Aqueous and organic solvents extraction process using ethanol, methanol and chloroform were carried out with four different Nigerian plants namely: Pterocarpus osun (uhe), Lawsonia inermis (lalle), Bixa orellana (annatto) and Hibiscus sabderriffa (zobo) to extract dye reagents from the plants. The ability of the dye reagents to replace Coomassie Brilliant Blue in the Bradford assay method of protein quantification were determined and compared. The solvents extracts gave good colourful results in the extraction of the dye reagents while only aqueous extract of Hisbiscus sabderiffa (zobo) gave similar results to that of solvent extracts. The solvent extracts obtained from Pterocarpus osun (uhe), Lawsonia inermis (lalle) and Bixa Orellana (annatto) plants could not be used to estimate amino acids from protein samples. However, solvent extracts of Hibiscus sabderriffa (zobo) was able to estimate amino acids from protein samples. The change in maximum wavelength (λmax) and the increased absorption with zobo dye reagent; on addition of protein samples showed that solvent extract of Hibiscus sabderiffa (zobo) dye has the potential to quantify and estimate amino acids in protein samples as much as the Coomassie Blue utilised in the Bradford assay method. The coefficient of correlation (r) values obtained for the proteins are 0.81, 0.92, 0.80 and 0.81 respectively for BSA, haemoglobin, fibrinogen and gamma globulin).