An alternative tracking dye for gel electrophoresis

Bromophenol blue (BPB) is regularly used as a dye marker to find out an ion front in the electrophoretic techniques. However, all the chemical, physical and toxicological properties of BPB have not yet been thoroughly investigated. Material safety data sheet of all standard companies providing BPB are advised that due care be exercised when handling this material as it may cause irritation with redness and pain. It is a well known fact that colorants from synthetic sources can be harmful and cause allergies. Thus, the present study is aimed in a preliminary manner, to find an additional/alternative tracking dye from natural sources to replace the synthetic BPB dye. Bixa orellana L., commonly known as annatto, yielding orange to red colour dye from its pericarp, was tested for its potential as a tracking dye. This dye has characteristics similar to those of BPB and shows no interference with any of the test proteins. The utility of this dye was tested using proteins that exhibit different physicochemical properties and compared with other commonly used staining methods as well as Western blot methods. Our studies show that the pigment from B. orellana L. can be used as a tracking dye in place of BPB. The procedure is found to be easy, practical and reliable.