{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,19]],"date-time":"2026-02-19T15:53:25Z","timestamp":1771516405406,"version":"3.50.1"},"reference-count":32,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2019,5,26]],"date-time":"2019-05-26T00:00:00Z","timestamp":1558828800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Austrian Federal Ministry of Science, Research and Economy","award":["GZ 402.000\/00013 -WF\/V\/6\/2016"],"award-info":[{"award-number":["GZ 402.000\/00013 -WF\/V\/6\/2016"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Rhein is used as an active ingredient in laxatives in medicinal herbal products and is a chemical marker for quality control purposes. Thus, a simple and effective method for the optimized extraction of a high amount of rhein from the fruit pulp of Cassia fistula was investigated using ultrasonic-assisted extraction (UAE). The response surface methodology was applied to find the most suitable parameters for optimizing the extraction process and to study the factors\u2019 relationships with each other. The best conditions for ultrasonic extraction were the application of 1:40 g\/mL solid-to-liquid ratio and 10% EtOH\u2013H2O as a solvent at 75 \u00b0C for 40 min. This method was compared to a conventional decoction in two variations. In these experiments, it was confirmed that the UAE was more favorable than the decoction methods. The resulting crude extract was further purified by liquid\u2013liquid extraction with a basic pH adjustment, followed by recrystallization. High-purity rhein was obtained by using chromatographic techniques and nuclear magnetic resonance spectroscopy. Therefore, this study suggests that UAE is an efficient alternative method for the extraction of rhein from C. fistula pod pulp. The resulting optimized conditions can be applied as a useful tool for the large-scale industrial production of a rhein-rich plant extract.<\/jats:p>","DOI":"10.3390\/molecules24102013","type":"journal-article","created":{"date-parts":[[2019,5,26]],"date-time":"2019-05-26T23:07:27Z","timestamp":1558912047000},"page":"2013","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":14,"title":["Optimization of Ultrasonic-Assisted Extraction and Purification of Rhein from Cassia fistula Pod Pulp"],"prefix":"10.3390","volume":"24","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7215-9123","authenticated-orcid":false,"given":"Bancha","family":"Yingngam","sequence":"first","affiliation":[{"name":"Department of Pharmaceutical Chemistry and Technology, Faculty of Pharmaceutical Sciences, Ubon Ratchathani University, Ubon Ratchathani 34190, Thailand"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Haiyu","family":"Zhao","sequence":"additional","affiliation":[{"name":"Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, No. 16 Nanxiaojie, Dongzhimen Nei Ave, Beijing 100700, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bian","family":"Baolin","sequence":"additional","affiliation":[{"name":"Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, No. 16 Nanxiaojie, Dongzhimen Nei Ave, Beijing 100700, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nipawan","family":"Pongprom","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Faculty of Science, Ubon Ratchathani University, Ubon Ratchathani 34190, Thailand"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7812-9291","authenticated-orcid":false,"given":"Adelheid","family":"Brantner","sequence":"additional","affiliation":[{"name":"Institute of Pharmaceutical Sciences, Department of Pharmacognosy, University of Graz, Universitaetsplatz 4\/1, A-8010 Graz, Austria"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2019,5,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Hsueh, T.P., and Tsai, T.H. 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