Comparative analysis of total tannins in Plectranthus barbatus Andrews water, acetone and methanolic extracts in Kenya

Abstract

The purpose of this study was to identify the most suitable solvent for use in extracting tannins from Plectranthus barbatus Andrews leaves, a plant indigenous to various parts of Kenya. The plant was traditionally used by the Gusii community in Kisii and Nyamira Counties for establishing land demarcations, enhancing ripening of bananas and as a stomachache remedy. The plant’s resistance to either wild or artificial fire, a feature predominant in plants with high tannin content makes it a good candidate for research. The tannin content and the most eco-friendly and economical solvent to use have not been established and this compound can also be used in preserving and tanning hides and skins. Furthermore, the plant contains nepetoidin B which is a powerful antioxidant capable of eliminating toxic free radicals present in chrome tanned leather. The leaves of the plant were collected from three locations in Nyamira County, Kenya and positively identified at the Kenya National Museum Herbarium in Nairobi. Extraction was carried out using 80% methanol, 80% acetone and water followed by determination of total tannins using the hide powder method. The percentage tannin content was found to be 56%, 36% and 60% respectively and furthermore phytochemical screening revealed that the leaves contained tannins of hydrolysable type. There was a significant difference (p<0.05) in the levels of tannins dissolved by the three solvents and the study concluded that water was the best solvent for use in extraction of tannins.