{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,11]],"date-time":"2026-08-11T16:13:41Z","timestamp":1786464821056,"version":"build-2736575974"},"reference-count":32,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2026,8,11]],"date-time":"2026-08-11T00:00:00Z","timestamp":1786406400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Fujian Province Science and Technology Plan Guidance Project","award":["2019N0020"],"award-info":[{"award-number":["2019N0020"]}]},{"name":"Fujian Province Science and Technology Plan Guidance Project","award":["2024N0008"],"award-info":[{"award-number":["2024N0008"]}]},{"name":"Key Laboratory of Fujian Provincial Colleges and Universities for Innovation and Utilization of Loquat Germplasm Resources (Putian University) Open Research Project","award":["2018001"],"award-info":[{"award-number":["2018001"]}]},{"award":["2018001"],"award-info":[{"award-number":["2018001"]}],"id":[{"id":"https:\/\/ror.org\/00jmsxk74","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Fujian Provincial Natural Science Foundation General Projects","award":["2024J0186"],"award-info":[{"award-number":["2024J0186"]}]},{"name":"Longyan University Ph.D. Research Start-up Project","award":["LB2024003"],"award-info":[{"award-number":["LB2024003"]}]},{"award":["LB2024003"],"award-info":[{"award-number":["LB2024003"]}],"id":[{"id":"https:\/\/ror.org\/0483s5p06","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Plants"],"abstract":"<jats:p>This study investigated the formation of a co-amorphous complex between ursolic acid and quercetin as a chemically defined model system for improving the formulation performance of a poorly soluble triterpenoid acid. Co-amorphous systems were prepared by solvent evaporation and physical grinding at different mass ratios. The optimal formulations were identified and evaluated by water-solubility measurement, powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FTIR), and in vivo expectorant\u2013antitussive assays. The solvent-derived system showed higher water solubility than the ground system. PXRD and FTIR results suggested that the solvent method more effectively promoted loss of crystallinity and probable intermolecular interactions, whereas the grinding method largely retained the crystalline features of ursolic acid. Both ursolic acid\u2013quercetin formulations exhibited enhanced expectorant and antitussive activities compared with pure ursolic acid. Although quercetin may contribute intrinsic pharmacological activity, the overall improvements were broadly consistent with the altered physicochemical properties of the co-amorphous systems, which may facilitate ursolic acid delivery. As a secondary exploratory comparison, plant-derived triterpenoid-acid-rich and flavonoid-rich fractions from Eriobotrya japonica leaves were also co-processed; however, because these fractions were not compositionally characterized, their results were interpreted cautiously and were not used as the primary basis for mechanistic conclusions. Overall, the present study demonstrates that co-amorphous complexation of ursolic acid and quercetin is a promising strategy for improving the solubility-related properties and in vivo activity of a poorly soluble triterpenoid acid.<\/jats:p>","DOI":"10.3390\/plants15162443","type":"journal-article","created":{"date-parts":[[2026,8,11]],"date-time":"2026-08-11T13:46:16Z","timestamp":1786455976000},"page":"2443","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Co-Amorphous Ursolic Acid\u2013Quercetin Complex Improves Solubility and In Vivo Expectorant\u2013Antitussive Activity"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2226-9487","authenticated-orcid":false,"given":"Yuhang","family":"Jiang","sequence":"first","affiliation":[{"name":"College of Life Science, Longyan University, Longyan 364000, China"},{"name":"Fujian Provincial Key Laboratory of Preventive Veterinary Medicine and Biotechnology, Longyan University, Longyan 364000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zehong","family":"Qiu","sequence":"additional","affiliation":[{"name":"College of Life Science, Longyan University, Longyan 364000, China"},{"name":"Fujian Provincial Key Laboratory of Preventive Veterinary Medicine and Biotechnology, Longyan University, Longyan 364000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Biaoshen","family":"Lin","sequence":"additional","affiliation":[{"name":"College of Life Science, Longyan University, Longyan 364000, China"},{"name":"Fujian Provincial Key Laboratory of Preventive Veterinary Medicine and Biotechnology, Longyan University, Longyan 364000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhongping","family":"Yang","sequence":"additional","affiliation":[{"name":"College of Life Science, Longyan University, Longyan 364000, China"},{"name":"Fujian Provincial Key Laboratory of Preventive Veterinary Medicine and Biotechnology, Longyan University, Longyan 364000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yanping","family":"Hong","sequence":"additional","affiliation":[{"name":"College of Life Science, Longyan University, Longyan 364000, China"},{"name":"Fujian Provincial Key Laboratory of Preventive Veterinary Medicine and Biotechnology, Longyan University, Longyan 364000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Kuo, P.J., Chen, L.T., Li, S.M., Chen, Z.R., and Chen, J.J. 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