Investigations on C-glycosyl flavonoids from Rhynchosia capitata, its antimicrobial and dyeing properties

Abstract

Natural dyes extracted from a novel source Rhynchosia capitata (R. capitata) Heyne ex roth were applied to cotton fabric by applying traditional and pad dyeing processes using pre-, post- and simultaneous-mordanting techniques. Both dyeing processes were carried out in the presence of natural mordants: Myrobalan, Pomegranate rind, Rhizhophora mucronata fruits, Manjistha, and eco-friendly metallic mordants such as tannic acid, stannous chloride (SnCl2), ferrous sulfate (FeSO4), and copper sulfate (CuSO4). The range of color developed on dyed materials was evaluated in terms of (L*, a*, b*, C*) CIELAB coordinates and dye absorption concentration on textile materials was studied by using K/S values. Natural mordant Rhizhopora mucronata fruits exhibited good absorption value. It was found that metallic mordants FeSO4 and CuSO4 exhibited higher K/S values than SnCl2. For other mordants except FeSO4 shade developed on cotton fabric varied from pale yellow to brown. The fastness properties ranged from good to excellent. High pressure thin layer chromatographic analysis for solvents of varying polarity has been investigated and maximum yield was obtained from 80 % aqueous ethanol fraction. Antimicrobial activity was carried out with the aid of two human pathogenic strains, Staphylococcus aureus and Klebsiella pneumonia and the cotton fabric dyed with plain extract of R. capitata shows good activity.