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1.
Genes (Basel) ; 13(5)2022 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-35627221

RESUMO

In tumor development, increased expression of DNA methyltransferase (DNMT) has been observed. In particular, cigarette smoke and tea polyphenols may influence DNMT3B mRNA expression by regulating microRNA (miR)-29b expression. Herein, we designed a case−control study to evaluate the joint effects of smoking and green tea consumption, with miR-29b and DNMT3B mRNA expression, in lung cancer development. A total of 132 lung cancer patients and 132 healthy controls were recruited to measure miR-29b and DNMT3B mRNA expression in whole blood. Results revealed that lung cancer patients had lower miR-29b expression (57.2 vs. 81.6; p = 0.02) and higher DNMT3B mRNA expression (37.2 vs. 25.8; p < 0.001) than healthy controls. Compared to non-smokers with both higher miR-29b and lower DNMT3B mRNA expression, smokers with both low miR-29b and higher DNMT3B mRNA expression had an elevated risk of lung cancer development (OR 5.12, 95% CI 2.64−9.91). Interactions of smoking with miR-29b or DNMT3B mRNA expression in lung cancer were significant. Interaction of green tea consumption with miR-29b expression and DNMT3B mRNA expression in lung cancer was also significant. Our study suggests that smokers and green tea nondrinkers with lower miR-29b expression and higher DNMT3B mRNA expression are more susceptible to lung cancer development.


Assuntos
Fumar Cigarros , Neoplasias Pulmonares , MicroRNAs , Estudos de Casos e Controles , Humanos , Neoplasias Pulmonares/genética , MicroRNAs/metabolismo , RNA Mensageiro/genética , Fumar/efeitos adversos , Fumar/genética , Chá
2.
Diagnostics (Basel) ; 11(10)2021 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-34679458

RESUMO

The COVID-19 pandemic is an ongoing global pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in 2020-2021. COVID-19 is becoming one of the most fatal pandemics in history and brings a huge challenge to the global healthcare system. Opportune detection, confinement, and early treatment of infected cases present the first step in combating COVID-19. Diagnosis via viral nucleic acid amplification tests (NAATs) is frequently employed and considered the standard procedure. However, with an increasing urge for point-of-care tests, rapid and cheaper immunoassays are widely utilized, such as lateral flow immunoassay (LFIA), which can be used for rapid, early, and large-scale detection of SARS-CoV-2 infection. In this narrative review, the principle and technique of LFIA applied in COVID-19 antigen and antibody detection are introduced. The diagnostic sensitivity and specificity of the commercial LFIA tests are outlined and compared. Generally, LFIA antigen tests for SARS-CoV-2 are less sensitive than viral NAATs, the "gold standard" for clinical COVID-19 diagnosis. However, antigen tests can be used for rapid and mass testing in high-risk congregate housing to quickly identify people with COVID-19, implementing infection prevention and control measures, thus preventing transmission. LFIA anti-SARS-CoV-2 antibody tests, IgM and/or IgG, known as serology tests, are used for identification if a person has previously been exposed to the virus or vaccine immunization. Notably, advanced techniques, such as LFT-based CRISPR-Cas9 and surface-enhanced Raman spectroscopy (SERS), have added new dimensions to the COVID-19 diagnosis and are also discussed in this review.

3.
BMC Cancer ; 21(1): 1066, 2021 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-34587932

RESUMO

BACKGROUND: Smoking increases DNA methylation and DNA damage, and DNA damage acts as a vital cause of tumor development. The DNA methyltransferase 3B (DNMT3B) enhances promoter activity and methylation of tumor suppressor genes. Tea polyphenols may inhibit DNMT activity. We designed a case-control study to evaluate the combined effects of smoking, green tea consumption, DNMT3B - 149 polymorphism, and DNA damage on lung cancer occurrence. METHODS: Questionnaires were administered to obtain demographic characteristics, life styles, and family histories of lung cancer from 190 primary lung cancer cases and 380 healthy controls. Genotypes and cellular DNA damage were determined by polymerase chain reaction and comet assay, respectively. RESULTS: The mean DNA tail moment for lung cancer cases was significantly higher than that for healthy controls. Compared to nonsmokers carrying the DNMT3B - 149 CT genotype, smokers carrying the TT genotype had a greater lung cancer risk (odds ratio [OR]: 2.83, 95% confidence interval [CI]: 1.62-4.93). DNA damage levels were divided by the tertile of the healthy controls' values. Compared to nonsmokers with low DNA damage, smokers with moderate DNA damage (OR: 2.37, 95% CI: 1.54-3.63) and smokers with high DNA damage (OR: 3.97, 95% CI: 2.63-5.98) had elevated lung cancer risks. Interaction between smoking and DNA damage significantly affected lung cancer risk. CONCLUSIONS: Our study suggested that the DNMT3B - 149 TT genotype, which has higher promoter activity, can increase the lung cancer risk elicited by smoking, and DNA damage may further promote smoking related lung cancer development.


Assuntos
DNA (Citosina-5-)-Metiltransferases/genética , Dano ao DNA , Neoplasias Pulmonares/genética , Polimorfismo Genético , Fumar/efeitos adversos , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Intervalos de Confiança , DNA (Citosina-5-)-Metiltransferases/antagonistas & inibidores , Feminino , Genes Supressores de Tumor , Genótipo , Humanos , Estilo de Vida , Masculino , Pessoa de Meia-Idade , não Fumantes , Razão de Chances , Regiões Promotoras Genéticas , Fumar/genética , Inquéritos e Questionários , Chá , DNA Metiltransferase 3B
4.
IDCases ; 25: e01207, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34307044

RESUMO

Although the incidence of tuberculosis (TB) is decreasing globally, it remains an endemic disease in Taiwan. The etiology of cutaneous TB can be endogenous or exogenous. The mechanism of infection could be direct inoculation, contiguity, or hematogenous dissemination. The clinical manifestations are diverse, ranging from scrofuloderma, acute miliary TB, tuberculous chancre, tuberculosis verrucosa cutis, and lupus vulgaris to tuberculid. Basis the bacterial load, cutaneous TB is classified as multibacillary or paucibacillary. We present a case of cutaneous TB that initially presented as a subcutaneous nodule and a mass. The cutaneous TB likely originated from underlying TB lymphadenitis and TB spine and presented as scrofuloderma.

5.
Eur J Cancer Prev ; 28(4): 316-322, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30157136

RESUMO

Tea polyphenols are strong antioxidants, which can be rapidly O-methylated by catechol-O-methyltransferase (COMT). Thus, it is possible that the genetic polymorphism of COMT can modulate the association of green tea consumption and lung cancer. Here, we designed a case-control study to evaluate the combined effect of green tea consumption and COMT genotypes on the risk of lung cancer. A total of 237 lung cancer patients and 474 healthy controls were recruited. Questionnaires were administered to obtain demographic data, smoking status, green tea consumption, fruits and vegetables intake, exposure to cooking fumes, and family history of lung cancer. Genotypes for COMT were identified by PCR. Smoking, green tea consumption, exposure to cooking fumes, and family history of lung cancer were associated with the development of lung cancer. When green tea drinkers carrying COMT HL/LL genotypes were selected as the reference group, drinkers carrying the COMT HH genotype had a higher risk for the development of lung cancer (odds ratio: 1.97, 95% confidence interval: 0.99-3.91). Among the current and ever smokers, the elevated risk for lung cancer was more apparent in green tea drinkers carrying the COMT HH genotype compared with green tea drinkers carrying COMT HL/LL genotypes (odds ratio: 5.84, 95% confidence interval: 1.75-19.45). Green tea drinkers with greater activity of the COMT genotype, whereby polyphenols are effectively excluded, will gain fewer protective benefits against lung cancer development.


Assuntos
Antioxidantes/administração & dosagem , Catecol O-Metiltransferase/genética , Neoplasias Pulmonares/epidemiologia , Polifenóis/administração & dosagem , Chá , Antioxidantes/metabolismo , Estudos de Casos e Controles , Catecol O-Metiltransferase/metabolismo , Inquéritos sobre Dietas/estatística & dados numéricos , Feminino , Humanos , Neoplasias Pulmonares/etiologia , Neoplasias Pulmonares/prevenção & controle , Masculino , Anamnese , Pessoa de Meia-Idade , Polifenóis/metabolismo , Fatores de Risco , Taiwan/epidemiologia , Fumar Tabaco/efeitos adversos , Fumar Tabaco/epidemiologia
6.
Artigo em Inglês | MEDLINE | ID: mdl-29966381

RESUMO

Air pollution is a very critical issue worldwide, particularly in developing countries. Particulate matter (PM) is a type of air pollution that comprises a heterogeneous mixture of different particle sizes and chemical compositions. There are various sources of fine PM (PM2.5), and the components may also have different effects on people. The pathogenesis of PM2.5 in several diseases remains to be clarified. There is a long history of epidemiological research on PM2.5 in several diseases. Numerous studies show that PM2.5 can induce a variety of chronic diseases, such as respiratory system damage, cardiovascular dysfunction, and diabetes mellitus. However, the epidemiological evidence associated with potential mechanisms in the progression of diseases need to be proved precisely through in vitro and in vivo investigations. Suggested mechanisms of PM2.5 that lead to adverse effects and chronic diseases include increasing oxidative stress, inflammatory responses, and genotoxicity. The aim of this review is to provide a brief overview of in vitro and in vivo experimental studies of PM2.5 in the progression of various diseases from the last decade. The summarized research results could provide clear information about the mechanisms and progression of PM2.5-induced disease.


Assuntos
Poluentes Atmosféricos/toxicidade , Tamanho da Partícula , Material Particulado/toxicidade , Poluentes Atmosféricos/análise , Progressão da Doença , Humanos , Material Particulado/química
7.
Int J Biol Sci ; 14(3): 253-265, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29559844

RESUMO

Inhaled particulate matter 2.5 (PM2.5) can cause lung injury by inducing serious inflammation in lung tissue. Renin-angiotensin system (RAS) is involved in the pathogenesis of inflammatory lung diseases and regulates inflammatory response. Angiotensin-converting enzyme II (ACE2), which is produced through the angiotensin-converting enzyme (ACE)/angiotensin II (Ang II) axis, protects against lung disease. However, few studies have focused on the relationships between PM2.5 and ACE2. Therefore, we aimed to explore the role of ACE2 in PM2.5-induced acute lung injury (ALI). An animal model of PM2.5-induced ALI was established with wild type (C57BL/6, WT) and ACE2 gene knockout (ACE2 KO) mice. The mice were exposed to PM2.5 through intratracheal instillation once a day for 3 days (6.25 mg/kg/day) and then sacrificed at 2 days and 5 days after PM2.5 instillation. The results show that resting respiratory rate (RRR), levels of inflammatory cytokines, ACE and MMPs in the lungs of WT and ACE2 KO mice were significantly increased at 2 days postinstillation. At 5 days postinstillation, the PM2.5-induced ALI significantly recovered in the WT mice, but only partially recovered in the ACE2 KO mice. The results hint that PM2.5 could induce severe ALI through pulmonary inflammation, and the repair after acute PM2.5 postinstillation could be attenuated in the absence of ACE2. Additionally, our results show that PM2.5-induced ALI is associated with signaling p-ERK1/2 and p-STAT3 pathways and ACE2 knockdown could increase pulmonary p-STAT3 and p-ERK1/2 levels in the PM2.5-induced ALI.


Assuntos
Lesão Pulmonar Aguda/induzido quimicamente , Material Particulado/toxicidade , Peptidil Dipeptidase A/genética , Lesão Pulmonar Aguda/metabolismo , Lesão Pulmonar Aguda/fisiopatologia , Enzima de Conversão de Angiotensina 2 , Animais , Citocinas/metabolismo , Gelatinases/metabolismo , Mediadores da Inflamação/metabolismo , Pulmão/enzimologia , Pulmão/metabolismo , Sistema de Sinalização das MAP Quinases , Masculino , Metaloproteinases da Matriz/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Peptidil Dipeptidase A/metabolismo , Fosforilação , Taxa Respiratória , Fator de Transcrição STAT3/metabolismo
8.
Ren Fail ; 39(1): 719-728, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29157100

RESUMO

BACKGROUND: The renin-angiotensin system (RAS) has significant influences on heart and renal disease progression. Angiotensin converting enzyme (ACE) and angiotensin converting enzyme II (ACE2) are major peptidases of RAS components and play counteracting functions through angiotensin II (Ang II)/ATIR and angiotensin-(1-7) (Ang-(1-7))/Mas axis, respectively. METHODS: There were 360 uremic patients on regular hemodialysis (HD) treatment (inclusive of 119 HD patients with cardiovascular diseases (CVD) and 241 HD patients without CVD and 50 healthy subjects were enrolled in this study. Plasma ACE, ACE2, Ang II and Ang-(1-7) levels of the HD patients were determined. RESULTS: We compared pre-HD levels of plasma ACE, ACE2, Ang II and Ang-(1-7) in the HD patients with and without CVD to those of the controls. The HD patients, particularly those with CVD, showed a significant increase in the levels of ACE and Ang II, whereas ACE2 and Ang-(1-7) levels were lower than those in the healthy controls. Therefore, imbalanced ACE/ACE2 was observed in the HD patients with CVD. In the course of a single HD session, the plasma ACE, ACE/ACE2 and Ang II levels in the HD patients with CVD were increased from pre-HD to post-HD. On the contrary, ACE2 levels were decreased after the HD session. These changes were not detected in the HD patients without CVD. CONCLUSIONS: Pathogenically imbalanced circulating ACE/ACE2 was detected in the HD patients, particularly those with CVD. HD session could increase ACE/Ang II/AT1R axis and decrease ACE2/Ang-(1-7)/Mas axis activity in the circulation of HD patients with CVD.


Assuntos
Doenças Cardiovasculares/sangue , Falência Renal Crônica/sangue , Peptidil Dipeptidase A/sangue , Uremia/sangue , Idoso , Idoso de 80 Anos ou mais , Enzima de Conversão de Angiotensina 2 , Doenças Cardiovasculares/complicações , Feminino , Humanos , Falência Renal Crônica/complicações , Falência Renal Crônica/terapia , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Uremia/complicações
9.
Asian Pac J Cancer Prev ; 18(10): 2717-2723, 2017 10 26.
Artigo em Inglês | MEDLINE | ID: mdl-29072397

RESUMO

Background: Smoking can cause increase of DNA methylation and hypermethylation of tumor suppressor genes, this possible contributing to subsequent lung cancer development. DNA methyltransferase 3B (DNMT3B) is crucial in regulation of DNA methylation and it has been proposed that green tea might lower cancer risk through inhibiting its activity. Here, we designed a case-control study to investigate whether the DNMT3B -149 genetic polymorphism could modulate lung cancer risk due to smoking. Possible interactions of smoking and green tea consumption with this DNMT3B genetic polymorphism were also assessed. Materials and Methods: A total of 190 lung cancer patients and 380 healthy controls were recruited. Questionnaires were administered to obtain data on sociodemographic and lifestyle variables, as well as family history of lung cancer. Genotypes for DNMT3B -149 were identified by polymerase chain reaction. Results: Smoking, green tea consumption, exposure to cooking fumes, family history of lung cancer, and the DNMT3B -149 genotype (odds ratio (OR)=2.65; 95% confidence interval (CI) 1.15-6.10) were all significantly associated with the development of lung cancer. Smokers carrying the DNMT3B -149 TT genotype were at elevated risk compared to non-smokers carrying DNMT3B -149 (OR=7.69; 95% CI 2.55-23.14). Interaction of smoking with DNMT3B -149 genotypes was significant regarding lung cancer risk. However, interaction between green tea drinking and DNMT3B -149 genotypes was not. Conclusions: The DNMT3B -149 TT genotype might increase the smokingassociated lung cancer risk.

10.
Int J Biol Sci ; 12(4): 454-65, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27019629

RESUMO

Inflammation-mediated abnormalities in the renin-angiotensin system (RAS) and expression of matrix metalloproteinases (MMPs) are implicated in the pathogenesis of lung injury. Angiotensin converting enzyme II (ACE2), an angiotensin converting enzyme (ACE) homologue that displays antagonist effects on ACE/angiotensin II (Ang II) axis, could also play a protective role against lung diseases. However, the relationship between ACE2 and MMPs activation in lung injury is still largely unclear. The purpose of this study is to investigate whether MMPs activity could be affected by ACE2 and which ACE2 derived signaling pathways could be also involved via using a mouse model with lung injury induced by cigarette smoke (CS) exposure for 1 to 3 weeks. Wild-type (WT; C57BL/6) and ACE2 KO mice (ACE2(-/-)) were utilized to study CS-induced lung injury. Increases in the resting respiratory rate (RRR), pulmonary immunokines, leukocyte infiltration and bronchial hyperplasia were observed in the CS-exposed mice. Compared to WT mice, more serious physiopathological changes were found in ACE2(-/-) mice in the first week of CS exposure. CS exposure increased pulmonary ACE and ACE2 activities in WT mice, and significantly increased ACE in ACE2(-/-) mice. Furthermore, the activity of pulmonary MMPs was decreased in CS-exposed WT mice, whereas this activity was increased in ACE2(-/-) mice. CS exposure increased the pulmonary p-p38, p-JNK and p-ERK1/2 level in all mice. In ACE2(-/-) mice, a significant increase p-STAT3 signaling was detected; however, no effect was observed on the p-STAT3 level in WT mice. Our results support the hypothesis that ACE2 deficiency influences MMPs activation and STAT3 phosphorylation signaling to promote more pulmonary inflammation in the development of lung injury.


Assuntos
Lesão Pulmonar/induzido quimicamente , Lesão Pulmonar/metabolismo , Metaloproteinases da Matriz/metabolismo , Peptidil Dipeptidase A/genética , Fator de Transcrição STAT3/metabolismo , Fumar/efeitos adversos , Enzima de Conversão de Angiotensina 2 , Animais , Feminino , Lesão Pulmonar/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Peptidil Dipeptidase A/deficiência
11.
Biomed Res Int ; 2013: 678476, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24151616

RESUMO

A novel spectrophotometric method for the quantification of urinary xanthurenic acid (XA) is described. The direct acid ferric reduction (DAFR) procedure was used to quantify XA after it was purified by a solid-phase extraction column. The linearity of proposed method extends from 2.5 to 100.0 mg/L. The method is precise, yielding day-to-day CVs for two pooled controls of 3.5% and 4.6%, respectively. Correlation studies with an established HPLC method and a fluorometric procedure showed correlation coefficients of 0.98 and 0.98, respectively. Interference from various urinary metabolites was insignificant. In a small-scale screening of elderly conducted at Penghu county in Taiwan (n = 80), we were able to identify a group of twenty individuals having hyperhomocysteinemia (>15 µ mole/L). Three of them were found to be positive for XA as analyzed by the proposed method, which correlated excellently with the results of the activation coefficient method for RBC's AST/B6 functional test. These data confirm the usefulness of the proposed method for identifying urinary XA as an indicator of vitamin B6 deficiency-associated hyperhomocysteinemic condition.


Assuntos
Hiper-Homocisteinemia/diagnóstico , Espectrofotometria/métodos , Deficiência de Vitamina B 6/diagnóstico , Xanturenatos/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Humanos , Hiper-Homocisteinemia/complicações , Hiper-Homocisteinemia/enzimologia , Hiper-Homocisteinemia/patologia , Hiper-Homocisteinemia/urina , Taiwan , Vitamina B 6/metabolismo , Deficiência de Vitamina B 6/complicações , Deficiência de Vitamina B 6/enzimologia , Xanturenatos/urina
12.
J Agric Food Chem ; 54(25): 9297-302, 2006 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-17147410

RESUMO

We report here the development of a probe-based ultraweak chemiluminescence (uwCL) method capable of detecting a panel of four oxygen-derived free radicals (ODFRs) including superoxide (O2-), hydrogen peroxide (H2O2), hydroxyl radical (*OH), and peroxyl radical (ROO*) using different probes specific for these radicals performed by the same uwCL analyzer. The selected radical-generating systems and their corresponding uwCL-probing emitters were validated. These ODFR-detecting systems were subsequently utilized by us to assess the radical-scavenging ability (RSA) of a variety of extracts and purified constituents derived from foods and herbal preparations. Our approach for assessing RSA for these constituents is based on the suppression of uwCL generated by each ODFR, and the degrees of inhibition have been shown to be dose-dependent. For this reason, the estimation of IC50 for each testing compound can be obtained from the curve constructed based on the percent of inhibitions of uwCL versus the concentrations of the compound tested. To illustrate the practical applications of our devised methodology, data for comparative studies of RSA activities of fermented extracts of Cordeceps sinensis, purified methylgallate isolated from Toona sinesis, resveratrol purified from grape seeds, plus epimedin C from the aerial part of the Epimedium plant (yinyanghuo) are to be presented.


Assuntos
Análise de Alimentos , Sequestradores de Radicais Livres/análise , Medições Luminescentes/métodos , Extratos Vegetais/química , Espécies Reativas de Oxigênio/análise , Fermentação , Sequestradores de Radicais Livres/química , Meliaceae/química , Espécies Reativas de Oxigênio/química
13.
J Biomed Sci ; 11(5): 692-6, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15316145

RESUMO

Previous reports have suggested that high-dose L-arginine could be used in diabetic patients as a prophylactic blocker for the initial glycation reaction of proteins by methylglyoxal (MG), a reactive dicarbonyl compound of glucose metabolism. Here, we present several lines of evidence to substantiate that this prophylactic intervention may be inappropriate and should be used with care. First, we demonstrated that when various concentrations of L-arginine (2.0-8.0 mM) were added to a fixed concentration of MG (1.56 microM) in a buffered lucigenin solution, dose-dependent generation of superoxide anion (O(-)(2))-mediated ultraweak chemiluminescence (uwCL) occurs. The suppression of uwCL generation by exogenously added superoxide dismutase further substantiated that the interaction between MG and L-arginine generated O(-)(2). This phenomenon can also be demonstrated in a serum-based system. Furthermore, when a fixed concentration of L-arginine (8.0 mM) was added exogenously to a group of sera obtained from either diabetic patients (n = 10) or their matched nondiabetic controls (n = 10), a marked discrepancy in the generation of O(-)(2)-mediated uwCL could be demonstrated (12,534 +/- 3,147 vs. 950 +/- 350 counts; p < 0.001). Taken together, this evidence demonstrates that the appropriateness of using high-dose L-arginine for prophylactic measures in diabetic patients may be questioned, because the inhibition of the glycation reaction between MG and proteins by high-dose L-arginine unexpectedly produces plethoric O(-)(2) as a by-product, which may subsequently aggravate the preexisting oxidative stress status of diabetic patients.


Assuntos
Arginina/efeitos adversos , Arginina/farmacologia , Diabetes Mellitus/tratamento farmacológico , Produtos Finais de Glicação Avançada/metabolismo , Aldeído Pirúvico/farmacologia , Diabetes Mellitus/sangue , Relação Dose-Resposta a Droga , Humanos , Valores de Referência , Superóxidos/sangue
14.
J Agric Food Chem ; 51(1): 58-62, 2003 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-12502385

RESUMO

In the interest of developing a simple and rapid ultraweak chemiluminescence assay for assessing the superoxide (O(2)(-))-scavenging activities of various aqueous extracts of food constituents, a specific and stable O(2)(-)-generating system was sought. Reported herein is the obtainment for the first time of a specific and stable O(2)(-)-generating system consisting of methylglyoxal (MG), a reactive 2-oxo aldehyde and arginine, which has been shown to produce much steadier lucigenin-based chemiluminesence (LBCL) than the conventional xanthine/xanthine oxidase system running in parallel and monitoring by an ultraweak chemiluminescence analyzer. Upon mixing of MG and arginine in a phosphate-buffered saline solution, pH 7.4, steady, time-dependent increments of LBCL can be visually observed. The plateau of LBCL can be reached in approximately 10 min and retained in a steadily stable state thereafter without fluctuation for the next 15 min. The lucigenin-based LBCL generation was shown to be specific since it could be effectively inhibited by active bovine SOD, but not by heat-inactivated enzyme or catalase. Conversely, the xanthine/xanthine oxidase system can merely produce a LBCL peak rapidly but decay instantaneously. To illustrate the application of the proposed method for assessing the O(2)(-)-scavenging ability of various food extracts, namely, Prunus mume (A), Lilum lancifolium (B), Creataegus pinnatifida (C), Tremella fuciformis (D), Fortunella margarita (E), and Scutellaria baicalensis (F), we used the following protocol: 12 min after monitoring of LBCL, 1 mg/mL of each of the test compounds was added to the assay system and various degrees of sudden drop of LBCL values were observed, indicating differences in O(2)(-)-scavenging abilities exerted by these food extracts that can be visually compared. Consequently, the percentages of inhibition of LBCL versus the concentrations of a test compound can be constructed. It follows that the concentration needed to inhibit 50% of LBCL (IC(50)) of a test compound can be extrapolated from the curve. Using this approach, we were able to obtain the IC(50) values of various compounds to be tested and the order of inhibitory efficiency of the above-mentioned food extracts was ranked, being A > B > C > D > E > F, respectively.


Assuntos
Análise de Alimentos , Sequestradores de Radicais Livres/análise , Medições Luminescentes , Superóxidos/química , Acridinas/química , Arginina/química , Sequestradores de Radicais Livres/química , Concentração de Íons de Hidrogênio , Cinética , Aldeído Pirúvico/química , Soluções , Água
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