NMR spectroscopy and antioxidant activity of flavanones and flavones isolated from Chromolaena tacotana (Klatt) R.M. King & H. Rob.
Fecha de publicación: 30/12/2020

Chromolaena tacotana is considered as a source of flavonoids. Here we examined the content and antioxidant properties of flavones and flavanones from the leaves of the plant. Four flavonoids, including (Cta) 5, 4′ dihydroxy-7-methoxy flavanone, (Ctb) 3,5,3′-trihydroxy-7,4′-dimethoxyflavone; (Ctc), 3,4′-dihydroxy -5,7- dimethoxyflavanone; and (Ctd) 4′-hydroxy-5,7-dimethoxyflavanone, were isolated from leaves extracts, were identified by their NMR spectroscopic data, and then free radical scavenging activities of the flavonoids were assessed against DPPH. The antioxidant activity for the flavanone Ctb was the highest even compared to that of quercetin, with IC50 of 6.27 μg/mL and 8.67 μg/mL respectively. The flavanones Cta, Ctc and Ctd presented a lowest activity against free radicals as expected according to their molecular substituents and the position within the structure. Data obtained from this study support the ethnomedicinal use of the leaves of C.

Topological properties and in vitro identification of essential nodes of the Paclitaxel and Vincristine interactomes in PC-3 cells
Fecha de publicación: 31/10/2019

Background:Microtubule-targeting agents (MTAs) disrupt microtubule dynamics, therebyinducing apoptosis via mitochondrial pathway activation through the modulation in theexpression of the Bcl-2 family.Methods:To describe topological features of the MTAs networks associated to intrinsicapoptosis induction in p53-null prostate cancer cells, we predicted and compared theinteractomes and topological properties of Paclitaxel and Vincristine, and thus, theessential nodes corresponding with the pro- and anti-apoptotic proteins and their kineticswere subjected to experimental analysis in PC-3 cell line.Results:The essential nodes of the apoptotic pathways, TP53, and CASP3, were identified inboth, Paclitaxel and Vincristine networks, but the intrinsic pathway markers BCL2, BAX,and BCL2L1 were identified as hub nodes only in the Paclitaxel network. Anin vitroanalysisdemonstrated an increase in BimEL and the cleaved-caspase-3 proteins in PC-3 cellsexposed to both treatments. Immunoprecipitation analysis showed that treatmentsinduced the releasing of Bax from the anti-apoptotic complex with Bcl-2 protein and therole of BimEL as a de-repressor from sequestering complexes, in addition, new proteincomplexes were identified between BimEL or Bcl-2 and cleaved-caspase-3, contributingdata to the Vincristine network for p53-null cells in response to MTAs.Conclusion: Conclusion:The differences in sensitivities, protein profiles, and protein complex kineticsobserved between the drugs confirmed that the selectivity and stimulation of the apoptoticsystem vary depending on the cell’s genotype, the drug used and its exposure period.

Cryptosporidium spp. CP15 and CSL protein-derived synthetic peptides’ immunogenicity and in vitro seroneutralisation capability
Fecha de publicación: 29/10/2018

Cryptosporidium spp. is a zoonotic intracellular protozoan and a significant cause of diarrhoea in humans and animals worldwide. This parasite can cause high morbidity in immunocompromised people and children in developing countries, livestock being the main reservoir. This study was aimed at performing preliminary tests on Swiss albino weaned mice (ICR) to evaluate the humoral immune response induced against peptides derived from Cryptosporidium parvum CP15 (15 kDa sporozoite surface antigen) and CSL (circumsporozoite-like antigen) proteins. Peptides were identified and characterised using bioinformatics tools and were chemically synthesised. The antibody response was determined and the neutralising effect of antibodies was measured in cell culture. Despite all peptides studied here were capable of stimulating antibody production, neutralising antibodies were detected for just two of the CP15-derived ones. Additional studies aimed at evaluating further the potential of such peptides as vaccine candidates are thus recommended.

Cryptosporidium spp. CP15 and CSL protein-derived synthetic peptides’ immunogenicity and in vitro seroneutralisation capability
Fecha de publicación: 29/10/2018

Cryptosporidium spp. is a zoonotic intracellular protozoan and a significant cause of diarrhoea in humans and animals worldwide. This parasite can cause high morbidity in immunocompromised people and children in developing countries, livestock being the main reservoir. This study was aimed at performing preliminary tests on Swiss albino weaned mice (ICR) to evaluate the humoral immune response induced against peptides derived from Cryptosporidium parvum CP15 (15 kDa sporozoite surface antigen) and CSL (circumsporozoite-like antigen) proteins. Peptides were identified and characterised using bioinformatics tools and were chemically synthesised. The antibody response was determined and the neutralising effect of antibodies was measured in cell culture. Despite all peptides studied here were capable of stimulating antibody production, neutralising antibodies were detected for just two of the CP15-derived ones. Additional studies aimed at evaluating further the potential of such peptides as vaccine candidates are thus recommended. © 2018 Elsevier Ltd

Chromolaena tacotana (Klatt) R. M. King and H. Rob. Source of Flavonoids with Antiproliferative and Antioxidant Activity
Fecha de publicación: 31/05/2018

Objetive: To determine the antioxidant and antiproferative activity of the flavonoids isolated from the leaves of Chromolaena tacotana. Methods: Extraction was carried out with dichloromethane (CH2Cl2) from the leaves by soxhlet, the flavonoids were isolated by column chromatography (Si gel G 60-200 microns 4 x 60cm) eluted with CHCl3, mixtures of CHCl3: MeOH and MeOH. The molecular structures were elucidated by 1HNMR, 13CNMR mono and 2D and UV spectroscopic methods with displacement reagents. Each flavonoid was evaluated for its antioxidant activity by the methods DPPH● and ABTS● + and the cytotoxic activity was evaluated by MTT analysis. Findings: These compounds were identified as 3,5,4’-trihydroxy-7- methoxyflavone (Ct1), 3,5,8-trihydroxy-7,4’dimethoxyflavone (Ct2), 5,4’-dihydroxy-7-methoxyflavanonol (Ct3) and 5, 7, 3’, 4’-tetrahydroxy-3-methoxyflavone (Ct4). The flavonoid that had the best response in antioxidant activity was Ct4 with and IC50 of 2.51mg/L of DPPH● and 2.13 mg/L of ABTS●+. Antiproliferative potential showed that MDA-MB-231 breast cancer cells were the most sensitivity cell line to the flavonoids, and Ct2 is the flavonoid with better antineoplastic potential on majority of cells, except for the most resistant SiHa cervix cancer cells. Application: The high antioxidant activity of flavonoids isolated from Chromolaena tacotana and its antiproliferative activity on different cell lines, make the species a plant with pharmacological potential.