IQ - Artigos publicados em periódicos

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Fully 3D printing of carbon black-thermoplastic hybrid materials and fast activation for development of highly stable electrochemical sensors
(2021-12) Silva Neto, Habdias de Araujo; Santhiago, Murilo; Duarte, Lucas da Costa; Coltro, Wendell Karlos Tomazelli
3D printing technologies have emerged as powerful tools for the development of electrochemical sensors. However, pre-treatment methods are often required to improve electrochemical properties of 3D printed sensing surface to enable higher electroanalytical performance. Herein, we report a toxic-free method for rapid activation of 3D printed electrochemical sensors. The proposed pre-treatment involves a combination of photochemical and electrochemical oxidation processes to degrade the excess of binder material impregnated on the cell surface. This strategy is simple, fast and exposes the carbon black nanoparticles to facilitate the faradaic reactions. The reported method ensured long-term stability (~2 months) and high heterogeneous rate constants (1.2 ± 0.3 × 10−3 cm s−1). In addition, peak currents were remarkably increased up to 353 ± 13%, clearly highlighting the potential use these 3D electrodes for electroanalytical applications. The treated electrode offered low detection limits (at µmol L−1 levels) for different analytes including metals like Cd(II) (0.009) and Pb(II) (0.006), midazolam maleate (0.54) and uric acid (0.71). Based on the achieved results, the activated, stable, and fully 3D printed electrochemical cell is very promising towards a plethora of high-performance electroanalytical applications.
O não silenciamento do acidente com o Césio 137 - a história recontada pelo olhar freireano
(2022-04-14) Nunes, Luclecia Dias; Mesquita, Nyuara Araújo da Silva
Radioactivity was discovered in the 19th century by Becquerel, Marie and Pierre Curie, was seen with enthusiasm by everyone and radioactive materials started to be used for the most diverse purposes. One of the areas of great application of radioisotopes is medicine, both in diagnosis and in the treatment of cancer. Cesium 137, is one of the radioisotopes that was used in radiotherapy equipment and later would become the material cause of the radiological accident that occurred in Goiânia in 1987, when collectors of recycled materials found an abandoned radiotherapy device, and saw the opportunity to earn money by selling the lead contained in the equipment. In this way, this article sought to (re)do a reading of this accident from the Freirean perspective, seeking to understand the social relations that emerged in the context of the actions imbricated in the history of the accident and its consequences. We understand that this accident could have been avoided if those involved had basic knowledge about symbols related to the scientific context and specifically to radioactivity, which highlights the importance of attending a school and the development of an education capable of providing students with the appropriate of scientific knowledge through scientific literacy.
Plug-and-play assembly of paper-based colorimetric and electrochemical devices for multiplexed detection of metals
(2021) Silva Neto, Habdias de Araujo; Cardoso, Thiago Miguel Garcia; McMahon, Catherine J.; Sgobbi, Lívia Flório; Henry, Charles S.; Coltro, Wendell Karlos Tomazelli
Heavy metals are the main pollutants present in aquatic environments and their presence in human organisms can lead to many different diseases. While many methods exist for analysis, colorimetric and electrochemistry are particularly attractive for on-site analysis and their integration on a single platform can improve multiplexed metals analysis. This report describes for the first time a “plug-and-play” (PnP) assembly for coupling a microfluidic paper-based device (μPAD) and a screen-printed electrochemical paper-based device (ePAD) using a vertical and reversible foldable mechanism for multiplexed detection of Fe, Ni, Cu, Zn, Cd and Pb in river water samples. The integration strategy was based on a reversible assembly, allowing the insertion of a pretreatment zone to minimize potential chemical interfering agents and providing a better control of the aspirated sample volume as well as to a lower sample evaporation rate. In comparison with lateral flow and electrochemical assays performed using independent devices, the integrated prototype proved that the reversible coupling mechanism does not interfere on the analytical performance (95% confidence interval). The limit of detection (LOD) values calculated for metals determined varied from 0.1 to 0.3 mg L−1 (colorimetric) and from 0.9 to 10.5 μg L−1 (electrochemical). When compared to other integrated devices based on horizontal designs, the use of a foldable coupling mechanism offered linear response in a lower concentration range and better LOD values for Fe, Ni and Cu. The proposed method successfully measured heavy metals in river water samples with concentrations ranging from 16 to 786 μg L−1, with recovery studies ranging from 76 to 121%. The new method also showed good correlation with conventional atomic absorption spectroscopic methods (95% significance level). Thus, the integration of μPADs and ePADs by a vertical folding mechanism was efficient for multiplexed heavy metal analysis and could be exploited for environmental monitoring.
Estudo morfo-anatômico de Hortia oreadica e análise da composição química dos óleos essenciais das folhas, flores e frutos
(2020-08) Santos, Danillo Luiz dos; Ferreira, Heleno Dias; Paula, José Realino de; Sá, Stone de; Ferri, Pedro Henrique; Fiuza, Tatiana de Sousa
Hortia oreadica (Rutaceae), known as "quina-do-campo" and "para-tudo", is popularly used as stimulant and stomachic. The aims of this study was to perform: morphological description and the study of the behavior of individuals of H. oreadica in relation to seasonal variations; anatomical study of the leaves and young stems; phytochemical screening of the powdered leaves; identify the components of the essential oil from inflorescences, leaves and fruits. The morphological and anatomical studies of the plant leaves and young stem were performed according to conventional techniques of plant anatomy. The essential oils were obtained by hydrodistillation in a Clevenger apparatus and analyzed by GC/MS. It was observed that H. oreadica is a shrub with simple and alternate sheets. Leaf blade glabrous on both sides with translucent points. Inflorescence corymb of dicásio, with about 580 flowers; thick branches. Flower with color ranging from pink to vinaceous and copious nectar. Green fruit, capsular and black seeds. Anatomically it was verified secretory cavities, prismatic crystals, and predominantly anomocytic stomata. The major components of the essential oil from the leaves, flowers and fruits were: amorpha-4,7(11)-diene and bicyclogermacrene. The morphological study of H. oreadica contributed to understanding the behavior of adult’s plants in relation to seasonal variation. Anatomical analysis of the leaves and young stems provided parameters for the correct identification of this species. This work presents the chemical composition of the essential oils from leaves, flowers and fruits of H. oreadica collected in Pirenópolis (Goiás).
Earwax: a clue to discover fluoroacetate intoxication in cattle
(2017) Shokry, Engy Shokry Abdel Samie; Santos, Fabrício Carrião dos; Cunha, Paulo Henrique Jorge da; Fioravanti, Maria Clorinda Soares; Noronha Filho, Antônio Dionísio Feitosa; Pereira, Naiara Zedes; Antoniosi Filho, Nelson Roberto
An innovative method was developed to detect fluoroacetate poisoning in cattle by headspace/gas chromatographic analysis of earwax samples of intoxicated cattle. Samples were collected from 2 groups of cattle subjected to induced fluoroacetate intoxication, each group receiving a different dose of acetamide (antidote). Monofluoroacetic acid was detected in samples of intoxicated cattle in concentrations inversely proportional to the dose of acetamide. Thus, earwax analysis represents a successful approach for detection and monitoring of fluoroacetate poisoning.
Enzymatic electroanalytical biosensor based on Maramiellus colocasiae fungus for detection of phytomarkers in infusions and green tea kombucha
(2021) Batista, Erica Aparecida; Silva, Giovanna Nascimento de Mello e; Sgobbi, Lívia Flório; Machado, Fabio Bahls; Macêdo, Isaac Yves Lopes de; Gonçalves, Emily Kussmaul; Oliveira Neto, Jerônimo Raimundo de; Scalize, Paulo Sergio; Gil, Eric de Souza
In this work, we developed an enzymatic voltammetric biosensor for the determination of catechin and gallic acid in green tea and kombucha samples. The differential pulse voltammetry (DPV) methodology was optimized regarding the amount of crude enzyme extract, incubation time in the presence of the substrates, optimal pH, reuse of the biosensor, and storage time. Samples of green tea and kombucha were purchased in local markets in the city of Goiânia-GO, Brazil. High performance liquid chromatography (HPLC) and Folin-Ciocalteu spectrophotometric techniques were performed for the comparison of the analytical methods employed. In addition, two calibration curves were made, one for catechin with a linear range from 1 to 60 µM (I = −0.152 * (catechin) − 1.846), with a detection limit of 0.12 µM and a quantification limit of 0.38 µM and one for gallic acid with a linear range from 3 to 60 µM (I = −0.0415 * (gallic acid) − 0.0572), with a detection limit of 0.14 µM and a quantification limit of 0.42 µM. The proposed biosensor was efficient in the determination of phenolic compounds in green tea.
Functionalized polyacrylamide as an acetylcholinesterase-inspired biomimetic device for electrochemical sensing of organophosphorus pesticides
(2018) Sgobbi, Lívia Flório; Machado, Sergio Antonio Spinola
A plethora of publications has continuously reported electrochemical biosensors for detection of pesticides. However, those devices rarely accomplish commercial application due to technical issues associated with the lack of stability and high cost of the biological recognition element (enzyme). Alternatively, the biomimetic catalysts have arisen as a candidate for application in electrochemical biosensors to overcome the enzymatic drawbacks, combining low cost scalable materials with superior stability. Herein, for the first time, we propose a biomimetic biosensor for organophosphorus pesticide detection employing a functionalized polyacrylamide, polyhydroxamicalkanoate (PHA), which mimics the performance of the acetylcholinesterase (AChE) enzyme. The PHA bears functional groups inserted along its backbone chain working as active sites. Thereby, PHA was immobilized on screen printed electrodes (SPE) through a blend formation with poly(ethylene glycol) methyl ether (mPEG) to prevent its leaching out from the surface. Under optimum conditions, the biomimetic sensor was employed for the amperometric detection of paraoxon-ethyl, fenitrothion and chlorpyrifos ranging from 1.0 and 10.0 μmol L−1 with a limit of detection of 0.36 μmol L−1, 0.61 μmol L−1, and 0.83 μmol L−1, respectively. Typical AChE-based interfering species did not affect the PHA performance, which endorsed its superior behavior. The proposed biomimetic biosensor, denoted as SPE/PHA/mPEG, represents a significant advance in the field, offering a new path for low cost devices by means of an artificial enzyme, simple configuration and superior stability. Moreover, the biosensor performance can be further improved by modifying the electrode surface to enhance electronic transfer rate.
Occupational stress monitoring using biomarkers and smartwatches: a systematic review
(2022) Morales, Analúcia Schiaffino; Barbosa, Maria Lúcia Kroeff; Morás, Laura Derengoski; Cazella, Sílvio César; Sgobbi, Lívia Flório; Sene Junior, Iwens Gervasio; Marques, Gonçalo
This article presents a systematic review of the literature concerning scientific publications on wrist wearables that can help to identify stress levels. The study is part of a research project aimed at modeling a stress surveillance system and providing coping recommendations. The investigation followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. In total, 38 articles were selected for full reading, and 10 articles were selected owing to their alignment with the study proposal. The types of technologies used in the research stand out amongst our main results after analyzing the articles. It is noteworthy that stress assessments are still based on standardized questionnaires, completed by the participants. The main biomarkers collected by the devices used in the selected works included: heart rate variation, cortisol analysis, skin conductance, body temperature, and blood volume at the wrist. This study concludes that developing a wrist wearable for stress identification using physiological and chemical sensors is challenging but possible and applicable.
Glucose sensing via a green and low-cost platform from electrospun poly (vinyl alcohol)/graphene quantum dots fibers
(2019) Cabral, Tayná Santos; Sgobbi, Lívia Flório; Delezuk, Jorge Augusto de Moura; Pessoa, Rodrigo Savio; Lobo, Anderson de Oliveira; Rodrigues, Bruno Vinícius Manzolli
Herein, a green and low-cost approach is proposed for the production of fluorescent fibers from the electrospinning of poly (vinyl alcohol) and graphene quantum dots (citric acid based) for biosensing purposes. This hybrid material was applied as a substrate for enzyme immobilization aiming at glucose sensing. This sensor showed a high effectivity for glucose detection in the range of 1 mM to 10 mM, with a corresponding detection limit of 12 µM. These results widen the perspectives of application of this material in the sensing field, via a simple strategy using a water-soluble polymer and a naturally occurring component from citrus fruits.
Biomimetic electrochemical sensors: new horizons and challenges in biosensing applications
(2021) Romanholo, Pedro Victor Valadares; Razzino, Cláudia do Amaral; Pereira, Paulo Augusto Raymundo; Prado, Thiago Martimiano do; Machado, Sergio Antonio Spinola; Sgobbi, Lívia Flório
The urge to meet the ever-growing needs of sensing technology has spurred research to look for new alternatives to traditional analytical methods. In this scenario, the glucometer is the flagship of commercial electrochemical sensing platforms, combining selectivity, reliability and portability. However, other types of enzyme-based biosensors seldom achieve the market, in spite of the large and increasing number of publications. The reasons behind their commercial limitations concern enzyme denaturation, and the high costs associated with procedures for their extraction and purification. In this sense, biomimetic materials that seek to imitate the desired properties of natural enzymes and biological systems have come out as an appealing path for robust and sensitive electrochemical biosensors. We herein portray the historical background of these biomimicking materials, covering from their beginnings until the most impactful applications in the field of electrochemical sensing platforms. Throughout the discussion, we present and critically appraise the major benefits and the most significant drawbacks offered by the bioinspired systems categorized as Nanozymes, Synzymes, Molecularly Imprinted Polymers (MIPs), Nanochannels, and Metal Complexes. Innovative strategies of fabrication and challenging applications are further reviewed and evaluated. In the end, we ponder over the prospects of this emerging field, assessing the most critical issues that shall be faced in the coming decade.
Voltammetric glassy carbon sensor approach for the extended stability studies of doxorubicin in lyophilized dosage form
(2022-07-01) Cunha, Carlos Eduardo Peixoto da; Rodrigues, Edson Silvio Batista; Oliveira Neto, Jerônimo Raimundo de; Somerset, Vernon Sydwill; Taveira, Stephânia Fleury; Sgobbi, Lívia Flório; Gil, Eric de Souza
Doxorubicin (DOX) is an anthracycline antibiotic that is widely used in the clinical treatment of cancer patients. DOX has a high market value. Electroanalytical methods for DOX analysis are an alternative and promising approach compared to chromatographic techniques. In this context, electroanalysis provides a low-cost method for determining drugs such as DOX lyophilized powder for the injection. Differential pulse voltammetry with a glassy carbon electrode was used. DOX stability after reconstitution was performed, and the correct time for safe administration to patients in hospitals was determined. The electroanalytical method showed a limit of detection of 0.54 µmol L‑1 and limit of quantification of 1.83 µmol L–1, which is enough for the application in quality control of DOX. The high-performance liquid chromatography analysis was also applied in pharmaceutical samples containing DOX to compare with the proposed method, showing that the obtained results are relatively similar for both methods. Therefore, the electroanalytical approach shows the viability of an attractive alternative technique for applying this sensor for drug quality control.
A simple and green method for the production of nanostructured materials from poly(vinyl alcohol)/graphene quantum dots
(2018) Rodrigues, Bruno Vinícius Manzolli; Cabral, Tayná Santos; Sgobbi, Lívia Flório; Delezuk, Jorge Augusto de Moura; Pessoa, Rodrigo Savio; Triboni, Eduardo Rezende; Moraes, Thaisa Brandão Ferreira de; Lobo, Anderson de Oliveira
Herein, a simple, low-cost and fast approach was proposed to produce fluorescent fibers from the electrospinning of poly (vinyl alcohol)/water-soluble graphene quantum dots (GQDs). Initially, the preparation of GQDs was explored via an easy bottom-up method based on the incomplete carbonization of citric acid under different times (30, 45 and 60 min). Next, fluorescent fibrous mats were prepared from the electrospinning of PVA solutions with different contents of GQDs. These materials were further characterized via several techniques, including High-Resolution Transmission Electronic Microscopy (HRTEM), UV–vis and fluorescence spectroscopies, Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The GQDs presented a strong blue photoluminescence under UV light exposure. Among the investigated carbonization times, 45 min led to GQDs with the highest fluorescence intensity (regardless the pH) and fluorescence quantum yield (10.5%). HRTEM analysis showed that this carbonization time led to GQDs with uniform and homogeneous dimensions, with an average diameter of 2.5 ± 0.2 nm. After electrospinning, HRTEM revealed a homogeneous distribution of GQDs into the polymeric ultrathin fibers, while increasing the GQDs content in the PVA matrix led to a clear increase in the fluorescence intensity. Interestingly, as the GQDs content increased, a slight red-shift was observed for the maximum of emission, which may be related to light re-adsorption or even as result of Föster Resonance Energy Transfer. This set of results widens the perspectives of application of this low-cost substrate in many fields, via a simple approach using a water-soluble polymer and a naturally occurring component from citrus fruits.
Bacterial cellulose-based electrochemical sensing platform: a smart material for miniaturized biosensors
(2020) Gomes, Nathalia Oezau; Carrilho, Emanuel; Machado, Sergio Antonio Spinola; Sgobbi, Lívia Flório
Substantial scientific and technological progresses have prompted the development of point of care testing for health monitoring. However, most of the commercially available devices rely on invasive analysis based on blood samples. In this scenario, wearable sensing platforms have arisen as a promising non-invasive analytical tool. To fully exploit their capabilities, challenges must be overcome regarding good mechanical flexibility of wet devices upon bending and stretching movements, preserving the device integrity over the skin. Herein, we successfully developed an electrochemical biosensor made on bacterial cellulose (BC) substrate, and as a proof of concept, we demonstrated the detection of lactate in artificial sweat by immobilizing lactate oxidase (LOx) directly on BC substrate instead of on electrode surface. BC is a smart biocompatible material used as wound dressing with remarkable mechanical properties due to its nanometric fibers. The significant advantages of the proposed substrate for biosensors include biocompatibility, mass production of screen-printed electrodes (SPE) on BC, and superior mechanical resistance in comparison with vegetal cellulose even when hydrated. The electrochemical sensing platform was designed using a carbon-based working electrode modified with Prussian blue nanocubes, an efficient electron mediator for hydrogen peroxide, and LOx immobilized directly onto BC surface. The fabricated biosensor exhibited excellent amperometric response to lactate in the range of 1.0–24.0 mmol L−1 in artificial sweat with detection limit of 1.31 mmol L−1, and quantification limit of 4.38 mmol L−1. The proposed sensing platform based on BC substrate paves the way to wearable devices with superior mechanical resistance and biocompatibility.
Do enzymatic or non-enzymatic pathways drive the postharvest darkening phenomenon in carioca bean tegument?
(2016) Siqueira, Beatriz dos Santos; Bassinello, Priscila Zaczuk; Santos, Suzana da Costa; Malgaresi, Gabriel; Ferri, Pedro Henrique; García Rodríguez, Armando; Fernandes, Kátia Flávia
Four genotypes of carioca bean were accelerate aged (40 °C/75% relative humidity) and evaluated to determine if differences in postharvest darkening trait was an enzymatic or non-enzymatic process. Chromaticity a* was the colour parameter with major alterations, and increase in chromaticity b* often masked the reddish of tegument. Peroxidase activity was not detected. Polyphenoloxidase remained active along the storage time, but its activity was higher in the lighter genotypes. Flavonoid, proanthocyanidin and total phenol content were much higher in darker genotypes, although just this last component presented significant alterations. Genotypes showed different susceptibilities to the darkening independent of phenolic content. Results of principal response curves analyse suggested different pathways for the darkening process: darkening in lighter genotypes seem to be mostly due to polyphenoloxidase activity while in dark ones there are the combination of enzymatic and non-enzymatic oxidation.
Chemical composition and seasonality variability of the Spiranthera odoratissima volatile oils leaves
(2018) Souza, Sônia Júlia Oliveira de; Ferri, Pedro Henrique; Fiuza, Tatiana de Sousa; Borges, Leonardo Luiz; Paula, José Realino de
Spiranthera odoratissima A. St.-Hil., Rutaceae, known as “manacá” is a shrub native of the Brazilian Cerrado. Their leaves and roots are popularly used to treat rheumatism, infection and abdominal pain. This study analyzed the chemical composition of volatile oils from leaves of S. odoratissima and verified the seasonal variability of its chemical composition. The volatile oils were obtained by hydrodistillation using a Clevenger type apparatus and analyzed by gas chromatography coupled to mass spectrometry. The main chemical components found in samples of volatile oils were β-caryophyllene, bicyclogermacrene, δ-cadinene, amorphous-4,7(11)-diene, α-epi-muurolol, α-cadinol, α-muurolol and γ-cadinene. The hierarchical clustering identified three groups: the first was characterized by α-epi-muurolol, the second by amorphous-4,7(11)-diene and the third group was characterized by α-muurolol. The discriminant canonical analysis was used to differentiate between clusters on the basis of oil composition. The results suggest that the rainfall presented a relationship with the chemical composition of the volatile oil. This is the first study conducted on the seasonal behavior of the chemical constituents in volatile oil from leaves of S. odoratissima.
Chemical composition of essential oils of leaves, flowers and fruits of Hortia oreadica
(2016) Santos, Danillo Luiz dos; Ferreira, Heleno Dias; Borges, Leonardo Luiz; Paula, José Realino de; Tresvenzol, Leonice Manrique Faustino; Santos, Pierre Alexandre dos; Ferri, Pedro Henrique; Sá, Stone de; Fiuza, Tatiana de Sousa
Hortia oreadica Groppo, Kallunki & Pirani, Rutaceae, known as “para-tudo”, “quina”, and “quina-do-campo”, is used in traditional medicine locally to treat stomach pain and fevers. The aims of this study were: analyze the chemical composition of essential oils from leaves, flowers and fruits of H. oreadica and verify the seasonal variation of the chemical components of essential oils from leaves. The essential oils were obtained by hydrodistillation using a Clevenger type apparatus and analyzed by GC/MS. The major components found in the samples of the essential oils were the amorpha-4,7(11)-diene (29.27% – flowers, 20.26% – fruits, 27.66–37.89% – leaves), bicyclogermacrene (23.28% – flowers, 20.64% – fruits, 14.71% to 31.37% – leaves). This work represents the first study of the chemical composition of essential oils from leaves, flowers and fruits and seasonal variation in the essential oils from leaves of H. oreadica.
Chemical composition and seasonal variability of the essential oils of leaves and morphological analysis of Hyptis carpinifolia
(2016) Sá, Stone de; Fiuza, Tatiana de Sousa; Borges, Leonardo Luiz; Ferreira, Heleno Dias; Tresvenzol, Leonice Manrique Faustino; Ferri, Pedro Henrique; Rezende, Maria Helena; Paula, José Realino de
Hyptis carpinifolia Benth., Lamiaceae, is a species known popularly as “rosmaninho” and “mata-pasto”, and leaves are employed in Brazilian folk medicine to treat colds, flu, and rheumatism. The aim of this study was to perform a morphological description of H. carpinifolia and to evaluate the seasonal chemical variability of the leaf essential oils during 12 months. Macroscopic characterization of H. carpinifolia was carried out with the naked eye and with a stereoscopic microscope. Essential oils were isolated from leaves by hydrodistillation in Clevenger apparatus and analyzed by gas chromatography/mass spectrometry. Major compounds were found to be 1,8-cineole (39.6–61.8%), trans-cadina-1(6),4-diene (2.8–17.5%), β-caryophyllene (4.4–10.0%), prenopsan-8-ol (4.2–9.6%) and β-pinene (2.9–5.3%). Results of essential oils compositions were processed by cluster analysis and principal component analysis. Data showed high variability in the concentration of the components. Besides, there was a seasonal variability of chemical composition, probably related mainly to the rainfall regime.
Unexpected stabilization of α-Ni(OH)2 nanoparticles in GO nanocomposites
(2018) Gonçalves, Josué Martins; Alves, Kamilla Moraes; Gonzalez Huila, Manuel Fernando; Duarte, Alfredo; Martins, Paulo Roberto; Araki, Koiti
Large specific charge capacity Ni(OH)2@GO nanocomposites, able to withstand high current densities and more than 500 redox cycles without significant loss of charge storage capacity, were realized thanks to unexpected stabilization of electrochemically active α-Ni(OH)2 nanoparticles by GO and were characterized by TEM, XRD, FTIR, TXRF, and confocal Raman microscopy. Stable and adherent films with low electric resistance, able to withstand current densities as high as 100 A·g−1, were generated, as demonstrated by CV, EIS, and galvanostatic charge-discharge measurements, showing good perspectives as electrode material for hybrid energy storage devices.
Variability of polyphenols and volatiles during fruit development of three pitanga (Eugenia uniflora L.) biotypes
(2019) Ramalho, Ruver Rodrigues Feitosa; Barbosa, João Marcos Gonçalves; Ferri, Pedro Henrique; Santos, Suzana da Costa
Changes in volatile constituents and phenolic compounds were investigated during fruit development of three pitanga biotypes. Constituents were submitted to multivariate analysis and fruit samples were differentiated by selina-1,3,7(11)-trien-8-one (38.2 ± 2.9%) and its epoxide (26.4 ± 7.2%) for the red-orange biotype; by curzerene (15.04 ± 2.1%) and atractylone (8.47 ± 2.1%) for the red biotype; and by spathulenol (3.7 ± 0.8%) and germacrone (54.7 ± 3.1%) for the purple biotype. Hydrolysable tannins such as mono-O-galloyl-d-glucose, 1,2,6-tri-O-galloyl-β-d-glucose, tellimagrandin II, and eugeniflorin D2 were identified, as well as oenothein B as the major compound (32.43 ± 7.1 mg/g dry fruit). During pitanga's maturation, anthocyanin content increased, while flavonoid and tannin contents decreased. Higher contents of the majority of phenolic compounds occurred in the red-orange biotype. Biosynthesis of phenolic compounds was influenced by biotype and degree of maturation, whereas chemovariation in essential oil constituents was mainly due to biotypes, thus confirming essential oil chemotypes of E. uniflora.
Chemical composition and chemotaxonomy of Nasutitermes spp. defensive secretion from Brazilian Cerrado for the differentiation of species
(2022) Oliveira Neto, Jerônimo Raimundo de; Oliveira, Naiara Raica Lopes de; Cruz, Alessandro de Carvalho; Ferri, Pedro Henrique; Azevedo, Neucírio Ricardo de
Nasutitermes spp. soldier defensive secretion has a toxic and repellent effect against predators. Chemical profile characterization of this secretion is an interesting tool to differentiate similar termite species. This study aimed to determine defensive secretion composition of Nasutitermes spp. soldier and to apply chemotaxonomy tool for the unambiguous species identification. Fifteen volatile compounds were identified by gas chromatography-mass spectrometry. Multivariate analysis classified populations into three groups. Principal component (PCA), axis 1, was able to separate two groups: group I, colonies 1 and 2 (Nasutitermes corniger) and group II, colony 3 (Nasutitermes ephratae). Therefore, determination of defensive chemical secretion profile proved to be very useful in termite chemotaxonomy, since it was able to differentiate morphologically similar specimens.

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