Isolation of Food Grade Dye from Flower Petals of Butea monosperma and Determination of Marker Compounds for Its Quantitative Analysis

[Image: see text] Health concerns associated with synthetic dyes/colorants have fostered the use of natural coloring materials for food applications. This study has been carried out to extract a natural dye from the flower petals of Butea monosperma (family Fabaceae) under an eco-friendly and organic solvent-free approach. Hot aqueous extraction of dry B. monosperma flowers followed by lyophilization of the resulting extract furnished an orange-colored dye in ∼35% yield. Silica gel column chromatography of dye powder resulted in the isolation of three marker compounds, viz. iso-coreopsin (1), butrin (2), iso-butrin (3) which were characterized by spectral methods, e.g., ultra violet, Fourier-transform infrared spectroscopy, nuclear magnetic resonance, and high-resolution mass spectrometry. The XRD analysis of isolated compounds established an amorphous nature for compounds 1 and 2 while compound 3 showed good crystallinity. The stability of dye powder and the isolated compounds 1–3 was determined by thermogravimetric analysis which showed excellent stability up to 200 °C. In trace metal analysis, the product B. monosperma dye powder exhibited low relative abundance <4% for Hg along with negligible concentrations of Pb, As, Cd, and Na. The detection and quantification of marker compounds 1–3 in the B. monosperma flower extracted dye powder were carried out by a highly selective UPLC/PDA method of analysis.