, 25 min.The optimum parameters for PICT assisted extraction of total triterpene acid were as follows: Na2CO3 content, 5% (w/w); milling period, 35 min (particle size, D95≤37μm); extraction solvent, 20% v/v aqueous ethanol; liquid/solid ratio, 1:40 g:ml. Aqueous ethanol was replaced by water, and no significant difference in yield was observed with other optimized parameters settings.The optimum parameters for PICT assisted extraction of syringin were as follows: HP-β-CD reagent. HP-β-CD content, 23% (w/w); circulating water temperature, 40℃; milling period, 45 min.Under the optimized parameters determined herein, significant enhancement such as improved yield, shorter time and more simplified procedures over heat-reflux extraction was observed, which makes PICT (a combination of physical and chemical method) a potential convenient tool for andrographolide from Andrographis paniculata, total triterpene acid from fir needles and syringin Eleutherococcus senticosus. Moreover, the favorable solvent is water, making PICT assisted extraction a less expensive and eco-friendly technique.
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