Chemical Constituents and Mechanisms of Discoloration of Taiwania (Taiwania cryptomerioides Hayata) Heartwood. The Structure Reconfirmation and Conversion Mechanism of Taiwanin A

Abstract

Summary: One of the color substances, taiwanin A, was isolated from Taiwania (Taiwania cryptomerioides Hayata) heartwood. According to the ¹³C-NMR, ¹H-NMR, HSQC, HMBC, and NOE difference spectroscopy analyses, the diene structure of taiwanin A was reconfirmed to be the trans-trans formulation. In addition, it was proven that deep orange crystalline taiwanin A changed to white and pale yellow compounds, taiwanin C and taiwanin E, after light irradiation. The conversion mechanism of taiwanin A into taiwanin C and taiwanin E is also proposed and discussed in this study.