RESUMO
ABSTRACT Objective: To analyze the molecular composition of a sample of Baltic amber taken from an amber bracelet, verify the presence or absence of compounds beneficial to human health, and discuss the therapeutic potential of this fossil resin. Material and Methods: For this, a qualitative analysis was performed by gas chromatography coupled with mass spectrometry (GC-MS system), which can perform an automated separation into individual components of amber. Results: The samples comprised terpenes and terpenoids: monoterpenoids, sesquiterpenoids, diterpenoids, hydronaphthalene, succinic acid, and isopimaric acid. These have therapeutic potential for several diseases, inhibit several stages of the inflammatory process, and improve the symptoms caused by it. Conclusion: The amber of this sample tested is formed by terpenes and terpenoids, substances with anti-inflammatory and analgesic. However, an in-depth study is needed on the release and absorption of substances in human skin or their actual effectiveness.
Assuntos
Espectrometria de Massas/métodos , Terpenos/química , Cromatografia Gasosa/métodos , Âmbar/uso terapêutico , Cromatografia/métodosRESUMO
Abstract Candida infection is an important cause of morbidity and mortality in immunocompromised patients. The increase in its incidence has been associated with resistance to antimicrobial therapy and biofilm formation. The aim of this study was to evaluate the efficacy of tea tree oil (TTO) and its main component - terpinen-4-ol - against resistant Candida albicans strains (genotypes A and B) identified by molecular typing and against C. albicans ATCC 90028 and SC 5314 reference strains in planktonic and biofilm cultures. The minimum inhibitory concentration, minimum fungicidal concentration, and rate of biofilm development were used to evaluate antifungal activity. Results were obtained from analysis of the biofilm using the cell proliferation assay 2,3-Bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) and confocal laser scanning microscopy (CLSM). Terpinen-4-ol and TTO inhibited C. albicans growth. CLSM confirmed that 17.92 mg/mL of TTO and 8.86 mg/mL of terpinen-4-ol applied for 60 s (rinse simulation) interfered with biofilm formation. Hence, this in vitro study revealed that natural substances such as TTO and terpinen-4-ol present promising results for the treatment of oral candidiasis.
Assuntos
Terpenos/farmacologia , Candida albicans/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Óleo de Melaleuca/farmacologia , Valores de Referência , Terpenos/química , Resinas Acrílicas , Candida albicans/crescimento & desenvolvimento , Testes de Sensibilidade Microbiana , Reprodutibilidade dos Testes , Análise de Variância , Estatísticas não Paramétricas , Microscopia Confocal , Biofilmes/crescimento & desenvolvimento , Óleo de Melaleuca/química , Bases de Dentadura/microbiologia , Antifúngicos/farmacologiaRESUMO
This review work focuses on how the secondary chemistry could help in the survival of plants in high mountain habitats under extreme environmental conditions. The elevated levels of stress in high areas of the tropic and subtropic change dramatically not only by following the annual cycles of winter and summer but they also change in a single day. Some species, however, are able to successfully grow at heights more than 3000 m in the tropical mountains due, in part, to highly specialized physiological processes that affect their physical and chemical responses. In this study, it describes some strategies of how the secondary metabolites could help the plants to stand the high levels of stress in the high mountain ecosystems.
Este trabajo de revisioÌn se centra en coÌmo la quiÌmica secundaria podriÌa ayudar en la supervivencia de plantas en haÌbitats de alta montanÌa en condiciones ambientales extremas. Los altos niveles de estreÌs en las zonas altas del troÌpico y subtroÌpico cambian dramaÌticamente no solo al seguir los ciclos anuales de invierno y verano, sino que tambieÌn cambian en un solo diÌa. Sin embargo, algunas especies pueden crecer con eÌxito a alturas superiores a 3000 m en las montanÌas tropicales debido, en parte, a procesos fisioloÌgicos altamente especializados que afectan sus respuestas fiÌsicas y quiÌmicas. En esta revisioÌn, se describen algunas estrategias de coÌmo los metabolitos secundarios podriÌan ayudan a las plantas a soportar los altos niveles de estreÌs en los ecosistemas de alta montanÌa.
Assuntos
Plantas/química , Estresse Fisiológico , Óleos Voláteis/química , Altitude , Floroglucinol/análise , Floroglucinol/química , Terpenos/análise , Terpenos/química , Flavonoides/análise , Flavonoides/químicaRESUMO
The skin is the largest organ of the human body and its main function is to protect it from the external environment. It is exposed to injuries that require a rapid healing process to recover its functionality. Microorganisms inhabit the skin, which makes up the normal microbial flora, but in situations of injury they can cause infections that slow down the regeneration process. Therefore, there is a great interest in the development of alternative methods to accelerate the regeneration process and prevent infections. In this work, the efficacy of flavonoid 3-O-methylgalangine and the terpenic derivative Filifolinone and its mixtures, isolated from plants of the genus Heliotropium, on the stimulation of cell proliferation was evaluated. The results showed that the mixtures stimulated proliferation and migration in MA104 cells mainly due to the presence of Filifolinone, that together with the known antibacterial activity of 3-O-methylgalangine, opens new alternatives for the use of natural compounds in healing processes.
La piel es el oÌrgano maÌs grande del cuerpo humano y su funcioÌn principal es protegerla del entorno externo. EstaÌ expuesta a lesiones que requieren un proceso de curacioÌn raÌpido para recuperar su funcionalidad. Los microorganismos que habitan en la piel, constituyen la flora microbiana normal, pero en situaciones de lesioÌn pueden causar infecciones que retardan el proceso de regeneracioÌn. Por lo tanto, existe un gran intereÌs en el desarrollo de meÌtodos alternativos para acelerar el proceso de regeneracioÌn y prevenir infecciones. En este trabajo, se evaluoÌ la eficacia del flavonoide 3-O-metilgalangina y el derivado terpeÌnico Filifolinona y sus mezclas, aisladas de plantas del geÌnero Heliotropium, en la estimulacioÌn de la proliferacioÌn celular. Los resultados mostraron que las mezclas estimularon la proliferacioÌn y la migracioÌn en las ceÌlulas MA104 debido principalmente a la presencia de Filifolinona, que junto con la actividad antibacteriana conocida de la 3-O-metilgalangina, abre nuevas alternativas para el uso de compuestos naturales en los procesos de curacioÌn.
Assuntos
Terpenos/farmacologia , Flavonoides/farmacologia , Heliotropium , Proliferação de Células/efeitos dos fármacos , Terpenos/química , Cicatrização , Flavonoides/química , Movimento Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Células Epiteliais/efeitos dos fármacosRESUMO
Abstract The use of a free-radical polymerization inhibitor, butylhydroxytoluene (BHT), and a common photo-initiator, camphorquinone (CQ), to reduce polymerization stress in dental composite was investigated in this study. Samples were prepared by mixing Bis-GMA, UDMA, and TEGDMA at a 1:1:1 ratio (wt%), and silanized borosilicate glass fillers at 70 wt% were added to form the composite. Sixteen groups of resin composite were prepared using combinations of four CQ (0.1%, 0.5%, 1.0%, and 1.5%) and four BHT (0.0%, 0.5%, 1.0%, and 1.5%) concentrations. For each group, six properties were tested, including flexural strength (FS), flexural modulus (FM), degree of conversion (DC), contraction stress (CS), stress rate, and gel point (GP). The effects of CQ and BHT combinations on each of these properties were evaluated using two-way analysis of variance (ANOVA) and Fisher's Protected Least Significant Differences test at the 5% significance level. Groups with low CQ and BHT showed moderate values for FS, FM, and CS with a 70% DC. Increasing the BHT concentration caused a decrease in CS and DC with an increase in GP values. Increasing the CQ content led to a steady increase in values for FS and FM. High CQ and BHT combinations showed the most promising values for mechanical properties with low stress values.
Assuntos
Terpenos/química , Hidroxitolueno Butilado/química , Resinas Compostas/química , Lâmpadas de Polimerização Dentária , Polietilenoglicóis/química , Ácidos Polimetacrílicos/química , Poliuretanos/química , Valores de Referência , Estresse Mecânico , Fatores de Tempo , Teste de Materiais , Análise de Variância , Bis-Fenol A-Glicidil Metacrilato/química , Maleabilidade , Módulo de Elasticidade , Polimerização , Metacrilatos/químicaRESUMO
The aim of the study was to comparatively evaluate the antibacterial activity of six Indian plant extracts and 0.2% chlorhexidine against clinical strains of Streptococcus mutans, which were isolated from the plaque samples of 45 pediatric patients. Six plant extracts were prepared in three different forms, namely aqueous extracts, organic solvent-based extracts and crude (raw) extracts. The antimicrobial sensitivity testing was done by agar well diffusion method. Antimicrobial activity of the extracts was determined by measuring the mean zones of inhibition (mm) produced against the bacterial isolates. Results showed that crude garlic extract exhibited greater antibacterial activity than chlorhexidine. Aqueous extract of amla and organic solvent-based extract of ginger showed the maximum antibacterial activity against S. mutans, whereas aqueous extract of tulsi and organic solvent based extract of amla showed the minimum antibacterial activity. This study suggests that plant extracts like garlic in crude form, amla as aqueous infusion and ginger as alcoholic tincture have potential for the control of S. mutans. These extracts can be used as an alternative remedy for dental caries prevention or in the form of mouthwash, which is safe and economical.
O objetivo do estudo foi avaliar comparativamente a atividade antibacteriana de seis plantas indianas contra linhagens clínicas de Streptococcus mutans, que foram isoladas das amostras de biofilme dental de 45 pacientes pediátricos, com 0,2% de clorexidina. Seis extratos vegetais foram preparados em três formas diferentes, a saber, extratos aquosos, extratos à base de solventes orgânicos e extratos brutos. Os testes de sensibilidade antimicrobiana foram realizados por método de difusão em agar. A atividade antimicrobiana dos extratos foi determinada através da medição da zona de inibição, em milímetros, produzida contra os isolados bacterianos. Os resultados mostraram que o extrato de alho cru apresentou maior atividade antibacteriana do que a clorexidina. O extrato aquoso de amla e o extrato à base de solventes orgânicos de gengibre mostraram a máxima atividade antibacteriana contra S. mutans, enquanto o extrato aquoso de tulsi (manjericão) e o extrato à base de solventes orgânicos de amla mostraram mínima atividades antibacteriana. Este estudo sugere que extratos de plantas como o alho em forma bruta, amla como infusão aquosa e gengibre como tintura alcoólica tem um potencial para o controle de S. mutans. Estes extratos podem ser utilizados como uma via alternativa para a prevenção de cáries dentárias ou sob a forma de bochechos, que são seguros e econômicos.
Assuntos
Humanos , Masculino , Feminino , Pré-Escolar , Criança , Adolescente , Placa Dentária/diagnóstico , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Streptococcus mutans/efeitos dos fármacos , Aloe/química , Clorexidina/farmacologia , Alho/química , Zingiber officinale/química , Glicerídeos/química , Índia , Testes de Sensibilidade Microbiana , Ocimum/química , Phyllanthus emblica/química , Terpenos/químicaRESUMO
Species from the Montanoa genus have been used for hundreds of years in Mexican traditional medicine. The Náhuatl name given by Aztecs to this plant was cihuapahtli, meaning womans medicine (cihua, woman; pahtli, medicine), because M. tomentosa has been used to treat female health disorders since pre-Hispanic times due to its uterotonic properties. Later on, the Spanish pronunciation transformed the word into zoapatle, the name still used by herb sellers in México. Despite its use in folk medicine, intensive scientific research on this plant did not begin until the early 1970s. The only two available reviews exclusively focused on the Montanoa species cover the period from 1529 to 1985. However, in the last two decades, important phytochemical, biochemical and biotechnological advances were achieved. This is a review of the history, botany, most relevant chemistry, biological activity and biotechnology of the secondary metabolites from the Montanoa genus so far.
Especies del género Montanoa han sido empleadas por siglos en la medicina tradicional Mexicana. El nombre asignado a esta planta por los Aztecas fue cihuapahtli, ó medicina para la mujer (cihua, mujer; pahtli, medicina). Específicamente, M. tomentosa es usada para tratar desordenes de la mujer desde tiempos prehispánicos por sus propiedades uterotónicas. La castellanización transformó esta palabra en zoapatle, este nombre sigue siendo usado por los curanderos en México. A pesar de su uso en la medicina folklórica, la investigación científica intensa en esta planta comenzó desde inicios de 1970. Las únicas dos revisiones disponibles y dedicadas exclusivamente a las especies de Montanoa cubren el periodo de 1529 a 1985. Sin embargo, en las últimas dos décadas, se han logrado importantes avances fitoquímicos, bioquímicos y biotecnológicos. Este trabajo presenta una revisión de la historia, botánica, química más relevante, actividades biológicas y biotecnología de los metabolitos secundarios del género Montanoa a la fecha.
Assuntos
Anticoncepcionais Femininos , Flavonoides/química , Montanoa/química , Plantas Medicinais , Terpenos/química , Biotecnologia , Etnobotânica , MéxicoRESUMO
Introducción: Schinus areira L., comúnmente conocido como "Aguaribay", "Gualeguay" o "Molle", pertenece a la familia Anacardiaceae, en donde se incluyen árboles ornamentales, arbustos y lianas, frutos y nueces comercialmente valiosas como el cajú o el pistacho. Objetivo: Obtener el aceite esencial de Schinus areira y su fracción en terpenos hidrocarburos para determinar sus efectos sobre la actividad cardiovascular y su acción en parámetros histopatológicos, bioquímicos y hematológicos en animales de experimentación. Materiales y Métodos: a) Se aisló el aceite esencial (AE) del Schinus areira por arrastre de vapor de agua y posteriormente a través de cromatografía de capa delgada, su fracción en terpenos hidrocarburos (FH); b) se cuantificó mediante cromatografía de masa la composición química del AE y de la FH; c) se determinó el efecto de ambos compuestos en parámetros histopatológicos, bioquímicos, hematológicos y la actividad cardiovascular en conejos despiertos normotensos con un tratamiento agudo y crónico y d) se evaluó el efecto a dosis crecientes de noradrenalina, el corazón ex vivo de ratón, previamente tratado con el AE de S. areira.
ABSTRACT: Introduction: Schinus areira L., commonly known as "Aguaribay", "Gualeguay" or "Molle", belongs to the Anacardiaceae family, where trees, shrubs and vines, fruits and nuts commercially valuable as cashews or pistachios are included. The research of active compounds present in plants for the treatment of cardiovascular diseases has increased significantly worldwide and because of these trends, many reports have evaluated the effects of various plants and their components in the cardiovascular system in order to provide a scientific basis for therapeutic applications target. The EO of Schinus areira and hydrocarbon fraction were obtained to determine their effects on cardiovascular activity and its action on histopathological, biochemical and hematological parameters in experimental animals. Materials and Methods: a) The essential oil (EO) of Schinus areira stripping water and subsequently through thin layer chromatography, the hydrocarbon fraction (HF) were isolated, b) were quantified by chromatography mass chemistry EO and HF, c) the effect of both oils on histopathological, biochemical, hematological and cardiovascular activity in conscious normotensive rabbits d) was determined the effects of increasing doses of noradrenaline were evaluated, the heart ex vivo mouse pretreated EO of S. areira.
Assuntos
Animais , Animais , Pressão Arterial , Óleos Voláteis/efeitos adversos , Anacardiaceae/efeitos adversos , Sistema Cardiovascular , Terpenos/química , ArgentinaRESUMO
The activity of five (1-5) abietane phenol derivatives against Leishmania infantum and Leishmania braziliensis was studied using promastigotes and axenic and intracellular amastigotes. Infectivity and cytotoxicity tests were performed with J774.2 macrophage cells using Glucantime as a reference drug. The mechanisms of action were analysed by performing metabolite excretion and transmission electron microscopy ultrastructural studies. Compounds 1-5 were more active and less toxic than Glucantime. The infection rates and mean number of parasites per cell observed in amastigote experiments showed that derivatives 2, 4 and 5 were the most effective against both L. infantum and L. braziliensis. The ultrastructural changes observed in the treated promastigote forms confirmed that the greatest cell damage was caused by the most active compound (4). Only compound 5 caused changes in the nature and amounts of catabolites excreted by the parasites, as measured by ¹H nuclear magnetic resonance spectroscopy. All of the assayed compounds were active against the two Leishmania species in vitro and were less toxic in mammalian cells than the reference drug.
Assuntos
Animais , Feminino , Camundongos , Antiprotozoários/farmacologia , Leishmania braziliensis/efeitos dos fármacos , Leishmania infantum/efeitos dos fármacos , Macrófagos/parasitologia , Terpenos/farmacologia , Antiprotozoários/química , Leishmania braziliensis/ultraestrutura , Leishmania infantum/ultraestrutura , Espectroscopia de Ressonância Magnética , Camundongos Endogâmicos BALB C , Microscopia Eletrônica de Transmissão , Testes de Sensibilidade Parasitária , Terpenos/químicaRESUMO
Vismia genus is an important source of natural medicinal products, thus, information collected in this review is an attempt to cover the most recent developments in the ethnopharmacology, pharmacology and phytochemistry of this genus. Anthraquinones and other quinonoid derivates, terpenoids and volatile constituents have been reported as the major constituents isolated from different Vismia species. On the other hand, pharmacological studies carried out to date have revealed the variety of anti-plasmodium, antioxidant, antimicrobial and antifungical properties of extracts and pure isolated compounds of the different species tested. The information summarized in this paper intends to serve as a reference tool to practitioners in the fields of etnopharmacology and chemistry of natural products.
El género Vismia es una fuente importante de productos naturales medicinales, es por esto que la información reunida en la presente revisión cubre los estudios más recientes en la etnofarmacología, farmacología y fitoquímica de este género. Antraquinonas y otros derivados quinoides, terpenos y constituyentes volátiles han sido reportados como los compuestos mayormente aislados de las diferentes especies de Vismia. Por otro lado, los estudios farmacológicos realizados hasta los momentos muestran las diversas propiedades antiplasmodicas, antioxidantes, antimicrobianas y antifúngicas que presentan tanto los extractos como los compuestos puros aislados de las diferentes especies ensayadas. La información resumida en este documento intenta servir de material de apoyo para investigadores en los campos de la etnofarmacologia y la química de productos naturales.
Assuntos
Antraquinonas/química , Clusiaceae/química , Extratos Vegetais/farmacologia , Terpenos/química , Xantonas/química , Antraquinonas/farmacologia , Etnofarmacologia , Extratos Vegetais/análise , Terpenos/farmacologia , Xantonas/farmacologiaRESUMO
Dental caries is considered a multi-factorial, infectious, chronic, localized, post-eruptive, transmissible disease that leads to the destruction of dental hard tissue. The recognition of Streptococcus mutans as the major bacterial species involved in dental caries has led to the implementation of prevention and control measures for eliminating or reducing it in oral cavity. The main goal of research on medicinal plants is the search for substances or compounds with antimicrobial activity. The aim of this study was to evaluate the antimicrobial activity of fractions obtained by two methods from Isertia laevis against S. mutans and S. sobrinus. The plant material was collected in Medina (Colombia), at an elevation of 550 meters above sea level. From the ethanol extract of leaves of I. laevis, fractions were obtained by two methods: extraction by column vacuum chromatography (CVC) and extraction by continuous liquid / liquid partitioning (CLLP). The evaluation of the antimicrobial activity of fractions against S. mutans and S. sobrinus was performed by well diffusion and bioautography assays. From the CVC technique, only the methanol and methanol-dichloromethane fractions showed activity against S. mutans and S. sobrinus, with a minimum inhibitory concentration of 2 mg/well. From the CLLP technique, only the dichloromethane fraction showed activity against both microorganisms, with a minimum inhibitory concentration of 1 mg/well. Compounds C1 and C2 were isolated from the three active fractions, and showed a minimum inhibitory concentration of 0.4 mg/well for S. mutans and S. sobrinus, with zones of inhibition measuring 6.5 and 6.2 mm, respectively. In conclusion: 1) the three active fractions of I. laevis showed activity against S. mutans and S. sobrinus, 2) compounds C1 and C2 were present equally in the three active fractions showing activity against the two bacteria, 3) compounds C1 and C2 may be triterpenoid and/or steroidal saponin structures, and 4) the two extraction methods lead equally to obtaining the active fractions.
La caries dental es considerada una enfermedad infecciosa multifactorial, cronica, localizada, poseruptiva y transmisible que conlleva a la destruccion del tejido dental duro. El claro reconocimiento de Streptococcus mutans como la principal especie bacteriana implicada en caries dental, ha conducido a la implementacion de medidas de prevencion y control para la eliminacion o disminucion de este microorganismo en cavidad oral. El objetivo fundamental de la investigacion en plantas medicinales, es la busqueda de sustancias o compuestos con actividad antimicrobiana para ser utilizadas en el control o prevencion de enfermedades infecciosas. En este sentido, en salud bucal muchas sustancias obtenidas de plantas han mostrado actividad antimicrobiana. El objetivo de este estudio fue evaluar la actividad antimicrobiana de fracciones obtenidas de la planta Isertia laevis mediante dos metodologias contra S. mutans y S. sobrinus. El material vegetal se colecto en el municipio de Medina (Cundinamarca- Colombia) situado a una altura de 550 metros sobre el nivel del mar. A partir del extracto etanolico de hojas de I. laevis se obtuvieron fracciones mediante dos metodologias, extraccion por cromatografia en columna al vacio (CCV) y extraccion por fraccionamiento liquido/liquido continuo (FLLC). La evaluacion de la actividad antimicrobiana de las fracciones frente a S. mutans y S. sobrinus se realizo por el metodo de difusion en pozo y bioautografico. De las fracciones obtenidas por CCV, solamente las fracciones metanol y metanol-diclorometano presentaron actividad antimicrobiana sobre S. mutans y S. sobrinus, con una concentracion minima inhibitoria de 2 mg/pozo. De las fracciones obtenidas por FLLC solamente la fraccion diclorometano presento actividad antimicrobiana sobre S. mutans y S. sobrinus, con una concentracion minima inhibitoria de 1 mg/pozo. De las 3 fracciones activas se aislaron los compuestos C1 y C2, que presentaron una concentracion minima inhibitoria de 0.4 mg/pozo tanto para S. mutans como para S. sobrinus con halos de inhibicion, respectivamente, de 6.5 y 6.2 mm. En conclusion, 1. Las fracciones metanol y diclorometano obtenidas por CCV y la fraccion diclorometano obtenida por FLLC de hojas de I. laevis presentaron actividad antimicrobiana sobre S. mutans y S. sobrinus; 2. Los compuestos C1 y C2 presentes por igual en las tres fracciones activas tuvieron accion inhibitoria sobre las dos bacterias en evaluacion; 3. Las pruebas quimicas cualitativas para los compuestos C1 y C2 indican que posiblemente corresponden a estructuras de saponinas triterpenicas y/o esteroidales; y 4. Las dos metodologias de extraccion conducen por igual a la obtencion de las fracciones activas.
Assuntos
Humanos , Streptococcus mutans/efeitos dos fármacos , Extratos Vegetais/farmacologia , Cariostáticos/farmacologia , Streptococcus sobrinus/efeitos dos fármacos , Rubiaceae , Solventes/química , Terpenos/química , Vácuo , Extratos Vegetais/química , Testes de Sensibilidade Microbiana , Cromatografia/métodos , Cromatografia Líquida , Imunodifusão , Etanol/química , Metanol/química , Fracionamento Químico , Cloreto de Metileno/químicaRESUMO
A series of seven limonene β-amino alcohol derivatives has been regioselectively synthesised in moderate to good yields. Two of these compounds were found to be significantly effective against in vitro cultures of the Leishmania (Viannia) braziliensis promastigote form in the micromolar range. The activities found for 3b and 3f were about 100-fold more potent than the standard drug, Pentamidine, in the same test, while limonene did not display any activity. This is the first report of antileishmanial activity by limonene β-amino alcohol derivatives.
Assuntos
Animais , Camundongos , Amino Álcoois/síntese química , Antiprotozoários/síntese química , Cicloexenos/química , Leishmania braziliensis/efeitos dos fármacos , Terpenos/química , Amino Álcoois/farmacologia , Amino Álcoois/toxicidade , Antiprotozoários/farmacologia , Antiprotozoários/toxicidade , Cicloexenos/farmacologia , Cicloexenos/toxicidade , Estrutura Molecular , Testes de Sensibilidade Parasitária , Relação Estrutura-Atividade , Terpenos/farmacologia , Terpenos/toxicidadeRESUMO
Horse radish peroxidase (HRP) from Armoracia rusticana catalyses the oxidation of (R)-limonene into the oxidized derivatives carveol and carvone. This study compares the direct addition (DA) of hydrogen peroxide with its continuous electrogeneration (EG) during the enzymatic oxidation of (R)-limonene. Reaction mixtures containing HRP, (R)-limonene as substrate, and hydrogen peroxide, added directly or electrogenerated, in 100 mM sodium-potassium phosphate buffer pH 7.0, at 25ºC were studied. Two electrochemical systems for the hydrogen peroxide electrogeneration were evaluated, both containing as auxiliary electrode (AE) a platinum wire and saturated calomel electrode (SCE) as reference. Reticulated vitreous carbon foam (RVCF) and an electrolytic copper web (CW) were evaluated as working electrodes (WE). Results were compared in terms of hydrogen peroxide electrogeneration, (R)-limonene residual concentration or conversion and product selectivity. Best results in terms of maximum H2O2 concentration (1.2 mM) were obtained using the CW electrode at -620 mV SCE, and continuous aeration. Use of the EG system under optimized conditions, which included the use of acetone (30% v/v) as a cosolvent in a 3 hrs enzymatic reaction, lead to a 45% conversion of (R)-limonene into carveol and carvone (2:1). In comparison to the results obtained with DA, the use of EG also improved the half-life of the enzyme.
Assuntos
Cicloexanos/química , Eletroquímica/métodos , Peroxidase do Rábano Silvestre/química , Peróxido de Hidrogênio/química , Terpenos/química , Armoracia/química , Catálise , Cromatografia Gasosa , Eletroquímica/instrumentação , Monoterpenos/química , Oxirredução , Solventes , EspectrofotometriaRESUMO
O objetivo deste estudo foi avaliar a microdureza de materiais resinosos polimerizados com unidades de fotoativação LED (diodos emissores de luz) e halógena. Vinte espécimes cilíndricos (3,0 mm de diâmetro e 2,0 mm de altura) foram preparados para cada material testado (Z100, Definite e Dyract). Os espécimes foram fotoativados na face superior (topo), utilizando duas unidades de fotoativação (Ultraled and Curing Light 2500), com tempos de 40 s e 60 s. As medidas de dureza foram realizadas nas superfícies do topo e da base de cada espécime. A análise estatística foi realizada por ANOVA e teste de Tukey (p<0,05). Não houve diferença significante na dureza na face superior entre as unidades LED e halógena para a Z100 e o Dyract. Por outro lado, a dureza foi menor quando a Definite foi polimerizada com o LED do que com a unidade halógena. Na base, a dureza de todos os materiais foi menor com o LED do que com a unidade halógena. A Z100 apresentou maior dureza que o Dyract e que a Definite independentemente da unidade de fotoativação. Não houve diferença significante na dureza entre os dois tempos de fotoativação para a face superior. Na base, a dureza foi maior quando os materiais foram polimerizados por 60 s. O LED não foi capaz de produzir a mesma dureza que a unidade halógena nos materiais resinosos testados.
Assuntos
Humanos , Resinas Compostas/química , Iluminação/instrumentação , Compômeros/química , Resinas Compostas/efeitos da radiação , Desenho de Equipamento , Dureza , Teste de Materiais , Polímeros/química , Dióxido de Silício/química , Siloxanas/química , Fatores de Tempo , Terpenos/química , Zircônio/químicaRESUMO
This study evaluated the effect of surface finishing methods on the average surface roughness of resin composites. Seven composites and two polishing systems were used. One hundred and twenty-six conical specimens of each material were prepared in stainless steel molds against a polyester strip. Forty-two of them remained intact and were used as controls. Each half of the remaining samples was polished with either diamond burs or diamond burs + aluminum oxide discs. The results showed no statistical difference in average surface roughness (Ra, µm) between the polyester strip and aluminum oxide discs (p>0.05). However, finishing with diamond burs showed a statistically higher average roughness for all composites (p<0.05). Statistical differences were detected among materials (p<0.05) in the use of diamond burs