Phytochemical studies on some species of family Bignoniaceae and Lapachol as a family characteristic

The isolation and subsequent identification of naphthoquinones, sterols and hydrocarbons from Bignoniaceae and Verbenanceae species collected in Tanzania is discussed. In the present investigation lapachol has been either isolated or detected in the root wood of nine out of eleven species studied including Tectonagrandis (Verbenaceae). Dehydro-µ-lapachone, squalene, 2-methylquinizarin and a new dihydroxynaphthoquinone (3.8-dihydroxy -2-(3-methyl2'-butenyl)-1,4-naphthoquinone) were isolated from Tectonagrandis. g-Sitosterol and campesterol were isolated from the root and stem woods of Markhamia Zanzibarica respectively. From Markhamia zanzibarica leaves a long chain hydrocarbon, tritriacontane was isolated along with a reddish compound whose identification failed due to lack of dept 135 N. M. R. u. v., i. r. spectra which were found necessary for the structure determination. g-Sitosterol and tritriacontane were also isolated from Kigelia africana root bark. From Millingtonia hortensis, root wood was isolated b-sitosterol. The contribution of lapachol to the chemotaxonomy of family Bignoniacea is discussed. Lapachol and its transformations are being suggested as potential biological markers for the family Bignoniaceae. The possible seasonal dependence of lapachol was observed in Millingtonia hortensis. The investigation noted that lapachol was more abundant at the end of the wet season than at the end of the dry season. Cytotoxicity study on the plant extracts and pur compounds were performed. Kigelia Africana root bark, g- sitosterol, lapachol and 3,8-dihydroxy-2-(3'-methyl-2' butenyl)-1,4-naphthoquinone were found to be quite active.