Cardiac magnetic resonance as a risk re-stratification tool in apical hypertrophic cardiomyopathy.

Apical hypertrophic cardiomyopathy (ApHCM) can result in the formation of a left ventricular apical aneurysm and progressive myocardial fibrosis, which is associated with a worse prognosis. We present the case of a 76-year-old man previously diagnosed with ApHCM seven years ago, who has been under clinical follow-up. Serial cardiac magnetic resonance (CMR) imaging was performed in 2013 and 2020 due to suspected apical aneurysm formation based on echocardiographic evaluation. The 2020 CMR imaging revealed an increase in myocardial fibrosis observed through late-gadolinium enhancement images and, for the first time, a small apical aneurysm that was not clearly visualized on two-dimensional echocardiography. The time course leading to the development of an ApHCM aneurysm is not well-defined and may impact the clinical course.

La miocardiopatía hipertrófica apical (MCHap) puede provocar la formación de un aneurisma apical del ventrículo izquierdo (LV) y una fibrosis miocárdica progresiva que se relaciona con un peor pronóstico. Se presenta el relato de un paciente de 76 años con diagnóstico previo de MCHap hace siete años en seguimiento clínico. Se realizó una resonancia magnética cardíaca (RMC) seriada en 2013 y 2020, ante la sospecha de formación de aneurisma apical mediante ecocardiografía. Las imágenes RMC del 2020 demostraron un aumento de la fibrosis miocárdica mediante imágenes de realce tardío con gadolinio y, por primera vez, un pequeño aneurisma apical que no fue definido en forma precisa en la ecocardiografía bidimensional. El tiempo de progresión hasta el desarrollo del aneurisma en la MCHap no está claramente definido y puede relacionarse con cambios en el curso clínico.

[Left atrium remodeling after catheter ablation of atrial fibrillation]. / Remodelado reverso de aurícula izquierda posablación de fibrilación auricular.

Atrial fibrillation (AF) is the most common cardiac arrhythmia. It has a high association with cardiovascular embolic events and heart failure. Structural and functional changes are a fundamental part of the pathophysiological process, leading to left atrial myopathy and progressive left ventricular dysfunction that modifies the prognosis of patients. We present the case of a 75-year-old patient with symptomatic paroxysmal AF with good functional class who was referred for pulmonary vein ablation after antiarrhythmic therapy failure. The initial echocardiogram showed preserved biventricular systolic function, mild diastolic dysfunction, and normal left atrium (LA) volumes. However, functional LA impairment was observed with decreased reservoir phase strain. Pulmonary vein isolation was successfully performed without evidence of new arrhythmic events, in addition to improvement in LA reservoir strain, left ventricular (LV) global longitudinal strain, and myocardial work index at three months follow-up. The patient has remained asymptomatic and is under clinical follow-up. LA and LV strain as new advanced echocardiography techniques is useful in the assessment of reverse remodeling of atrial myopathy and LV structural assessment.

Insights of tricuspid regurgitation mechanisms in patients with right ventricular apical pacing by three-dimensional echocardiography.

OBJECTIVE: Device lead-induced tricuspid regurgitation (LITR) mechanisms are well-defined by 3D transthoracic echocardiography (3D-TTE). There is a lack of data on the Latin-American population. The objective of this study was to describe the prevalence of several mechanisms and insights in patients with permanent right ventricular (RV) implanted devices by 3D-TTE examination. METHODS: We performed a cross-sectional analysis of 101 patients with permanent cardiac devices such as pacemakers or defibrillators. 3D-TTE was obtained on all patients in RV-focused apical views to perform a complete tricuspid valve (TV) evaluation: leaflets, subvalvular apparatus, precise lead location, and functional assessment to evaluate possible mechanisms of tricuspid regurgitation (TR). RESULTS: In a total of 101 patients, the leads did not interfere with TV function in 53 p. (59%), while LITR was observed in 38 (41%) patients. Adherent, impinging, entangled, and mixed lead-induced mechanisms were observed. Time in years since device implantation was significantly higher in patients with LITR. CONCLUSIONS: LITR was present in a high proportion of our population. LITR is the result of damage to the TV as well as its subvalvular apparatus due to the fibrotic and inflammatory response over time when leads are situated in unfavorable locations.

[Cardiac progression of systemic light chain amyloidosis]. / Progresión cardiaca de amiloidosis sistémica de cadera ligera.

Systemic light chain amyloidosis is a disease characterized by the accumulation of amyloid protein in multiple organs and systems. We present the case of a 52-year-old male patient with a diagnosis of systemic light chain amyloidosis associated with cardiac and renal involvement. A renal biopsy showed the presence of renal amyloidosis associated with proteinuria, and the patient was referred for cardiovascular evaluation. The baseline electrocardiogram showed micro voltage in frontal leads that were discordant with the left ventricular hypertrophy evidenced in the transthoracic echocardiogram (TTE). Cardiac magnetic resonance imaging (CMR) confirmed the presence of cardiac amyloid infiltration with a pattern of extensive ventricular late-gadolinium enhancement. Despite being referred and receiving specific systemic chemotherapy treatment, the evolution was not favorable after four months of follow-up with worsening cardiac infiltration, increasing values of biomarkers, and progression of dyspnea. The TTE was useful in revealing the unfavorable evolution and worsening of diastolic function parameters and increased wall thickness in the context of infiltration. The electrocardiogram and echocardiogram were easily accessible tools that allowed the monitoring of the response to treatment.

Cardiac Multimodality Imaging Assessment of Dystrophic Myocardial Calcification in a Human Immunodeficiency Virus-Infected Patient With Dilated Cardiomyopathy.

Dystrophic myocardial calcification represents the sequelae of local tissue damage and cellular necrosis. We present the case of a 72-year-old man who presented with exertional chest pain. He had a medical history of human immunodeficiency virus (HIV) infection and chronic dilated cardiomyopathy with severe left ventricular (LV) systolic dysfunction and wall motion abnormalities at the inferior and lateral LV walls. A cardiac magnetic resonance (CMR) examination from 16 years ago showed a subendocardial late gadolinium enhancement (LGE) distribution consistent with prior myocardial infarction (MI). Recently, a pharmacological stress myocardial perfusion imaging by CMR had been positive for myocardial ischemia in the left descending coronary artery (LAD) territory. A cardiac CT angiography (CCTA) showed non-significant LAD obstruction <50% consistent with microvascular ischemia and the presence of dystrophic myocardial calcification as an unusual progression of a prior MI. Conservative approach and optimal medical therapy were employed in our patient, and there was no symptom progression during the two-month follow-up period.

[Different phenotypes of mitral regurgitation in patients with right apical ventricular pacing: an echocardiographic approach in a heterogeneity of clinical scenarios]. / Distintos fenotipos de insuficiencia mitral en pacientes con estimulación apical del ventrículo derecho: un abordaje ecocardiográfico en una heterogeneidad de escenarios clínicos.

The presence of mitral regurgitation (MR) in patients with right ventricular apical pacing can be the result of multiple phenomena. On the one hand, this stimulation causes an asynchronous activation of the left ventricle (LV) and the papillary muscles, leading to a deterioration of the LV ejection fraction and causing an inadequate closure of the valve apparatus. However, there is a wide heterogeneity of ischemic and non-ischemic myocardial conditions that can coexist with mechanical alteration of the LV and the mitral valve leading to or worsening MR in these patients, which can make the etiological determination of valvular regurgitation difficult. Transthoracic echocardiography study allows comprehensive evaluation of mitral valve regurgitation and ventricular function parameters and mechanical asynchrony as a result of artificial pacing. The comprehensive study of these phenomena is relevant in clinical decision-making to define those patients who benefit from cardiac resynchronization therapy to alleviate symptomatic MR.

Cardiac Computed Tomography as an Alternative Technique in the Assessment of Acute Myocardial Ischemia in the Context of COVID-19 Infection.

Coronavirus disease 2019 (COVID-19) has been shown to result in coagulation abnormalities and predisposes patients to thrombotic status, both in the venous and arterial circulations. Herein, we report the case of a 60-year-old patient with COVID-19 pneumonia confirmed by polymerase chain reaction (PCR) who experienced signs and symptoms of myocardial ischemia. A cardiac computed tomography (CT) demonstrated an extensive coronary artery multivessel disease and ischemic dilated cardiomyopathy in a non-invasively approach allowing to define the coronary obstructive involvement in the acute stage of the disease.

Pattern formation mechanisms of self-organizing reaction-diffusion systems.

Embryonic development is a largely self-organizing process, in which the adult body plan arises from a ball of cells with initially nearly equal potency. The reaction-diffusion theory first proposed by Alan Turing states that the initial symmetry in embryos can be broken by the interplay between two diffusible molecules, whose interactions lead to the formation of patterns. The reaction-diffusion theory provides a valuable framework for self-organized pattern formation, but it has been difficult to relate simple two-component models to real biological systems with multiple interacting molecular species. Recent studies have addressed this shortcoming and extended the reaction-diffusion theory to realistic multi-component networks. These efforts have challenged the generality of previous central tenets derived from the analysis of simplified systems and guide the way to a new understanding of self-organizing processes. Here, we discuss the challenges in modeling multi-component reaction-diffusion systems and how these have recently been addressed. We present a synthesis of new pattern formation mechanisms derived from these analyses, and we highlight the significance of reaction-diffusion principles for developmental and synthetic pattern formation.

Prolapse and regurgitation of the four heart valves in a patient with Ehlers-Danlos Syndrome: a case report.

BACKGROUND: The Ehlers-Danlos Syndrome (EDS) is part of a group of connective tissue diseases that affect the synthesis and processing of collagen leading to alterations in the structure of many tissues and organs. CASE SUMMARY: Herein, we reported a case of a patient with prolapse of the four cardiac valves. Non-significant regurgitation of the mitral, aortic, and tricuspid valves was observed. The pulmonary regurgitation (PR) was considered significant. Dilatation of the right ventricle with preserved systolic function was also noted. A cardiac magnetic resonance confirmed the findings of the echocardiogram and determined a severe PR (regurgitant fraction of 41%). The physical examination revealed hyperlaxity of the joints, skin hyperelasticity, defects in wound healing, and abdominal hernias suggesting EDS. The stress test did not develop any symptoms or complex arrhythmias. In this patient, the heart team initially decided medical treatment and evolutionary control. At the moment, he remains asymptomatic. DISCUSSION: Valvular involvement in EDS is an infrequent event and the compromise of the four cardiac valves is exceptional. The existence of severe PR with a marked increase in ventricular volumes, even in the absence of symptoms, in most cases requires an intervention on the valve. However, in patients with EDS, there are a high rate of complications and interventions should be avoided as much as possible.

High-throughput mathematical analysis identifies Turing networks for patterning with equally diffusing signals.

The Turing reaction-diffusion model explains how identical cells can self-organize to form spatial patterns. It has been suggested that extracellular signaling molecules with different diffusion coefficients underlie this model, but the contribution of cell-autonomous signaling components is largely unknown. We developed an automated mathematical analysis to derive a catalog of realistic Turing networks. This analysis reveals that in the presence of cell-autonomous factors, networks can form a pattern with equally diffusing signals and even for any combination of diffusion coefficients. We provide a software (available at http://www.RDNets.com) to explore these networks and to constrain topologies with qualitative and quantitative experimental data. We use the software to examine the self-organizing networks that control embryonic axis specification and digit patterning. Finally, we demonstrate how existing synthetic circuits can be extended with additional feedbacks to form Turing reaction-diffusion systems. Our study offers a new theoretical framework to understand multicellular pattern formation and enables the wide-spread use of mathematical biology to engineer synthetic patterning systems.

Montrichardia linifera (Araceae) biological potential, phytochemical prospection and polyphenol content / Montrichardia linifera is commonly known in Brazil as "aninga." In November 2008 and August 2009, we collected plant samples and extracted leaves and stems using hexane or dichloromethane and methanol to evaluate its biological and chemical potential, phytochemical profile and polyphenol content. Differences in the chemical composition of the collections were evident. In the first collection, the apolar extracts were the richest in metabolite composition while the polar extracts were the richest in the second collection. In general, extracts from Aug/2009 had higher antioxidant and cytotoxic activities than extracts from Nov/2008 and the stem and leaf extracts from the Aug/2009 collection showed the highest polyphenol content. As an insecticide against Sitophilus zeamais, the hexane extract of the leaves (Aug/2009) presented concentration-dependent insecticidal activity. Only the methanolic extract of stems and leaves (Aug/2009) presented a small inhibition halo (9 and 7 mm, respectively) against Aeromonas hydrophila when evaluating its antibacterial potential. The study demonstrates that, collection period is an important factor to consider in phytochemical and biological activity studies of M. linifera. / Potencial biológico, prospección fitoquímica y contenido de polifenoles de Montrichardia linifera (Araceae) / Potencial biológico, prospecção fitoquímica e teor de polifenóis de Montrichardia linifera (Araceae)

Montrichardia linifera es comúnmente conocida en Brasil como "aninga". Fue colectada dos veces (Nov/2008 y Ago/2009), y sus hojas y tallos fueron extraídos con hexano o diclorometano y metanol. El potencial biológico y químico, perfil fitoquímico y contenido de polifenoles de sus extractos fueron evaluados. Fueron encontradas diferencias en la composición química: de la primera colecta, los extractos apolares fueron más ricos, mientras que de la segunda colecta, los polares fueron los más ricos. Extractos de Ago/2009 mostraron, en general, actividades antioxidante y citotóxica mayores que los de Nov/2008. Los extractos de los tallos y hojas de Ago/2009 mostraron un mayor contenido de polifenoles. Cuanto al ensayo insecticida sobre Sitophilus zeamais, el extracto hexánico de las hojas (Ago/2009) presentó actividad insecticida concentración-dependiente. Cuando evaluado el potencial antibacteriano, apenas los extractos metanólicos de los tallos y hojas (Ago/2009) presentaron un halo de inhibición pequeño (9 y 7 mm, respectivamente) contra Aeromonas hydrophila. Este estudio muestra que el período de la colecta es un factor importante a ser considerado cuando los objetivos son estudios fitoquímicos y de actividades biológicas de M. linifera.

Montrichardia linifera é comumente conhecida no Brasil como "aninga". Foi coletada duas vezes (Nov/2008 e Ago/2009), e suas folhas e caules foram extraídos com hexano ou diclorometano e metanol. O potencial biológico e químico, perfil fitoquímico e teor de polifenóis de seus extratos foram avaliados. Foram encontradas diferenças na composição química: da primeira coleta, os extratos apolares forem mais ricos, enquanto que da segunda coleta, os polares foram os mais ricos. Extratos de Ago/2009 mostraram, em geral, atividades antioxidante e citotóxica maiores que os de Nov/2008. Os extratos dos caules e das folhas de Ago/2009 mostraram um maior teor de polifenois. Quanto ao ensaio inseticida sobre Sitophilus zçamais, o extrato hexânico das folhas (Ago/2009) apresentou atividade inseticida dependente da concentração. Quando avaliado o potencial antibacteriano, apenas os extratos metanólicos dos caules e folhas (Ago/2009) apresentaram um halo de inhibição pequeno (9 e 7 mm, respectivamente) contra Aeromonas hydrophila. Este estudo mostra que o período da coleta é um fator importante a ser considerado quando os objetivos são estudos fitoquímicos e de atividades biológicas de M. linifera.

Força muscular e índice de fadiga dos extensores e flexores do joelho de jogadores profissionais de futebol de acordo com o posicionamento em campo / Muscular strength and fatigue index of knee extensors and flexors of professional soccer players according to their positioning in field / Fuerza muscular e índice de fatiga de los extensores y flexores de las rodillas de jugadores profesionales de fútbol, de acuerdo con el posicionamento en campo

INTRODUÇÃO: Assimetrias na capacidade de produção de força entre músculos dos membros inferiores e fadiga muscular podem favorecer a ocorrência de lesões em atletas de futebol. Considerando-se que existem diferenças individuais determinadas pelas diversas funções exercidas pelos jogadores, é possível que a presença de assimetrias de força e fadiga muscular esteja relacionada ao posicionamento em campo. OBJETIVOS: 1) Investigar diferenças na assimetria de pico de torque (PT), na assimetria de trabalho (T) e no índice de fadiga (IF) dos extensores e flexores do joelho de atletas profissionais de futebol de acordo com a posição em campo; e 2) Determinar se o IF dos flexores é superior ao dos extensores. MÉTODOS: Foram analisadas avaliações isocinéticas de 164 atletas profissionais de futebol (atacantes, zagueiros, laterais, meio-campistas e goleiros). O protocolo para avaliação da força concêntrica dos extensores e flexores do joelho consistiu em cinco repetições a 60°/s e 30 repetições a 300°/s. O teste de Kruskall-Wallis foi utilizado para verificar diferenças na assimetria de PT, assimetria de T e IF dos extensores e flexores do joelho entre jogadores de diferentes posicionamentos. O teste de Wilcoxon foi realizado para verificar se havia diferença entre o IF dos extensores e flexores. RESULTADOS: Não houve diferença entre os jogadores dos cinco posicionamentos para as assimetrias de PT e T, bem como para o IF dos extensores e flexores (p > 0,05). O IF flexor foi superior ao extensor em ambos os membros inferiores (p < 0,01). CONCLUSÃO: Variáveis isocinéticas comumente associadas a lesões não foram diferentes entre jogadores de diferentes posicionamentos. Os atletas apresentaram o IF flexor superior ao extensor, o que pode estar relacionado à maior frequência de estiramentos dos isquiossurais em comparação ao quadríceps.

INTRODUCTION: Strength asymmetry among the muscles of the lower limbs and muscle fatigue may predispose soccer players to injuries. Regarding the individual differences determined by diverse roles performed by players, it is possible that the presence of asymmetries of muscle strength and fatigue is related to playing position. OBJECTIVES: 1) To investigate differences in asymmetry of peak torque (PT), work asymmetry (W) and fatigue index (FI) of knee extensors and flexors of professional soccer players according to their positioning in field; 2) To determine if FI of knee flexors is higher than those of knee extensors. METHODS: Data from isokinetic assessment of 164 professional soccer players (forwards, fullbacks, wingers, midfielders and goalkeepers) were analyzed. The protocol of evaluation of concentric strength of knee extensors and flexors consisted of five repetitions at 60°/s and 30 repetitions at 300°/s. Kruskall-Wallis test was carried out to verify differences in PT asymmetry, W asymmetry and FI of knee extensors and flexors among players of different positions. The Wilcoxon test was performed to verify if there is difference between FI of knee extensors and flexors. RESULTS: There was no difference among playing positions for asymmetries of PT and W, as well as for FI of knee extensors and flexors (p > 0.05). The FI of knee flexors was higher than FI of knee extensors in both lower limbs (p < 0.01). CONCLUSION: Isokinetic variables, commonly associated with injuries, were not different among players of different positions. The athletes had flexor FI higher than extensor FI, which can be related to greater frequency of strain injury of hamstrings in comparison to quadriceps.

INTRODUCCIÓN: Asimetrías en la capacidad de producción de fuerza entre músculos de los miembros inferiores y la fatiga muscular pueden favorecer la ocurrencia de lesiones en atletas de fútbol. Considerándose que existen diferencias individuales, determinadas por las diversas funciones desempeñadas por los jugadores, es posible que la presencia de asimetrías de fuerza y fatiga muscular esté relacionada con el posicionamiento en campo. OBJETIVOS: 1) Investigar diferencias en la asimetría de pico de torsión (PT), en la asimetría de trabajo (T) y en el índice de fatiga (IF) de los extensores y flexores de las rodillas de atletas profesionales de fútbol, de acuerdo con la respectiva posición en campo; y 2) Determinar si el IF de los flexores es superior al de los extensores. MÉTODOS: Se analizaron evaluaciones de 164 atletas profesionales de fútbol (delanteros, zagueros, laterales, mediocampistas y arqueros). El protocolo, para evaluación de la fuerza concéntrica de los extensores y flexores de las rodillas, consistió en cinco repeticiones a 60°/s y 30 repeticiones a 300°/s. La prueba de Kruskall-Wallis fue utilizada para verificar diferencias en la asimetría de PT, asimetría de T e IF de los extensores y flexores de rodillas entre jugadores de diferentes posicionamientos. La prueba de Wilcoxon fue realizada para verificar si había diferencia entre el IF de los extensores y flexores. RESULTADOS: No hubieron diferencias entre los jugadores de las cinco posiciones cuanto a las asimetrías de PT y T, así como para el IF de los extensores y flexores (p > 0,05). El IF del flexor fue superior al del extensor en ambos miembros inferiores (p < 0,01). CONCLUSIÓN: Las variables isocinéticas, comúnmente vinculadas a lesiones, no fueron diferentes entre jugadores en diversas posiciones. Los atletas presentaron el IF de flexor superior al del extensor, lo que puede estar relacionado con más frecuencia de estiramientos de los isquiosurales en comparación con el cuádriceps.

Determinação da atividade antioxidante e do teor total de polifenol em amostras de chá de ervas comercializadas em sachets / Determination of total antioxidant activity and total content of polyphenols in samples of tea leaves marketed in bags

OBJETIVO: Os chás de ervas são tradicionalmente utilizados na medicina popular em muitas regiões do Brasil. Os chás contêm compostos antioxidantes que combatem o stress oxidativo e seu consumo tem sido associado à diminuição dos níveis de colesterol, pressão arterial e até de doenças cardiovasculares. O objetivo deste estudo foi determinar a capacidade antioxidante total, o teor total de polifenóis, o consumo (scavenging) de H2O2 e a presença de outros grupos de compostos antioxidantes em 43 amostras de chás em sachets. MÉTODOS: O método CUPRAC (cupric ion reducing antioxidant capacity) foi utilizado para determinar a capacidade antioxidante total. O teor total de polifenóis foi obtido com o uso do reagente de Folin-Ciocalteu; o ensaio de scavenging baseou-se no consumo de solução de H2O2 após adição do chá; e a presença de flavonóides, carotenos e catequinas foi investigada por cromatografia em papel. RESULTADOS: A capacidade antioxidante total nas amostras analisadas seguiu a ordem: camomila > hortelã > carqueja >cidreira > boldo > verde > mate > preto > branco > erva doce. O teor total de polifenóis obedeceu à sequência: branco > hortelã > preto > mate > boldo > verde > camomila > carqueja > cidreira > erva doce. As divergências encontradas entre as amostras de um mesmo grupo de chá podem ser atribuídas à época da colheita, ao tipo de solo, local de plantio, variações climáticas e partes da planta utilizadas na elaboração dos sachets. CONCLUSÃO: Conclui-se que todas as amostras analisadas apresentaram capacidade antioxidante e consumo de H2O2. Em apenas uma delas não foi possível detectar flavonóides, carotenos ou catequinas.

OBJECTIVE: Tea leaves are traditionally used in folk medicine in many regions of Brazil. They contain antioxidant compounds that can protect against oxidative stress and their regular intake have been associated with decreased of cholesterol levels, blood pressure and, thereby, with the lowered risk of coronary heart disease. The objective of this study was to determine the total antioxidant capacity, the total polyphenols content,scavenging of H2O2 and presence of other groups of antioxidant compounds in 43 tea samples packed in bags. METHODS: The CUPRAC method (cupric ion reducing antioxidant capacity) was used to quantify the total antioxidant capacity. The polyphenols content was performed using the Folin-Ciocalteu reagent. The scavenging assay was based on the consumption of H2O2 after addition of tea; the presence of flavonoids, carotenes and catechins was evaluated by paper chromatography. RESULTS:The total antioxidant capacity found in tea samples followed the order: chamomile > mint > carqueja > balm > boldo > green > mate > black > white > fennel. For total polyphenol content the order was: white > mint > black > matte > boldo > green > chamomile > carqueja > balm > fennel. The differences found in the samples from the same kind of tea can be attributed to the harvest season, soil type, planting location, climate differencesand from the parts of the vegetal material used in the preparation of the tea bags. CONCLUSION: All samples analyzed presented antioxidant activity and ability to scavenge H2O2. It was not possible to detect flavonoids, carotenes and catechins in only one sample.

A critical study of use of the Fe(II)/3-hydroxy-4-nitroso-2,7-naphthalenedisulfonic acid complexes in the quantification of polyphenols in medicinal plants.

A critical study of the use of the Fe(III)/3-hydroxy-4-nitroso-2,7-naphthalenedisulfonic acid (NRS) complexes on the quantification of the polyphenols content in aqueous extracts of plants, expressed as pyrogallic acid, [PA], is presented. The reaction used is based on the reduction of Fe(III) to Fe(II) by [PA] in the presence of NRS in a buffered medium (Tris; pH 8.0) with formation of Fe(II)/NRS complexes. A calibration curve of absorbance (at 730 nm) vs. [PA] is linear (r=0.998; n=7) from 1.0 to 7.0 µmolL(-1) [PA]. LD and RSD were 0.5 µmolL(-1) and 2.5% (6.0 µmolL(-1) [PA], n=10), respectively. The influence of pH, type of buffer solution and interfering species possibly present in the samples were evaluated. Aqueous extracts of twelve medicinal plants used in the Brazilian folk medicine were analysed by using both Fe(III)/NRS complexes and the Folin-Ciocalteu reagent.