Antioxidant Activities Of Naturally Green Colored Cotton And Its Pigment Components

Because of its natural colors, naturally green colored cotton does not have to be dyed orbleached, which can not only reduce the production costs, and also reduce the environmentalpollution. Nowadays, green environmental consciousness is deeply rooted in the mind of humanbeing. Naturally green colored cotton attracts more and more attention. However the color of itsfabrics is affected by several factors, including pH, light irradiation, temperature and metallic ion.It is extremely unstable substance. Thus it is very important for the application of green cotton tostudy the pigment composition and develop new performance. This paper took naturally greencolored cotton as the study object. Effects of different pretreatments on the antioxidantproperties of naturally green cotton fibers were studied. Then, normal phase chromatography wasused to isolate the pigment of green cotton and the ultraviolet spectral properties of the greencomponents were investigated. In the last, the pH dependence and antioxidant activities of thepigment components were studied.White cotton fibers were selected as the reference to study the antioxidant activities of thegreen colored cotton fibers after various pretreatments. The DPPH·and ABTS+·scavengingactivities of cotton fibers were researched. The results indicated that green cotton fibers havemuch more excellent antioxidant properties than the white cotton fibers. Petroleum etherdegreasing treatment and bio-enzyme scouring can further enhance the antioxidant properties ofgreen cotton fibers. Alkali scouring might change the structure of pigment, increases its watersolubility, leading to lots of pigment loss. So the antioxidant properties decreased. It’s better towash the fibers and fabrics by neutral detergent which could remain the antioxidant propertybetter.This paper segmented the extractions of green colored cotton pigment by using normalphase chromatography, analyzed the spectral characteristics of enriched components and studiedthe antioxidant activities of enriched components. The results show that normal phase columnwas more effective for the separation of pigment in green colored cotton. The yellowish greencomponent could be enriched by the0%methanol. The main functional groups of enrichment were basically the same. Green cotton pigment and its segment have niceDPPH·and ABTS+·scavenging antioxidant activity. IE50, the quality of pigment that need toscavenge50%radicals, was used to evaluate the antioxidant activities. When scavenged DPPH·,the IE50of the crude pigment is0.0356mg, slightly higher than that of Vc. It’s about1.7timesthan that of Vc. The DPPH·scavenging activities of the enrichment fractions from high to lowwere60%methanol enrichment components,0%methanol enrichment components,100%methanol enrichment components,30%methanol enrichment components and10%methanolenrichment components and IE50were1.7times,2.5times,4.3times,6.4times and7.4timesmore than that of Vc respectively. When scavenging DPPH·, the IE50of the crude pigment wasabout1.8times more than that of Vc. The ABTS+·scavenging activities of the enrichmentfractions from high to low were60%methanol enrichment components,0%methanolenrichment components,100%methanol enrichment components,10%methanol enrichmentcomponents and30%methanol enrichment components and IE50were about2.5times,4.2times,4.4times,6.0times and6.4times more than that of Vc respectively.The investigation of the pH dependence of the pigment components of green colored cottonshowed that alkali condition had a greater impact on the visible absorbance of pigment in greencotton fibers. When pH value was more than7, the absorbance between380and550increasedwith the increasing of pH value, which resulted yellow-green in deepen color. It was similar tothe color deepening of green cotton fabrics when treated with alkali solution during the practicalapplication. The bluish green component of0%methanol enrichment components disappearedafter UV irradiation. The yellow light of10%methanol and30%methanol enriched fractionsdeepened. While the visible absorbance of60%methanol and100%methanol enrichmentcomponents didn’t change significantly. Resulting in the yellow light of the green cotton pigmentgradually deepened.