The anthraquinone, quinizarin, is the usual starting material for the syntheses of other anthraquinones given its availability, affordability, and adaptability to a variety of chemical procedures, in addition to the fact that these products are readily purified chromatographically [19-21].
1,4-Anthraquinone was prepared by quinizarin reduction according to established methods .
The 9-hydroxy and 9-methoxy derivatives of quinizarin were prepared as previously described .
NADPH, [AcPyADP.sup.+], and quinizarin (96% pure) were from Sigma-Aldrich, St.
The abbreviations used for the anthraquinones evaluated are as follows: the parent compound quinizarin, QZ; 1,4-anthraquinone, AQ; 2-hydroxy-1,4-anthraquinone, 2OH; 2-methoxy-1,4-anthraquinone, 2MeO; 9-hydroxy-1,4-anthraquinone, 9OH; 9-methoxy-1,4-anthraquinone, 9MeO.
Bigelow, "A study of the preparation of quinizarin," Journal of the American Chemical Society, vol.