Extraction Of Saponins From Radix Notoginseng And Flavones From Lespedeza Virgata DC. By Pressurized Microwave-assisted Extraction

Radix notoginseng(Sanqi),the main active constituent of which is saponin,is an important herb to stanch a cut and alleviate pain.The herb is often used to treat various kinds of bleeding and pains.It is a well-known traditional Chinese medicine and is mainly cultivated in Wenshan of Yunnan, China.The genus Lespedeza(Leguminosae)has about 60 species distributing from east Asia to north Australia and north America.The whole plants were used in the treatment of acute and chronic nephritis,azothemia,diuresis.The most important bioactive compounds present within this medicinal species are flavones including rutin and so on.It is reported that flavones have shown significant scavenging of free oxygen radicals and antioxidative activity.The microwave-assisted extraction of active components of Radix notoginseng and Lespedeza virgata DC.was studied in this thesis.Determination of total saponins from Radix Notoginseng by microwave-assisted extraction and absorption spectroscopy was reported.The effects of solvent concentration,ratio of solution to solid,microwave power and radiation time were evaluated by single factor and orthogonal experiments. The extraction conditions of total saponins from Radix Notoginseng by microwave-assisted method were optimized as solvent:sample ratio 100:1 (v/w)of 60%(v/v)ethanol and microwave power of 255 W for 10×20s.Under the optimized conditions the relative standard deviation and the recovery were 1.54%(n=5)and 97.7%～101.8%respectively.Compared with Soxhlet extraction and ultrasound-assisted extraction,microwave-assisted extraction was simple and accurate with good reproducibility.It is suitable for the determination of saponins in all kinds of traditional Chinese medicines.A detail procedure for intermittently extracting Notoginseng Saponin R1, Ginseng Saponin Rg1 and Rb1 from Radix Notoginseng was developed by using an obturated microwave-assisted extraction(MAE)device with pressure and temperature controlling units.The effects of solvent concentration,ratio of solution to solid,microwave power and radiation time were evaluated by single factor and orthogonal experiments.Compared with Soxhlet extraction, cold-maceration and ultrasonic extraction,microwave extraction was a rapid method with a higher yield and less solvent consumption.Less microwave energy was consumed by using intermittent microwave extraction than continuous microwave extraction.Determination of flavonoids from Lespedeza virgata DC.by pressurized microwave-assisted extraction and absorption spectroscopy was reported.The effects of solvent concentration,ratio of solution to solid,microwave power and radiation time were evaluated by single factor and orthogonal experiments. The extraction conditions of flavonoids from leaf of Lespedeza virgata DC.by microwave-assisted extraction method were optimized as:solvent:sample ratio 80:1(v/w),50%(v/v)ethanol and microwave power of 340 W for 6min. The extraction conditions of flavonoids from branch were optimized as: solvent:sample ratio 80:1(v/w),50%(v/v)ethanol and microwave power of 340 W for 5min;and the extraction conditions of flavonoids from root were optimized as:solvent:sample ratio 90:1(v/w),60%(v/v)ethanol and microwave power of 425 W for 5min.Under the optimized conditions the average contents of flavonoids were 10.43%(leaf),5.91%(branch)and 5.29% (root),respectively.Compared with Soxhlet extraction,ultrasound-assisted extraction and cold-maceration by ethol,microwave-assisted extraction was simple and accurate with good reproducibility.It is suitable for the determination of flavonoids in all kinds of traditional Chinese medicines.High performance liquid chromatography-mass spectrometry method was developed for the analysis and identification of compounds extracted from Lespedeza virgata DC..Moreover,different methods were compared on the species and contents of flavonoids extracted from different parts of Lespedeza virgata DC..