Analysis On The Characteristics And Quality Control Of Leaves

Ziziphus jujuba leaf tea (ZJLT) is a new type of flower and plant tea, which has been gained a lot of popularity in recent years. The tea is made by processing the leaves of the wild jujube, Ziziphus jujuba Mill. var. spinosa (Bunge) Hu ex H. F. Chow, and it was believed to have many healthy efficacies. In recent years, ZJLT has got the attention of people gradually for its special effect on nourishing heart, soothing nerves and aiding sleep. Presently, although some researches have shown that the aqueous extract of ZJLT has the same central nervous inhibiting effect as SZS (the seed of Ziziphus jujube), the concrete functional ingredients are still unknown. Antioxidant activity is an important indicator to evaluate the quality of tea, and there is no research about determination of antioxidant activity and identification of antioxidants. Commercially available ZJLT is mainly made by processing wild jujube leaves. It is still a common phenomenon of passing some plant leaves with similar patterns off as Ziziphus jujuba leaves in spite of abundant resources. Because of different growing environment and climate, Ziziphus jujuba leaves from different origin have some difference in active ingredients in some extent. In addition, quality of ZJLT changes due to different processing craft of different manufacturer. It is hard to.identify the authenticity and estimate the quality of ZJLT just using visual inspection. Hence, it is quite necessary to develop an effective method to distinguish the authenticity and evaluate the quality of commercially available ZJLT. Therefore, to solve above existing problems, this study has successfully isolated and verified main active chemical ingredients in ZJLT and developed a quality control method and evaluation system with a variety of modern analytical techniques. The main research results obtained list as follows:1.An efficient HPLC-DAD-ESI-TOF/MS method and HPLC-ESI-IT/MS2method were performed to clarify the principal bioactive compounds of ZJLT. Some research results have been observed:First, ZJLT infusion contains rich flavonoids, mainly flavonol glycosides, such as Quercetin-3-O-rutinoside, Kaempferol-3-O-robinobioside, Kaempferol-3-O-rutinoside, etc., which are presumably the possible effective components that cause the sedative and hypnotic activities and some catechins, such as gallocatechin, epigallocatechin, epigallocatechin-3-gallate and table catechol. Second, caffeine and theophylline, which have important functions in refreshing the human body, were not detected in the ZJLT infusion. iN addition, research about utilization of rutin was performed, the result shows that ZJLT infusion contain large amount of rutin, and the intake of rutin approximately equals to take1.2pills of Compound Rutin Tablets when drinking2.0g ZJLT. The health care function to human body is apparent.2. This study has determined the antioxidant capacity in vitro through the developed model of scavenging DPPH free radical as well as screened and identified the antioxidant ingredients in ZJLT by using HPLC-DAD-DPPH-ESI-TOF/MS method. Besides, semi-quantitative analysis for flavonoid compounds in different tea samples was performed. The result indicated that the water extract of ZJLT had a good antioxidant capacity to scavenging DPPH free radical with clearance rate about seventh of rutin and one-thirteenth of caffeic acid. Furthermore, result of identification shows that ZJLT contains a number of high active antioxidative compounds, such as Quercetin-3-O-rutinoside (rutin), Quercetin-3-O-robinobioside, Kaempferol-7-O-glucoside, Quercetin-3-O-β-L-arabinosyl-(12)-a-L-rhamnoside, Quercetin-3-O-β-D-xylosyl-(12)-a-L-rhamnoside, tryptophan, etc., and content of which changed in different Laoshan ZJLT samples approximately at25.7-34.9mg/g.3. An HPLC fingerprinting method based on the distribution and relative amount of11bioactive flavonoids was established for the quality evaluation of commercially available ZJLT from China. Separation of the crude flavonoid extract was achieved on a column filled with C18material with high carbon content. The flavonoids in ZJLT were identified based on UV spectroscopy and accurate mass measurements by TOF-MS. Twenty-one batches of practical samples collected from different habitats were analyzed by using the developed HPLC method to construct the HPLC characteristic fingerprint of ZJLT. Then, combined with clustering and similarity analyses, the HPLC characteristic fingerprint was used for the authentication and quality evaluation of commercial ZJLT. Results indicated that the proposed HPLC characteristic fingerprint reflected the inherent characteristics of ZJLT collected from different regions. Authenticity identification and quality control of commercially available wild Jujube tea were achieved based on the HPLC characteristic fingerprint analysis. This new approach to bioactive component profiling provided a promising reference method for the quality evaluation of commercial wild flower and plant tea.