Banca de QUALIFICAÇÃO: DAYSEANE SALES BERNARDO CAMPELO GOMES

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : DAYSEANE SALES BERNARDO CAMPELO GOMES
DATE: 29/08/2024
TIME: 09:00
LOCAL: Remoto
TITLE:

Evaluation of the antimicrobial activity of secondary metabolites of Piper aduncum and their synthetic analogues containing an oxadiazole nucleus

KEY WORDS:

Piper aduncum; chemotypes; alkynylphenols; 1,2,4-oxadiazoles;
epoxides; Klebsiella pneumoniae; Staphylococcus aureus and Enterococcus faecalis.

PAGES: 112
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Orgânica
SPECIALTY: Síntese Orgânica
SUMMARY:

In the search for bioactive compounds from plants, the present study was aimed at
evaluating the antimicrobial potential of secondary metabolites of Piper aduncum as
well as their synthetic derivatives containing an oxadiazole nucleus. Initially, the
chemical composition of the essential oil from the leaves of P. aduncum, a plant rich
in dillapiole, was determined and surprisingly did not indicate the presence of
dillapiole, but of α-macrocarpene (14.11%), anisyl formate (14.04%), and cis-
dihydroagarofuran (13.78%) as constituents, corresponding to a new chemotype of
the plant. The essential oil exhibited antimicrobial activity against Enterococcus
faecalis and Klebsiella pneumoniae with a minimum inhibitory concentration of 4096
µg/mL for both bacteria. The dichloromethane extract of P. aduncum roots contained
the alkenylphenol 4-tetradecylphenol, a class of metabolites that rarely occurs in
plants. This is the first report in P. aduncum. Additionally, alkenylphenol derivatives
containing an oxadiazole nucleus were synthesized by the reaction of different
amidoximes. The 1,2,4-oxadiazoles were synthesized 84a-f by microwave irradiation,
with yields ranging from 50-87% and reaction time of 15-45 min, including three new
oxadiazoles containing the epoxide group with yields ranging from 53 to 59%. The
compounds were characterized by IR and H 1 NMR. The synthesized oxadiazoles
exhibited antimicrobial activity with MIC values ranging from 1 to 4 mg/mL, with
compound 84e being the most active with MIC of 1 mg/mL against the bacterium
Staphylococcus aureus. The results contribute significantly to the chemistry and
occurrence of P. aduncum, considering that previous reports revealed dillapiole as a
chemical marker of the oil as well as flavonoids and prenylated benzoic acid obtained
from specimens in a region close to our collection site. This shows that there are two
chemotypes for the plant in the same region of the Atlantic Forest, indicating that
they are allopatric species.

COMMITTEE MEMBERS:
Interno - CLECIO SOUSA RAMOS
Interno - JOAO RUFINO DE FREITAS FILHO
Externa ao Programa - 3342881 - GISELLE BARBOSA BEZERRA - UFRPEExterna à Instituição - QUEILA PATRÍCIA DA SILVA BARBOSA FREITAS