Antioxidant Activity Of Plant Extracts Research Articles

Antioxidant activity and essential oil composition of Satureja hortensis L. as influenced by sulfur fertilizer.

The quantity and quality of essential oils in plants can be influenced by various factors, including genetic traits, agricultural practices and environmental conditions such as nutrient availability. Macronutrients such as sulfur (S) are among the major factors influencing plant growth and development. Therefore this study was carried out to determine the effect of S fertilization at three levels (0, 0.05 and 0.1 g S kg(-1) soil) on the essential oil composition and antioxidant activity of Satureja hortensis L. Application of 0.05 g S kg(-1) soil increased the levels of α-terpinene, p-cymene, myrcene, α-thujene and α-pinene but decreased the level of γ-terpinene in the essential oil. This S application was most suitable for obtaining higher proportions of α-terpinene, p-cymene, myrcene, α-thujene and α-pinene, while application of 0.1 g S kg(-1) soil was preferable for carvacrol. γ-Terpinene was most abundant in the control. All extracts showed a considerable DPPH-inhibitory effect, with IC50 ranging from 0.720 g L(-1) in the control to 0.363 g L(-1) with application of 0.1 g S kg(-1) soil. The maximum antioxidant effect was observed with application of 0.1 g S kg(-1) soil. The results revealed that the use of chemical fertilizers such as S could improve the antioxidant activity of plant extracts significantly. Studying the secondary plant metabolites, mainly essential oils, is an interesting research area, so further studies are recommended to determine the effect of chemical fertilizers on the composition and antioxidant activity of essential oils of other aromatic plants.

Anti-oxidative Potential and Biocompounds of Five Lamiaceae Family Herbal Species

:The present study was designed to evaluate the antioxidants compound and activities in Salvia officinalis, Mentha spicata, Lavandula angustifolia, Satureja hortensis and Origanum vulgare methanol extracts. Antioxidant activities of plant extracts were assessed using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ability to reduce Fe3+ to Fe2+ assay. Free radical scavenging activity of S. officinalis was recorded as high as 90.1 % followed by L.angustifolia (88.7 %) at 300 µg/ml. This value was found close to the activity of synthetic antioxidant, butylated hydroxytoluene (BHT) (94.0 %) at the same concentration. In this study, Salvia officinalis and L. angustifolia had higher total phenolic contents (21.7 ± 1.18 and 19.2 ± 1.06 mg GA/100 g DW) whereas S. officinalis had the largest flavonoid contents (4.8 ± 0.12 mg CE / 100 g DW). Results showed strong correlation between antioxidant activity and carotenoids content (r=0.82), phenolic compounds (r= 0.92), vitamin C (r= 0.81), vitamin E (r= 0.79) and tannins content (r= 0.81). It can be concluded from the current results that antioxidative potency of L. angustifolia and S. officinalis is attributed to the presence of higher contents of biocompound like carotenoids, phenolics, vitamins and flavonoids.

Anti-diabetic and spasmolytic potential of Farsetia hamiltonii Royle from Cholistan desert

Ethnopharmacological relevanceFolk herbal practitioners of the Cholistan desert claim Farsetia hamiltonii Royle (Brassicaceae) to treat diabetes, oxidative damages, diarrhea, fever, and abdominal cramps. The aim of this study was to scientifically find the potential of Farsetia hamiltonii in treating diabetes and gastrointestinal diseases. Materials and methodsIn vivo anti-diabetic activity of Farsetia hamiltonii was studied on alloxan induced diabetic rats to justify its traditional use. The in vitro antispasmodic activity on isolated tissues of rabbit jejunum was also evaluated. In addition, several enzyme inhibition studies (lipoxygenase, tyrosinase, acetylcholinesterase (AchE), carbonic II anhydrase and phosphodiesterase I) and antioxidant activity of plant extracts were also conducted. ResultsIn vivo experiments, Farsetia hamiltonii methanol extract (300mg/kg) significantly lowered the fasting blood glucose (107.6±1.249mg/dL up to 4th day) comparable to positive control (Glibenclamide) throughout the study period. The in vitro antispasmodic activity on isolated tissues of rabbit jejunum on methanol extract showed concentration dependent (0.01–0.3mg/ml) relaxation of spontaneous contractions with EC50 value 0.011µM and high K+ (80mM) induced contraction (0.01–0.1mg/ml) with EC50 value 0.066mg/ml.Farsetia hamiltonii DCM and methanol extracts exhibited some antilipoxygenase activities while tyrosinase, acetylcholinesterase (AchE), carbonic II anhydrase, phosphodiesterase I, and antioxidant activity of plant extracts were not significant. ConclusionsOur results validate the traditional use of Farsetia hamiltonii for the traditional therapeutic potential in treating diabetes and gastrointestinal diseases.

Antioxidant and anti-inflammatory activities of extracts from Cassia alata, Eleusine indica, Eremomastax speciosa, Carica papaya and Polyscias fulva medicinal plants collected in Cameroon.

BackgroundThe vast majority of the population around the world has always used medicinal plants as first source of health care to fight infectious and non infectious diseases. Most of these medicinal plants may have scientific evidence to be considered in general practice.ObjectiveThe aim of this work was to investigate the antioxidant capacities and anti-inflammatory activities of ethanol extracts of leaves of Cassia alata, Eleusine indica, Carica papaya, Eremomastax speciosa and the stem bark of Polyscias fulva, collected in Cameroon.MethodsChemiluminescence was used to analyze the antioxidant activities of plant extracts against hydrogen peroxide or superoxide anion. Comet assays were used to analyze the protection against antioxidant-induced DNA damage induced in white blood cells after treating with hydrogen peroxide. Flow cytometry was used to measure γδ T cells proliferation and anti-inflammatory activity of γδ T cells and of immature dendritic cells (imDC) in the presence of different concentrations of plant extracts.ResultsEthanol extracts showed strong antioxidant properties against both hydrogen peroxide and superoxide anion. Cassia alata showed the highest antioxidant activity. The effect of plant extracts on γδ T cells and imDC was evidenced by the dose dependent reduction in TNF-α production in the presence of Cassia alata, Carica papaya, Eremomastax speciosa Eleusine indica, and Polyscias fulva. γδ T cells proliferation was affected to the greatest extent by Polyscias fulva.ConclusionThese results clearly show the antioxidant capacity and anti-inflammatory activities of plant extracts collected in Cameroon. These properties of leaves and stem bark extracts may contribute to the value for these plants in traditional medicine and in general medical practice.

Determination of total phenol, in-vitro antioxidant and anti-inflammatory activity of seeds and fruits of Zizyphus spina-christi grown in Oman

To perform phytochemical screening and to evaluate the in-vitro antioxidant and anti-inflammatory activities of ethanolic extract of seeds and fruits of Zizyphus spina-christi (ZSC) growing in Oman. Alcoholic extract of the dry powdered seeds and fruits of ZSC was obtained by cold maceration method and was subjected to preliminary phytochemical screening. Total phenolic content were estimated by using Folin-Ciocalteu reagent and 1,1-diphenyl-2-picrylhydrazyl (DPPH) was used to determine in-vitro antioxidant activity of plant extracts. Anti-inflammatory activity was investigated by protein denaturation method. Phytochemical analysis of both the extracts revealed the presence of major classes of phytochemicals such as tannins, alkaloids, flavonoids, cardiac glycosides etc.. ZSC seeds were found to contain the highest total phenolics but ZSC fruits exhibited the maximum antioxidant activity. The anti-inflammatory activity of both parts of the plant extract was significant and comparable with the standard anti-inflammatory drug, diclofenac. Based on the results of this pilot study, it can be concluded that ZSC is a good source of natural antioxidants which can be used to prevent progression of many chronic diseases. Further detailed phytochemical studies are needed to identify the chemical compounds responsible for exhibiting potent anti-inflammatory activity.

Antioxidant activity and total phenolic content of different varieties of Portulaca grandiflora

Crude extracts from the whole plant of five different varieties (white, purple red, orange, pink and red) of Portulaca grandiflora were screened for their in vitro antioxidant and total phenolic content. These plants were extracted by methanol, acetone and ethanol, respectively. Their total phenolic content as determined by Folin-Ciocalteu reagent, were ranging from 46.39-82.19 mg GAE/100 g, 36.72-56.45 mg GAE/100 g, and 41.46-85.70 mg GAE/100 g for methanolic, acetone and ethanolic extract, respectively. The antioxidant activity of plant extracts as determined by DPPH scavenging assay were ranging from 0.69-2.14 mg/mL, 1.40-4.38 mg gallic acid/g, and 7.32-29.21 mg ascorbic acid/g when expressed as IC50, GEAC and AEAC, respectively. The highest antioxidant activity was observed in acetone extract of orange variety (PG 3). Therefore, each part of the PG 3, i.e. leaf, stem and flower was separated and further evaluated. The results showed that the leaf of PG 3 contained the highest phenolic content and antioxidant activity. The present study suggests that extracts from P. grandiflora could be utilised as natural sources for antioxidant.

Preliminary phytochemical screening and in vitro antioxidant activities of Parkinsonia aculeata Linn.

Butanol and hexane leaves extracts of Parkinsonia aculeata L. (Fabaceae) were assessed for its antioxidant potential by in vitro methods. Phytochemical analysis and antioxidant activity of plant extracts were studied using different in vitro assays. UPLC analysis of extracts was carried out for the identification of chemical constituents. The total phenolic contents of the butanol and hexane leaf extract were 42 mgGAE/g and 34 mgGAE/g whereas flavonoid contents of these extracts were found to be 0.044 mgRE/g and 0.005 mgRE/g, respectively. Among both extracts, butanol extract shows maximum inhibition (%) of 93.88%, 80.02%, 52.06%, 94.68%, and 69.37% in DPPH, non-site-specific and site-specific, FTC, and TBA assays and absorbance of 0.852 and 0.522 in reducing power and CUPRAC assay at the highest concentration tested. The FRAP and TAC values of butanol extract were found to be 678 μM Fe(II)/g and 36 mgAAE/100 mg. UPLC analysis of extracts revealed the presence of various polyphenols. The tested plant extracts were found to possess potent antioxidant and free radical scavenging activity which may be due to the presence of flavonoids and polyphenols.

Effect of flavonoids content on antioxidant activity of commercial cosmetic plant extracts

Abstract The aim of this work was to evaluate the antioxidant capacity and flavonoids content in 10 commercial cosmetic plant extracts used in cosmetics industry. Antioxidant activity of plant extracts were measured using two methods: FRAP (Ferric Reducing Antioxidant Power) and TEAC (Trolox Equivalent Antioxidant Capacity). The relationship between flavonoids content and antioxidant capacity of plant extracts were checked. As a result of this research it was found that FRAP and TEAC values of plant extracts significantly depend on the flavonoids content. The highest antioxidant activity, both in FRAP and TEAC assays, was observed for arnica flowers, hawthorn flowers and lungwort herb extracts. These extracts can be used as source of natural antioxidants for the prolongation of the oxidative stability of cosmetic products. Additionally, they can replace synthetic antioxidants

Antioxidative effects of extracts from Trifolium species on blood platelets exposed to oxidative stress

Clovers (Trifolium) may possess a significant therapeutic potential, but the effects of compounds from these plants on blood platelets and haemostasis have been poorly recognized. The present study was designed to evaluate the antioxidative action of extracts from three species of clovers: Trifolium pratense, Trifolium pallidum and Trifolium scabrum in the protection of human blood platelets in vitro. Platelet suspensions were pre-incubated with crude extract and phenolic fraction of T. pratense or phenolic fractions of T. scabrum and T. pallidum, at the final concentrations of 0.5-50 μg/ml. Then, for the induction of oxidative stress, 100 μM peroxynitrite was added. The antioxidative activity of plant extracts was assessed by measurements of the level of 3-nitrotyrosine, thiol groups and lipid peroxidation products (hydroperoxides and thiobarbituric acid-reactive substances). Despite the significant differences in the composition of the investigated extracts, we observed antioxidative effects of all used mixtures. The presence of Trifolium extracts considerably reduced the peroxynitrite-mediated modifications of proteins and diminished peroxidation of lipids in platelets. Our results indicate on a strong antioxidative activity of the tested extracts-statistically significant effects were found even for the lowest concentrations (0.5 μg/ml) of all extracts. This action may be useful in the protection of blood components, very susceptible to oxidative modifications. The obtained results suggest that the examined clovers are a promising source of compounds, valuable for the protection against oxidative stress-induced damage to blood platelets.

Effects of Salvia officinalis and Thymus vulgaris on oxidant-induced DNA damage and antioxidant status in HepG2 cells

Salvia officinalis (SO) and Thymus vulgaris (TV) are medicinal plants well known for their curative powers. However, the molecular mechanisms responsible for these abilities of sage and thyme have not been fully understood yet. In this study we investigated the composition and the quantitative estimation of plant extracts, the protective effects of plant extracts against hydrogen peroxide- and 2,3-dimethoxy-1,4-naphthoquinone-induced DNA damage, and levels of enzymatic and non-enzymatic antioxidants (superoxide dismutase, glutathione peroxidase, glutathione) in human HepG2 cells. To measure antioxidative activity of plant extracts we used three assays: 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). The results showed that the oxidant-induced DNA lesions were significantly reduced in cells pre-treated with the plant extracts studied. The observed DNA-protective activity could be explained by both elevation of GPx activity in cells pre-treated with SO and TV and antioxidant activity of SO and TV.

GC/MS profiling, in vitro antioxidant, antimicrobial and haemolytic activities of Smilax macrophylla leaves

The current study has been designed to appraise the antioxidant, antimicrobial and haemolytic potential of Smilax macrophylla leaves. The n-hexane fraction was analysed by Gas Chromatography/Mass Spectrometer which revealed the presence of 38 compounds. All examined extracts and fractions of plant leaves showed significant antimicrobial activity. The haemolytic effect of the plant was found to be in a range of 3.41–8.48%. S. macrophylla leaves contained substantial level of total phenolic contents (2.2–6.2 Gallic acid equivalent mg/g) and total flavonoid contents (1.2–4.5 Catechin, mg/g) of dry plant matter. Leaf extract and fractions also exhibited a good antioxidant potential when measured by DPPH radical scavenging assay (Inhibitory concentration 50%=33.4–72.3μg/mL). The antioxidant activity of plant extracts was also studied using sunflower oil as an oxidative substrate and found that it stabilized the oil. Significant (p<0.05) variations were observed in the results. The correlation between the results of different antioxidant assays and oxidation parameters of oil indicated that leaf extracts and fractions, exhibit considerable total phenolic contents, total flavonoid contents and scavenging power, along with more potent for enhancing the oxidative stability of sunflower oil. Considering these results, S. macrophylla could be used as a source for the exploration of new antimicrobial, antioxidant agents, functional food and nutraceutical applications.

Essential Oil Constituents, Antioxidant and Antimicrobial Activities of Salvia virgata Jacq. from Iran

The chemical composition of essential oil isolated by hydrodistillation from the aerial part of Salvia virgata under different ontogenesis (pre-flowering and full-flowering) conditions were determined using Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GC-MS). Twenty nine constituents were identified in S. virgata essential oils under different ontogenesis conditions that represented 98.36 - 99.18 % of the oils. The main components of the oil were β-caryophyllene (24.58-42.54 %), caryophyllene oxide (10.25-19.88 %), sabinene (8.64-19.58 %), 1-Octen -3-Ol (7.54-8.59 %), terpinene-4-ol (4.25-6.64 %) and α-thujene (3.74-6.46 %). The total phenolic content and the antioxidant activity of plant extract were determined by Folin-Ciocalteau and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assays and ferric reducing antioxidant power (FRAP) assay respectively. Total phenols varied from 21.84 to 24.38 (mg GAE/g dw) and the IC50 in the radical scavenging assay ranged from 22.12 to 24.45 mg/ml and FRAP values ranged form 26.84 to 28.46 μM Quercetin E/g dw. Antimicrobial activity of the essential oil was evaluated using the disc diffusion method. The oils of various ontogenesis conditions showed moderate antimicrobial activity against Staphylococcus aureus and Candida albicans two medically important pathogens.

Essential Oil Composition, Total Phenolic Content, Antioxidant Activity and Antifungal Properties of Iranian Thymus daenensis subsp. daenensis Celak. as in Influenced by Ontogenetical Variation

The chemical composition of essential oil isolated by hydro distillation from the aerial parts of Thymus daenensis subsp. daenensis Celak., at different harvest times were determined using Gas Chromatography (GC) and Gas Chromatography/Mass Spectrometry (GC-MS). Twenty six components were identified in Thymus daenensis essential oils. The main components of the oil were thymol (66.62-71.49 %), p-cymene (5.52-7.12 %), β-caryophyllene (3.91-4.09 %), δ-terpinene (3.22-4.3 %) and carvacrol (2.64-2.77 %). The total phenolic content and the antioxidant activity of plant extract was determined by Folin-Ciocalteau and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assays and ferric reducing antioxidant power (FRAP) assay respectively. Total phenols varied from 18.82 to 18.97 (mg GAE/g dw) and the IC in the radical scavenging assay ranged from 8.23 to 8.46 mg/ml and FRAP values ranged form 24.23 to 26.45 µM Quercetin E/g dw. The highest thymol content and radical scavenging effect was found in flowering stage. The essential oil showed 47.89-90.34 % inhibitory properties on Alternaria solani, Fusarium solani and Rhizoctonia solani. The results showed that Flowering stage of harvesting times increased in dry plant weight, and antioxidant activity, and thymol content. Also the oil of T. daenensis has a high antifungal activities against three phathogenic fungi.

Antioxidant and antimicrobial activity of different extracts from leaves and roots of Jovibarba heuffelii (Schott.) A. Löve and D. Löve

The present study investigated antimicrobial and antioxidant activity, total phenolic content and flavonoid concentration of methanolic, acetone and ethyl acetate extracts from fresh leaves and roots of Jovibarba heuffelii (Schott.) A. Love and D. Love. The extracts were prepared and used to evaluate the antimicrobial activity against a panel of gram-positive and gram-negative bacteria as well as against fungi. Antimicrobial activity was evaluated using broth microdilution method. J. heuffelii extract showed moderate antibacterial activity, while its antifungal activity was significantly higher. The concentration of total phenolic compounds of the extracts from roots ranged from 47.98 to 31.33 mg of GAE/g. The concentrations of flavonoids in the tested plant extracts ranged from 5.26 to 16.44 mg of RuE/g. The high contents of total phenolic compounds and flavonoids indicated that these compounds contribute to the antimicrobial activity. Antioxidant activity of plant extracts was examined in vitro using 2,2-diphenyl-1-picrylhydrazyl (DPPH) reagent and compared with the reference substances values (3-tert-butyl-4-hydroxyanisole (BHA), rutin, chlorogenic acid). The results pointed to high antioxidant activity of phenolic compounds in J. heuffelii extracts.

Antioxidant and hepatoprotective effects of Oxalis corniculata against carbon tetrachloride (CCl4) induced injuries in rat

Many human diseases are caused due to oxidative stress involving excessive production of free radicals that can be ameliorated by the antioxidant activities of plant extracts. Present study was designed to characterize the chemical composition of Oxalis corniculata methanol extract (OCME) and its various fractions; O. corniculata n-hexane (OCHE), O. corniculataethyl acetate (OCEE), O. corniculata chloroform (OCCE) and O. corniculata aqueous (OCAE); and to determine the antioxidant potential by different in vitro assays. OCME was also evaluated for its antioxidant capacity against hepatotoxicity induced with carbon tetrachloride (CCl4: 1 ml/kg b.w., 20% in olive oil, seven doses) in rat. The results showed the presence of flavonoids, alkaloids, terpenoids, saponins, cardiac glycosides, phlobatannins and steroids in OCME while tannins were absent. Total amount of phenolic and flavonoids was affected by the solvents and the sequence of solvents for phenolic contents was OCME > OCAE > OCCE > OCEE > OCHE while for flavonoids was OCME > OCCE > OCAE > OCEE > OCHE. Free radicals were scavenged by the extract/fraction in a dose response curve in all models. Biochemical parameters of serum; aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), gamma-glutamyl transpeptidase (γ-GT), total bilirubin, cholesterol and triglycerides were significantly increased while total protein and albumin were decreased by CCl4. Treatment of CCl4 significantly decreased the liver contents of reduced glutathione (GSH) and activities of antioxidant enzymes; catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), glutathione-S-transferase (GST), glutathione reductase (GSR) and quinone reductase (QR) whereas elevated the thiobarbituric acid reactive substances (TBARS) contents, and hepatic lesions. All the parameters were brought back to control levels by the supplement of OCME. The results of the present study suggest the antioxidant potential of OCME and its fractions as evidenced by scavenging of free radicals and hepatoprotective capacity. Key words: Oxalis corniculata, carbon tetrachloride (CCl4), 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS), diphenylpicrylhydrazyl (DPPH), hepatoprotective, lipid peroxidation.

Phytochemical composition of the essential oil, total phenolic content, antioxidant and antimicrobial activity in Iranian Satureja sahendica Bornm. at different ontogenesis conditions

The effects of different ontogenesis conditions (pre-flowering, full-flowering and post flowering) on the yield, essential oil composition, total phenolic content, antioxidant and antimicrobial activity of Satureja sahendica Bornm. was investigated. The essential oil was obtained from the aerial parts of the plant by hydro distillation and analyzed by gas chromatography (GC) and gas chromatography–mass spectrometry (GC-MS). In total, 33 components were identified in the essential oil of S. sahendica under different harvesting times, that represented 98.54 to 98.72% of the oils. The major components were thymol (28.76 to 42.24%), P-cymene (23.89 to 34.33%), γ-terpinene (13.78 to 19.37%) and myrcene (1.87 to 2.28). The highest essential oil yield was obtained in flowering stage. The highest thymol content was observed in the pre-flowering and the highest p-cymene and γ-terpinene contents as precursors of thymol and carvacrol were observed in flowering and post-flowering stages. Total phenolics and antioxidant activity of plant extracts were measured by the Folin-Ciocalteu and DPPH free radical scavenging assays, respectively. The total phenolic content under different ontogenesis conditions varied from 24.78 to 25.56 (mg gallic acid equivalent/g dw). IC50 values in the DPPH assay ranged from 7.85 to 8.34 μg/ml and the highest activity was observed in pre-flowering stage. Antimicrobial activity of the essential oil of S. sahendica was evaluated using the disc diffusion method; and minimum inhibitory concentrations (MIC) and minimum fungicidal/bactericidal concentrations (MFC/MBC) were recorded using the micro dilution method. This study confirms that the essential oil of S. sahendica possesses high antimicrobial activities in in vitro against Candida albicans and Staphylococcus aureus, two medically important pathogens. The maximum activity of S. sahendica oil was observed in the oil obtained at pre-flowering stage, against Gram-positive bacteria (S. aureus) and the yeast (C. albicans).

ANTIOXIDANT POTENTIAL IN LIPOPHILIC AND HYDROPHILIC EXTRACTS FROM MEDICINAL HERBS (&lt;i&gt;SALVIA OFFICINALIS&lt;/i&gt; AND &lt;i&gt;ECHINACEA ANGUSTIFOLIA&lt;/i&gt;). A COMPARISON BETWEEN ASSAYS BASED ON ELECTRON PARAMAGNETIC RESONANCE AND SPECTROPHOTOMETRY

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.

Improving meat quality through natural antioxidants

Nowadays, consumers are demanding more natural foods, obliging the industry to include natural antioxidants in foods. Natural antioxidants have been used instead of synthetic antioxidants to retard lipid oxidation in foods to improve their quality and nutritional value. This review discusses some aspects of recent research on antioxidant activity of plant extracts and natural compounds to improve meat quality. Many herbs, spices, and their extracts have been reported as having high antioxidant capacity, such as some plants of the Lamiaceae family, e.g., oregano (Origanum vulgare L.), rosemary (Rosmarinus officinalis L.), and sage (Salvia officinalis L.). The antioxidant activity of these plants is attributed to their phenolic compound content, which includes volatile compounds also known as essential oils. Several factors that cause some differences on the antioxidant activity of plant extracts include: type of solvent used during extraction, measurement method, and number of samples. Some studies have demonstrated that shelf-life and meat quality can be improved by using natural antioxidants in some stages of meat production. The main effects of these compounds are reducing microbial growth and lipid oxidation during storage. Nevertheless, more research is needed to determine antimicrobial activity of natural antioxidants in meat during storage, identify the main metabolic pathway of these compounds, and its effect on other meat quality parameters.

Antioxidant activities, total phenolics and HPLC analyses of the phenolic compounds of extracts from common Mediterranean plants

In this study, the total phenolic amounts and antioxidant activities of plant extracts obtained from some common Mediterranean plant species collected from different places in Jordan were determined. The phenolic constituents of these extracts were also determined using HPLC. The total phenolic amounts ranged from 52.8 to 876.9 mg GAE per 100 g dry material. The antioxidant activities were evaluated according to the 2,2-diphenyl-1-picrylhydrazyl radical scavenger method. Sage (Salvia officinalis) showed the highest antioxidant activity (91%), while the lowest (11.3%) was seen in parsley (Petroselinum crispum). A strong correlation (r = 0.85) between antioxidant activity and total phenolic content was found. The phenolic compounds identified by HPLC were gallic acid, protocatechuic acid, catechin, gentisic acid, chlorogenic acid, vanillic acid, syringic acid, caffeic acid, epicatechin and benzoic acid. All the investigated plants contain gallic acid, whose phenolic content ranged from 0.4 to 37.8 mg per 100 g, catechin (0.3–339.9 mg per 100 g), protocatechuic acid (0.3–41.9 mg per 100 g) and gentisic acid (0.3–35.8 mg per 100 g), while caffeic acid (0.3–2.6 mg per 100 g) was detected in six species only. These natural plant phenolics could thus be a good source of antioxidants for applications in food.

Contribution of major lipophilic antioxidants to the antioxidant activity of basil extracts: an EPR study

The present research analyses the contribution of some lipid antioxidants to the antioxidant activity of lipophilic extracts from basil by an electron paramagnetic resonance (EPR) study using the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH). DPPH assay is considered an easy and accurate method with regard to measuring the antioxidant activity of plant extracts and EPR has already been employed to determine antioxidant activities of lipophilic plant extracts. Lipid extracts were obtained from basil grown hydroponically for 20 or 35 days from sowing and in soil for 35 days from sowing. Fast and slow rate constants were distinguishable in the decay kinetics of DPPH mixture added with lipid extract. Antioxidants with kinetics characterized by a fast decay rate were tocopherols and chlorophylls, whereas those characterized by a slow decay rate were carotenoids, among which were β-carotene, lutein, β-apo-8'-carotenal and zeaxanthin. The 20-day hydroponically grown sample, which showed higher contents of tocopherol, chlorophyll and carotenoid molecules, was the sample endowed with the higher content of fast lipophilic antioxidants (FLA) and slow lipophilic antioxidants (SLA). The three samples showed different compositions of FLA and SLA, giving rise to different decay kinetics. Despite the differences, in all samples tocopherol contributed about 0.3% to the bulk of FLA, whereas the figure for chlorophyll was about 40%, evidencing the relevant but little-studied role of chlorophyll as an antioxidant.