Development of natural pigments from Tectona grandis (teak) leaves: Agricultural waste material from teak plantations

Abstract

The purpose of the research was to develop a new pigment from teak leaves, an agricultural waste material from the teak industry. Teak leaves were extracted by various polarity solvents to provide a variety of color extracts. The ethyl acetate extract gave reddish-brown with the highest intensity. The ethyl acetate extract was selected to develop the pigment by adsorption method. It was found that the type of substrate affects the color and the intensity of the obtained pigments. Using aluminium hydroxide Al(OH)3 as a substrate provided the purple pigment with the highest color intensity because Al(OH)3 could adsorb both flavonoids and anthraquinones contained in the extract. The other substrates showed a lighter color because they could adsorb only flavonoids. Increasing the mass ratio between Al(OH)3 and the extract, when preparing the pigment, increased the color intensity of the pigment, with a mass ratio of 10:5, resulting in the color compounds in the pigment being in the range of 12–20%, which meets commercial requirements. The pigments also exhibited higher thermal and light stability than the extract. These results demonstrate the possibility of teak leaves being used as a new source for the development of natural pigments in cosmetic products.