Development of a "green process" for the isolation of natural functional extracts with anti-cancer activity - Application of high-pressure technology

Dissertação para obtenção do Grau de Mestre em Engenharia Química e Bioquímica

The knowledge of the healing power of some species of plants is ancient. Nowadays, the preference for natural products has increased, and with it, the interest in recover and isolate bioactive phytochemicals with potential health benefits. The main goal of this thesis was to isolate anticancer bioactive compounds, namely terpenes and fatty acids, from Portuguese Lavandula (L. angustifolia and L. stoechas) and Mentha species (M. spicata, M. piperita var. citrata and M. pulegium), using supercritical fluid extraction (SFE). All extractions were performed at 50ºC and 250 bar in a two step methodology: a first step with supercritical CO2, during 60 minutes, followed by a second step, with a mixture of CO2 and ethanol (90:10 %v/v), for 180 minutes. Different fractions of the extracts were recovered every 30 minutes, and the resulting samples were characterized in terms of global yield (% g/g), screened for the presence of terpenes, by thin layer chromatography (TLC) and analyzed by gas chromatography coupled with mass spectrometry detection (GC-MS). Furthermore, ORAC, HORAC and HOSC assays were conducted for the determination of antioxidant activity. Cell-based assays in human HT-29 colorectal adenocarcinoma cells were also performed, in order to determine the potential of the extracts as cancer cell-growth inhibitors. The fractions of the extract of M. piperita var. citrata presented the highest antioxidant activity, whereas the fractions of L. angustifolia, L. stoechas and M. spicata extracts revealed to be the most promising colorectal cancer cell-growth inhibitors. The bioactive responses were correlated with the phytochemical composition of the extracts, and the main compounds, such as camphor, fenchone, carvone, linoleic acid, among others, were highlighted. However, it is possible that the bioactivities were due to synergistic effects between several compounds. Results of this thesis demonstrated that SFE is a reliable tool to extract anticancer bioactive components from some Lavandula and Mentha plants.