Extraction and Analysis of Spectral Properties and ChroMophoric Characterization of Natural Dye Extract from Barks of Terminalia brownii Fresen (Combretaceae)

Abstract

Terminalia brownii is known for its medicinal properties has been used to treatment and management of malaria, ulcers, diarrhea, coughs, hepatitis etc. In Elgeyo-Marakwet County, and amongst the Marakwet community of Kenya, the plant has been known for its dyeing properties and has been used historically for the dyeing of traditional handbags locally known as “kiondos”. Literature evaluation indicates little is known concerning the dyeing properties of this plant, hence there was need for such work to be done. This coupled with the fact that there has been an attempted shift to natural dyes from their synthetic counterparts which are considered to be poisonous, allergens and in some cases carcinogenic. In this work, two extraction methods namely soxhlet and maceration were compared for their percentage yields with maceration being chosen as a preferred method. The extracts were then separated and identified via UV-VIS, FT-IR and LC-MS. Preliminarily the UV-Vis was used for identification of chromophores present in the dye extracts at maximum absorption (λ max ) due to electron transitions from HOMO-LUMO whereas the FT-IR was used to identify the specific vibrational chemical bonds characteristic of the individual functional groups present in the dye extracts. LC-MS in tandem with collision induced dissociation (CID) was used to accurately identify and characterize the chromophoric compounds based on their structures, molecular (product ion) and fragmentation pattern which were then compared with LC-MS data, library and the literature. Several compounds with dyeing properties such as Catechin, Epi-Catechin, Baccatin, Gentianose, Geniposide and Genipin were identified. Gentianose, geniposide baccatin and genipin are being reported for the first time as chromophoric compounds in Terminalia brownie.