Banca de DEFESA: GABRIEL FULGENCIO DOS SANTOS
Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.STUDENT : GABRIEL FULGENCIO DOS SANTOS
DATE: 07/10/2024
TIME: 09:00
LOCAL: UFRRJ sala 49
TITLE:
Ent-kaurene diterpenoids isolated from stingless bee mandaçaia geopropolis and evaluation of the antifungal potential (Melipona quadrifasciata anthidioides
KEY WORDS:
Geopropolis, ent-kaurene diterpenes, sporotrichosis, Sporothrix brasilliensis
PAGES: 90
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUMMARY:
In Brazil there are a variety of species of stingless bees (meliponines), belonging to the Apidade family. The bee Melipona quadrifasciata anthidioides, object of study in this work, is capable of producing geopropolis, a resinous substance with a complex matrix, consisting of a mixture of clay with plant exudates. Several biological activities of geopropolis have been evaluated, such as antibacterial, antifungal, antiviral and antioxidante. Sporotrichosis is an infection caused by the fungus of the genus Sporothrix, being a zoonosis, which in Brazil is endemic and transmitted by the fungus Sporothrix brasilliensis. Treatment options, such as Itraconazole, have been hampered by the emergence of new fungal isolates with drug resistance. Therefore, the search for new substances that can be used in the treatment of sporotrichosis is of scientific interest. This work aimed to evaluate the chemical profile, the content of phenolics and total flavonoids, the antioxidant capacity, isolate and characterize substances from mandaçaia geopropolis (Melipona quadrifasciata anthidioides), in addition to investigating the in vitro antifungal activity against clinical isolates of S. brasiliensis. The geopropolis was collected in Bosque da Barra, Rio de Janeiro, and the ethanolic extract of mandaçaia geopropolis (EEGP-M) was prepared in an ultrasonic bath for two hours. Subsequently, the ethanolic extract was solubilized in methanol: water (7:3 v/v) and partitioned with hexane and dichloromethane, respectively, generating the fractions: Fr. Hex, Fr. DCM and Fr. MeOH:H2O. Fr. Hex was subjected to open column chromatography on silica gel, where two diterpenes with an ent-kaurene skeleton were isolated, the diterpene kaurenoic acid, and a cinnamic acid derivative, kaur-16-en-19-oic acid, 15-[(1-oxo-3-phenyl-2-propen-1-yl) oxy], furthermore, another diterpene, ent-caurenal, was characterized as an enriched fraction. Total phenolic and flavonoid content was evaluated in comparison to gallic acid (GA) and quercetin (QE) standards, respectively. Fr. DCM obtained the best results, with 1.89 mg EAG/100mg in phenolics and 0.42 EQE/100mg in flavonoids. The DPPH assay was used to determine the antioxidant capacity of the extract and its fractions, again the Fr. DCM fraction showed the best result (EC50 = 200 µg/mL), corroborating the results of total phenols and flavonoids. Antifungal activity was investigated against clinical strains of S. brasiliensis. The best result was observed for the isolated cinnamic acid derivative (MIC = 0.469 mM), however kaurenoic acid (MIC = 1.875 mM) and the fraction enriched with ent-kaurenal aldehyde (0.187 mg/mL) also showed good results; among the ethanolic extract and its fractions, Fr. Hex showed the best antifungal response (MIC= 0.281 mg/mL). The antifungal activity test demonstrated the inhibition potential of the ethanolic extract, its fractions and substances isolated from mandaçaia geopropolis against S. brasilliensis, signaling that this natural product is promising for the treatment of sporotrichosis
COMMITTEE MEMBERS:
Externa à Instituição - ALESSANDRA LEDA VALVERDE - UFF
Externo ao Programa - 1221906 - LUCIANO RAMOS SUZART - nullPresidente - 1177598 - ROSANE NORA CASTRO