Collagen and muscle stain obtained from Sorghum bicolor.

Crude ethanolic extracts of the leaves of Sorghum bicolor L. Moench were used as stains for tissue sections. The alkaline mixtures did not stain any of the tissues used but the acidic and neutral alcoholic mixtures stained collagen fibres, muscles and red blood cells in shades of pinkish-yellow. Good contrast was obtained when nuclei were pre-stained with Weigert's haematoxylin. The ethanolic extract of S. bicolor was run through a column using silica gel (60-120 mesh) as the stationary phase and various dilutions of hexane, chloroform and ethanol as the mobile phase. Eight major fractions monitored with thin-layer chromatography were obtained but the staining compound was contained in the reddish-brown compound. Re-chromatography of this fraction showed a pure dye, which was used as a stain and subsequently eluted from the sections. Phytochemical screening of the eluted compound revealed that this is a flavonoid, previously described as apigeninidin, (3-deoxypelargonidin).