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1.
J Mol Graph Model ; 128: 108716, 2024 05.
Artigo em Inglês | MEDLINE | ID: mdl-38277856

RESUMO

Cassava extracts containing cyanogenic compounds demonstrate anticancer properties. The cyanogenic glucoside linamarin found abundantly in cassava can release hydrogen cyanide (HCN) upon hydrolysis, a potent cytotoxin. However, linamarin's hydrolysis mechanism by human enzymes is poorly delineated and constitutes a bottleneck for therapeutic development. This study aimed to investigate linamarin's hydrolysis mechanism by human ß-glucosidase and identify structural derivatives with enhanced hydrolytic potential using density functional theory calculations. Results revealed α-anomeric derivatives as promising, with leaving group ability and steric bulk strongly governing hydrolysability. We identified several linamarin analogs with predicted rapid hydrolysis kinetics that may enable swift cytotoxic HCN release against cancer cells. This investigation enriches understanding of cyanogenic glycoside reactivity to facilitate their development as targeted antineoplastic agents. The identified derivatives set the groundwork for experimental evaluation of enhanced linamarin-inspired compounds as innovative cancer therapeutics.


Assuntos
Manihot , Neoplasias , Humanos , Hidrólise , Nitrilas , Cianeto de Hidrogênio , Glicosídeos/química , Glicosídeos/toxicidade , Manihot/química
2.
Toxicon ; 232: 107200, 2023 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-37419285

RESUMO

Several natural compounds reduce tumour cell growth and metastasis by inducing programmed cell death. Cassava (Manihot esculenta Crantz) contains cyanogenic glycosides such as, linamarin and lotaustralin, can be enzymatically cleaved by linamarase to release hydrogen cyanide (HCN), which can have therapeutic benefits against hypertension, asthma, and cancer. We have developed a technology for isolating bio-active principles from cassava leaves.The present study is designed to analyze the cytotoxic effect of cassava cyanide extract (CCE) against human glioblastoma cells (LN229). The treatment of CCE demonstrated a dose dependent toxicity on glioblastoma cells. At higher concentration tested, the CCE (400 µg/mL) was found to be cytotoxic, reducing the cell viability to 14.07 ± 2.15% by negatively influencing the mitochondrial activity, and lysosomal and cytoskeletal integrity. Coomassie's brilliant blue staining confirmed cells' morphological aberration after 24 h of treatment with CCE. Moreover, DCFH-DA assay and Griess reagent showed an increase in ROS but a decrease in RNS production at a concentration of CCE. Flow cytometry analysis revealed that CCE interfered with G0/G1, S, and G2/M stages of the cell cycle of glioblastoma, and Annexin/PI staining indicated a dose-dependent increase in cell death, confirming the toxic nature of CCE on LN229 cells. These findings suggest that cassava cyanide extract has potential as an antineoplastic agent against glioblastoma cells, which is an aggressive and difficult-to-treat type of brain cancer. However, it is important to note that the study was conducted in vitro, and further research is necessary to assess the safety and efficacy of CCE in vivo. Additionally, it is essential to establish the optimal dose and potential side effects before considering its use as a therapeutic agent.


Assuntos
Antineoplásicos , Glioblastoma , Manihot , Humanos , Cianetos/análise , Cianetos/metabolismo , Manihot/toxicidade , Manihot/metabolismo , Glioblastoma/tratamento farmacológico , Antineoplásicos/farmacologia , Extratos Vegetais/farmacologia
3.
Foods ; 11(10)2022 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-35626954

RESUMO

In 2009, Food Standards Australia New Zealand set a total cyanide content limit of 10 ppm for ready-to-eat cassava products to address food safety concerns about cyanogenic glucosides in cassava. This study surveys a range of cassava food products available in Melbourne, Australia, ten years after the implementation of these regulations. Of all the products tested, the mean cyanide content was greatest in ready-to-eat cassava chips (48.4 ppm), although imported ready-to-eat products had a higher mean cyanide content (95.9 ppm) than those manufactured in Australia (1.0 ppm). Cyanide was detected in frozen cassava products (grated mean = 12.9 ppm; whole root mean = 19.8 ppm), but was significantly reduced through processing according to packet instructions in both product types. Three methods were used to quantify total cyanide content: the evolved cyanide method, the picrate absorbance method and the picrate chart method, with satisfactory agreement between methods. The picrate absorbance and chart methods reported mean cyanide contents 13.7 ppm and 23.1 ppm higher, respectively, than the evolved cyanide method. Our results reaffirm the need for the ongoing testing of cassava food products, especially ready-to-eat products whose cyanide content will not be reduced before consumption.

4.
J Exp Bot ; 73(7): 1853-1867, 2022 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-34905020

RESUMO

While cassava is one of the most important staple crops worldwide, it has received the least investment per capita consumption of any of the major global crops. This is in part due to cassava being a crop of subsistence farmers that is grown in countries with limited resources for crop improvement. While its starchy roots are rich in calories, they are poor in protein and other essential nutrients. In addition, they contain potentially toxic levels of cyanogenic glycosides which must be reduced to safe levels before consumption. Furthermore, cyanogens compromise the shelf life of harvested roots due to cyanide-induced inhibition of mitochondrial respiration, and associated production of reactive oxygen species that accelerate root deterioration. Over the past two decades, the genetic, biochemical, and developmental factors that control cyanogen synthesis, transport, storage, and turnover have largely been elucidated. It is now apparent that cyanogens contribute substantially to whole-plant nitrogen metabolism and protein synthesis in roots. The essential role of cyanogens in root nitrogen metabolism, however, has confounded efforts to create acyanogenic varieties. This review proposes alternative molecular approaches that integrate accelerated cyanogen turnover with nitrogen reassimilation into root protein that may offer a solution to creating a safer, more nutritious cassava crop.


Assuntos
Manihot , Cianetos/metabolismo , Manihot/genética , Manihot/metabolismo , Nitrilas/análise , Nitrilas/metabolismo , Raízes de Plantas/metabolismo
5.
J Biomol Struct Dyn ; 40(19): 9270-9278, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34018467

RESUMO

Cassava linamarase is a hydrolyzing enzyme that belongs to a glycoside hydrolase family 1 (GH1). It is responsible for breaking down linamarin to toxic cyanide. The enzyme provides a defensive mechanism for plants against herbivores and has various applications in many fields. Understanding the structure of linamarase at the molecular level is a key to avail its reaction mechanism. In this study, the three-dimensional (3D) structure of linamarase was built for the first time using homology modelling and used to study its interaction with linamarin. Molecular docking calculations established the binding and orientation nature of linamarin, while molecular dynamics (MD) simulation established protein-ligand complexes' stability. Binding-free energy based on MM/PBSA was further used to rescore the docking results. An ensemble structure was found to be relatively stable compared to the modelled structure. This study sheds light on the exploration of linamarase towards understanding its reaction mechanisms.Communicated by Ramaswamy H. Sarma.


Assuntos
Manihot , Manihot/química , Manihot/metabolismo , Simulação de Acoplamento Molecular , Nitrilas , Complexos Multienzimáticos/metabolismo , Simulação de Dinâmica Molecular
6.
Nat Prod Res ; 35(21): 4169-4172, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32223339

RESUMO

During the last three decades, studies of linamarin extracted from cassava have received increased attention due to the presence of high cyanogenic compounds in these extracts. The methods that are utilized to isolate linamarin are either tedious or use acidic conditions resulting in poor yields. In this study, a novel cryocooled method of extraction has been developed to isolate linamarin from Cassava root peel. Approximately 18 g of linamarin was isolated from 1 kg of fresh Cassava root peel, which is the highest amount reported to date. Linamarin was fully characterized using NMR, IR and LCMS. The anti-cancer properties of pure linamarin and Cassava crude extract were evaluated by a comprehensive cytotoxic assay, using MCF-7, HepG2, NCI H-292, AN3CA and MRC-5 cell lines. The crude extract showed higher cytotoxicity compared to pure linamarin. The results of the biological evaluation are comparable to other reported studies in the literature.


Assuntos
Manihot , Nitrilas , Verduras
7.
Nat Prod Res ; 35(23): 5339-5343, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32336151

RESUMO

Cnidoscolus quercifolius is an Euphorbiaceae endemic to the northeast region of Brazil, which is used in folk medicine as anti-inflammatory, analgesic and antibiotic. An ethanolic extract was prepared with the leaves from C. quercifolius, and also partitioned and chromatographed leading to the isolation of cyanoglucoside linamarin (1), cinnamic acid (2), as well as a mixture of steroids and terpenoids (3-6). Structural elucidation of the compounds was done by IR, MS and NMR analysis. For the cyanoglucoside (1) were also evaluated its antimicrobial and antileishmanial viabilities by plaque microdilution and MTT test, respectively. Both tests showed from moderate to zero activity against the organisms evaluated. In addition, the antiproliferative activity of compounds 1 and 5-6 were tested against tumor cells, which did not show statistically significant growth inhibition 50% (GI50). The obtained results suggested that further pharmacological studies should prove the folk medicinal uses.


Assuntos
Anti-Infecciosos , Euphorbiaceae , Antibacterianos/farmacologia , Anti-Infecciosos/farmacologia , Medicina Tradicional , Extratos Vegetais/farmacologia , Folhas de Planta
8.
Metabolites ; 10(7)2020 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-32674262

RESUMO

Cyanogenic glucosides (CG), the monoglycosides linamarin and lotaustralin, as well as the diglucosides linustatin and neolinustatin, have been identified in flax. The roles of CG and hydrogen cyanide (HCN), specifically the product of their breakdown, differ and are understood only to a certain extent. HCN is toxic to aerobic organisms as a respiratory inhibitor and to enzymes containing heavy metals. On the other hand, CG and HCN are important factors in the plant defense system against herbivores, insects and pathogens. In this study, fluctuations in CG levels during flax growth and development (using UPLC) and the expression of genes encoding key enzymes for their metabolism (valine N-monooxygenase, linamarase, cyanoalanine nitrilase and cyanoalanine synthase) using RT-PCR were analyzed. Linola cultivar and transgenic plants characterized by increased levels of sulfur amino acids were analyzed. This enabled the demonstration of a significant relationship between the cyanide detoxification process and general metabolism. Cyanogenic glucosides are used as nitrogen-containing precursors for the synthesis of amino acids, proteins and amines. Therefore, they not only perform protective functions against herbivores but are general plant growth regulators, especially since changes in their level have been shown to be strongly correlated with significant stages of plant development.

9.
Environ Sci Pollut Res Int ; 27(15): 18498-18509, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32193739

RESUMO

The potential of cassava (Manihot esculenta Crantz.) for simultaneous Hg and Au phytoextraction was explored by investigating Hg and Au localization in cassava roots through Micro-Proton Induced X-Ray Emission, High-Resolution Transmission Electron Microscopy (HR-TEM) and X-Ray Diffractometry (XRD). The effect of Hg and Au in the cyanogenic glucoside linamarin distribution was also investigated using Matrix Assisted Laser Desorption Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (MALDI-FT-ICR-MS) imaging. Hg was located mainly in the root vascular bundle of plants grown in 50 or 100 µmol L-1 Hg solutions. Au was localized in the epidermis and cortex or in the epidermis and endodermis for 50 and 100 µmol L-1 Au solutions, respectively. For 50 µmol L-1 solutions of both Hg and Au, the two metals were co-localized in the epidermis. When the Hg concentrations were increased to 100 µmol L-1, Au was still localized to a considerable extent in the epidermis while Hg was located in all root parts. HR-TEM and XRD revealed that Au nanoparticles were formed in cassava roots. MALDI-FT-ICR-MS imaging showed linamarin distribution in the roots of control and plants and metal-exposed plants thus suggesting that linamarin might be involved in Hg and Au uptake and distribution.


Assuntos
Manihot , Mercúrio , Nanopartículas Metálicas , Glicosídeos , Ouro , Raízes de Plantas
10.
Metab Brain Dis ; 35(1): 65-74, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31802307

RESUMO

Cassava (Manihot esculenta Crantz) is a tropical plant that is used as fresh food, processed food, or raw material for the preparation of flours with high nutritional value. However, cassava contains cyanogenic glycosides, such as linamarin and lotaustralin, that can trigger severe toxic effects and some neurological disorders, including motor impairment, cognitive deterioration, and symptoms that characterize tropical ataxic neuropathy and spastic epidemic paraparesis (Konzo). These alterations that are associated with the consumption of cassava or its derivatives have been reported in both humans and experimental animals. The present review discusses and integrates preclinical and clinical evidence that indicates the toxic and neurological effects of cassava and its derivatives by affecting metabolic processes and the central nervous system. An exhaustive review of the literature was performed using specialized databases that focused on the toxic and neurological effects of the consumption of cassava and its derivatives. We sought to provide structured information that will contribute to understanding the undesirable effects of some foods and preventing health problems in vulnerable populations who consume these vegetables. Cassava contains cyanogenic glycosides that contribute to the development of neurological disorders when they are ingested inappropriately or for prolonged periods of time. Such high consumption can affect neurochemical and neurophysiological processes in particular brain structures and affect peripheral metabolic processes that impact wellness. Although some vegetables have high nutritional value and ameliorate food deficits in vulnerable populations, they can also predispose individuals to the development of neurological diseases.


Assuntos
Ensaios Clínicos como Assunto/métodos , Manihot/toxicidade , Doenças do Sistema Nervoso/induzido quimicamente , Doenças do Sistema Nervoso/metabolismo , Síndromes Neurotóxicas/metabolismo , Neurotoxinas/toxicidade , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/patologia , Avaliação Pré-Clínica de Medicamentos/métodos , Humanos , Doenças do Sistema Nervoso/patologia , Síndromes Neurotóxicas/patologia , Neurotoxinas/administração & dosagem , Neurotoxinas/isolamento & purificação
11.
J Mol Model ; 25(9): 295, 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31478108

RESUMO

Cyanogenesis is an enzyme-promoted cleavage of ß-cyanoglucosides; the release of hydrogen cyanide is believed to produce food poisoning by consumption of certain crops as Cassava (Manihot esculenta Crantz). The production of hydrogen cyanide by some disruption of the plant wall is related to the content of two ß-cyanoglucosides (linamarin and lotaustralin) which are stored within the tuber. Some features about the mechanistic bases of these transformations have been published; nevertheless, there are still questions about the exact mechanism, such as the feasibility of a difference in the kinetics of cyanogenesis between both cyanoglucosides. In this work, we have performed a theoretical analysis using DFT and QTAIM theoretical frameworks to propose a feasible mechanism of the observed first step of the enzyme-catalyzed rupture of these glucosides; our results led us to explain the observed difference between linamarin and lotaustralin. Meanwhile, DFT studies suggest that there are no differences between local reactivity indexes of both glucosides; QTAIM topological analysis suggests two important intramolecular interactions which we found to fix the glucoside in such a way that suggests the linamarin as a more reactive system towards a nucleophilic attack, thus explaining the readiness to liberate hydrogen cyanide.


Assuntos
Glucosídeos/química , Cianeto de Hidrogênio/química , Manihot/química , Nitrilas/química , Biocatálise , Biotransformação , Glucosídeos/metabolismo , Cianeto de Hidrogênio/metabolismo , Cinética , Manihot/enzimologia , Estrutura Molecular , Nitrilas/metabolismo , Tubérculos/química , Tubérculos/enzimologia , Teoria Quântica , Termodinâmica
12.
Genes Nutr ; 14: 9, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30984301

RESUMO

Tubers are important crops as well as staple foods in human nutrition. Among tubers, the potato in particular has been investigated for its health effects. However, except for its contribution to energy and effects related to resistant starch, the role of potatoes and other tubers in human health is still debated. In order to establish firm evidence for the health effects of dietary tubers and processed tuber products, it is essential to assess total intake accurately. The dietary assessment in most studies relies mainly on self-reporting and may give imprecise quantitative information on dietary intakes. Biomarkers of food intake (BFIs) are useful objective means to assess intake of specific foods or may be used as an additional measure to calibrate the measurement error in dietary reports. Here, intake biomarkers for common tubers, including potatoes and heated potato products, sweet potato, cassava, yam, and Jerusalem artichoke, are reviewed according to the biomarker of food intake reviews (BFIRev) standardized protocols for review and validation. Candidate BFIs for heated potato product include α-chaconine, α-solanine, and solanidine; less evidence is available to indicate peonidin 3-caffeoylsophoroside-5-glucoside and cyanidin 3-caffeoylsophoroside-5-glucoside as putative biomarkers having high potential specificity for purple sweet potato intake; linamarin may in addition be considered as a putative BFI for cassava. Other tubers also contain toxic glycosides or common contaminants as characteristic components but their putative use as intake biomarkers is not well documented. Alkyl pyrazines, acrylamide, and acrolein are formed during cooking of heated potato products while these have not yet been investigated for other tubers; these markers may not be specific only to heated potato but measurements of these compounds in blood or urine may be combined with more specific markers of the heated products, e.g., with glycoalkaloids to assess heated potato products consumption. Further studies are needed to assess the specificity, robustness, reliability, and analytical performance for the candidate tuber intake biomarkers identified in this review.

13.
Food Chem Toxicol ; 125: 225-232, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30615957

RESUMO

Potential toxicity of cyanogenic glycosides arises from enzymatic degradation to produce hydrogen cyanide. Information on the metabolism of cyanogenic glycosides is available from in vitro, animal and human studies. In the absence of ß-glucosidase enzymes from the source plant material, two processes appear to contribute to the production of cyanide from cyanogenic glycosides; the proportion of the glycoside dose that reaches the large intestine, where most of the bacterial hydrolysis occurs, and the rate of hydrolysis of cyanogenic glycosides to cyanohydrin and cyanide. Some cyanogenic glycosides, such as prunasin, are actively absorbed in the jejunum by utilising the epithelial sodium-dependent monosaccharide transporter (SGLT1). The rate of cyanide production from cyanogenic glycosides due to bacterial ß-glycosidase activity depends on; the sugar moiety in the molecule and the stability of the intermediate cyanohydrin following hydrolysis by bacterial ß-glucosidase. Cyanogenic glycosides with a gentiobiose sugar, amygdalin, linustatin, and neolinustatin, undergo a two stage hydrolysis, with gentiobiose initially being hydrolysed to glucose to form prunasin, linamarin and lotaustralin, respectively. While the overall impact of these metabolic factors is difficult to predict, the toxicity of cyanogenic glycosides will be less than the toxicity suggested by their theoretical hydrocyanic acid equivalents.


Assuntos
Glicosídeos/metabolismo , Nitrilas/metabolismo , Animais , Feminino , Microbioma Gastrointestinal/fisiologia , Trato Gastrointestinal/metabolismo , Trato Gastrointestinal/microbiologia , Glicosídeos/análise , Glicosídeos/química , Glicosídeos/toxicidade , Humanos , Cianeto de Hidrogênio/análise , Cianeto de Hidrogênio/química , Cianeto de Hidrogênio/toxicidade , Hidrólise , Cinética , Masculino , Nitrilas/análise , Nitrilas/química , Nitrilas/toxicidade
14.
Insects ; 9(1)2018 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-29534004

RESUMO

Honeybees (Apis mellifera) pollinate flowers and collect nectar from many important crops. White clover (Trifolium repens) is widely grown as a temperate forage crop, and requires honeybee pollination for seed set. In this study, using a quantitative LC-MS (Liquid Chromatography-Mass Spectrometry) assay, we show that the cyanogenic glucosides linamarin and lotaustralin are present in the leaves, sepals, petals, anthers, and nectar of T. repens. Cyanogenic glucosides are generally thought to be defense compounds, releasing toxic hydrogen cyanide upon degradation. However, increasing evidence indicates that plant secondary metabolites found in nectar may protect pollinators from disease or predators. In a laboratory survival study with chronic feeding of secondary metabolites, we show that honeybees can ingest the cyanogenic glucosides linamarin and amygdalin at naturally occurring concentrations with no ill effects, even though they have enzyme activity towards degradation of cyanogenic glucosides. This suggests that honeybees can ingest and tolerate cyanogenic glucosides from flower nectar. Honeybees retain only a portion of ingested cyanogenic glucosides. Whether they detoxify the rest using rhodanese or deposit them in the hive should be the focus of further research.

15.
Eur J Nutr Food Saf ; 8(4): 215-224, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-33313363

RESUMO

AIMS: This study was conducted to detect the presence of cyanide in popular fruit and vegetable smoothies and juices marketed as raw and natural. STUDY DESIGN: Eleven (11) popular varieties of drinks were analyzed for total cyanide (TCN). Drinks contained raw vegetables and fruits, flax seeds, whole apples with seeds, raw almond milk, and pasteurized almond milk as ingredients. PLACE AND STUDY DURATION: Samples were collected from health food eateries located within Las Vegas, Nevada (USA) during the summer of 2017. METHODOLOGY: Fifty milliliters (mL) of a homogenized smoothie and juice drink and 1 gram of flax seeds were subjected to the above-referenced methods for sample preparation per USEPA Methods 9012B (digestion) followed by USEPA method 9014 (colorimetry). RESULTS: The highest TCN was detected in drinks containing raw flax seed followed by unpasteurized raw almond milk, then fresh whole apple juice. No TCN was observed in drinks that contained none of the above mentioned items (e.g. flax seed, raw almond milk) or those utilizing pasteurized ingredients. CONCLUSION: This study observed that TCN is present in smoothies and juices containing raw flax seeds, fresh whole apples, and/or unpasteurized almond milk. Concentrations were detected as high as 341 µg L-1 in commercially available smoothies containing vegetables, raw flax seeds, almond milk and fruits. Smoothies with vegetables, fruits, unpasteurized almond milk, and no flax seeds contained 41 ug L-1 TCN, while similar smoothies with pasteurized almond milk contained negligible to 9.6 ug L-1 CN-. Unpasteurized almond milk and raw flax seeds were the major sources of TCN in drinks. With the increased demand for raw and natural foods, there is a potential sublethal exposure of TCN by consumers.

16.
Plant Direct ; 2(2): e00038, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31245705

RESUMO

Cyanogenic glucosides are present in many plants, including eudicots, monocots, and ferns and function as defence compounds based on their ability to release hydrogen cyanide. In this study, the diurnal rhythm of cyanogenic glucoside content and of transcripts and enzymes involved in their biosynthesis was monitored in cassava plants grown in a glasshouse under natural light conditions. Transcripts of CYP79D1, CYP79D2, CYP71E7/11, and UGT85K5 were at minimal levels around 9 p.m., increased during the night and decreased following onset of early morning light. Transcripts of UGT85K4 and HNL10 showed more subtle variations with a maximum reached in the afternoon. Western blots showed that the protein levels of CYP71E7/11 and UGT85K4/5 decreased during the light period to a near absence around 4 p.m. and then recovered during the dark period. Transcript and protein levels of linamarase were stable throughout the 24-hr cycle. The linamarin content increased during the dark period. In the light period, spikes in the incoming solar radiation were found to result in concomitantly reduced linamarin levels. In silico studies of the promoter regions of the biosynthetic genes revealed a high frequency of light, abiotic stress, and development-related transcription factor binding motifs. The synthesis and endogenous turnover of linamarin are controlled both at the transcript and protein levels. The observed endogenous turnover of linamarin in the light period may offer a source of reduced nitrogen to balance photosynthetic carbon fixation. The rapid decrease in linamarin content following light spikes suggests an additional function of linamarin as a ROS scavenger.

17.
Front Plant Sci ; 8: 220, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28286506

RESUMO

Cassava (Manihot esculenta Crantz), a staple crop for millions of sub-Saharan Africans, contains high levels of cyanogenic glycosides which protect it against herbivory. However, cyanogens have also been proposed to play a role in nitrogen transport from leaves to roots. Consistent with this hypothesis, analyses of the distribution and activities of enzymes involved in cyanide metabolism provides evidence for cyanide assimilation, derived from linamarin, into amino acids in cassava roots. Both ß-cyanoalanine synthase (CAS) and nitrilase (NIT), two enzymes involved in cyanide assimilation to produce asparagine, were observed to have higher activities in roots compared to leaves, consistent with their proposed role in reduced nitrogen assimilation. In addition, rhodanese activity was not detected in cassava roots, indicating that this competing means for cyanide metabolism was not a factor in cyanide detoxification. In contrast, leaves had sufficient rhodanese activity to compete with cyanide assimilation into amino acids. Using transgenic low cyanogen plants, it was shown that reducing root cyanogen levels is associated with elevated root nitrate reductase activity, presumably to compensate for the loss of reduced nitrogen from cyanogens. Finally, we overexpressed Arabidopsis CAS and NIT4 genes in cassava roots to study the feasibility of enhancing root cyanide assimilation into protein. Optimal overexpression of CAS and NIT4 resulted in up to a 50% increase in root total amino acids and a 9% increase in root protein accumulation. However, plant growth and morphology was altered in plants overexpressing these enzymes, demonstrating a complex interaction between cyanide metabolism and hormonal regulation of plant growth.

18.
Neurologia ; 32(8): 516-522, 2017 Oct.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-27130308

RESUMO

INTRODUCTION: This study evaluated the protective effects of 2 commercial formats of Ginkgo biloba on motor alterations induced by cassava (Manihot esculenta Crantz) juice consumption in male Wistar rats. METHODS: The effects were evaluated with the open field and swim tests at 0, 7, 14, 21, and 28 days of treatment, one hour after administering the product. RESULTS: Compared to controls, open field crossings increased after day 21 of cassava juice consumption, and lateral swimming in the swim test was reported after day 7. CONCLUSION: Ginkgo biloba extracts prevented motor alterations associated with cassava juice consumption, probably due to the flavonoid content in both formats of Ginkgo biloba.


Assuntos
Ginkgo biloba/efeitos adversos , Manihot/efeitos dos fármacos , Atividade Motora/efeitos dos fármacos , Ratos Wistar , Animais , Comportamento Animal/efeitos dos fármacos , Masculino , Manihot/química , México , Nitrilas , Ratos , Natação
19.
J Exp Bot ; 67(18): 5403-5413, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27506218

RESUMO

Rising sea levels are threatening agricultural production in coastal regions due to inundation and contamination of groundwater. The development of more salt-tolerant crops is essential. Cassava is an important staple, particularly among poor subsistence farmers. Its tolerance to drought and elevated temperatures make it highly suitable for meeting global food demands in the face of climate change, but its ability to tolerate salt is unknown. Cassava stores nitrogen in the form of cyanogenic glucosides and can cause cyanide poisoning unless correctly processed. Previous research demonstrated that cyanide levels are higher in droughted plants, possibly as a mechanism for increasing resilience to oxidative stress. We determined the tolerance of cassava to salt at two different stages of development, and tested the hypothesis that cyanide toxicity would be higher in salt-stressed plants. Cassava was grown at a range of concentrations of sodium chloride (NaCl) at two growth stages: tuber initiation and tuber expansion. Established plants were able to tolerate 100mM NaCl but in younger plants 40mM was sufficient to retard plant growth severely. Nutrient analysis showed that plants were only able to exclude sodium at low concentrations. The foliar cyanogenic glucoside concentration in young plants increased under moderate salinity stress but was lower in plants grown at high salt. Importantly, there was no significant change in the cyanogenic glucoside concentration in the tubers. We propose that the mechanisms for salinity tolerance are age dependent, and that this can be traced to the relative cost of leaves in young and old plants.


Assuntos
Abastecimento de Alimentos , Manihot/fisiologia , Plantas Tolerantes a Sal/fisiologia , Mudança Climática , Cianetos/metabolismo , Manihot/crescimento & desenvolvimento , Tubérculos/crescimento & desenvolvimento , Tubérculos/fisiologia , Tolerância ao Sal/fisiologia
20.
Neurologia ; 31(8): 516-22, 2016 Oct.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-25524044

RESUMO

INTRODUCTION: Cassava, also known as yuca or manioc (Manihot esculenta Crantz), is a staple food in tropical and subtropical regions since it is an important source of carbohydrates. Nevertheless, it contains cyanogenic compounds including lotaustralin and linamarin, which have been shown by experimental models to affect brain structures such as the thalamus, the piriform cortex, the hippocampus, and others. These findings may explain the presence of such neurological diseases as konzo and tropical ataxic neuropathy. However, hippocampal involvement in the neurological alterations associated with the chemical compounds in cassava has yet to be explored. METHOD: Male Wistar rats (3 months old), were assigned to 4 groups (n = 8 per group) as follows: a vehicle-control group (receiving injectable solution 1µl) and three groups receiving linamarin (10, 15, and 20mM). The substances were microinjected intrahippocampally (CA1) every 24hours for 7 consecutive days, and their effects on locomotor activity, rotarod, and swim tests were assessed daily. RESULTS: Linamarin microinjected into the dorsal hippocampus produced hyperactivity and loss of motor coordination which became more evident as treatment time increased. In the swim test, rats treated with linamarin displayed lateral rotation beginning on the fourth day of microinjection. CONCLUSIONS: Microinjection of linamarin into the dorsal hippocampus of the rat is associated with impaired motor coordination, suggesting that the dorsal hippocampus, among other brain structures, may be affected by the neurological changes associated with inappropriate consumption of cassava in humans.


Assuntos
Discinesia Induzida por Medicamentos/fisiopatologia , Hipocampo , Nitrilas , Animais , Discinesia Induzida por Medicamentos/psicologia , Masculino , Microinjeções , Atividade Motora , Nitrilas/administração & dosagem , Equilíbrio Postural/efeitos dos fármacos , Ratos , Ratos Wistar , Natação/psicologia
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