Applicability of alkanet (Alkanna tinctoria) extract for the histological staining of liver tissue

Staining of tissue is a significant process in histotechnology and staining techniques are used in the examination and diagnosis of diseases. The increase of international awareness for the environment, ecology, and health directed people to reduce toxic effluents and stop usage of dangerous chemical dyes. The present trend throughout the world is shifting towards to use of natural products over their synthetic alternatives. Therefore, in this study, the dyeing ability of alkanet plant on the cells of unstained sections taken from Wistar rat liver was investigated. The extract of Alkanna tinctoria contain naphthaquinone group of dyestuff. Chemical characterization of A. tinctoria extract was performed with HPLC-TOF/MS and UV spectra analysis, respectively. Different metal salts were used in the staining processes in order to obtain different colors. In the staining of without adding mordant (metal salt) to the extract, pale brown staining was obtained in the cytoplasm. Light pink color was obtained with the addition of CuSO₄ mordant. Dark pink-red color was achieved by adding alum, and also NiSO₄ was added for light purple staining. The staining of cytoplasm of different cells in liver tissue was achieved successfully with the extract of A. tinctoria and different colors were obtained using various mordants.