Banca de QUALIFICAÇÃO: GIZELY DE VASCONCELOS LEITE CAVALCANTE

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : GIZELY DE VASCONCELOS LEITE CAVALCANTE
DATA : 27/06/2019
HORA: 08:30
LOCAL: Sala de aula do Química I
TÍTULO:

CHEMICAL AND BIOLOGICAL PROSPECTION OF MARINE BACTERIA COLLECTED IN THE BRAZILIAN COAST

PALAVRAS-CHAVES:

marine bacteria; Streptomyces; chemical prospecting; cytotoxicity.

PÁGINAS: 100
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Orgânica
ESPECIALIDADE: Química dos Produtos Naturais
RESUMO:

The importance of natural products in the discovery of new drugs has been widely documented, including their contribution to the development of current medications. Marine organisms, in turn, may be considered the most recent source of bioactive natural products in relation to terrestrial plants and non-marine micro-organisms. For some time, modern medicine relies on natural microbial products to treat infectious diseases, cancer and other persistent diseases. Included among current efforts to discover new drugs originating from natural products are studies of new populations of bacteria, including those residing in the marine environment. Collectively, these bacteria are producing a wealth of new structures, including agents that are advancing through various stages of clinical development, solidifying the importance of exploring new habitats and resources in the search for new secondary bacterial metabolites. This paper reports the chemical and biological study carried out with gram-positive and gram-negative marine bacteria collected in Rio Grande do Norte, Ceará and the coast of São Paulo, focusing on the isolation of secondary metabolites present in a gram-positive bacterium of the genus identified such as Streptomyces. Several large-scale cultures of the microorganisms with the highest cytotoxic activity were obtained in order to obtain a sufficient quantity to obtain crude extracts that were analyzed by chromatographic techniques such as High Efficiency Liquid Chromatography, Adsorption Chromatography and Molecular Exclusion Chromatography. The chromatographic fractionation of the ethyl acetate extract of the bacterium BRB-081 resulted in the isolation of eighteen substances, among which two acids, called Phenylacetic Acid and Vanillic Acid, the latter being reported for the first time in the genus, the third, a tyramine called N -methylthyramine with antifungal and antitumor activity reported. The other isolated compounds are still in the elucidation phase. The structural determination of the isolated secondary metabolites was performed using the techniques: 1H and 13C Nuclear Magnetic Resonance through uni and bidimensional pulse sequences, mass spectrometry and comparison with literature data. In addition to the isolated substances, 43 substances of the hexane phase were identified by CG-MS. LC-MS analyzes provided the exact mass and fragmentation profile compatible with the structure of Surugamide A and two other analogs, one of which is unknown in chloroform fractions, this chemical class has only recently been described, offers much to investigate. The isolated substances, phases, fractions and crude extracts obtained were submitted to cytotoxic assays using human colon cancer cells (HCT-116). In these tests, it was observed that the BRB081 extract was the most active among the extracts produced and that the analysis of the phases in hexane and chloroform also showed activity considered satisfactory, being the chloroform phase the most active. Fractions containing surugamides were also tested and showed promising results. However, the isolated substances did not present satisfactory cytotoxicity, demonstrating the synergism between the molecules.

MEMBROS DA BANCA:
Presidente - 1569526 - RENATA MENDONÇA ARAUJO
Interna - 1805556 - LUCIENE DA SILVA SANTOS
Externa à Instituição - NATHALIA KELLY DE ARAUJO - IFRN