Walnut (Juglans regia L.) leaves: phenolic compounds, antibacterial activity and antioxidant potential of different cultivars.

Different cultivars of walnut (Juglans regia L.) leaves (Cv. Lara, Franquette, Mayette, Marbot, Mellanaise and Parisienne) grown in Portugal, were investigated in what concerns phenolic compounds and antimicrobial and antioxidant properties. Phenolics analysis was performed by reversed-phase HPLC/DAD and 10 compounds were identified and quantified: 3- and 5-caffeoylquinic acids, 3- and 4-p-coumaroylquinic acids, p-coumaric acid, quercetin 3-galactoside, quercetin 3-pentoside derivative, quercetin 3-arabinoside, quercetin 3-xyloside and quercetin 3-rhamnoside. The antimicrobial capacity was screened against Gram positive (Bacillus cereus, B. subtilis, Staphylococcus aureus) and Gram negative bacteria (Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae) and fungi (Candida albicans, Cryptococcus neoformans). Walnut leaves selectively inhibited the growth of Gram positive bacteria, being B. cereus the most susceptible one (MIC 0.1mg/mL). Gram negative bacteria and fungi were resistant to the extracts at 100mg/mL. Lara walnut leaves were also submitted to antibacterial assays using 18 clinical isolates of Staphylococcus sp. Antioxidant activity was accessed by the reducing power assay, the scavenging effect on DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals and beta-carotene linoleate model system. In a general way, all of the studied walnut leaves cultivars presented high antioxidant activity (EC(50) values lower than 1mg/mL), being Cv. Lara the most effective one.     

Bioactive properties and chemical composition of six walnut (Juglans regia L.) cultivars

The chemical composition, antioxidant potential and antimicrobial activity were studied in six walnuts (Juglans regia L.) cultivars (cv. Franquette, Lara, Marbot, Mayette, Mellanaise and Parisienne) produced in Portugal. Concerning their chemical composition the main constituent of fruits was fat ranging from 78.83% to 82.14%, being the nutritional value around 720 kcal per 100 g of fruits. Linoleic acid was the major fatty acid reaching the maximum value of 60.30% (cv. Lara) followed by oleic, linolenic and palmitic acids. The aqueous extracts of walnut cultivars were investigated by the reducing power assay, the scavenging effect on DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals and β-carotene linoleate model system. All the walnut extracts exhibited antioxidant capacity in a concentration-dependent manner being the lowest EC₅₀ values obtained with extracts of cv. Parisienne. Their antimicrobial capacity was also checked against gram positive (Bacillus cereus, Bacillus subtilis, Staphylococcus aureus) and gram negative bacteria (Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae) and fungi (Candida albicans, Cryptococcus neoformans), revealing activity against the different tested microorganisms.     

Antioxidant properties, total phenols and pollen analysis of propolis samples from Portugal

Pollen analysis, total phenols content and antioxidant activity were studied for the first time in Portuguese propolis samples from Bornes and Fundão regions. Total phenols content was determined by colorimetric assay and their amount was of 329 mg/g of GAE in Bornes sample and 151 mg/g of GAE in Fundão propolis. The antioxidant capacity of propolis extracts was assessed through the scavenging effects on DPPH (2,2-diphenyl-1-picrylhydrazyl) and reducing power of iron (III)/ ferricyanide complex assays. A concentration-dependent antioxidative capacity was verified in DPPH and reducing power assays. Low values of EC₅₀ on DPPH scavenging assay were obtained for Bornes and Fundão propolis (of 6.22 μg/mL and 52.00 μg/mL, respectively). For reducing power the values were 9.00 μg/mL, for Bornes propolis, and 55.00 μg/mL, for Fundão propolis. The high activity of propolis from Bornes could be related with their different pollen composition. The results obtained indicate that Portuguese propolis is an important source of total phenols showing antioxidant properties that could be beneficial for human health.     

Chemical composition, and antioxidant and antimicrobial activities of three hazelnut (Corylus avellana L.) cultivars.

Hazelnut (Corylus avellana L.) is a very popular dry fruit in the world being consumed in different form and presentations. In the present work, three hazelnut cultivars (cv. Daviana, Fertille de Coutard and M. Bollwiller) produced in Portugal, were characterized in respect to their chemical composition, antioxidant potential and antimicrobial activity. The samples were analysed for proximate constituents (moisture, fat, crude protein, ash), nutritional value and fatty acids profile by GC/FID. Antioxidant potential was accessed by the reducing power assay, the scavenging effect on DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals and beta-carotene linoleate model system. Their antimicrobial capacity was also checked against Gram positive (Bacillus cereus, B. subtilis, Staphylococcus aureus) and Gram negative bacteria (Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae) and fungi (Candida albicans, Cryptococcus neoformans). Results showed that the main constituent of fruits was fat ranging from 56% to 61%, being the nutritional value around 650 kcal per 100 g of fruits. Oleic was the major fatty acid varying between 80.67% in cv. F. Coutard and 82.63% in cv. Daviana, followed by linoleic, palmitic, and stearic acids. Aqueous hazelnut extract presented antioxidant activity in a concentration-dependent way, in general with similar behaviour for all cultivars. Hazelnut extracts revealed a high antimicrobial activity against Gram positive bacteria (MIC 0.1 mg/mL) showing a good bioactivity of these fruits.     

Human cancer cell antiproliferative and antioxidant activities of Juglans regia L.

Several studies suggest that regular consumption of nuts, mostly walnuts, may have beneficial effects against oxidative stress mediated diseases such as cardiovascular disease and cancer. Walnuts contain several phenolic compounds which are thought to contribute to their biological properties. The present study reports the total phenolic contents and antioxidant properties of methanolic and petroleum ether extracts obtained from walnut (Juglans regia L.) seed, green husk and leaf. The total phenolic contents were determined by the Folin–Ciocalteu method and the antioxidant activities assessed by the ability to quench the stable free radical 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and to inhibit the 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced oxidative hemolysis of human erythrocytes. Methanolic seed extract presented the highest total phenolic content (116 mg GAE/g of extract) and DPPH scavenging activity (EC₅₀ of 0.143 mg/mL), followed by leaf and green husk. In petroleum ether extracts, antioxidant action was much lower or absent. Under the oxidative action of AAPH, all methanolic extracts significantly protected the erythrocyte membrane from hemolysis in a time- and concentration-dependent manner, although leaf extract inhibitory efficiency was much stronger (IC₅₀ of 0.060 mg/mL) than that observed for green husks and seeds (IC₅₀ of 0.127 and 0.121 mg/mL, respectively). Walnut methanolic extracts were also assayed for their antiproliferative effectiveness using human renal cancer cell lines A-498 and 769-P and the colon cancer cell line Caco-2. All extracts showed concentration-dependent growth inhibition toward human kidney and colon cancer cells. Concerning A-498 renal cancer cells, all extracts exhibited similar growth inhibition activity (IC₅₀ values between 0.226 and 0.291 mg/mL), while for both 769-P renal and Caco-2 colon cancer cells, walnut leaf extract showed a higher antiproliferative efficiency (IC₅₀ values of 0.352 and 0.229 mg/mL, respectively) than green husk or seed extracts. The results obtained herein strongly indicate that walnut tree constitute an excellent source of effective natural antioxidants and chemopreventive agents.     

Antioxidant,anti-microbial and antimutagenicity activities of pistachio (Pistachia vera) green hull extract

Antioxidant, anti-microbial and antimutagenicity activities of pistachio (Ahmadaghaei variety) green hull extracts (crude and purified extracts) were studied. At first, different solvents were compared for determining of the best solvent for extraction of phenolic compounds from pistachio green hull. Water and acetonitrile with 49.32 and 6.22 (mg of gallic acid equivalents/g sample) were the best and the worst solvent in the extraction of phenolic compounds, respectively. The antioxidant capacity of crude and purified extracts were assessed through ABTS assay, DPPH assay and β-carotene bleaching (BCB) method. A concentration-dependent antioxidative capacity was verified in ABTS, DPPH assays and BCB method. The anti-microbial capacity was screened against Gram positive and Gram negative bacteria, and fungi. Aqueous and purified extracts inhibited the growth of Gram positive bacteria; Bacillus cereus was the most susceptible one with MIC of 1 mg/mL and 0.5 mg/mL for the crude and purified extracts, respectively. The results of antimutagenicity test showed that phenolic compounds of pistachio green hull have antimutagenicity activity against direct mutagen of 2-nitrofluorene. The results obtained indicate that pistachio green hull may become important as a cheap and noticeable source of compounds with health protective potential and anti-microbial activity.     

Melilotus albus and Dorycnium herbaceum extracts as source of phenolic compounds and their antimicrobial,antibiofilm, and antioxidant potentials

Melilotus albus Medic. and Dorycnium herbaceum Vill. (Fabaceae) acetone, ethyl acetate, and ethanol extracts were investigated for their in vitro antimicrobial, antibiofilm, and anti-oxidant activity with quantification of phenolic compound contents. In general, D. herbaceum extracts showed better antibacterial and antioxidant activity than M. albus extracts. Bacteria Bacillus subtilis, Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa, and Proteus mirabilis were the most susceptible with the minimum inhibitory concentrations (MICs), determined by microdilution method, between 1.25–10 mg/mL. Antifungal activity was lower with the detectable MICs at 10 mg/mL and 20 mg/mL. The plant extracts, using the crystal violet assay, inhibit P. aeruginosa biofilm formation in concentration range from 5 mg/mL to 20 mg/mL whereas the effect on mature bacterial biofilm was lower. The antioxidant activity was evaluated using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radicals scavenging and reducing power model systems. The intensity of DPPH radicals scavenging activity, expressed as half maximal effective concentration (EC₅₀) values, was from 84.33 μg/mL to >1000 μg/mL. The extracts demonstrated reduced power in a concentration-dependent manner, with ethanol extract as the most active. The total phenols, flavonoids, and proanthocyanidins were determined spectrophotometrically while total extractable tannins were obtained by precipitation method. The phenolic compounds showed differences in their total contents depending on solvents polarities and plant species. Although the plants M. albus and D. herbaceum have not yet been fully explored, these results contribute better understanding of their biotic properties and potential application as antimicrobial and antioxidant agents.     

Medicinal Potential of the Root of Arctotis arctotoides.

Abstract

The antioxidant and antimicrobial activity of the acetone, methanol, and water extracts from the root of Arctotis arctotoides. (L.f.) O. Hoffm (Asteraceae) were assessed in an effort to validate the medicinal potential of the subterranean part of the herb. The antioxidant activities of acetone and methanol extracts as determined by the ABTS, DPPH, and FRAP methods were higher than that of water extracts. The extracts showed significant activity against both Gram-positive and Gram-negative bacteria. The strongest activity was found in the acetone extract on Bacillus cereus., Staphylococcus aureus., Micrococcus kristinae., and Streptococcus pyrogens. with an MIC of 0.1 mg/mL. Although not completely fungicidal, these extracts showed significant growth inhibition against all the fungi tested. Antioxidant and antimicrobial activities of the extracts were strongly correlated with total phenols and to a lesser extent with their flavonoids and proanthocyanidins contents. This study has validated the medicinal potential of the underground part of A. arctotoides..     

Extracts of Agrimonia eupatoria L. as sources of biologically active compounds and evaluation of their antioxidant,antimicrobial, and antibiofilm activities

In this study, we determined the concentration of total phenols, flavonoids, tannins, and proanthocyanidins in the water, diethyl ether, acetone, and ethanol extracts of Agrimonia eupatoria L. We also investigated the antioxidant activity of these extracts using two methods [2,2-diphenyl-1-picrylhydrazyl (DPPH) and reducing power] and their in vitro antimicrobial (antibacterial and antifungal) activity on some selected species of bacteria and fungi. In addition, the effects of the acetone and water extracts on the inhibition of biofilm formation of Proteus mirabilis and Pseudomonas aeruginosa were investigated using the crystal violet method. The concentration of total phenols was measured according to the Folin–Ciocalteu method and the values obtained ranged from 19.61 mgGA/g to 220.31 mgGA/g. The concentration of flavonoids was examined by the aluminum chloride method and the values obtained ranged from 20.58 mgRU/g to 97.06 mgRU/g. The total tannins concentration was measured by the polyvinylpolypyrrolidone method and the values obtained ranged from 3.06 mgGA/g to 207.27 mgGA/g. The concentration of proanthocyanidins was determined by the butanol–HCl method and the values obtained ranged from 4.15 CChE/g to 103.72 CChE/g. Among the various extracts studied, the acetone extract exhibited good antioxidant activity (97.13%, as determined by the DPPH method). The acetone extract was active in the absorbance value range from 2.2665 to 0.2495 (as determined by the reducing power method). The strongest antimicrobial activity was detected on G⁺ bacteria, especially on probiotic species, and the acetone extract demonstrated the highest activity. Biofilm inhibitory concentration required to reduce biofilm coverage by 50% values for acetone extract was 4315 μg/mL for P. mirabilis and 4469.5 μg/mL for P. aeruginosa. The results provide a basis for further research of this plant species.     

Coffee silverskin: A possible valuable cosmetic ingredient

Abstract

Context: Currently, there is a great tendency in cosmetic area to use natural extracts. Coffee silverskin (CS) is the most abundant solid by-product generated during roasting of coffee processing.

Objectives: To evaluate different CS extracts as promising cosmetic ingredients, regarding antioxidant, antimicrobial, and cytotoxic properties.

Materials and methods: Aqueous, hydroalcoholic and ethanolic CS extracts were obtained by an environmentally friendly procedure considering costs and pollution. Extracts were characterized for total phenolic and flavonoid contents (TPC and TFC, respectively), antioxidant activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), antimicrobial activity expressed as minimal inhibitory concentration (MIC) and cytotoxicity using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) and lactate dehydrogenase (LDH) assays in two skin cell lines (fibroblasts and keratinocytes).

Results: The TPC of extracts was 18.33–35.25?mg of gallic acid equivalents per g of material on a dry basis (mg GAE/g?db). The TFC of extracts was 1.08–2.47?µg cathechin equivalents per g dry material (µg CE/g db). The antioxidant activity was high, with values ranging between 95.95 and 216.40?µmol Fe²⁺/g for aqueous and alcoholic samples, respectively. Preliminary assays for antimicrobial potential showed that extracts display antibacterial activity. The MIC varied from 31.3 to 250?µg/mL for Gram-positive, and from 31.3 to 1000?µg/mL for Gram-negative. Extracts did not affect in vitro cell viability, with values near 100% in all concentrations tested.

Conclusion: Results seem show that CS is a safe source of natural antioxidants with antifungal and antibacterial activity and no cytotoxicity, with potential usefulness for cosmetic applications.     

Antioxidant activity of selected plant species; potential new sources of natural antioxidants

The aim of this study was to examine six plants from Serbia for their potential antioxidant activity. Therefore, six antioxidant activity assays were carried out, including: total antioxidant capacity, DPPH free-radical scavenging, the inhibitory activity toward lipid peroxidation, Fe³⁺- reducing power, Fe²⁺- chelating ability and hydroxyl radical scavenging activity. Total phenolic and flavonoid contents were also determined for each alcoholic extract. Cotinus coggygria extract contained the highest amount of total phenols (413 mg GAE /g dry extract), while the highest proportion of flavonoids was found in the Echium vulgare methanol extract (105 mg RU/g). Cotinus coggygria and Halacsya sendtneri alcoholic extracts showed the highest total antioxidant capacity (313 and 231 mg AA/g dry extract), as well as DPPH free-radical scavenging (IC₅₀ = 9 and 99 μg/ml), inhibitory activity toward lipid peroxidation (IC₅₀ = 3 and 17 μg/ml) and reducing power. Whereas, the greatest hydroxyl radical scavenging activity, as well as ferrous ion chelating ability showed Echium vulgare, Echium rubrum and Halacsya sendtneri.     

In vitro antioxidant activity of Bombax malabaricum flower extracts

Context: Bombax malabaricum DC. (Bombacaceae) is a traditional Chinese herbal medicine used for the treatment of inflammatory conditions, diarrhea, fever, chronic inflammation, catarrhal affection, and as a diuretic. However, little information is available about its antioxidative activity.

Objective: Water, 50% ethanol, and 80% acetone extracts from flowers of B. malabaricum were investigated for their in vitro antioxidant activity in this article for the first time. Then the relationships between antioxidant activity measured by different methods and total phenolic content (TPC) and total flavonoid content (TFC) were established.

Materials and methods: The antioxidant activities of extracts from B. malabaricum flower were investigated including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity, oxygen radical absorbance capacity (ORAC), reducing power, and inhibition on phosphatidylcholine liposome peroxidation.

Results: Results showed that all the extracts possessed remarkable antioxidant capacity compared with ascorbic or gallic acids. Total antioxidant activities evaluated by ORAC assay of different extracts ranged from 700.03 to 1482.46 μmol Trolox equivalents/g. The highest TPC of 130.38?mg gallic acid equivalents (GAE)/g was observed in 80% acetone extract, whereas the lowest TPC of 57.09?mg GAE/g was obtained in the water extract. Furthermore, TFC exhibited significant (P?<?0.05) positive correlations with DPPH radical-scavenging activity, ORAC, and reducing power.

Discussion and conclusion: These findings demonstrate that the flowers of B. malabaricum have excellent antioxidant activities and thus might be a potential source of natural antioxidants.     

Chemical composition,antioxidant and antibacterial activities of two Spondias species from Northeastern Brazil

Context: The leaves of Spondias tuberosa Arr. Cam. (Anacardiaceae) and Spondias mombin L. have been traditionally used for medicinal purposes. Some studies reveal their antibacterial, antimicrobial, and antiviral properties.

Objective: Determine the chemical composition, antioxidant, and antimicrobial activities of Spondias species to justify its ethnopharmacological use.

Materials and methods: Spondias species extracts were prepared with methanol:water 80:20 and analyzed by silica gel column chromatography and reversed phase liquid chromatography (HPLC). The antioxidant activity was evaluated by scavenging the radicals 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and 2,2-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS?+) and measuring antimicrobial activity (agar well diffusion method, minimum inhibitory concentration and minimum bactericidal concentrations).

Results: The HPLC analysis of Spondias extracts demonstrated the occurrence of high yield of flavonoids. Found in S. mombin were quercetin (2.36?±?0.01?mg/g) and ellagic acid (41.56?±?0.01?mg/g) and in S. tuberosa species rutin (53.38?±?1.71?mg/g), quercetin (24.46?±?0.87?mg/g), and ellagic acid (169.76?±?0.17?mg/g). The antibacterial activity of the extracts against the various bacteria strains varied from 8.8 to 20.1?mm. MIC values from 62.5 to 125 µg/mL were satisfactory when compared with other plant products. Medium DPPH scavenging activity IC₅₀ for Spondias extracts varied from 0.042 to 0.558?mg/mL and for ABTS from 0.089 to 0.465?mg/mL. DPPH scavenging activity for constituent ellagic acid IC₅₀?=?0.042?mg/mL and for quercetin IC₅₀?=?0.081?mg/mL.

Discussion and conclusion: The chemical study of Spondias leaf extracts showed the occurrence of quercetin, rutin and ellagic acid, substances with relevant antioxidant and antimicrobial activities.     

Comparative analysis of the antioxidant and DNA protection capacities of Anadenanthera colubrina, Libidibia ferrea and Pityrocarpa moniliformis fruits

This study aimed to explore the antioxidant and DNA protection abilities of hydroalcoholic extracts from fruits of Anadenanthera colubrina (ACHE), Libidibia ferrea (LFHE) and Pityrocarpa moniliformis (PMHE). These extracts were tested by five antioxidant methods (phosphomolibdenium and reducing power assays; superoxide, hydrogen peroxide and nitric oxide scavenging) and DNA protection capacity. Total phenolic content was measured by Folin-Ciocalteu method. ACHE exhibited the highest phenolic content (578 mg/g GAE), followed by LFHE (460 mg/g GAE) and PMHE (448 mg/g GAE). In phosphomolibdenium assay, ACHE showed 24.81% of activity in relation to ascorbic acid, whereas LFHE and PMHE had 21.08% and 18.05%, respectively. These plants showed high ability to inhibit reactive species tested with IC50 values ranged from 10.66 to 14.37 μg/mL for superoxide radical; 26.05 to 45.43 μg/mL for hydrogen peroxide; 178.42 to 182.98 μg/mL for reducing power; and 199.2 to 283 μg/mL for nitric oxide. Furthermore, these extracts had capacity to break the DNA damage induced by hydroxyl radicals. The antioxidant activity of these plants is related with their higher phenolic content and show that they may be used as source of bioactive compounds, relevant to the maintenance of oxidative stability of the food matrix, cosmetics and/or pharmaceutical preparations.     

Antioxidant activity and total phenolic content of methanol extracts of Ixora coccinea

Objective: To investigate the in vitro antioxidant activity of methanol extracts of Ixora coccinea L. (Rubiaceae) flower, leaf and stem.

Materials and methods: The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, total antioxidant capacity (TAC) and xanthine oxidase inhibition assay were carried out to evaluate the antioxidant potential of the extract. The IC₅₀ values were calculated for the DPPH and xanthine oxidase assays in order to evaluate the antioxidant efficiency of each of the I. coccinea extracts. The phenol contents were also determined.

Results: I. coccinea flowers revealed the best antioxidant property, presenting much lower IC₅₀ value (6.6?mg/mL for DPPH assay). The flower extract showed a significantly higher antioxidant capacity compared to the other extracts. Furthermore, the highest phenolic content (polyphenols) was found in the flower extract (210.55?±?6.31 µg GAE/mg extract). Moreover, I. coccinea extracts scavenged the superoxide radical generated by the xanthine/xanthine oxidase system. The xanthine oxidase inhibition activity was in the order of allopurinol > leaf > flower > stem with the percentage of inhibition ranged from 39.7% to 77.3% for the plant parts investigated. The highest phenolic contents (polyphenols) were found in the flower extracts (210.55?±?6.31 µg GAE/mg extract).

Conclusions: I. coccinea could be considered as a potential source of natural antioxidant.     

Efficacy of Bottle Gourd Seeds’ Extracts in Chemical Hazard Reduction Secreted as Toxigenic Fungi Metabolites

Bottle gourd seeds are surrounded by innumerable bioactive components of phytochemicals. This work aimed to evaluate the effectiveness of bottle gourd extracts as antimicrobial and an-ti-mycotoxigenic against toxigenic fungi and mycotoxins. Polar and nonpolar extracts were made from the seeds. The polar eco-friendly extract was prepared by an ultrasonication-assisted technique utilizing aqueous isopropanol (80%), whereas the non-polar extract was obtained using petroleum ether (40–60). The antioxidant efficacy, total phenolic content, and flavonoid content of the extracts were all measured. The fatty acid profile was measured using GC equipment, and the influence on toxigenic fungus and mycotoxin release was also investigated. The antioxidant efficacy of the polar extract is reflected. The total phenolic values of the oil and polar extract were 15.5 and 267 mg of GAE/g, respectively. The total flavonoid content of the oil was 2.95 mg catechol/g, whereas the isopropyl extract of seeds contained 14.86 mg catechol/g. The polar extract inhibited the DPPH more effectively than oil. When compared to other seed oils, the fatty acid composition differed. The pathogens were distinguished by the MIC and MFC for the polar extract. Three sterols were found in the oil, with a high concentration of B-sitosterols. The oil’s valuable -carotene content and tocopherol content were recorded. When compared to traditional antibiotics, the polar extract has shown promising antimicrobial activity against infections and toxigenic fungi. Bottle gourd extracts, as a non-traditional bioactive source, are viewed as a potentially promising alternative that might contribute to increased food safety, shelf-life, and security.     

Scavenging capacity of strawberry tree (Arbutus unedo L.) leaves on free radicals

Despite strawberry tree (Arbutus unedo L.) leaves had a long use in traditional medicine due to its antiseptic, diuretic, astringent and depurative properties, the potential of their antioxidant activity are still lacking. Our study goals to assess the antioxidant and free radical scavenging potential of water, ethanol, methanol and diethyl ether extracts of A. unedo leaves. Total phenols content was achieved spectrophotometrically using Folin–Ciocalteau reagent with gallic acid as standard. Antioxidant activity was evaluated using three different methods: reducing power of iron (III)/ferricyanide complex assay, scavenging effect on DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals and scavenging effect on superoxide radicals by using the PMS–NADH–nitroblue tetrazolium system. Ethanol extracts of A. unedo leaves were the highest in reducing power (IC₅₀ 232.7 μg/mL) and DPPH scavenging effect (IC₅₀ 63.2 μg/mL) followed by water extracts (with IC₅₀ of 287.7 and 73.7 μg/mL, respectively); whereas diethyl ether extracts were the lowest. In the scavenging on superoxide radical assay, methanol extracts obtained the best results (IC₅₀ 6.9 μg/mL). For all the methods tested the antioxidant activity was concentration dependent. In accordance with antioxidant activity, highest total phenols content were found in ethanol, followed by water, methanol and diethyl ether extract. The results indicated that A. unedo leaves are a potential source of natural antioxidants.     

Antioxidant and antimicrobial activities of branches extracts of five Juniperus species from Turkey

Context: Several Juniperus species (Cupressaceae) are utilized in folk medicine in the treatment of infections and skin diseases.

Objective: This work was designed to evaluate the antioxidant and antimicrobial potential of methanol and water branches extracts of Juniperus species from Turkey: Juniperus communis L. var. communis (Jcc), Juniperus communis L. var. saxatilis Pall. (Jcs), Juniperus drupacea Labill. (Jd), Juniperus oxycedrus L. subsp. oxycedrus (Joo), Juniperus oxycedrus L. subsp. macrocarpa (Sibth. & Sm.) Ball. (Jom).

Materials and methods: Total phenolics, total flavonoids and condensed tannins were spectrophotometrically determined. The antioxidant properties were examined using different in vitro systems. The toxicity was assayed by Artemia salina lethality test. The antimicrobial potential against bacteria and yeasts was evaluated using minimum inhibitory concentration and minimum bactericidal concentration (MIC/MBC) measurements. The effect on bacteria biofilms was tested by microtiter plate assay.

Results: Both in the DPPH (1,1-diphenyl-2-picrylhydrazyl) and TBA (thiobarbituric acid) test Jom resulted the most active (IC₅₀?=?0.034?±?0.002?mg/mL and 0.287?±?0.166 µg/mL). Joo exhibited the highest reducing power (1.78?±?0.04 ASE/mL) and Fe²⁺ chelating activity (IC₅₀?=?0.537?±?0.006?mg/mL). A positive correlation between primary antioxidant activity and phenolic content was found. The extracts were potentially non-toxic against Artemia salina. They showed the best antimicrobial (MIC?=?4.88-30.10 µg/mL) and anti-biofilm activity (60–84%) against S. aureus.

Discussion and conclusion: The results give a scientific basis to the traditional utilization of these Juniperus species, also demonstrating their potential as sources of natural antioxidant and antimicrobial compounds.     

Chemical composition of five wild edible mushrooms collected from Southwest China and their antihyperglycemic and antioxidant activity

Evaluation of the chemical composition and antihyperglycemic and antioxidant activity of five wild edible mushrooms (Clitocybe maxima, Catathelasma ventricosum, Stropharia rugoso-annulata, Craterellus cornucopioides and Laccaria amethystea) from Southwest China. The chemical composition assay includes proximate analysis (moisture, ash, crude protein, crude fat, total carbohydrates and total energy), bioactive compounds analysis (total phenolic, flavonoid, ascorbic acid, ergosterol, tocopherol), fatty acid analysis, amino acid analysis, phenolic compounds analysis and mineral analysis of these mushrooms. Furthermore, assays of α-glucosidase inhibitory and α-amylase inhibitory activity were used for evaluating antihyperglycemic activity of the mushrooms, and assays of reducing power, chelating effect on ferrous ions, scavenging effect on hydroxyl free radicals and 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity were used for evaluating antioxidant activity of the mushrooms. Based on the results, ethanolic and aqueous extract of these mushroom all showed antihyperglycemic and antioxidant potential. In particular, the aqueous extract of C. ventricosum revealed the highest α-glucosidase inhibitory activity (EC50 value 2.74 μg/mL), DPPH radical scavenging activity (EC50 value 2.86 mg/mL) and reducing power (EC50 value 0.96 mg/mL), while the aqueous extract of L. amethystea showed the highest α-amylase inhibitory activity (EC50 value 4.37 μg/mL) and metal chelating activity (EC50 value 2.13 mg/mL).     

Antioxidant and antimicrobial activities of ethanol and aqueous extracts from Urtica urens

Context: Urtica urens L. (Urticaceae) is an important and commonly used plant for its medicinal and pharmacological properties.

Objective: We analyzed the antioxidant and antimicrobial activities of the leaves of Urtica urens in ethanol (EtOH) and water (WA) solvents, employing standard analytical methods.

Materials and methods: Polyphenol, flavonoid and tannin content of Urtica urens leaves were determined, after their extraction, using EtOH (70%) and WA extracts as well as the antioxidant (DPPH, ABTS, β-carotene and FRAP) and the antibacterial (via the method of dilution tests) activities of EtOH and WA extracts.

Results: The 70% EtOH of Urtica urens showed the highest values of total phenolic (31.41?mg GAE/g DW), flavonoids (6.81?mg quercetin/g DW), tannin (8.29?mg GAE/g DW) and TEAC (560?mmol Trolox/g DW), compared to the WA. The results of DPPH for EtOH (95.56%) were higher than that of WA (64.56%) at a concentration of 40?mg/L. The extracts displayed a FRAP 106.23 for EtOH and 30.55?μmol Fe(II)/g DW for WA. The results clearly indicated that EtOH was the strongest radical scavenger (IC_50?=_?245.65?±?10.2?μg/mL). Ethanol was the most effective with minimum inhibitory concentration (MIC)?Discussion and conclusion: The results indicate that leaves of Urtica urens could be used as natural antioxidant and antimicrobial agents.