Banca de QUALIFICAÇÃO: JÚDSON CLEBER DE PAIVA MOTA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE : JÚDSON CLEBER DE PAIVA MOTA
DATA : 02/09/2024
HORA: 09:00
LOCAL: meet.google.com/kkt-kopz-ein
TÍTULO:

EVALUATION OF BIOLOGICAL ACTIVITIES OF ABIETAN DITERPENES FROM PLECTRANTHUS GRANDIS AND DERIVATIVES

PALAVRAS-CHAVES:

Spectroscopy; Antiacetylcholinesterase; Antimicrobial; Antioxidant; Barbatusin; Derivatization.

PÁGINAS: 80
GRANDE ÁREA: Outra
ÁREA: Ciências Ambientais
RESUMO:

Plectranthus grandis is a medicinal plant popularly known as boldo-grande, used by the population against gastrointestinal and hepatic disorders. It has proven gastroprotective activity, attributed to diterpenes that were isolated from this plant, scientifically validating its populares use. This work reports the isolation of abietan diterpenes by chromatographic techniques, synthesis and isolation of five derivatives, four of which are new in the literature. The derivatives were synthesized through condensation reactions between the most electrophilic carbonyl (C-3) of barbatusin and different nucleophiles (hydroxylamine hydrochlorides, phenylhydrazine, semicarbazide) in addition to 2,4- Dinitrophenylhydrazine, as well as the production of a salt via acid-base reaction, having as product the corresponding derivatives OXIB, Ph-HB, 2,4-DNPHB, SCB and SALB. The structural characterizations were performed using hydrogen 1H and carbon 13C nuclear magnetic resonance spectroscopy. The derivatives OXIB, Ph-HB, 2,4-DNPHB and SCB present azomethine bond, (C=N) allowing the formation of diastereoisomers with E and Z configuration, being identified the formation of the E isomer for OXIB, with a singlet at 7.271 ppm for the oxime hydrogen (HO-N), in the 1H NMR spectrum. The UV-Vis absorption spectra of barbatusin were recorded in the range of 200-800 nm, in which it presented maximum absorption bands (λmax) in the ultraviolet region, at 225 nm and 272 nm, at pH = 7.15. In a basic medium (pH = 11.5), the substance presented a band with maximum absorption (λmax) at 224 nm in the ultraviolet region, and a band with maximum absorption (λmax) at 454 nm in the visible region, the color transitioning from yellow to wine-red, which is attributable to the electronic transition of the chromophore groups. In an acidic medium (pH = 4.1), there was absorption in the ultraviolet region, presenting a band with maximum absorption (λmax) at 270.0 nm with no coloration in the system. With the analysis of the antioxidant potential of barbatusin against the DPPH radical and the ABTS•+ radical, the substance presented moderate free radical scavenging activity, (DPPHIC50 μg/mL = 10.18 ± 0.04), (ABTS•+ IC50 μg/mL = 9.38 ± 0.03), when compared to quercertin (DPPHIC50 μg/mL = 1.63 ± 0.03), (ABTS•+ IC50 μg/mL = 0.95 ± 0.03). Regarding the evaluation of the antiacetylcholinesterase potential of barbatusin, the substance showed moderate activity (AchE IC50 μg/mL = 11.85 ± 0.04) when compared to physostigmine (AchE IC50 μg/mL = 1.15 ± 0.04). Regarding the antimicrobial potential, the antimicrobial activity of barbatusin was recorded in all microorganisms, against the bacteria P. mirabilis, and yeasts C. albicans, C. krusei, C. parapsilosis and C. tropicalis, evidencing it to be a substance with potential antimicrobial use. The derivatives OXIB and 2,4-DNPHB were inactive against P. mirabilis bacterial strains, indicating that the carbonyl (C-3) of barbatusin is crucial for combating these microorganisms. Against yeasts, 2,4-DNPHB showed lower inhibition concentrations against C. albicans, C. krusei, C. parapsilosis and C. tropicalis strains with (% inhibition μg/mL = 5), (% inhibition μg/mL = 2) and (% inhibition μg/mL = 29), respectively, indicating that it is more efficient. The derivative OXIB was inactive against C. albicans yeasts and did not show significant changes against C. parapsilosis yeasts, however, it was more potent against C. krusei yeasts (% inhibition μg/mL = 11) when compared to barbatusin (% inhibition μg/mL = 32). For the C. tropicalis strains, the substances analyzed presented the same inhibition concentration (% inhibition μg/mL = 29).

MEMBROS DA BANCA:
Externo à Instituição - ROBERTO LIMA DE ALBUQUERQUE - UECE
Presidente - 13136 - LEANDRO BEZERRA DE LIMA
Externa à Instituição - SIMONE ALVES SERAFIM ROCHA - UERN