Comparative pharmacobotanical study of some species belonging to Cucurbitaceae family

The present thesis is following three major directions that are aimed to provide a complete study of three species belonging to Cucurbitacee family, namely Bryonia alba L., Echinocystis lobata (Michx.) Torr. et A. Gray and Ecballium elaterium (L.) A. Rich.The first approach that is offered by this thesis is the botanical study of the three species. This is the first approach of that kind that is done for each species. Even though scientific literature offers some data on the botanical description of some of the features of these species, no complete and conclusive data on these species could be found and therefore the information that is brought hereby offer a new approach towards the characterization of the microscopic and macroscopic description of these species. The methods that are used for the microscopic study allow to bring data that are presented for the first time in this manner. It is thus the first description of the anatomical structure of reproductive organs for B. alba and the first description of all the vegetative and reproductive organs for E. obata and E. elaterium. For the trichomes of the species, the ones belonging to B. alba and E. lobata are described for the first time (the ones of B. alba are also described by SEM). Therefore, the results obtained in the botanical study are original and may complete the existing data in scientific literature and help to perform the complete and correct identification of these species.The second section of this thesis is in itself the most innovative realisation as it describes the study of the composition in flavonoids of these species. Even if the plants belonging to Cucurbitaceae family are largely known for their content of cucurbitacins, the flavonoids are lesser known and studied. They are nevertheless important compounds and the present studies were aimed to show that they might be responsible for biological activities that were never described before in scientific literature. The novelty of this study concerns therefore the HPLC-DAD and HPLC-MS study of flavonoids and polyphenols, followed by their isolation by preparative HPLC-DAD. Isolated products by these techniques were subsequently analyzed in order to properly identify their structure by means of MS and NMR techniques. In the last stage, these products were used for the biological assays and were tested in order to establish their involvement in the biological activities that the total extracts exhibited.The biological activities that are assessed in this study are also novel and innovative. These plants are generally known for their cytotoxicity, as their content of cucurbitacins is largely cited. The present study showed no significant cytotoxicity for the extracts belonging to the three plants. These findings are important, as the plants that proved weak cytotoxicity (B. alba and E. lobata) are the ones that prove to contain the highest amounts of flavonoids. The only species that has proved moderate cytotoxicity is E. elaterium, the species which contains the lowest amounts of flavonoids. Another important novelty is the assessment of the anti-plasmodial activity of these plants. Even though the anti-plasmodial tests showed no activity, the results correlate with the ones obtained for the assessment of the cytotoxicity, showing that there is no cellular toxicity for these samples. It is especially the extracts of the species that are richer in flavonoids that have shown no toxicity. Subsequently, the species were studied for the antioxidant properties, as the flavonoids are well known to exhibit such properties. Our work demonstrated antioxidant properties for these species. Classical and chemical assays were used. The capacity to inhibit the activity of an enzyme was assessed on the HRP model and it was found that the most potent extracts were the ones of B. alba. Subsequently, this extract and its isolated products were tested for the global antioxidant activity on two different models, the equine isolated neutrophils ex vivo and activated with PMA and the human HL-60 monocytes transformed in macrophages and activated with PMA. All these assays are performed for the first time for the species B. alba. By justifying the involvement of these products in the redox processes, it could be justified that these products can be involved in the processes that accompany inflammation. By the different approaches that were treated in the present thesis, new and important data could be added to scientific literature regarding the three species belonging to Cucurbitaceae family. Originality and innovative contributions are found not only in the different ways of describing these species, but also in the obtained results, that can help to justify the importance of these plants as medicinal species. Therefore, Bryonia alba L., Echinocystis lobata (Michx.) Torr. et A. Gray and Ecballium elaterium (L.) A. Rich. have proved to be important sources of bioactive compounds and may have an important potential in the treatment of different disorders. Nevertheless, their absence of toxicity should be confirmed with more samples and in vivo studies.