Browsing by Author "Oliveira, Alaide Braga de"

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    Antiplasmodial activity and cytotoxicity, isolation of active alkaloids, and dereplication of Xylopia sericea leaves ethanol extract by UPLC-DAD-ESI-MS/MS.
    (2019) Gontijo, Douglas da Costa; Brandão, Geraldo Célio; Nascimento, Maria Fernanda Alves do; Oliveira, Alaide Braga de
    Objectives: To assess the antiplasmodial activity of the ethanol extract of Xylopia sericea leaves, Annonaceae, often associated with antimalarial use and to perform a bioguided isolation of active compounds. Methods: Dereplication of ethanol extract by the UPLC-DAD-ESI-MS/MS technique allowed the identification of the major constituents, isolation and identification of alkaloids. The antiplasmodial and cytotoxic activity of the extract, fractions and isolated compounds was evaluated against the chloroquine-resistant W2 strain Plasmodium falciparum and HepG2 cells, respectively. Key findings: Ethanol extract showed high reduction of parasitemia as well as moderate cytotoxicity (86.5 3.0% growth inhibition at 50 lg/ml and CC50 72.1 5.1 lg/ml, respectively). A total of eight flavonoids were identified, and two aporphine alkaloids, anonaine and O-methylmoschatoline, were isolated. Anonaine disclosed significant antiplasmodial effect and moderate cytotoxicity (IC50 23.2 2.7 lg/ml, CC50 38.3 2.3 lg/ml, SI 1.6) while O-methylmoschatoline was not active against P. falciparum and showed a low cytotoxicity (33.5 1.9% growth inhibition at 50 lg/ml, CC50 274.4 0.5 lg/ml). Conclusions: Characterization of Xylopia sericea leaves ethanol extract by UPLCDAD-ESI-MS/MS as well as its antiplasmodial activity and the occurrence of anonaine and O-methylmoschatoline in this Xylopia species are reported by the first time.
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    In vitro antiplasmodial activity and identification, using tandem LC-MS, of alkaloids from Aspidosperma excelsum, a plant used to treat malaria in Amazonia.
    (2019) Nascimento, Myrth Soares do; Pina, Nayla di Paula Vieira; Silva, Andressa Santa Brigida da; Gomes, Luís Fabio dos Santos; Vasconcellos, Flávio de; Brandão, Geraldo Célio; Nascimento, Maria Fernanda Alves do; Oliveira, Alaide Braga de; Barbosa, Wagner Luiz Ramos
    Ethnopharmacological relevance: Aspidosperma excelsum Benth. (Apocynaceae), a native tree in the Brazilian Amazonia, is traditionally used to treat various diseases, including malaria. Aim of study: To investigate the chemical constitution, antiplasmodial activity and cytotoxicity of samples obtained from A. excelsum trunk bark by different procedures aiming to evaluate their potential as an antimalarial phytomedicine. Materials and methods: A hydroethanolic extract and alkaloid extracts were prepared and assayed for antiplasmodial activity and cytotoxicity against chloroquine-resistant Plasmodium falciparum (W2 strain) and HepG2 cells, respectively. Taking into account the known occurrence and antimalarial activity of Aspidosperma monoterpene indole alkaloids (MIA), acid-base extractions were carried out and the fractions were assayed for antiplasmodial activity and cytotoxicity. All the samples were analysed by hyphenated chromatographic techniques, such as UPLC-DAD-ESI-MS/MS and HRMS (HPLC-MS MicroTOF), comparing their chemical composition to the literature data. Results: The hydroethanolic extract disclosed a moderate in vitro activity against chloroquine-resistant Plasmodium falciparum (W2 strain) with IC50 23.68 ± 3.08 µg/mL), low cytotoxicity to HepG2 cells (> 250 µg/ mL) and good SI (> 10.56). A total of 20 known monoterpene indole alkaloids were identified, seven of which are here firstly described for A. excelsum. Known highly active alkaloids, namely demethylaspidospermine, aspidocarpine, and ochrolifuanine are present in active alkaloid fractions and might contribute to their observed antiplasmodial effect. An alkaloid fraction (Ae-Alk2), obtained directly from trunk bark by extraction with dil. aqueous HCl, pointed out for its activity (IC50 8.75 ± 2.26 µg/mL, CC50 185.14 ± 1.97 µg/mL, SI 21.16) and should be highlighted as the most promising out of the assayed samples. Conclusion: The present results represent a preliminary support to the alleged antimalarial use of A. excelsum trunk bark and allowed to highlight alkaloid fractions as promising phytomedicines.
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    Phytochemical characterization and antioxidant, antibacterial and antimutagenic activities of aqueous extract from leaves of Alchornea glandulosa.
    (2018) Gontijo, Douglas da Costa; Diaz, Marisa Alves Nogueira; Brandão, Geraldo Célio; Gontijo, Pablo da Costa; Oliveira, Alaide Braga de; Fietto, Luciano Gomes; Leite, João Paulo Viana
    Plant extracts exist as a complex matrix which serves as a source of numerous bioactive metabolites. The ultra performance liquid chromatography with diode-array detection-coupled electrospray ionization-mass spectrometry/mass spectrometry technique was used to characterize the aqueous extract from leaves of Alchornea glandulosa (EAG), a species popularly used to treat gastrointestinal problems as an antiulcer agent. Quantification of phenolic derivatives was determined using Folin–Ciocalteu and aluminum trichloride (AlCl3) methods. In addition, antioxidant (2,2-diphenyl-1-picrylhydrazyl [DPPH• ] radical scavenging, β-carotene–linoleic acid, and lipid peroxidation), antibacterial (agar well diffusion method and minimum inhibitory concentration), antimutagenic (Ames test), and antigenotoxic (plasmid cleavage) assays were also performed on this plant extract. The ellagitannin tris-galloyl-hexahydroxydiphenic acid-glucose was identified as the predominant compound along with tannins as majority metabolites. EAG showed high antioxidant activity accompanied by moderate antibacterial activity against Staphylococcus aureus. The highest antimutagenic activity was observed for TA97 strain without metabolic activation (S9) and with metabolic activation, TA100 and TA102 were completely inhibited. In addition, EAG exhibited potential signs of antigenotoxic action. The high antioxidant and antimutagenic activity observed for EAG suggests important therapeutic uses that still need to be verified in future studies.
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    Phytochemistry and antiplasmodial activity of Xylopia sericea leaves.
    (2019) Gontijo, Douglas da Costa; Nascimento, Maria Fernanda Alves do; Brandão, Geraldo Célio; Oliveira, Alaide Braga de
    Aiming to investigate the antiplasmodial activity and the phytochemical composition of Xylopia sericea leaves, the essential oil and dichloromethane extract were analyzed by gas and liquid chromatography, respectively, both of them coupled to mass spectrometry, and were evaluated against the chloroquine-resistant Plasmodium falciparum strain (W2) and for cytotoxicity to HepG2 cells. Low growth inhibition of P. falciparum as well as low cytotoxicity to HepG2 cells were observed for the essential oil. The leaves dichloromethane extract showed moderate growth inhibition of P. falciparum and low cytotoxicity to HepG2 cells. Bioguided chromatographic fractionation of this extract led to fractions with increased antiplasmodial activity from which liriodenine (IC50 6.1 ± 0.1 μg/mL, CC50 > 1000.0 μg/mL, SI > 164), an aporphine alkaloid, and an acetogenin-rich fraction containing mainly isomers of annomontacin and 4-deoxy-annomontacin (IC50 22.7 ± 1.9 µg/mL, CC50 336.1 ± 15.5 µg/mL, SI = 15) might be highlighted for their antiplasmodial activity.