Author(s): B. K. Satheesahbabu and Muthi Ul Haque
The aim of the present investigation was to study the suitability of Annatto seed extract as coloring agent for pharmaceutical use and to evaluate its stability of color intensity when exposed to different light sources like Ultraviolet, tungsten and sunlight. The Annatto seed extract was extracted from the Annatto seeds by solvent extraction method using ethyl acetate as a solvent. Annatto seed extract was subjected for color intensity stability study in dry form and in solution of 5% potassium hydroxide, the tablets and simple syrup IP was prepared using Annatto seed extract as coloring agent were subjected to color intensity stability studies by placing them at different light sources like Ultraviolet, tungsten and sunlight. In all cases color intensity was decreased with time but rate of decrease was more with sun light. This suggested that annatto seed extract was light sensitive. To establish this fact same study was conducted with tablets packed in aluminum foil and results suggested that loss of color intensity was very negligible or no loss of color intensity. Annatto seed extract comprised with many coloring principles among all bixin an oil soluble and nor bixin water soluble attributed more for its coloring characteristics. To prove which principle was responsible for light sensitivity, bixin and norbixin were isolated from the extract by conducting Thin Layer Chromatography and Preparative Thin Layer Chromatography. The isolated pure bixin and norbixin were subjected for color intensity stability. The results proved that color intensity of bixin decreased whereas norbixin not with sunlight. So bixin was attributed light sensitivity and study was concluded that Annatto seed extract could be useful as coloring agent for pharmaceutical dosage form packed in light resistance containers.