Mosquitocidal and Antimicrobial Nor-halimanoids, Ent-clerodanoids and other Metabolites from Some Tanzanian Tessmannia and Annonaceae Species

Abstract

This Thesis reports results from chemical investigations and larvicidal, mosquitocidal, mosquito repellent and antimicrobial activity of 16 Tanzanian plant species of the families Leguminosae, Annonaceae, Eurphorbiaceae and Meliaceae, and constituents of some of the plant species. Three Tessmannia species T densiflora, T martiniana var pauloi and T martiniana var martiniana that are reported to occur only in Tanzania, yielded series of nor-halimanoid and entclerodanoid diterpenes, some exhibiting mosquitocidal and antimicrobial activities, while others such as the nor-halimanoids tessmannic acid and its methyl, 2-methylpropyl and 1-methylbutyl esters and the ent-clerodanoids cis-kolavenolic acid, ent-(18-hydroxycarbonyl)-cleroda-3, 13(E)-dien-l 5-oate, (9-epi)-ent-( 18- hydroxycarbonyl)-cleroda-3, l 3(E)-dien-l 5-oate as well as the ISocoumann chlotessmin, are novel natural products, and so are 0-(3-hydroxy-4-hydroxycarbonyl-5-pentylphenyl)-3-chloro-4-methoxy-5-pentyl-2-oxybenzoic acid and 5-pentyl-3-methoxy-N-butylaniline. Several other mosquitocidal and antimicrobial compounds were obtained from the Annonaceae species Uvaria lungonyana, Uvariodendron pycnophyllum, Polyalthia tanganyikensis and Annona squamosa, among them the aromadendrane sesquiterpenoid tanganyikenol and the kaurane diterpenoid l 7-acetoxy-ent-kauran-19-al obtained from P. tanganyikensis and A. squamosa respectively, are being reported for the first time. Structural determination of all the isolated compounds was achieved based on spectroscopic data. These results further demonstrate the abundance of bioactive clerodane and halimane diterpenes in the Caesalpiniaceae family, as previously reported elsewhere.