Olga Burmistrova1, Juan Perdomo1, M Fátima Simões2, Patricia Rijo3, José Quintana1, Francisco Estévez4. 1. Department of Biochemistry and Molecular Biology, University of Las Palmas de Gran Canaria, Plaza Dr. Pasteur s/n, 35016 Las Palmas de Gran Canaria, Spain. 2. Faculdade de Farmácia da Universidade de Lisboa, iMed.ULisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal. 3. Faculdade de Farmácia da Universidade de Lisboa, iMed.ULisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal; C BIOS, Universidade Lusófona, Campo Grande 376, 1749-024 Lisboa, Portugal. 4. Department of Biochemistry and Molecular Biology, University of Las Palmas de Gran Canaria, Plaza Dr. Pasteur s/n, 35016 Las Palmas de Gran Canaria, Spain. Electronic address: festevez@dbbf.ulpgc.es.
Abstract
BACKGROUND: Abietane diterpenes have attracted much attention because they display a wide range of biological activities, including antitumor activities. These compounds are the most diverse of the diterpenoids isolated from species of Plectranthus. Naturally occurring diterpene parvifloron D is the main phytochemical constituent of Plectranthus ecklonii. To examine the therapeutic potential of the plant, we evaluated whether parvifloron D displays cytotoxicity against human tumor cells. METHODS: The cytotoxicity was analyzed by colorimetric 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. Apoptosis was evaluated by fluorescent microscopy, transmission electron microscopy, flow cytometric analysis of annexin V-FITC and propidium iodide-stained cells and DNA fragmentation. Protein expression and processing and release of mitochondrial proteins were analyzed by Western blot. Caspase activity was determined using colorimetric substrates. The membrane potential and intracellular reactive oxygen species were detected by flow cytometry. RESULTS: Parvifloron D displays strong cytotoxic properties against leukemia cells (HL-60, U-937, MOLT-3 and K-562) and in particular P-glycoprotein-overexpressing K-562/ADR cells, but has only weak cytotoxic effects on peripheral blood mononuclear cells (PBMCs). Overexpression of the protective mitochondrial proteins Bcl-2 and Bcl-xL did not confer resistance to parvifloron D-induced cytotoxicity. Growth inhibition of HL-60 cells that was triggered by parvifloron D was found to be caused by a rapid induction of apoptotic cell death. This apoptosis was prevented by the non-specific caspase inhibitor z-VAD-fmk, and by the selective caspase-9 inhibitor z-LEHD-fmk. Cell death induced by parvifloron D was found to be (i) associated with the dissipation of the mitochondrial membrane potential and the release of cytochrome c, (ii) amplified by inhibition of extracellular signal-regulated kinases (ERKs) 1/2 signaling and (iii) caused by a mechanism dependent on intracellular reactive oxygen species generation. CONCLUSION: Parvifloron D is a potent cytotoxic compound against several human tumor cells and also a fast and potent apoptotic inducer in leukemia cells.
BACKGROUND:Abietanediterpenes have attracted much attention because they display a wide range of biological activities, including antitumor activities. These compounds are the most diverse of the diterpenoids isolated from species of Plectranthus. Naturally occurring diterpeneparvifloron D is the main phytochemical constituent of Plectranthus ecklonii. To examine the therapeutic potential of the plant, we evaluated whether parvifloron D displays cytotoxicity against humantumor cells. METHODS: The cytotoxicity was analyzed by colorimetric 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. Apoptosis was evaluated by fluorescent microscopy, transmission electron microscopy, flow cytometric analysis of annexin V-FITC and propidium iodide-stained cells and DNA fragmentation. Protein expression and processing and release of mitochondrial proteins were analyzed by Western blot. Caspase activity was determined using colorimetric substrates. The membrane potential and intracellular reactive oxygen species were detected by flow cytometry. RESULTS:Parvifloron D displays strong cytotoxic properties against leukemia cells (HL-60, U-937, MOLT-3 and K-562) and in particular P-glycoprotein-overexpressing K-562/ADR cells, but has only weak cytotoxic effects on peripheral blood mononuclear cells (PBMCs). Overexpression of the protective mitochondrial proteins Bcl-2 and Bcl-xL did not confer resistance to parvifloron D-induced cytotoxicity. Growth inhibition of HL-60 cells that was triggered by parvifloron D was found to be caused by a rapid induction of apoptotic cell death. This apoptosis was prevented by the non-specific caspase inhibitor z-VAD-fmk, and by the selective caspase-9 inhibitor z-LEHD-fmk. Cell death induced by parvifloron D was found to be (i) associated with the dissipation of the mitochondrial membrane potential and the release of cytochrome c, (ii) amplified by inhibition of extracellular signal-regulated kinases (ERKs) 1/2 signaling and (iii) caused by a mechanism dependent on intracellular reactive oxygen species generation. CONCLUSION:Parvifloron D is a potent cytotoxic compound against several humantumor cells and also a fast and potent apoptotic inducer in leukemia cells.
Authors: Vera M S Isca; Milan Sencanski; Nenad Filipovic; Daniel J V A Dos Santos; Ana Čipak Gašparović; Lucília Saraíva; Carlos A M Afonso; Patrícia Rijo; Alfonso T García-Sosa Journal: Int J Mol Sci Date: 2020-05-23 Impact factor: 5.923
Authors: Ana Ribeirinha Antão; Gabrielle Bangay; Eva María Domínguez-Martín; Ana María Díaz-Lanza; Patrícia Ríjo Journal: Front Pharmacol Date: 2021-11-30 Impact factor: 5.810
Authors: Marisa Nicolai; Joana Mota; Ana S Fernandes; Filipe Pereira; Paula Pereira; Catarina P Reis; Maria Valéria Robles Velasco; André Rolim Baby; Catarina Rosado; Patrícia Rijo Journal: Pharmaceuticals (Basel) Date: 2020-06-10