| This study investigated the best extraction method of sterols from the rhizome of Chinese Begonia (Begonia grandis var. sinensis). Single factor and orthogonal experiments were used to determine the optimal extraction conditions of sterols. The extracted sterols were separated and purified by silica gel adsorption method. The effects of temperature, time, concentrations and kinds of adsorbents on the separation of sterols were also studied. Then the purified sterols were characterized by UV-vis absorption spectra (UV-Vis), infrared spectroscopy (IR), High Performance Liquid Chromatography (HPLC) and Gas Chromatography-Mass Spectrometry (GC-MS).β-Cyclodextrin was used as a wall material to prepare sterols micro-capsules, and the technology was optimized. The antimicrobial activity of sterol extracts against bacteria and fungi were also investigated. In addition, the effect of sterols on the blood-lipid lowering was performed using animal experiments.The main research subjects and results are listed as follows:1, Three methods were used to extract the sterol from rhizome of Chinese Begonia. The results showed that ultrasonic technology was the best methods for extracting sterol. The yield using this method was 0.76 mg/g of sterol. The extraction rate was also the highest, which achieved 84.4 mg/g. While the yied and the extraction rate of the other two methods were lower than ultrasonic technology.2, The optimal conditions of ultrasonic technology were investigated using single factor experiment and orthogonal experiment. The optimal conditions of this methods were listed as follows:material to liquid ratio at 1'.24, extraction temperature 55℃, extraction time 52 min. The content of sterols extracted at this condition was 1.78 mg/g.3, Sterols were isolated and purified for the purpose of evaluating the adsorption rate using silica gel. The orthogonal test results showed that the optimum conditions of silica static adsorption were as follows:adsorption time 2.5 h, adsorption temperature 35℃, adsorption concentration 0.4mg/mL, elution agent for the petroleum ether/ethyl acetate was 10:1. Under this optimum conditions, the adsorption rate was found to be 87.54%.4, The structure characterization of the sterols were performed by UV-Vis absorption (UV-Vis), infrared spectroscopy (IR), High-performance Liquid Chromatography (HPLC) and Gas Chromatography-Mass Spectroscopy (GC-MS).β-Sitosterol, stigmasterol, methylenecholest-5,24(28)-diene-3β-ol and ergosta-5-en-3β-ol were detected in rhizome of Chinese Begonia. Among these sterols,β-sitosterol was the most abundant, accounted for 43.42% of the total concentration, followed by stigmasterol.5, P-Cyclodextrin was used as wall material. The orthogonal test results showed that the optimum conditions for the produce of the sterol microencapsulation were:water addition 60mL, mixing temperature 50℃, stirring time 50 min, sterol (mL):β-cyclodextrin (g) 1:10 (V:m). The finished sterol microencapsulation had a strong antioxidant capacity in comparison with vitamin E,β-sitosterol. The antioxidant capacity enhanced with the concentration increased.6, Antimicrobial activity of sterol extracts against bacteria and fungi by Oxford plate assay and by growth rate method, respectively. The minimum inhibitory concentrations (MIC) were tested by two-fold serial dilution method. The results showed that sterol extracts had strong inhibition on microorganism with broad-spectrum. The similar effect of antimicrobial activity on gram positive bacterias and gram negative bacterias were observed. It could also inhibit the growth of fungi.7, The results of the animal experiment showed that great effect of sterols on the blood-lipid lowering was obtained. |
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