Studies On The Determination, Purification Of Flavonoids Of Cyclocarya Paliurus And Its Biological Activities

Cyclocarya paliurus (Batal.) Iljinskaja. is a Juglandaceae plant. Cyclocarya paliurus tea is known as medicinal tea, which had been reported to have many physiological activities, such as preventing diabetes mellitus, hypertension and coronary heart disease, etc. The previous studies showed that the biological activities of Cyclocarya paliurus were related to flavonoids, triterpenoids and polysaccharide. Now, there are not deep researches on Cyclocarya paliurus flavonoids, which greatly influence the utilization of Cyclocarya paliurus. In this paper, the determination, extraction, purification and antioxidant activities of Cyclocarya paliurus flavonoids have been studied profoundly, which will provide theoretic foundation for the exploitation of bioactive components of Cyclocarya paliurus. The main studies and results in the paper are concluded as follows:1. Determination method of the content of total flavonoids was obtained. Three colorimetries which were direct determination, AlCl₃ colorimetric and NaNO₂-Al(NO₃)₃ colorimetric methods were compared. The result showed that AlCl₃ colorimetry was a better method for the determination of total flavonoids in Cyclocarya paliurus with high precision, reproducibility, stability and good recovery.2. The condition of the extraction of total flavonoids of Cyclocarya paliurus with ethanol reflux was studied, which was applied orthogonal experiment design. The results showed that the yield of total flavonoids was 22.04 mg/g at the optimum condition. The condition of the extraction total flavonoids from Cyclocarya paliurus with microwave assisted extraction was studied, which accorded with central composite rotatable design (CCRD) and response surface methodology (RSM). The yield in the optimum condition was 15.6437mg/g. In terms of the yield of total flavonoids, ethanol reflux is higher than microwave assisted extraction. But the microwave assisted extraction is convenient, need shorter time and can save the energy and reduce cost.3. The purification and structure elucidation of the flavonoids in Cyclocarya paliurus were studied. Three flavonoid compounds were isolated and purified from Cyclocarya paliurus using the AB-8 macroreticular resin absorption combined with the prepared high performance liquid chromatography technology. They were identified as quercetin-3-O-β-D- glucuronate, kaempferol-3-O-β-D-glucuronate and kaempferol-7-O-α-L- rhamnose by UV, IR, ESI-MS (both negative and positive ionizations) and NMR spectra. This method is high-efficiency, fast and high throughput, which is suitable for purification Cyclocarya paliurus flavonoid. Now, there is no correlative report about this aspect.4. In vitro antioxidant activities of different extracts of Cyclocarya paliurus leaves ware studied. The results showed that the extracts of Cyclocarya paliurus had rather strong scavenging activities on DPPH radicals, superoxide anion radicals and hydroxyl radicals, and their clearance abilities increased with the increase of extract concentration. The 70% ethanol extract could inhibit the lipid peroxidation, but the effect was weaker in comparison with butylated hydroxytoluene (BHT) and a-tocopherol. This study indicated that Cyclocarya paliurus had strong antioxidant activities in vitro.5. The protective effect of Cyclocarya paliurus on carbon tetrachloride induced liver-damaged mice was observed. The model of chronic hepatic injury was made by Carbon tetrachloride (CCl₄ ) in rats. Reagent fits were used to determine activities of AST and ALT in blood serum and measured the content of malondialdehyde (MDA), the activity of superoxide dismutase (SOD) and the total antioxidation capacity (T-AOC) of liver tissues. The results indicated that the Cyclocarya paliurus had protective against acute liver damage. But the mechanisms underlying hepatoprotection is not clear and more studies should be carried out in the future.