Emery, Neil NE

The seed oil of Carapa guianensis, known as Crabwood oil (CWO) and its fractionation was studied, focussing on chemical composition and physicochemical functionality. Compounds never reported before in CWO were identified, including limonoids such as Trichillin, ketostearic and hydroxyoleic acids. Yield of olein and stearin fractions correlated strongly with solvent polarity. Important bioactives were partitioned as a function of solvent polarity in the olein vs. stearin fractions. For example, up to 35% more of Gedunin were present in the liquid fractions. Solid fat content, crystallization and melting temperature and microstructure were significantly affected by fractionation and shown to be strongly correlated with solvent polarity. Fractionation was demonstrated to be a powerful tool to extend the physical functionality of CWO and concentrate its bioactives.

Author Keywords: Carapa guianensis, Chemical characteristics, Crabwood Oil, Dry and Solvent fractionation, Fractionation, Physical characteristics

The oyster mushroom, Pleurotus ostreatus, is one of the most widely cultivated edible basidiomycetes. It has gained increased attention for its economic, environmental, and medicinal properties. While a lot is known about cytokinins (CKs) and their actions at the molecular and cellular levels in plants, much less is known about the function of CKs in other kingdoms. Cytokinins, which have been detected in several fungal species, play a role in pathogenic attack against plants or during plant growth promotion by plant beneficial microbes; however, the role of CKs in fungal physiology, separate from plant associations remains largely unknown. This thesis focuses on the occurrence of fungal-derived CKs in P. ostreatus when grown in vitro as submerged or aerial mycelium. Cytokinin profiling by UHPLC-HRMS/MS revealed that P. ostreatus produces CKs and that the tRNA degradation pathway is the main source of these molecules. CK dynamics within fungal growth supported previous evidence, which suggested that tRNA degradation products have a role in the physiological development of fungi for which CKs act as fungal growth regulators. A second component of the thesis demonstrated that P. ostreatus responds to exogenous applications of aromatic and isoprenoid CKs and their effects were dependent on the dose and CK type. N6-Benzyladenine (BAP), Kinetin (KIN), N6-isopentenyladenine (iP), and trans-zeatin (tZ) bioassays revealed hormone-type responses (hormesis: biphasic response). At low doses, mycelium growth could be stimulated, whereas, at high doses only inhibitory effects were observed. This stimulation/inhibition was observed whether the measured response was an increase/decrease of aerial mycelium colony diameter, biomass accumulation or a change in mycelium morphology as compared to the controls. Results indicated there is potential to alter mycelium growth and development of P. ostreatus; thus, CKs may play the role of a "mycohormone" and may be specifically helpful for medicinal fungi by increasing growth and efficiency to produce many biologically active substances with valuable medical and environmental applications.

Author Keywords: cytokinins, fungal-derived CKs, hormesis, mycelium, mycohormone, Pleurotus ostreatus