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La méthode microgravimétrique statique a permis d’observer que la pulpe de l’aiélé est plus hygroscopique que l’amande de karité à 25°C. A l’inverse, on fait l’observation contraire entre 35 et 55°C. Le modèle d’Oswin décrit le mieux les données de sorption des deux produits sur toute la gamme d’activité de l’eau. Les isothermes de l’amande de karité et de la pulpe de l’aiélé présentent le phénomène d’hystérésis entre 25 et 55°C. La conservation de ces oléagineux doit s’effectuer dans une atmosphère d’humidité relative comprise entre 40 et 60% afin d’obtenir des teneurs en eau recommandées. Un modèle adapté de prédiction des isothermes de sorption de ces oléagineux en deçà de 25°C et au delà de 55°C a été obtenu. L’extraction de la matière grasse au CO2 supercritique donne des rendements inférieurs à ceux obtenus de l’extraction à l’hexane. L’indice d’acide des matières grasses extraites au CO2 est supérieur à celui des lipides extraits à l’hexane. Ces indices, pour les lipides extraits des produits stockés à 18°C, sont les plus élevés. Quelque soient le mode de stockage et le solvant d’extraction, l’indice d’iode baisse avec le stockage. Le CO2 présente une sélectivité vis-à-vis de l’acide linolénique. Les lipides extraits au CO2 présentent les taux d’acides gras libres les plus élevés. Il ressort des résultats que le stockage -33°C est le meilleur. Toutefois, il ne doit pas dépasser 5 mois. L’extraction des lipides au CO2 supercritique doit utiliser les fruits frais ou stockés à -33°C. Les produits stockés à 18°C sont les plus durs et la dureté est corrélée négativement à la teneur en eau, mais positivement à l’indice d’acide des matières grasses extraites / The static microgravimetric method permitted to observe that the Canarium pulp was more hygroscopic at 25°C than the sheanut kernels. On the other hand, sheanut kernel was more hygrocopic in the temperature range 35°C-55°C. The Oswin model best described the sorption data of the two products in the whole water activity range. Hysteresis was observed in the entire temperature range 25-55°C for sheanut kernel and Canarium pulp. It is suggested that these products should be stored in an environment with a relative humidity of 40-60%, in order to attain the recommended moisture content for storage. A model was adapted to predict the sorption isotherms of shea and Canarium below 25°C and above 55°C. The oil yields obtained with supercritical CO2 were lower than those obtained with hexane. The acid values of butter and oil extracted with carbon dioxide were greater than those of lipids extracted using hexane. The acid values of samples stored at 18°C were the largest. The iodine value of the oils decreased with an increase of the storage period, irrespective of the storage temperature and the solvent used for extraction. The extraction with CO2 did not extract linolenic acid. The proportion of free fatty acids increased when carbon dioxide was used for extraction. From the foregoing, it is suggested that storage at -33°C for up to 5 months presents the best means of preserving these products. Only fresh or fruits stored at -33°C should be used for the extraction of lipids using carbon dioxide. The products stored at 18°C were the most hard and the hardness was correlated negatively to the water content, but positively to the acid value of fatty material extracted

Natural products are acknowledged sources of novel compounds for use in the treatment of diseases such as cancer, malaria, and human African trypanosomiasis. However, health burdens of such diseases still remain high, with drug resistance leading to failure of current medication. Therefore, there is a need for new treatments, and this project considers the potential of Nigerian ethno-medicinal plants and their products. Firstly, the aims were to isolate cytotoxic compounds through bio-guided evaluation and fractionation from 3 medicinal plants; Vitellaria paradoxa, Cyperus articulatus and Securidaca longepedunculata used traditionally in the treatment of cancer in North-East Nigeria. Extracts from S. longepedunculata were the most active when assessed in a panel of cancer cell lines, with IC50 values below 10 µg/ml, whilst fractions isolated from V. paradoxa and C. articulatus were moderately cytotoxic and able to overcome drug resistance mechanisms in drug resistant cell lines. In the second part of the thesis, novel cryptolepine analogues were semi-synthesized using environmentally friendly methods and evaluated for cytotoxic, anti-plasmodial and anti-trypanosomal activity. The compounds were found to be highly cytotoxic in cancer cell lines with the ability to overcome drug resistant mechanisms, with sub-µM IC50 values, and were also active against drug resistant strains of Plasmodium parasites in addition to Trypanosoma brucei, with IC50 values below 500 nM, and 300 pM respectively. / Schlumberger Faculty for the Future Foundation