Navegando por Autor "Lopes, Miriam Teresa Paz"
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Item Angiotensin-(1-7) is an endogenous ligand for the G protein-coupled receptor Mas.(2003) Santos, Robson Augusto Souza dos; Silva, Ana Cristina Simões e; Maric, Christine; Rabelo, Denise Maria Rover da Silva; Machado, Raquel do Pilar; Buhr, Insa de; Walther, Silvia Heringer; Pinheiro, Sérgio Veloso Brant; Lopes, Miriam Teresa Paz; Bader, Michael; Mendes, Elizabeth Pereira; Lemos, Virgina Soares; Santos, Maria José Campagnole dos; Schultheiss, Heinz-Peter; Speth, Robert; Walther, ThomasThe renin–angiotensin system plays a critical role in blood pressure control and body fluid and electrolyte homeostasis. Besides angiotensin (Ang) II, other Ang peptides, such as Ang III [Ang-(2–8)], Ang IV [Ang-(3–8)], and Ang-(1–7) may also have important biological activities. Ang-(1–7) has become an angiotensin of interest in the past few years, because its cardiovascular and baroreflex actions counteract those of Ang II. Unique angiotensin-binding sites specific for this heptapeptide and studies with a selective Ang-(1–7) antagonist indicated the existence of a distinct Ang-(1–7) receptor. We demonstrate that genetic deletion of the G proteincoupled receptor encoded by the Mas protooncogene abolishes the binding of Ang-(1–7) to mouse kidneys. Accordingly, Mas-deficient mice completely lack the antidiuretic action of Ang-(1–7) after an acute water load. Ang-(1–7) binds to Mas-transfected cells and elicits arachidonic acid release. Furthermore, Mas-deficient aortas lose their Ang-(1–7)-induced relaxation response. Collectively, these findings identify Mas as a functional receptor for Ang-(1–7) and provide a clear molecular basis for the physiological actions of this biologically active peptide.Item Melaleuca leucadendron (L.) L. flower extract exhibits antioxidant and photoprotective activities in human keratinocytes exposed to ultraviolet B radiation.(2020) Silva, Luan Silvestro Bianchini; Perasoli, Fernanda Barçante; Carvalho, Karen Vitor; Vieira, Karla Murata; Lopes, Miriam Teresa Paz; Souza, Gustavo Henrique Bianco de; Santos, Orlando David Henrique dos; Freitas, Katia MichelleRecently, there has been a demand for the replacement of chemical sunscreens with natural compounds that could prevent or restore UV-induced skin damage. Here, we investigated the photoprotective influence of the Melaleuca leucadendron ethanolic flower extract (EEMec) on factors involved in cellular and molecular UVBinduced oxidative stress in human skin keratinocytes (HaCaT). The phytochemical constituents, antioxidant potential by DPPH assay, content of total phenolic and flavonoid compounds in EEMec were evaluated. HaCaT cells were treated with EEMec followed by irradiation with UVB. CAT activity; GSH and ROS levels; and SOD1, GPx, CAT and COX-2 expression assays were employed to verify the oxidative stress, as well as EEMec effect on transmembrane transport, and pro-inflammatory and pro-apoptotic protein expression. EEMec reverted the viability loss of HaCaT cells after irradiation with UVB, exhibited significant antioxidant capacity and free radical scavenging activity in vitro, inhibited COX-2 expression and ensure protection of DNA-damage. EEMec shown a great photoprotective property to prevent keratinocytes damage induced by UV radiation and, thus a candidate potential to application as an adjuvant in sunscreen formulations as a strategy to reduce risk of sunburn and prevent skin diseases associated with UV-induced inflammation and cancer.Item Psychotria viridis : chemical constituents from leaves and biological properties.(2017) Soares, Débora Barbosa da Silva; Duarte, Lucienir Pains; Cavalcanti, André Dias; Silva, Fernando César; Braga, Ariadne Duarte; Lopes, Miriam Teresa Paz; Takahashi, Jacqueline Aparecida; Vieira Filho, Sidney AugustoThe phytochemical study of hexane, chloroform and methanol extracts from leaves of Psychotria viridis resulted in the identification of: the pentacyclic triterpenes, ursolic and oleanolic acid; the steroids, 24-methylene-cycloartanol, stigmasterol and β-sitosterol; the glycosylated steroids 3-O-β-D-glucosyl-β- sitosterol and 3-O-β-D-glucosyl-stigmasterol; a polyunsaturated triterpene, squalene; the esters of glycerol, 1-palmitoylglycerol and triacylglycerol; a mixture of long chain hydrocarbons; the aldehyde nonacosanal; the long chain fat acids hentriacontanoic, hexadecanoic and heptadenoic acid; the ester methyl heptadecanoate; the 4-methyl-epi-quinate and two indole alkaloids, N,N-dimethyltryptamine (DMT) and N-methyltryptamine. The chemical structures were determined by means of spectroscopic (IR, 1H and 13C NMR, HSQC, HMBC and NOESY) and spectrometric (CG-MS and LCMS-ESI-ITTOF) methods. The study of biologic properties of P. viridis consisted in the evaluation of the acetylcholinesterase inhibition and cytotoxic activities. The hexane, chloroform, ethyl acetate and methanol extracts, the substances 24-methylene-cycloartanol, DMT and a mixture of 3-O-β-D-glucosyl-β-sitosterol and 3-O-β-D-glucosyl-stigmasterol showed cholinesterase inhibiting activity. This activity induced by chloroform and ethyl acetate extracts was higher than 90%. The methanol and ethyl acetate extracts inhibit the growth and/or induce the death of the tumor cells strains B16F10 and 4T1, without damaging the integrity of the normal cells BHK and CHO. DMT also demonstrated a marked activity against tumor cell strains B16F10 and 4T1.