Taxonomic Revision of the Family Asclepiadaceae Sensu Lato Representatives in the Sudanese Flora And phytochemical Screening of two Leptadenia species

Abstract

Asclepiadaceae is a family of dicotyledonous flowering plants, which includes a number of species distributed all over the Sudan. ‘It contains species used as a source of animal food and others are medicinal herbs that contain some bioactive compounds and are used in local medicine. The present study constitutes two -parts. The fn'st part comprises a systematic survey of the Sudanese representatives of the family based mainly on material deposited in the local herbaria in the Sudan and Kew herbarium (from the net), in addition to species reported in the Sudanese floras and relevant publications. In the second part, the phytochemical analysis of two selected species from the family namely: Leptadenia arborea and L. pyrotechnica is carried out. The Herbarium authenticated material from the family Asclepiadaceae contain 36 genera includes 65 speices, were studies in details. These taxa were treated according to the Angiosperm Phylogeny Group (APG) system of new classification; which have incorporated within the family Apocynaceae. It has been fotmd in this study that 5 6 species belong to the sub-family Asclepiadoideae, 7 species included in the sub-family Periplocoideae and only two species belong to the sub-family Secamonoideae. For the studied taxa, taxonomic keys were constructed to differentiate between sub-families, genera and species. For each species standard up-dated scientific binomial, synonyms and vernacular names are given. A brief description, details of information recorded fiom herbarium material were studied and economic uses are includes when available. Phytochemical screening of the two studies Leptadenia species (leaves, stems and fruits) using quantitative analysis methods in ether, ethanol and water as solvents sequential showed various secondary products. Phytochemical analysis of arborea collected fiom Shambat and West of Omdurman resulted in the presence of alkaloids, flavonoids, tannins, saponins and sterols. L. pyrotechnica stems and fruits collected from Northern Sudan and White Nile State showed the presence of carbohydrates, reduced sugar, alkaloids, flavonoids, tannins, saponins, sterols and coumarins. The chemical constituents of Leptadenia_arb0rea and L. pyrotechnica is similar. However, L. pyrotechnica shows the presence of coumarins and carbohydrates and reduced sugars which are absent in L. arborea. Furthermore, proximate composition of aerial parts of the above-motioned two taxa was carried out to determine their nutritive values. Both gave results confirming a reasonable animal feeding value. In view of the above, the family Asclepiadaceae in the Sudan needs more studies in the different taxonomic approaches and detailed chemical analysis.