{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T18:29:11Z","timestamp":1790015351755,"version":"4.0.1"},"reference-count":59,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2019,7,31]],"date-time":"2019-07-31T00:00:00Z","timestamp":1564531200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100002873","name":"Chulalongkorn University","doi-asserted-by":"publisher","award":["GRU 6203023003-1"],"award-info":[{"award-number":["GRU 6203023003-1"]}],"id":[{"id":"10.13039\/501100002873","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100002873","name":"Chulalongkorn University","doi-asserted-by":"publisher","award":["Thesis grant"],"award-info":[{"award-number":["Thesis grant"]}],"id":[{"id":"10.13039\/501100002873","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004704","name":"National Research Council of Thailand","doi-asserted-by":"publisher","award":["GRB_BSS_101_59_61_08"],"award-info":[{"award-number":["GRB_BSS_101_59_61_08"]}],"id":[{"id":"10.13039\/501100004704","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Hyperpigmentation is considered by many to be a beauty problem and is responsible for photoaging. To treat this skin condition, medicinal cosmetics containing tyrosinase inhibitors are used, resulting in skin whitening. In this study, taraxerol methyl ether (1), spinasterol (2), 6-hydroxyflavanone (3), (+)-dihydrokaempferol (4), 3,4-dihydroxybenzoic acid (5), taraxerol (6), taraxerone (7), and lupeol acetate (8) were isolated from Manilkara zapota bark. Their chemical structures were elucidated by analysis of their nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) data, and by comparing them with data found in the literature. The in vitro antityrosinase, antioxidant, and cytotoxic activities of the isolated compounds (1\u20138) were evaluated. (+)-Dihydrokaempferol (4) exhibited higher monophenolase inhibitory activity than both kojic acid and \u03b1-arbutin. However, it showed diphenolase inhibitory activity similar to kojic acid. (+)-Dihydrokaempferol (4) was a competitive inhibitor of both monophenolase and diphenolase activities. It exhibited the strongest 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2\u2032-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), and ferric reducing antioxidant power (FRAP) activities of the isolated compounds. Furthermore, (+)-dihydrokaempferol (4) also demonstrated potent cytotoxicity in breast carcinoma cell line (BT474), lung bronchus carcinoma cell line (Chago-K1), liver carcinoma cell line (HepG2), gastric carcinoma cell line (KATO-III), and colon carcinoma cell line (SW620). These results suggest that M. zapota bark might be a good potential source of antioxidants and tyrosinase inhibitors for applications in cosmeceutical products.<\/jats:p>","DOI":"10.3390\/molecules24152798","type":"journal-article","created":{"date-parts":[[2019,7,31]],"date-time":"2019-07-31T11:37:07Z","timestamp":1564573027000},"page":"2798","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":59,"title":["Antityrosinase, Antioxidant, and Cytotoxic Activities of Phytochemical Constituents from Manilkara zapota L. Bark"],"prefix":"10.3390","volume":"24","author":[{"given":"Sutthiduean","family":"Chunhakant","sequence":"first","affiliation":[{"name":"Program in Biotechnology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chanya","family":"Chaicharoenpong","sequence":"additional","affiliation":[{"name":"Institute of Biotechnology and Genetic Engineering, Chulalongkorn University, Bangkok 10330, Thailand"},{"name":"Molecular Crop Research Unit, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2019,7,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1111\/j.1749-6632.1999.tb07814.x","article-title":"Fundamental aspects of reactive oxygen species, or what\u2019s the matter with oxygen?","volume":"893","author":"Fridovich","year":"1999","journal-title":"Ann. 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