Phytochemical investigations of some plant species of family rubiaceae and their dyeing properties

Ten species of family Rubiaceae and three from outside Rubiaceae were subjected to preliminary screening with {i) dilute sodium hydroxide and (ii) with a number of multivalent metal salts. The plants included Agathisanthermum bojeri, Canthium zanzibaricus, Chassalia spp, Catunaregan nilotica, Crossopteryx febrifuga, Lamprothamnus zanguebaricus, Vangueria tomentosa, Leptactina hexamera, Posfaerea spp, Heinsia spp, (all Rubiaceae). Cassia siamea (Caesalpiaceae), Tectona grandis {Verbenaceae) and Acacia mearnsii (Mimosaceae). Crossopteryx febrifuga, Lamprothamnus zanguebaricus, Leptactina hexamera, Tectona grandis, Cassia siamea and Acacia mearnsii produced very intense coloured solutions with sodium hydroxide. These were selected as the most probable source of vat dyes. The three Rubiaceous plants also gave good results with the metal salts to be a source of mordant dyes. The rest of plants were not dealt with any further. The selected plants were subjected to detailed dyeing experiments {vat, mordant, direct and azoic dyeing). Alizarin was used as a standard natural vat and mordant dye. As a vat dye, alizarin, gave from light pink to violet colours, while, colours such as red-rose, black-violet and brawn-violet were produced by mordanting alizarin with aluminium, iron(II} and copper(II} respectively. The synthetic azoic dyes, Naphthol AS (coupling component) and the four Fast Salts (Blue, Scarlet, Black and Orange) were used as standards to the azoic dyeing with plant extracts. The dyed fabrics with synthetic azoic dyes produced the colours as the names of the salts depicted. With all dyeings using these plants' extracts the direct dyeings with C. febrijuga, L. zanguebaricus and L. hexamera produced very good dyed fabrics in terms of colour shades. This was followed by vat dyeing together with the extract of Cassia siamea. Colour fastness tests on the direct and vat dyed fabrics, showed that the direct dyed samples were very good as compared to the vat dyed samples. Tectona grandis and Acacia mearnsii extracts, proved a failure as vat dyes. The mordant dyeing using C. febrifuga, L. zanguebaricus, L. hexamera and C. siamea produced fair shades with no definite colours. T. grandis and A. mearnsii were not effective as mordant dyes. C. febrifuga, L. zanguebaricus, T. grandis and A. mearnsii extracts showed good colours as azoic dyes. In terms of performance, of all the plants investigated and the methods used, C. febrifuga, L. zanguebaricus and L. hexamera are likely to be good source of natural direct dyes. These three plants and Cassia siamea were found to be good sources of natwal vat and mordant dyes. Lamprothamnus zanguebaricus and Leptactina hexamera were phytochemically investigated. From the stem bark of L. zanguebaricus, were isolated 1-(3-Hydroxy-4-methoxy-5-methylphenyl)ethanone (a new compound), 1-(3-Hydroxy-4-methoxy- phenyl)ethanone and a partially identified para-disubstituted benzene long chain ester. From the stem bark of Leptactina hexamera, was isolated a white compound which seem to be highly oxygenated and its structure could not be identified.