Yuzhi Wang

Bio: Yuzhi Wang is an academic researcher from Hunan University. The author has contributed to research in topics: Extraction (chemistry) & Fingerprint. The author has an hindex of 3, co-authored 3 publications receiving 182 citations.

Analysis of Flavonoids in Portulaca oleracea L. by UV–Vis Spectrophotometry with Comparative Study on Different Extraction Technologies

Abstract: Portulaca oleracea L. is a traditional edible and medicinal plant in China. Flavonoids are one of the main active ingredients of this plant. Five extraction technologies of flavonoids from P. oleracea L. were investigated and compared, including microwave-assisted extraction, ultrasonic extraction, reflux extraction, Soxhlet extraction, and marinated extraction. The results showed that microwave-assisted extraction was most suitable for the extraction of flavonoids from P. oleracea L. because of its high effect and short extraction time. The found optimum extraction conditions were that the ethanol concentration was 70% (v/v), solid–liquid ratio was 1:50, extracting temperature was 50 °C and irradiation time was 9 min. Quantification was performed by means of UV–Vis spectrophotometry with chromogenic system of NaNO2–Al (NO3)3–NaOH. Under the optimum conditions, the calibration curve for the analyte was linear with the correlation coefficients greater than 0.9999. The average recovery was 102.6%, and its RSD was 1.13%(n = 5). Eight types of P. oleracea L. according to different habits were investigated. The total content of flavonoids was 7.16, 7.10, 9.38, 6.82, 6.78, 11.36, 5.12, and 1.76 mg g−1, respectively.

Ultrasonically Assisted Extraction of Rutin from Artemisia selengensis Turcz: Comparison with Conventional Extraction Techniques

Abstract: Ultrasonically assisted extraction (UAE) followed by high performance liquid chromatography (HPLC) analysis method for the fast extraction and determination of rutin in Artemisia selengensis Turcz has been developed. Artemisia selengensis Turcz has been used as food and herbal medicine for thousands of years in China. Rutin is one of the main active ingredients of this plant. The extraction of rutin from Artemisia selengensis Turcz was investigated by UAE. Special emphasis has been given to optimize the extraction conditions which were those with 90:10 (v/v) methanol–ethanol as solvent, 30:1 liquid–solid ratio, and 40 min extraction time. In order to show the superiority of UAE, other extractions were investigated, including microwave-assisted extraction, reflux extraction, and marinated extraction. The results showed that UAE was most suitable for the extraction of rutin in Artemisia selengensis Turcz because of its high extraction efficiency. Reversed phase-HPLC with ultraviolet detection was employed for the analysis of rutin in Artemisia selengensis Turcz. Under the optimum conditions, the calibration curve for the analyte was linear in the range of 0.34–20.7 μg mL−1. The mean recovery of rutin was 100.77%, and its relative standard deviation was 0.37% (n = 5). Three kinds of Artemisia selengensis Turcz from different habitats were investigated. The total content of rutin was 9.90, 6.23, 5.56 mg g−1, respectively.

Fingerprint profile of active components for Andrographis paniculata Nees by HPLC-DAD

Abstract: Andrographis paniculata Nees (A. paniculata) has been used as herbal medicine for thousands of years in China. In this work, a quick extraction method with microwave-assisted treatment was studied for a complete extraction of active compounds from A. paniculata. Furthermore, the proposed fingerprint method, enhanced fingerprint by HPLC-DAD, has the advantage of efficiency and accuracy. In comparison with common fingerprint at fixed wavelength, enhanced fingerprint compiled additional spectral data and was hence more informative. It could efficiently identify, distinguish and assess A. paniculata. So it could be used to conduct the quality control of this traditional Chinese medicine comprehensively.

Techniques for analysis of plant phenolic compounds.

Abstract: Phenolic compounds are well-known phytochemicals found in all plants. They consist of simple phenols, benzoic and cinnamic acid, coumarins, tannins, lignins, lignans and flavonoids. Substantial developments in research focused on the extraction, identification and quantification of phenolic compounds as medicinal and/or dietary molecules have occurred over the last 25 years. Organic solvent extraction is the main method used to extract phenolics. Chemical procedures are used to detect the presence of total phenolics, while spectrophotometric and chromatographic techniques are utilized to identify and quantify individual phenolic compounds. This review addresses the application of different methodologies utilized in the analysis of phenolic compounds in plant-based products, including recent technical developments in the quantification of phenolics.

Intensification of extraction of natural products using ultrasonic irradiations—A review of current status

Abstract: Extraction of active chemical compounds from natural products is one of the most important research areas for pharmaceutical and chemical industries. Traditional techniques used for the solvent extraction of natural products are associated with longer extraction times and lower yields, use of large amount of organic solvents and poor extraction efficiency. Ultrasound can be effectively used to improve the extraction rate by increasing the mass transfer rates and possible rupture of cell wall due to formation of microcavities leading to higher product yields with reduced processing time and solvent consumption. The present work presents an exhaustive overview of different aspects of ultrasound assisted extraction (UAE) of various natural products. Mechanism of UAE has been discussed and recommendations for optimum operating conditions have been reported for maximizing the yield. An overview of different applications of UAE has been also presented. Possible intensification of UAE by coupling with traditional solvent and supercritical extraction processes has also been discussed. Overall it appears that ultrasonic irradiations can be effectively used for intensification of the extraction of important constituents from natural products.

Microwave-Assisted Extraction of Flavonoids: A Review

Abstract: Flavonoids are major bioactive compounds known to be beneficial against many chronic diseases such as cancer, cardiovascular disorders, and inflammation. Food products obtained from plants are key sources of flavonoids for humans. However, during different food-processing steps, flavonoids are lost in remarkable amounts. Supplementation of flavonoids as a food additive will help in retaining the required health-beneficial amount of flavonoids in the diet, and extraction is an important step in the preparation of food additives. Microwave extraction is one of the most advanced extraction methods, which has the potential of playing a major role in flavonoid extraction and analytical quantification. The present paper reviews the potential application of microwave extraction for flavonoids and the advantage of microwave-assisted process over the other extraction processes generally employed for extraction.

High‐throughput micro plate assays for screening flavonoid content and DPPH‐scavenging activity in sorghum bran and flour

Abstract: BACKGROUND: Sorghum possesses phenolic compounds that are health-promoting constituents of the grain. There are approximately40000sorghumaccessions, manyofwhichhavenotbeenevaluatedforthegrain’shealth-promotingpotential. Conventional methods for measuring total phenolic content, flavonoid content and 2,2-diphenyl-1-picrylhydrazyl (DPPH)scavenging capacity are time-consuming and labour-intensive, resulting in low overall throughput. The objective of this study was to develop a high-throughput screening assay for large sorghum sample sets to determineflavonoid and phenolic content and to modify existing DPPH and total phenolic assays. RESULTS: The 96-well assays exhibited a correlation of >0.9 with the conventional assays. The 96-well assays allowed for up to 64 samples to be run per day compared with 20‐24 samples (depending on the test) for the conventional methods. The 96-well assays had excellent accuracy (97.65‐106.16% recovery), precision (1.06‐8.28% coefficient of variation (CV)) and reproducibility (1.32‐2.13% CV inter-day and 1.36‐2.09% CV intra-day).

Portulaca oleracea L.: A Review of Phytochemistry and Pharmacological Effects

Abstract: Portulaca oleracea L., belonging to the Portulacaceae family, is commonly known as purslane in English and Ma-Chi-Xian in Chinese. It is a warm-climate, herbaceous succulent annual plant with a cosmopolitan distribution. It is eaten extensively as a potherb and added in soups and salads around the Mediterranean and tropical Asian countries and has been used as a folk medicine in many countries. Diverse compounds have been isolated from Portulaca oleracea, such as flavonoids, alkaloids, polysaccharides, fatty acids, terpenoids, sterols, proteins vitamins and minerals. Portulaca oleracea possesses a wide spectrum of pharmacological properties such as neuroprotective, antimicrobial, antidiabetic, antioxidant, anti-inflammatory, antiulcerogenic, and anticancer activities. However, few molecular mechanisms of action are known. This review provides a summary of phytochemistry and pharmacological effects of this plant.