Banca de DEFESA: KAIO DE SOUZA GOMES

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : KAIO DE SOUZA GOMES
DATE: 18/12/2023
TIME: 09:00
LOCAL: Sala 302 do Bloco B do Campus de Santo André da Universidade Federal do ABC
TITLE:

Cytotoxic Evaluation, Cell Death Mechanisms and Synergic Effects with Ion Cu2+ of Neolignans and Alkaloids in Human Breast Cancer Cell Lines

PAGES: 225
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Orgânica
SPECIALTY: Química dos Produtos Naturais
SUMMARY:

In this work, were isolated, from hexanic extract of leaves of Ocotea cymbarum (H. B. K.) Ness. (Lauraceae), two neolignans – biseugenol (I) and dehydrodieugenol B (II), which structures were determined by NMR and MS in comparison with previously reported data. Both compounds were evaluated against human breast cancer cell lines MC7 and MDA-MB-231, using MTT assay, being compound I few active (IC50 > 500uM) and compound II active in tested cell lines, with IC50 between 100 and 250 uM for both lines. Besides that, the mechanism of cell deaths induced by compound II was determined by staining with Annexin-V/FITC and propidium iodide in different incubation times. It was possible to determine, with 24 h of incubation of MCF7 cells with compound II, 37% of cellular population had phosphatidylserine externalized, indicating the induction of apoptosis by compound II. To evaluate synergic effects of compounds I and II with ion Cu2+, both cell lines were incubated wit equimolar solutions of neolignans and Cu(ClO4)2.6H2O and cell viability was determined by MTT. It was possible to observe no differences in cytotoxicity when compound II is combined with Cu2+, however, the combination of Compound I and Cu2+ increases the cytotoxicity, with IC50 between 100 and 250 uM. The behaviour of this mixture in MCF7 spheroids to understand the caused effects considering the tumoral microenvironment, using fluorescence staining and imaging by fluorescence microscopy. It was possible to observe, in quiescence zone and in the necrotic nucleus, higher fluorescence intensity in red filter, indicating more dead cells stained, suggesting that the mixture permeates the spheroid. Intracellular copper disbalance caused by mixing compound I and Cu2+ was quantified by ICP-MS. The results showed increase in copper concentration of 50 times in comparison with untreated cells (p>0.0001) – 18.7 ng of Cu/mg of proteins and 0.37 ng of Cu/mg of protein, respectively, while the copper concentration in cells treated with compound I was similar to negative control (0.29 ng of Cu/ mg of protein). This alteration allow to infer that compound I may act as ionophore, carrying Cu intracellular medium and inducing a copper-dependent cell death, the cuproptosis. To evaluate the synergic effects of other class of natural products, two alkaloids, lycoricidine and narciclasine, were prepared using synthetic sequence in which the key-step is a enantioselective dearomative carboamination of benzene, where the principle is a cycloaddition between an arenophile and an arene commercially available, in this case, benzene and had in total seven steps in the longer linear sequence. These compounds had their cytotoxic potential evaluated by MTT assay against cell lines MCF7 and MDA-MB-231, as well as their synergic effects with Cu2+. Among the  tested compounds, narciclasine showed activity in both cell lines, with IC50 ranging between 10 and 25 uM, while lycoricidine was inactive. The only structural difference between both compounds is the presence of a phenolic hydroxyl in narciclasine, which may generate stable radicals, inducing damage to proteins, nucleic acids, membranes and organelles. No difference on cytotoxicity was found when narciclasine was combined with Cu2+, while the combination lycoricidine+Cu2+ showed cytotoxicity in concentrations of 50 and 100 uM, for MCF7 and MDA-MB-231 cell lines, respectively.

COMMITTEE MEMBERS:
Presidente - Interno ao Programa - 1623577 - JOAO HENRIQUE GHILARDI LAGO
Membro Titular - Examinador(a) Interno ao Programa - 3323134 - LUIZ DUARTE RAMOS
Membro Titular - Examinador(a) Externo à Instituição - VALDIR FLORENCIO DA VEIGA JÚNIOR - IME
Membro Titular - Examinador(a) Externo à Instituição - LETICIA VERAS COSTA LOTUFO - USP
Membro Titular - Examinador(a) Externo à Instituição - ANDREA MARIA AGUILAR - UNIFESP
Membro Suplente - Examinador(a) Interno ao Programa - 1844792 - AMEDEA BAROZZI SEABRA
Membro Suplente - Examinador(a) Externo ao Programa - 1671688 - ANDRE SARTO POLO
Membro Suplente - Examinador(a) Externo à Instituição - JORGE MAURICIO DAVID - UFBA