Utilisation of Tectona grandis (teak) leaf extracts as natural hair dyes

Abstract There is now a preference for hair dye products containing natural dyes because they are safer for human use. Teak leaves contain flavonoids, anthraquinones and naphthoquinones, and their extracts can be used as natural dyes. The objective of this research was to evaluate the use of teak leaf extracts as natural hair dyes. This research was carried out on both young and mature teak leaves that were extracted either with water or with ethanol‐water mixtures using the decoction method. The colour substances in the extracts were studied by quantifying the flavonoid and anthraquinone content, and identified using liquid chromatography‐mass spectrometry (LC‐MS); the colour values were measured with the CIELab system. The solubility, stability and hair dyeing efficacy of the extracts were assessed. The results showed that young leaf extract is redder with a higher total flavonoid content than mature leaf extract. Fifty percent ethanol was the best solvent for extracting the high flavonoids from teak leaves. Polysorbate 20 significantly increased the water solubility of both young and mature leaf extracts. Hair dyed with young leaf extract became reddish brown, while hair dyed with mature leaf extract became brown. Stability testing found some flavonoid degradation of the extracts, but only slight colour changes occurred in the extracts. The LC‐MS profiles showed high‐intensity flavonoid peaks that could be applied to control the colour quality of the extracts with other parameters. These results demonstrate that teak leaf extracts are effective natural hair dyes that can be used in the development of hair dye products.