Isolation, characterization and biological evaluation of onconutraceuticals compounds in the Mediterranean area: new tools for the treatment of oncological diseases

The main objective of the PhD project was the evaluation of the onconutraceutical potential of food matrices from the Mediterranean area, in particular Citrus sinensis (sweet orange), Humulus lupulus (hops) and Lycium barbarum (goji berries). It is known that the daily intake of fruit and vegetables, the introduction of foods rich in bioactive substances into the diet and a healthy and correct lifestyle could represent possible strategies aimed at reducing the incidence of cancer. The discipline that deals with the study of foods with anticancer activity is Onconutraceutics. In detail, the bioactive extracts of the plant matrices under study were characterized by high-performance liquid chromatography experiments coupled with high-resolution mass spectrometry studies. The results obtained highlighted the presence of a wide variety of bioactive molecules, including Nobiletin in C. sinensis, Xanthohumol in H. lupulus and Rutin in L. barbarum, whose antitumor properties are described in the literature. Initially, the methanolic extracts of C. sinensis and H. lupulus were fractionated by semipreparative reverse-phase liquid chromatography, yielding 4 and 3 fractions, respectively. Among these we obtained two main bioactive aliquots: NCF from C. sinensis, containing polymethoxyflavones and in particular Nobiletin and XCF from H. lupulus, consisting of prenylflavonoids whose main compound was represented by Xanthohumol. The purpose of the fractionation was to obtain fractions with a high onconutraceutical potential. In order to evaluate the potential use of NCF, XCF or their combination as chemo-sensitizing agents and to reduce the cytotoxicity of chemotherapy treatments, we investigated the potential synergistic effects of these natural compounds with 5-Fluorouracil and Oxaliplatin (FOX) on CR-CSphC isolated from both naïve primary CRC and liver metastases of chemotherapy-refractory patients. The results obtained demonstrated that the administration of NCF, XCF and their combination (Mix) significantly reduced the proliferation of CR-CSphC, and consequently the expansion of metastatic CR-CSC in chemotherapy-refractory patients. Interestingly, these natural plant-derived compounds, singly or in combination, are useful as additive molecules to chemotherapy, possibly limiting antitumor cytotoxicity against normal cells. The results obtained, therefore, could provide a starting point for the use of these matrices as adjuvants of the classic pharmacological treatment and prevention of colorectal cancer. The next phase of the research project concerned the evaluation of the potential antioxidant and anticancer properties of the phytocomplexes extracted from five Mediterranean area matrices on tumor and healthy cells. Analysis of the initial screening data showed that L. barbarum extract (LBE) had the highest antiproliferative capacity on the HeLa cervical cancer cell line and had no significant effect on MCF10A healthy cells. Subsequently, since the IC50 on HeLa cells was slightly elevated and since MCF10A cells were used as healthy cells, it was thought to use the corresponding breast cancer cell line MCF-7 to evaluate the possible biological properties of the LBE extract. The obtained results showed that goji berry extract is able to reduce the viability of MCF-7 tumor cells without having a significant effect on MCF10A healthy cells. An interesting aspect that emerged is also a double behaviour on reactive oxygen species, as it has both an antioxidant and a pro-oxidant action. The antiproliferative activity of LBE is probably due to the pro-oxidant action exerted inside the tumor cells in the first hours of administration. The state of imbalance within the cell has led to disabling the structures necessary for cell survival and proliferation and inducing cell death, through a strong activation of endoplasmic reticulum stress. In conclusion, the obtained results further confirm the belief in the health benefits deriving from Lycium barbarum, as a very promising natural medicine in the prevention and treatment of cancer due to their high content of active compounds. The anticancer actions of LBE together with the lack of toxic effects on normal cells make the constituents of L. barbarum attractive chemopreventive agents.