Separation and potential valorization of chemical constituents of soursop seeds

Abstract

Seeds of Annona muricata, by-products from the edible fruit, were assessed chemically and biologically. Using larvicidal bioassay, activity-directed fractionation of ethanolic extract led to the isolation of three known acetogenins: annonacin, murisolin and annonacinone. Their structures were established by spectroscopy experiments. Synergistic activity of these acetogenins was observed. The low water solubility of annonacin was demonstrated to be one of the limiting factors of its larvicidal activity. The catalytic hydrogenation of annonacin afforded a mixture of diastereoisomers which is more active against Culex quinquefasciatus larvae than annonacin. Micro-Kjeldahl analysis showed that residues of extraction (insoluble matter) contained 25.6% crude proteins. Solvent partitioning of the kernel ethanolic extract yielded: oil (30.4% of kernels), mixture of acetogenins (4.2% of kernels) and mixture of carbohydrates (5.2% of kernels). The oil was weakly toxic to Artemia salina nauplii. Eight fatty acids were identified. Sucrose was the major carbohydrate. Potential valorization of these components is discussed.