| Plant polyphenols which widely exist in plant are important secondary metabolites with various bioactivities. Previous studies indicate that they are closely related to human digestion, nutrition and health, and have been widely used in the field of food, drug and cosmetic industry. In this work, Pistacia chinensis Bunge, a prospective energy plant was studied. The residues of the plant were used to develop valuable substances, such as polyphenols. The results were showed as follows.Firstly, the extraction methods of the polyphenols were optimized. Different solvents were used to isolate polyphenols from the leaf tissues with the assistance of ultrasonic or microwave. Based on the single factor experiments and orthogonal tests, the optimal parameters were achieved as 50% ethanol,20 minutes of ultrasonic treatment,1:20 of material to liquid ratio and 70℃ extraction temperature. The average extraction efficiency of polyphenols was 7.86% based on the above isolation system.The free radical scavenging ability of the crude extract was tested in the following experiments. The scavenging rate on DPPH, hydroxyl and ABTS radicals were 87.71%,93.33% and 92.49%, respectively. According to the ICso value, the radical scavenging ability of the extract was higher than that of vitamin C in all the tests, and was similar to that of the pure tea polyphenols (98%) on DPPH, but lower than that of the latter on hydroxyl and ABTS.The third part of work is to detect the genotoxic and antigenotoxic effects of the extract based on the luminescence reporter gene (SOS-Lux test). The results indicated that the product did not induce any detectable SOS response at the concentration of 10 mg/mL, revealing no obvious toxic at the experimental conditions. However, more than 90%SOS response induced by mitomycin C (MMC) or almost all the SOS response triggered by hydrogen peroxide (H2O2) can be eliminated by the extract at the concentration of 5 mg/mL for MMC or 6 mg/mL for H2O2, indicating that the extract has strong effects on recovering the mutagen damage. Similar results were obtained in the bacterial filamentous inhibition assays.The plant leaf tissue also contains abundant essential oil besides polyphenols. To further exploit the value of the plant residues, a co-production technology of the two compounds was developed. The first step was designed for the extraction of the essential oil from leaf tissue by the supercritical CO2 extraction technology, and the optimized parameters were achieved as the fluid pressure of 20MPA at 50℃ for 2 h. The average collection rate of high-quality essential oil was 0.28%. The solid residues were then used in the second step for polyphenols extraction. The latter yield was 7.63%, which has no significant difference compared with that from the one-step direct polyphenols collection methods. To further evaluate the co-production technology, the total content of several essential compounds such as polyphenols, flavonoids and tannins were detected. No obvious distinction was found in the content of the chemicals between the one-step polyphenols extraction way and the co-production technology. The essential oil was also submitted for GC-MS analysis. 33 components were detected in the oil, and 22 of that were identified, which comprise 67.8% of the essential oil. The above results indicated that this co-production technology was promising in the comprehensive utilization of the P. chinensis plant. |
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