Application of extracts of Henna (Lawsonia inamis) leaves as a counter stain

Abstract

Aqueous (cold and hot) and ethanol extracts solutions of the Henna plant (Lawsonia inamis) leaves was adapted for the first time as a counter stain in Gram staining reaction. Different extracts of L. inamis leaves were formulated into various staining solutions of different concentrations and modified with hydrogen peroxide, ferric chloride, potassium alum and potassium permanganate. These staining solutions were used to stain both known Gram positive and Gram negative bacterial isolates using Gram staining technique. The experimental Henna plant extracts solutions were used with usual counter stains (neutral red, safranine and dilute carbol fuchsin) as positive controls. Phytochemical screening of the extracts revealed the presence of tannin (hennatonic acid or Lawsone) and saponin. The aqueous extracts of the Henna plant (cold and hot) oxidized with potassium permanganate (pH 7.00 to 7.16) gave a better staining reaction with Gram negative bacteria, while the ethanol extract oxidized with potassium permanganate (pH 6.55) had no staining reaction with Gram negative bacteria. Hence the aqueous Henna leaves extracts (cold or hot) when oxidized with potassium permanganate can be a substitute to the usual counter stains used in Gram staining procedure. The results of staining ability of the various henna leaves extracts solutions are discussed.