Detection of Pigments and Natural Colorants from Thai Herbal Plants for Possible Use as Coloring Dyes

摘要

Fourteen Thai herbal plants were extracted using methanol, ethanol, and acetone. Comparison of the various extraction methods for pigments and polyphenols (colorants) showed that methanol provided a more complete extraction than ethanol and acetone. Percentage yield ranged from 1.7 to 40.7 and was dependent on the plant extracted and solubility of pigments and polyphenols (colorants) extracted by the various solvents. The absorption spectra of pigments and polyphenols (colorants) in the plant extract were present in the visible region (351 to 665 nm) and the absorption spectra of polyphenols were present in the ultraviolet region (200 to 349 nm). Color of plant extracts varied and included violet blue, yellow-green, red, orange-red, gray-purple, blue-green, gray-orange, gray-yellow, and black. High-performance liquid chromatography (HPLC) was used to separate and identify compounds of plant pigments and polyphenols (colorants). Ya-nang had the greatest number of peaks and chlorophyll A and chlorophyll B were found only in Ya-nang. Numerous pigments and polyphenols were detected. Such compounds have the potential to be used as coloring dyes.