HPLC-MS identification of three major flavonoids in the textile dye extract from dried leaves of Anogeissus leiocarpus

Abstract

The availability of scientific information useful for the orientation of artisanal and industrial tinctorial practices to ensure the protection of the environment and the health of artisans and consumers remains a major concern for a large number of actors. Qualitative, quantitative analyses and structural identifications works using spectrophotometric, chromatographic and spectral methods were carried out on the total aqueous extract from leaves of A. leiocarpus. This extract was used to dye skeins of cotton fibers. With an extraction yield of about 5 %, A. leiocarpus leaves gave a total flavonoid content of the order 458.759±27.773 mgEQ/g of dye powder. Hydrolysable and condensed tannins rates are 13.25 % and 12.96 %, respectively. The HPTLC chromatographic profile of the dye showed that the extract of the A. leiocarpus leaves contains flavonols. The elongation vibrations νO-H and νC-O respectively of alcohols and oxide ethers in infra-Red testify to the presence of flavonic-type dyeing molecules which, by the phenomenon of co-pigmentation, contribute to the final shades in tinctorial practice. High-performance liquid chromatography coupled with mass spectroscopy revealed the presence of major flavonoid molecules such as quercetin 3-O-rhamnoside, quercetin 3-O-glucuronide and kaempferol 3-O-hexoside. Tinctorial practice techniques applied to skeins of cotton fibers have resulted in shades of various colours ranging from anise to chartreuse green. In addition to being a natural acid dye, the textile dye extracted from A. leiocarpus leaves can be classified in the group of metal dyes in terms of the quality of the shades obtained with the use of mordants such as alum, hydrated iron and copper sulphates.