A novel ring-expanded product with enhanced tyrosinase inhibitory activity from classical Fe-catalyzed oxidation of rosmarinic acid, a potent antioxidative Lamiaceae polyphenol

✍ Scribed by Aya Fujimoto; Yoshimi Shingai; Mitsuhiro Nakamura; Tomomi Maekawa; Yoshiaki Sone; Toshiya Masuda

• Book ID: 104005002
• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 234 KB
• Volume: 20
• Category: Article
• ISSN: 0960-894X
• DOI: 10.1016/j.bmcl.2010.10.040

✦ Synopsis

The iron-ion catalyzed oxidation of the ethanol solution of rosmarinic acid, a potent antioxidant polyphenol of Lamiaceae (Labiatae) plants, afforded a highly tyrosinase-inhibitory active product. The structure of the active product in the oxidation product mixture was determined using extensive NMR spectroscopy to have a novel oxygen-containing seven-membered ring system. The formation mechanism of the unique ring structure from the catechol part of the rosmarinic acid was proposed.