Abstract Graphene oxide (GO) is one of the main precursors for the production of graphene and other graphene-based materials. We report a simple, safe, and fast synthesis method to obtain graphene oxide as a functional material for battery-type electrodes. Washing and lyophilization processes were performed to evaluate their effects on exfoliation and removal of functional groups from graphene sheets. Sample GO1 consisted of a 10-layer stack of oxidized graphene, while sample GO2 had 8 stacked layers. The difference between them was an extra washing and lyophilization process in the GO2 sample. The electrochemical performance of graphene oxide-based electrodes, classified as battery-type, indicated an improved specific capacity of 10.15 C.g-1 for GO1 against 4.55 C.g-1 for GO2 at a specific current of 0.5 A.g-1. This superior battery-type behavior of the GO1 electrode, also confirmed by electrochemical impedance spectroscopy, was most likely due to a higher degree of oxygenated groups on its surface, as shown by energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) studies.

In this study, we investigated the chemical composition, and antioxidant and antibacterial properties of ethanolic extracts of propolis (EEP) from Melipona quadrifasciata quadrifasciata and Tetragonisca angustula. Chemical composition of EEP was determined by colorimetry and chromatographic (HPLC-DAD and UPLC-Q/TOF-MS/MS) analysis. Antimicrobial activity of EEP was evaluated against gram-positive (S. aureus, methicillin-resistant S. aureus, E. faecalis) and gram-negative (E. coli and K. pneumoniae) bacteria by the minimal inhibitory concentration (MIC) test using the microdilution method. Furthermore, the growth curve and integrity of cell membrane of S. aureus and E. coli were investigated using standard microbiological methods. HPLC-DAD analysis showed that the EEP of M. quadrifasciata quadrifasciata has a more complex chemical composition than the EEP of T. angustula. Moreover, UPLC-MS analyses of M. quadrifasciata quadrifascita indicated flavonoids and terpenes as major constituents. The bactericidal activity of both EEPs was higher against gram-positive bacteria than for gram-negative bacteria. The EEP from M. quadrifasciata quadrifasciata presented MIC values lower than the EEP from T. angustula for all tested bacteria. The EEP from M. quadrifasciata quadrifasciata caused lysis of the bacterial wall and release of intracellular components from both E. coli and S. aureus. Our findings indicate that the chemical composition of propolis from stingless bees is complex and depends on the species. The extract from M. quadrifasciata quadrifascita was more effective against gram-positive than gram-negative strains, especially against S. aureus and methicillin-resistant S. aureus compared to T. angustula extract, by a mechanism that involves disturbance of the bacterial cell membrane integrity.

Este estudo avaliou a resposta inflamatória aguda induzida por carragenina na bexiga natatóriade tilápia do Nilo suplementada com a mistura dos extratos naturais de própolis e Aloe barbadensis (1:1), nas concentrações de 0,5%, 1% e 2% na dieta durante o período de 15 dias. Trinta e seis peixes foram distribuídos em quatro tratamentos com três repetições: peixes suplementados com 0,5% da mistura dos extratos de própolis e Aloe (1:1) injetados na bexiga natatória com 500 µg de carragenina; peixes suplementados com 1% da mistura dos extratos de própolis e Aloe (1:1) injetados na bexiga natatória com 500 µg de carragenina; peixes suplementados com 2% da mistura dos extratos de própolis e Aloe (1:1) injetados na bexiga natatória com 500 µg de carragenina e peixes não suplementados injetados na bexiga natatória com 500 µg de carragenina. Seis horas após as injeções foram coletadas amostras de sangue e exsudato da bexiga natatória dos peixes. Foi observado aumento na contagem de leucócitos no exsudato da bexiga natatória de peixes suplementados com os extratos de própolis e Aloe injetados com carragenina. As células mais frequentes foram os macrófagos seguidos pelos leucócitos granulares, trombócitos e linfócitos. A suplementação com própolis e Aloe a 0,5% provocou aumento significativo no número de células no foco inflamatório, principalmente dos macrófagos, células responsáveis pela atividade fagocitária nos tecidos, agente da resposta imune inata nos peixes.

This study evaluated the acute inflammatory response induced by carrageenin in the swim bladder of Nile tilapia supplemented with the mixture of natural extracts of propolis and Aloe barbadensis (1:1) at a concentration of 0.5%, 1% and 2% in diet during 15 days. Thirty-six fish were distributed into four treatments with three replicates: fish supplemented with 0.5% of admix of extracts of propolis and Aloe (1:1) injected with 500 µg carrageenin; fish supplemented with 1% of admix of extracts of propolis and Aloe (1:1) injected with 500 µg carrageenin; fish supplemented with 2% of admix of extracts of propolis and Aloe (1:1), injected with 500 µg carrageenin and unsupplemented fish injected with 500 µg carrageenin. Six hours after injection, samples of blood and exudate from the swim bladder of fish were collected. It was observed an increase in the leukocyte count in the swim bladder exudate of fish supplemented with extracts of propolis and Aloe injected with carrageenin. The most frequent cells were macrophages followed by granular leukocytes, thrombocytes and lymphocytes. Supplementation with propolis and Aloe to 0.5% caused a significant increase in the number of cells on the inflammatory focus mainly macrophages, cells responsible for the phagocytic activity in tissues, agent of innate fish immune response.

Aloysia gratissima (Gill. et Hook) Tronc. (Verbenaceae) is native to South America with folk therapeutic applications for a wide range of diseases. The polyphenolic and carotenoid profile, toxicity, and antioxidant activity of aqueous extract of Aloysia gratissima were investigated. HPLC analyses showed high amounts of ferulic acid, trans-cinnamic acid and p-coumaric acid, and also trans-β- carotene and lutein which fluctuated throughout the seasons. Furthermore, the extract investigated not only exerted antioxidant activity but also inhibited lipid peroxidation. Toxicity was achieved only at the highest dose tested. Therefore, A. gratissima is a potential species for medicinal purposes.

Effects of the interaction of irradiance and nutrient levels on growth and contents of photosynthetic pigments, carotenoids and proteins in Gracilaria domingensis (Kütz.) Sonder ex Dickie (Gracilariales, Rhodophyta) were investigated experimentally. Nutrient availability provided by dilutions of the nutrient solution of von Stosch (25 and 50%, which corresponded to nitrate concentrations of 125 and 250 μmol, respectively) and two photon flux densities [low PFD (50±5) and high PFD (100±5) μmol photons.m-2.s-1] were tested. Growth rates of G. domingensis were stimulated by high PFD. The interaction between high nutrient availability (50% VSES) and high PFD stimulated the accumulation of total soluble protein. Phycobiliprotein concentrations (phycoerythrin, phycocyanin, and allophycocyanin) and carotenoid contents were influenced by irradiance levels. Phycobiliprotein concentrations were higher at low PFD and high irradiances stimulated carotenoid accumulation. These results reflect the function of these pigments in photoprotection and the acclimation of G. domingensis to changes in irradiance levels. Our results indicate that light is a limiting factor for G. domingensis growth, that variations in phycobiliprotein contents under different irradiance levels are related to photoacclimation process, and that higher carotenoid contents at high irradiances are due to a photoprotection mechanism.

Este trabalho descreve o ciclo gametogênico da vieira Nodipecten nodosus mantida em ambiente de cultivo. Para isto, durante um ano, amostras de indivíduos reprodutores foram coletadas a cada 30 dias e submetidas à avaliação macroscópica e microscópica e à quantificação de astaxantina. Para a avaliação microscópica, secções de 5 μ da porção mediana feminina da gônada foram submetidas à metodologia de análise histológica padrão em parafina e coloração HE. O restante da porção feminina da gônada foi liofilizado para extração e quantificação de astaxantina em HPLC. A avaliação microscópica permitiu a descrição de quatro estágios bem definidos para o ciclo reprodutivo. Na análise ao longo do ano, foram observados períodos preferenciais de desova em dezembro e janeiro e de julho a setembro. A análise da quantidade de astaxantina, mostrou, nos estádios de pré-desova avançada e de desova inicial, uma maior quantidade desse carotenoide em comparação aos estádios de gametogênese, pré-desova inicial, desova avançada e repouso. Em função desses resultados, foi possível estabelecer um quadro descritivo dos estágios sexuais da porção feminina da gônada e quantidade de astaxantina em cada estágio sexual da vieira Nodipecten nodosus.

This work describes the gametogenic cycle of the scallop Nodipecten nodosus kept in a culture system. To this end, during one year, samples were taken from the broodstocks every 30 days to be submitted to macroscopic and microscopic analyses and to measure the amount of astaxanthin. To perform the microscopic evaluation, 5 μ slices from the median portion of the female part of the gonad were submitted to the pattern methodology for histological analyses with paraffin and HE coloration. The remaining portion of the female gonad was lyophilised to extract and quantify the levels of astaxanthin using HPLC. The microscopic analyses revealed four well defined stages for the reproductive cycle. Analyses of data taken throughout the year indicated preferential spawning periods from December to January and from July to September. The astaxanthin analyses showed higher amounts of this carotenoid during the advanced pre-spawning and the initial spawning periods than during gametogenesis, initial pre-spawning, advanced spawning, and the spent stages. According to these results, it was possible to establish a descriptive table of the sexual stages of the female portion of the gonad and the amount of astaxanthin in the sexual stage of the scallop Nodipecten nodosus.

Em moluscos bivalves marinhos, carotenóides insaturados estão presentes na dieta natural, com um importante papel em diversos processos biológicos, em especial na reprodução. A elucidação dos efeitos destes compostos em Nodipecten nodosus requer o desenvolvimento de um protocolo adequado para a extração de carotenóides das gônadas desses animais. Para isso, gônadas de vieiras cultivadas (75 mm de comprimento) foram liofilizadas e maceradas em N2 líquido. Amostras em triplicata com 50 mg foram coletadas para a utilização em cada tratamento. Os conteúdos de carotenóides totais e astaxantina foram determinados via espectrofotometria de luz UV-visível e cromatografia líquida de alta eficiência (CLAE), respectivamente. O efeito da composição em organosolventes das soluções de extração foi testado utilizando-se acetona (Ac = O) e hexano (Hex) em quatro proporções (Ac = O:Hex): 1:1, 1:3, 1:5, e 2:3; em quatro tempos de extração: 0, 5, 10, e 15 minutos. Os resultados mostraram que o melhor rendimento de extração (0,312 ± 0,016 µg carotenóides/mg) foi obtido com Ac = O:Hex, 1:3, por 15 minutos. Com a utilização de protocolo de extração exaustiva (10x), uma quantidade superior (0,41 ± 0,001 µg de carotenóides/mg) foi obtida de amostras de gônada, comparativamente aos valores obtidos em extrações únicas. O conteúdo de astaxantina foi reduzido em 8,6% em testes de preservação deste metabólito em extratos crus (-18 °C, 26 dias de incubação em atmosfera de N2).

In marine bivalve mollusks, unsaturated molecules called carotenoids are present in the natural diet and play an important role in different biological process, especially in reproduction. In order to gain more insights into these compounds in Nodipecten nodosus it was necessary to develop a suitable protocol for extraction of carotenoids from the gonads. Female gonads of cultured scallops (75 mm length) were lyophilized and macerated in liquid N2. To verify the effect of composition in organosolvents on the extracting solutions, two organic solvents were tested: acetone and hexane (Ac = O:Hex) at four ratios, 1:1, 1:3, 1:5, and 2:3, in four static extraction times: 0, 5, 10, and 15 minutes. Total carotenoids and astaxanthin contents were determined in the crude extracts by UV-visible spectrophotometry and high performance liquid chromatography (HPLC), respectively. Triplicate aliquots of 50 mg were used for each treatment. The results indicated that the best single extraction (0.312 ± 0.016 µg carotenoids/mg) was attained with Ac = O: Hex 1:3, for 15 minutes. Through exhaustive extraction methodology (10x), a superior yield (0.41 ± 0.001 µg carotenoids/mg) was obtained from a gonad sample in comparison to the highest value found for a single extraction. Astaxanthin content was reduced by 8.6% in carotenoid extract preservation assay, i.e., -18 °C, 26 days incubation, under N2 atmosphere.

Cell cultures of Mandevilla velutina have proved to be an interesting production system for biomass and secondary metabolites able to inhibit the hypotensive activity of bradykinin, a nonapeptide generated in plasma during tissue trauma. The crude ethyl acetate extract of cultured cells contains about 31- to 79-fold more potent anti-bradykinin compounds (e.g., velutinol A) than that obtained with equivalent extracts of tubers. Somaclonal variation may be an explanation for the wide range of inhibitor activity found in the cell cultures. The heterogeneity concerning morphology, differentiation, carbon dissimilation, and velutinol A production in M. velutina cell cultures is reported. Cell cultures showed an asynchronous growth and cells in distinct developmental stages. Meristematic cells were found as the major type, with several morphological variations. Cell aggregates consisting only of meristematic cells, differentiated cells containing specialized cell structures such as functional chloroplasts (cytodifferentiation) and cells with embryogenetic characteristics were observed. The time course for sucrose metabolism indicated cell populations with significant differences in growth and metabolic rates, with the highest biomass-producing cell line showing a cell cycle 60% shorter and a metabolic rate 33.6% higher than the control (F2 cell population). MALDI-TOF mass spectrometric analysis of velutinol A in selected cell lines demonstrated the existence of velutinol A producing and nonproducing somaclones. These results point to a high genetic heterogeneity in general and also in terms of secondary metabolite content.