Abstract
Recently, detection of antioxidant activity of plant extracts has caught the attention of researchers. Determination of antioxidant activity is usually performed using stable free radicals. A number of assays is available for screening the antioxidant activity of food constituents, but few of these methods are applicable to lipophilic substances. EPR is the analytical technique that directly measures free radicals making possible the analysis of turbid or highly colored samples. The aim of this study was to determine how the detection technique, plant species and the different growing conditions influenced the antioxidative activity of aqueous and lipid extracts from leaves. Sage (Salvia officinalis L.) and coneflower (Echinacea angustifolia DC.) grown in hydroponics and in soil, were analyzed. Radical decay kinetics, due to plant extracts, were monitored by an EPR spectrometer, equipped with a data acquisition system and a software package designed for analysis and simulation of spectra. Parameters obtained by the fitting of the curves allowed the calculation of the antioxidant potential. The radicals Fremy’s salt (hydrophilic) and 1,1-diphenyl-2-picrylhydrazyl (DPPH, lipophilic) were employed. Comparisons with data obtained by a spectrophotometric detection with the radical cation ABTS+ [2,2’-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)] were also made. Fremy’s salt and DPPH gave 1st and 2nd order kinetics, respectively. EPR can give more reliable measurements of the antioxidant potential than spectrophotometric assay. The reduced sensitivity of spectrophotometric detection was showed both for sage and coneflower extracts. Antioxidant potential of sage resulted extraordinary high compared to coneflower and a different ratio of aqueous to lipid antioxidant potential in the two species could be monitored. Antioxidant potentials were also higher for coneflower grown in hydroponics than in soil. In addition to the technique adopted, the detection of antioxidant potential was influenced by the growing conditions of plants and hydroponics showed to be able to increase antioxidant potential of both coneflower lipophilic and hydrophilic extracts. By registration of EPR kinetics we can get reliable measurements of the antioxidant potential of plant extracts, avoiding the artifacts due to the appearance of other radicals resulting from oxidative processes.
Highlights
Traditional systems of medicine have been used country of origin
Kinetics could not be registered for the radical cation ABTS+ due to a very large Electron Paramagnetic Resonance (EPR) line and this radical could not be used for determination of the antioxidant potential by EPR
The fact that the decay kinetic constants due to the addition of aqueous and lipophilic extracts of sage were 10and 100-fold higher when compared to those of Fremy’s salt and DPPH, respectively and that kinetics showed 1st and 2nd order fittings gives a warrant about the proportion between EPR amplitude and antioxidant amounts
Summary
Traditional systems of medicine have been used country of origin. Anyway, in the United States and throughout the world for centuries. Cristina Sgherri et al / American Journal of Agricultural and Biological Sciences 7 (4) (2012) 417-424 systems, for the treatment of chronic illnesses, is growing These therapies, usually known as alternative medicine, include the use of medicinal herbs which generally refer to plant parts-sometimes ground, extracted, or otherwise prepared-used for health benefits. Both sage (Salvia officinalis L.) and coneflower (Echinacea angustifolia DC.) have been used as medicines by different cultures throughout the centuries. They can interact enzymatically and non-enzymatically with damaging oxygen free radicals and their derivatives, protecting plants from oxidative stress and mammals from oxidative stressrelated diseases such as cancer, cardiovascular pathologies and aging (Calucci et al, 2003)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: American Journal of Agricultural and Biological Sciences
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
