Isolation and identification of 1,2-dihydroxy-9,10-anthraquinone (Alizarin) from the roots of Maddar plant (Rubia tinctorum)

A. Ashnagar¹*, N. Gharib Naseri² and A. Safarian Zadeh¹

¹School of Pharmacy, Ahwaz Jundi Shapour Univ. of Medical Sciences, Ahwaz (Iran) ²Ahwaz Faculty of Petroleum Engineering, Petroleum University of Technology, Ahwaz (Iran)

ABSTRACT: The roots of madder (Rubia tinctorum) are source of anthraquinone dyes with alizarin being the main component. Free alizarin (I) is present in madder root in only small quantities, most of it is present as its glycoside i.e. ruberythric acid(III) On the basis of the importance of alizarin, in this research, it was isolated, purified and its structure was confirmed by various spectra. Maceration of the powdered madder roots in various polar and non-polar solvents, as well as Soxhlet extraction resulted in the formation of a reddish solid material (5.2% and 14.2% yield, respectively). Successive TLC and column chromatography of the solid material on silica gel with methanol as the mobile phase, gave three fractions with Rf = 0.21, 0.48 and 0.68. The fraction with Rf = 0.68 was the major one. 1HNMR, 13CNMR, IR, UV and Mass spectra of this fraction were taken. On the basis of the results obtained from the spectra, the chemical structure of alizarin was determined and confirmed.

KEYWORDS: Alizarin; 1,2-dihydroxy-9,10-anthraquinone; 1,2-dihydroxy-9; 10-anthracenedione; Rubia tinctorum

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