Chemically, this genus is not homogenous. As pointed out 5. Conclusion previously some species contain monoterpenes, diterpenes, In conclusion, the present results therefore offer a scientific sesquiterpene lactones [15] and caryophyllane derivatives [16].
Our findings suggest that Pulicaria different flavonoid profiles [17]. The Pulicaria species proved jaubertii, Rumex nervosus, Peganum harmala, Caralluma various activities such as antiinflammatory, antilukemic [18], wissmannii are a potential antioxidants sources. Both Pulicaria potential cancer chemopreventive and cytotoxic agents [19].
The flowers of Pulicaria to determine pharmacokinetic properties of the selected plants. Some investigation reported that this species reveal 6. Acknowledgments antimalarial properties [20]. References Rumex nervosus Vahl has been used traditionally for treatment 1. It was BS, Maiga A. An ethnobotanical survey of herbal drugs of investigated that the methanolic extract of Rumex nervosus Gourma district, Mali.
Pharm Biol ; Vahl produced an important peripheral analgesic effect, with a 2. Harman D. Free radical theory of aging, increase the power of protection against the abdominal cramp, via oral functional life span. Annals of the New York Academy of pathway [21]. In our study, Rumex nervosus Vahl showed Sciences ; Cancer Inst. Bioactive C, Schmidtke M, Abate A, Neubert RH, Evaluation of the compounds and antioxidant potential of mango peel anti-microbial and anti-inflammatory activities of the extract.
Food Chem ; Cohen ML, Epidemiology of drug resistance: implications Rumex abyssinicus. Fitoterapia ; Dubuisson D, Dennis SG.
The formalin test: A 6. Antibacterial activity of plant extracts and meperidine and brain stem stimulation in Rats and Cats. Pain ; J Microbiol. Antinociceptive 7. J Pharm Pharmaceut Sci. Nature Pharmacy Series Spectrum Books Prashanth D, John US. Medicinal plants and antimicrobial activity J Ethnopharmacol. Antimicrobial agents from plants: antibacterial activity of plant volatile oils. J Appl Microbiol. Sandhu DS, Heinrich M. The use of health foods, spices and other botanicals in the Sikh community in London.
Phytotherapy Res ; Medical ethnobotany of the Teribes of Bocas del Toro, Panama. J Ethnopharmacol ; Screening for antimicrobial activity of ten medicinal plants used in Colombian folkloric medicine: A possible alternative in the treatment of nonnosocomial infections.
Anderberg AA. Cladistic interrelationships and major clades of the Ericales. Plant Syst Evol ; Studies on the flora of Yemen, on the flora of Tihama plain. Feddes Repertorium ; Sesquiterpene lactones and kaurane glycosides from Francoeuria crispa.
Photochem ; 29 8 Caryophyllene derivatives from Pulicaria Arabica. Then, other authors investigated the neutralizing effect of CAT on the bond strength of bleached teeth, with conflicting results 6, DES is a low-viscosity desensitizing gel based on dual desensitizing action for treatment of dentin hypersensitivity produced by tooth bleaching: potassium nitrate acting on nerve desensitization and NaF acting on remineralization of dental surfaces.
Tay et al. NaF alone also showed a lower antioxidant activity. In the same manner than NE, sodium bicarbonate is sold accompanying in-office bleaching products for being used as a neutralizer when hydrogen peroxide accidentally contacts oral mucosa. Although the antioxidant activity of sodium bicarbonate was higher than both types of catalase CAT and NE , they had similar behavior in reverting bond strength decrease 3. Natural antioxidants existing in medicinal plants have been proposed as alternative.
A blood-red viscous sap called Dragon's blood with antioxidant properties is released upon making cuts on the bark of CL tree. CL is widely distributed in the upper Amazonian valleys of Ecuador and Peru and marketed as a health product 9. Variations in plant material, extraction method, processing and antioxidant assays employed might affect the concentrations of active compounds that could be reflected in the antioxidant activity.
Previous studies have shown that UT exhibited antioxidant activity even at low concentrations 9,22, This result agrees with those of a previous study 22 in which UT achieved similar results to AAcidS when its concentration was twice or six times the concentration of ascorbic acid.
As mentioned by Sandoval et al. Despite the higher antioxidant activity of some substances AAcidS, AAcidG, SodAsS, SodAsG and VitE , it is not clear in the literature which is the minimum antioxidant activity to revert the problems occurred after the bleaching procedure and, unfortunately, the shelf life of these products are shortened and can be affected by storage conditions temperature, time, light exposure Further studies are needed to evaluate the neutralizing effect of the some of the tested products to increase the lower bond strength of bleached teeth, and to evaluate the correlation between the antioxidant activity and bond strength values immediately after bleaching procedures.
The DPPH assay provided an easy and rapid way to determine the antioxidant activity of most of the substances tested in this study. Abrir menu Brasil. Brazilian Dental Journal. Abrir menu. Key words: antioxidant, dental adhesive, free radical. Braz Dent J ; Penetration of the pulp chamber by carbamide peroxide bleaching agents. J Endod ; Improvement of bonding to bleached bovine tooth surfaces by ascorbic acid treatment.
Dent Mater J ; Oper Dent ; The effects of anti-oxidant agents as neutralizers of bleaching agents on enamel bond strength. Braz J Oral Sci ; In vitro antioxidant activities of mouthrinses and their components.
J Clin Periodontol ; Effects of sangre de drago from Croton lechleri Muell. J Ethnopharmacol ; Antioxidant properties of proanthocyanidins of Uncaria tomentosa bark decoction: a mechanism for anti-inflammatory activity.
Phytochemistry ; The chemistry behind antioxidant capacity assays. J Agric Food Chem ; Use of a free radical method to evaluate antioxidant activity.
Lebenson Wiss Technol ; Screening of Brazilian plant extracts for antioxidant activity by the use of DPPH free radical method. Phytother Res ; Comparison of the effect of hydrogel and solution forms of sodium ascorbate on orthodontic bracket-enamel shear bond strength immediately after bleaching: an in vitro study.
Indian J Dent Res ; The stock solution of DPPH slowly deteriorates; thus an automatic burette with a nitrogen atmosphere could be a choice to minimize the loss of free radical activity Blois For substrates of known molar mass, working in terms of molar units completely obscures the interpretation of the data on a molecular basis; it is more appropriate to use the relative molar mass for DPPH Sanchez-Moreno et al.
Use of only a single mass-in-volume concentration does not help to elucidate the structural basis of antioxidant activity, since it provides only two points on the titration curve Yepez et al.
Working in terms of numbers of free radicals necessitates the use of the Avogadro number to bring the values on to a mole basis Schwarz et al. However, in case of complex mixtures such as plant extracts, the results should be expressed as DPPH equivalents per gram of material. A reaction time of 30 min was followed by Kim et al. However, shorter reaction time of 5 and 10 min has also been reported Lebeau et al. As the rate of reaction varies widely among substrates Bondet et al.
Idealised plots of absorbance A left hand scale and filled circles , and percentage reduction Q right hand scale and open squares , vs.
The simplest approach in interpreting the data is to plot absorbance against substrate concentration, extending the concentration range beyond the end-point to define the subsequent section of the plot so that the intersection point may be defined most accurately Fig.
The value of molar extinction coefficient for DPPH in methanol or ethanol at nm is given as 1. Antioxidants in food may be water soluble, fat soluble, insoluble being bound to cell walls and hence may not be free to react with DPPH, hence they react at different rates and follow differing kinetics, and the reaction will often not reach completion in a reasonable assay time.
This change is compared with the change induced by Trolox and the antioxidant activity of the sample is expressed in micromoles of Trolox equivalents TE Molyneux Ozcelik et al. The evaluation of antioxidant activity by the changes of DPPH absorbance should be carefully interpreted since the absorbance of DPPH at nm is decreased by light, oxygen, pH, and type of solvent in addition to the antioxidant.
Electrochemical methods for the determination of antioxidant activity based on the application of biosensors Ruiz et al. DPPH method has been used to evaluate the antioxidant ability of phenol compounds Sanchez-Moreno et al. Sung-Kun et al. Ionita et al. Buijnster et al. The OW-DPPH approach for assessing antioxidant activity is based on a direct proportionality between magnitude of OW signal and the optical absorbance. The aliquots of antioxidant were added to the methanolic solution of DPPH.
An aliquot of mixture was pipetted directly on the OW and the magnitude of OW signal was online monitored until the steady state is reached. The OW signal and the absorbance of the solution decreases depending upon the intrinsic antioxidant activity of antioxidant as well as on the speed of the reaction between DPPH and the antioxidant.
The antioxidant activity is calculated by determining the decrease in the absorbance at different concentration by using the equation. These methods were applied for screening and evaluation of scavenging capacity of several pure compounds and complex matrices, such as plant extracts and beverages. Furthermore, the sample dilution factor plays an important role since the exhaustion of scavenging ability of the sample should take place during the period of absorbance measurement.
The proposed method was applied to several food products and the total antioxidant capacity was expressed as Vitamin C equivalent antioxidant capacity VCEAC. The configuration of the MSFIA system was designed to allow the determination of total antioxidant capacity of several samples with stopped flow approach, as the reaction kinetics is strongly influenced by the type of antioxidant compound. With slight modification in the system, it is possible to allow the sample exchange standard or sample without disturbing the content of the flow cell and make adjustments of the samples, which have intrinsic absorption at the wavelength of detection.
The development of an automated DPPH method, based on SIA technique was supposed to be suitable for rapid testing of anti-oxidation activity in large series of plant extracts Polasek et al. Ethanol-water served also as the SIA carrier. All solvents used for the dissolution of standards, extract samples and dilution of stock solutions, DPPH reagent, and SIA carrier stream were degassed by min sonication in Sonorex Super 10P Bandelin ultrasound bath sonication level SIA is the modification of FIA technique to automate assays which is achieved by carrying out analyses in a flow system where a pump is used to continuously draw sample and reagent solutions into different lines or segments of plastic tubing, as well as push them forward through the system.
Aliquots of the sample solution are dispensed into the carrier stream by an injection valve. Bringing solutions from different lines together, or including a reagent in the carrier stream enables seamless, automated reagent addition. Connecting a detector at the end of the sample's flow path ensures automated detection of the processed sample. In this method, two identical glassy carbon disk electrodes were mounted in an electrochemical cell.
Selectivity of detector was tested by different antioxidant compounds in ethanol-phosphate buffer solution pH 7. Scheme of biamperometric measurement. This assay is easy to perform and has acceptable accuracy, precision and reproducibility. The RDSC assay may be conducted in aqueous alcohol and acetone for hydrophilic antioxidants or in the organic solvents for lipophilic antioxidants without solubilizing agents, which makes it possible to directly compare the radical scavenging capacities of hydrophilic and lipophilic antioxidants.
These approaches take into account both the kinetic and the thermodynamic measurements of the radical-antioxidant reactions and make it possible to compare data between laboratories. The development and application of a highthroughput RDSC assay using a microplate reader with spectrophotometric detector and 96 well plates was described and validated Zhihong et al. This assay may be conducted in aqueous alcohol and acetone for hydrophilic antioxidants or in the organic solvents for lipophilic antioxidants without solubilizing agents.
The assay for evaluating lipophilic antioxidants is in high demand. This RDSC assay is easy to perform and has acceptable accuracy, precision, and reproducibility. The high-throughput RDSC assay may be used for screening and investigating the potential natural antioxidants. It is also observed that activity of natural antioxidants often decreases during their isolation and purification due to decomposition Yamaguchi et al.
Yamaguchi et al. Koleva et al. The HPLC method is sensitive and can be used as a quality control tool for the rapid determination of free radical scavenging activity of variety of products including plant extracts, foods, drugs and polyherbal formulations. The applicability of HPLC method was extended to determine the antioxidant activity of crude plant extracts and drugs Dapkevicius et al.
The HPLC method developed was specific for DPPH with an acceptable reproducibility and short run time allowing for rapid determination of radical scavenging activity of several samples Chandrasekar et al.
This HPLC method is often used in combination with other methods. Changqing et al. The sample was separated by HPLC and the eluate split into two flows. The method was applied to the identification of antioxidant compounds in a fraction, obtained by solid-phase extraction, of an extract of a Thai medicinal plant. Y represents a Y connecter. This method has been applied to evaluate antioxidant compounds in fruit and vegetables Pukalskas et al.
This technique would permit the rapid determination of antioxidant activity and provide structural identification of the antioxidant compounds involved Nuengchamnong et al.
A rapid and simple method has been developed for the screening and identification of natural antioxidants of Flos Lonicerae Japonicae FLJ.
However, these methods might not be adopted widely because the online instrumental system required was complex and not commercial. Online HPLC method offers broad range of applicability. The compounds of over a broad range of polarity and pKa can be evaluated which exhibit different kinetic behavior towards DPPH. It can employ both isocratic and gradient runs with mobile phases of different composition and pH can be carried out Dapkevicius et al.
The major advantage of this method is that it is immediately clear which constituent possesses radical scavenging activity. Thus it is no longer necessary to purify every single constituent for off-line assays, leading to very significant reductions of cost and faster results. The plates were evaluated visually and a quantitative determination could be achieved by eluting the spots with DPPH reagent Takao et al. A method was developed to measure the radical scavenging activity of compounds separated by reversed-phase TLC RP-TLC using phenolic acids as model analytes.
The method is simple and fast, making it suitable for automated systems in screening applications where high throughput and cost efficiency are required Teijo et al.
TLC separation combined with the detection of antioxidants in situ by postchromatographic derivatization, was introduced by Olga et al. Li et al. The activity was evaluated by measuring the area of bright yellow bands against the purple background by a CCD video camera after dipping the plate in DPPH solution. Comparison of the results showed good correlation between the activities measured by TLC-DPPH and by the conventional spectrophotometric assay. Also, no sample purification is needed and both separation and the activity measurement can be done in the same TLC-DPPH plate simultaneously.
HSCCC is a liquid—liquid chromatographic technique with no solid support matrix; therefore eliminates the irreversible adsorption of samples Yoichiro This method has been successfully used to separate and isolate many natural products David et al.
Following preparative isolation and purification by HSCCC, the activity of the collected fractions has been evaluated by use of off-line methods which is a time-consuming and labor-intensive process Pukalskas and van Beek ; Perez-Bonilla et al. There are various methods for the determination of antioxidant potential of different biological samples. However, a single method is not suitable for all and there is no shortcut approach to determine antioxidant activity.
Amongst all the available methods, DPPH method has been widely applied for estimating antioxidant activity, however, its applications should to be carried out bearing in mind the basis of the method, and the need wherever possible to establish the stoichiometry for the quenching reaction, so that the antioxidant activity may be related to the structure of the substrate molecule. The method offers advantages of being rapid, simple and inexpensive and provides first hand information on the overall antioxidant capacity of the test system.
The trend in antioxidant activity obtained by using the DPPH method is comparable to trends found using other methods.
For a better understanding of the mechanisms involving the DPPH radical and potential antioxidants, it would be interesting to characterize the reaction intermediates and products. To do this, it is necessary to separate these compounds by chromatography and to identify them.
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