Aromatase inhibitors isolated from a flowering tea, snow Chrysanthemum (the capitula of Coreopsis tinctoria Nutt.)

AbstractMethanol extract from the capitula ofCoreopsis tinctoria Nutt. (Asteraceae), which is also known as a flowering tea or blooming tea “SnowChrysanthemum, ” was found to inhibit the enzymatic activity of aromatase. A total of 24 known isolates (1–24) were identified from the extract, including three chalcones (1–3), an aurone (4), five flavanones (5–9), four flavanols (10–13), a flavonol (14), and two biflavanones (15,16). Among them, okanin (1,Ki  = 1.6 μM), (2S)-naringenin (5, 0.90  μM), isookanin (6, 0.81  μM), (2S)-7,3',5'-trihydroxyflavaone (7, 0.13  μM), and (2S)-5,7,3',5'-tetrahydroxyflavanone (8, 0.32  μM) exhibited relatively potent competitive inhibition. Specifically, the isolates7 and8, having a common 3',5'-resorcinol moiety at the B ring in their flavanone skeleton, exhibited potent inhibitory activities compared to those of a clinically applied aminoglutethimide (0.84  μM) and naturally occurring flavone, chrysin (0.23 μM), which is a common non-steroidal aromatase inhibitor. Importantly, the active flavonoid constituents (1 and5–8) did not inhibit the activity of 5α-reductase enzyme, which normally reacts with the same substrate “testosterone,” thus, these compounds were suggested to be specific to aromatase.
Source: Journal of Natural Medicines - Category: Drugs & Pharmacology Source Type: research