Banca de DEFESA: GEANNE ALEXSANDRA ALVES CONSERVA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : GEANNE ALEXSANDRA ALVES CONSERVA
DATA : 19/02/2021
HORA: 09:00
LOCAL: por participação remota
TÍTULO:

BIOACTIVE METABOLITES OF Nectandra oppositifolia Ness & Mart. (LAURACEAE) - MOLECULAR CHARACTERIZATION AND EVALUATION OF ANTIPARASITARY POTENTIAL

PÁGINAS: 250
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Orgânica
ESPECIALIDADE: Química dos Produtos Naturais
RESUMO:

Extracts from the plant species Nectandra oppositifolia (Lauraceae), with unknown chemical composition
and biological properties, exhibited antiparasitic potential, especially against Leishmania (L.) infantum and
Trypanosoma cruzi. Chemical analysis of the essential oils (EOs) from the leaves and twigs indicated that
both are composed of sesquiterpenes with anti-T. cruzi activity. Against the trypomastigote forms of this
protozoan, the EOs from the leaves and twigs showed EC50 values of 8.5 and 51.7 μg/mL, respectively. As
for the amastigote forms, only the EO from the leaves was active, exhibiting an EC50 value of 14.1 μg/mL,
with no toxicity against NCTC cells. A bio-monitored assay with the n-hexane extract of the twigs yielded
three compounds: secosubamolide A (1), isolinderanolide D (2) e isolinderanolide E (3) that, against T. cruzi,
showed potential for both the trypomastigote and amastigote forms, with EC50 values of 12.5, 12.9 and 29,9
μM and 12.3, 25.3 and 10.1, μM respectively. Investigation of a possible mode of action for these compounds
revealed that all three caused alterations in the mitochondrial membrane potential (ΔΨm). Against
intracellular forms of L. (L.) infantum, compound 1 (EC50 of 5.4 μM) was selected for evaluation of
immunomodulatory effects. Analyses showed that compound 1 did not induce alteration in nitric oxide levels.
Furthermore, this compound suppressed TNF and production of exarcebatory cytokines IL-6 and IL-10,
increasing levels of MCP-1 (CCL2), a chemokine responsible for maturation of granulomas in the liver and
parasite load reduction during experimental visceral leishmaniasis. Finally, compounds 1 – 3 were submitted
to in silico analyses of pharmacokinetic properties and predicted as non-mutagenic blockers, noncarcinogenic,
non-hERG, with acceptable levels of intestinal absorption, high metabolic stability, low
inhibitory promiscuity with the five main CYP isoforms, and not recognized as PAINs. Bio-monitored studies
conducted with the n-hexane extract of the leaves allowed for isolation of neolignane licarine A (4), which
exhibited activity against promastigote and amastigote forms of L. (L.) infantum, with EC50 values of 45.4
μM and 5.4 μM, respectively. However, compound 4 displayed toxicity (CC50) of 54.1 μM against NCTC
cells. Regarding T. cruzi, 4 showed activity exclusively against trypomastigote forms (EC50 of 54.3 μM),
with no toxicity against mammalian cells. Aiming to improve the pharmacological potential for compound
4, ADME properties were predicted in silico, and based on these results five derivatives were prepared (4a –
4e) which were tested for anti-T. cruzi and cytotoxic activities, with 4d (EC50 of 5,0 μM) and 4e (EC50 of
10,5 μM) standing out. Of these, only 4d displayed toxicity (CC50 value of 45.5 μM) for NCTC cells while
the remainder exhibited CC50 > 200 μM. The mode of action induced by 4d and 4e showed that both
compounds caused a probable mitochondrial failure, with alteration of the electric potential in the plasmatic
membrane (ΔΨp) as well as causing an increase in production of reactive oxygen species. Furthermore, the
parasite’s bio-energetic system was compromised, as a result of increase in ATP production, suggesting a
compensatory cellular stress. Studies with the ethanolic extracts of leaves and twigs (N. oppositifolia) allowed
for isolation of constituents: ethyl pyroglutamate (5), methyl protocatechuate (6), (Z)-2-(2,4-dihydroxy-2,6,6-
trimethylcyclohexylidene) acetic acid (7), vanillic acid (8), (-)-evofolin B (9), 7-hydroxy-6-methoxy
coumarine (10), indole-3-aldehyde (11), moupinamide (12), abscisic acid (13), azelaic acid (14), ethyl
protocatechuate (15), verrucosine (16), nectandrin B (17) and kaempferol-3-O-α-L-(3,4-di-E-p-coumaroyl)
rhamnopyranoside (18). Against T. cruzi, compounds 7, 9, 15, 16 and 17 exhibited activity exclusively for
amastigote forms, with EC50 values of 28.2, 27.8, 18.1, 36.8 and 31.0 μM, respectively. For trypomastigote
forms, only 13 and 18 showed activity, with EC50 values of 31.4 and 6.7 μM, respectively. Analyses of
possible modes of action induced by compound 18 pointed to mitochondrial alterations as well as for levels
of intracellular Ca2+. Additionally, a decrease in ATP levels was observed, which could be connected to the
mitochondrial alteration, leading to parasite death. Therefore, it is possible to infer that the presented results
are promising in the search for prototypes of new drugs for treatment of Visceral Leishmaniasis and Chagas
Disease. Moreover, the data acquired corroborates for chemical and biological knowledge of the genus
Nectandra, the species N. oppositifolia in particular, describing the occurrence of compounds 1 – 3, 5 – 9,
11– 15 and 18 in the genus for the first time.

MEMBROS DA BANCA:
Presidente - Interno ao Programa - 1623577 - JOAO HENRIQUE GHILARDI LAGO
Membro Titular - Examinador(a) Externo à Instituição - NIDIA FRANCA ROQUE - USP
Membro Titular - Examinador(a) Externo à Instituição - CAROLINA AMARAL FRADE BRUNO DE SOUSA
Membro Titular - Examinador(a) Externo à Instituição - BEATRIZ HELENA LAMEIRO DE NORONHA SALES MAIA - UFPR
Membro Titular - Examinador(a) Externo à Instituição - FERNANDA RODRIGUES GARCEZ - UFMS
Membro Suplente - Examinador(a) Externo à Instituição - IVANA CORREA RAMOS LEAL - UFRJ
Membro Suplente - Examinador(a) Externo à Instituição - MARCUS TULIUS SCOTTI - UFPB