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.     

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.     

Characterization of increased phenolic compounds from fermented Bokbunja (Rubus coreanus Miq.) and related antioxidant activity

This study examined the changes in the phenolic acid-content and antioxidant activity of Rubi Fructus (RF), the fruit of Rubus coreanus Miq., after fermentation with yeast (Saccharomyces cerevisiae). The phenolic acids were fractionated into three forms, free (Fr. A), ester (Fr. B), and insoluble-bound phenolic acids (Fr. C) and quantified by high performance liquid chromatography with a diode array detector (HPLC-DAD). This method was validated and allowed the successful identification of 11 phenolic acids in the RF extracts. HPLC-DAD analysis of the samples showed substantial increases in the levels of protocatechuic, vanillic and p-coumaric acid as the result of yeast fermentation. The total phenolic content (TPH) was also increased by fermentation. The total phenolics in Fr. A and Fr. B increased from 117 to 173 mg GAE/100 g and from 488 to 578 mg GAE/100 g, respectively. The total phenolics in Fr. C decreased from 264 to 175 mg GAE/100 g. The antioxidant activity of the fermented RF was measured as the 1,1-diphenoly-2-picrylhydrazyl (DPPH) radical scavenging capacity, which is expressed as the IC₅₀. The IC₅₀ for Fr. A and Fr. B decreased from 5.9 to 4.0 mg/ml (mg of dried RF equiv./ml) and from 1.2 to 0.8 mg/ml, respectively. In Fr. C, the IC₅₀ value increased from 2.1 to 2.8 mg/ml. In summary, the fermented RF had a higher total phenolic content and better DPPH radical-scavenging activity than the unfermented material.     

Phenolic composition and biological activities of Juniperus drupacea Labill. berries from Turkey

The present study was designed to define the phenolic profile and the biological potential of berries methanol extract of Juniperus drupacea Labill. from Turkey.The total phenolic content (Folin-Ciocalteau assay) was 48.06 ± 0.99 mg GAE/g extract. The HPLC-DAD-ESI-MS analysis allowed the determination of the complete phenolic profile of J. drupacea berries. Phenolic acids represented more than 60% of the total phenolics, and tyrosol was the major one (1324 ± 0.64 μg/g extract); within the flavonoids amentoflavone was detected as the main constituent (927 ± 0.35 μg/g extract).The extract exhibited good antioxidant properties, as determined by different in vitro models: DPPH test (IC₅₀ 0.38 ± 0.02 mg/mL), reducing power (12.63 ± 0.14 ASE/mL), Fe²⁺ chelating ability (IC₅₀ 2.26 ± 0.06 mg/mL), and TBA test (IC₅₀ 2.47 ± 1.13 μg/mL).Cytotoxicity against Artemia salina was highlighted (LC₅₀ 489.47 ± 27.8 μg/mL), and a significant decrease (p ? 0.05; p ? 0.01) in HepG2 cells viability was observed at the higher concentrations (5-10 μg/mL).The extract displayed good antibacterial activity towards Gram-positive bacteria and in particular Staphylococcus aureus was the most susceptible strain (MIC 78.12 μg/mL).     

In vitro antioxidant,antidiabetic and antilipidemic activities of Symplocos cochinchinensis (Lour.) S. Moore bark

Symplocos cochinchinesis is used in Indian system of traditional medicine to treat diabetes mellitus. The present study investigates the in vitro antioxidant, antidiabetic and antilipidemic activities of S. cochinchinensis bark methanolic extract (SCBe) in streptozotocin (STZ) induced diabetic rats. In in vitro studies SCBe showed very good scavenging activity on 2,2-diphenyl-picrylhydrazyl (DPPH) (IC₅₀ 820.34 ± 1.74 μg/ml), hydroxyl (IC₅₀ 884.19 ± 0.45 μg/ml) and nitric oxide (IC₅₀ 860.21 ± 1.18 μg/ml) radicals, as well as high reducing power. SCBe (250 and 500 mg/kg) was administered to STZ (40 mg/kg) induced diabetic rats for 28 days. SCBe showed a significant decrease in blood glucose and significant increase in plasma insulin and liver glycogen levels in treated diabetic rats. Further, SCBe showed antilipidemic activity as evidenced by significant decrease in serum TC, TG, LDL-C levels and significant increase in HDL-C level in treated diabetic rats. SCBe also restored the altered plasma enzymes (SGOT, SGPT and ALP), total protein, urea and creatinine levels to near normal. The action of SCBe was comparable to the antidiabetic drug glibenclamide. Results of this experimental study indicated that SCBe possessed antioxidant, antidiabetic and antilipidemic activities.     

In vitro and in vivo antioxidant activity of Symplocos cochinchinensis S. Moore leaves containing phenolic compounds

Methanol extract of Symplocos cochinchinensis S. Moore leaves was evaluated for its in vitro and in vivo antioxidant activity. The total phenolic content of the extract was 230 mg of gallic acid equivalents/g extract. The extract showed very good scavenging activity on 2,2-diphenyl-picrylhydrazyl (DPPH) (IC₅₀ 620.30 ± 0.14 μg/ml), hydroxyl (IC₅₀ 730.21 ± 1.05 μg/ml), nitric oxide (IC₅₀ 870.31 ± 0.19 μg/ml) radicals, as well as high reducing power. The extract also showed strong suppressive effect on lipid peroxidation. In in vivo study CCl₄ induced oxidative stress produced significant increase in SGOT, SGPT and LDH levels along with reduction in liver SOD, CAT, GSH and GPx levels. Pre-treatment of rats with the extract (250 and 500 mg/kg) for 7 days showed significant reduction in the levels of SGOT, SGPT and LDH compared to CCl₄ treated rats. SOD, CAT, GSH and GPx levels were increased significantly due to treatment with the extract. The activity of the extract was comparable to the standard drug, silymarin (25 mg/kg). The results suggest that the leaves of S. cochinchinensis are a source of natural antioxidants.     

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.     

Bioactive phenolics and antioxidant propensity of flavedo extracts of Mauritian citrus fruits: Potential prophylactic ingredients for functional foods application

The flavedo extracts of twenty-one varieties of citrus fruits (oranges, satsumah, clementine, mandarins, tangor, bergamot, lemon, tangelos, kumquat, calamondin and pamplemousses) grown in Mauritius were examined for their total phenolic, flavonoid and vitamin C contents and antioxidant activities. Total phenolics correlated strongly with the trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant capacity (FRAP) and hypochlorous acid (HOCl) scavenging activity assays (r > 0.85). Based on their antioxidant activities in these three assays nine citrus fruits namely, one orange, clementine, tangor and pamplemousse variety, two tangelo varieties and three mandarin varieties, were further characterized for their flavanone, flavonol and flavone levels by HPLC and their antioxidant activities were assessed by the copper-phenanthroline and iron chelation assays. The flavanone, hesperidin, was present at the highest concentrations in all flavedo extracts except for pamplemousses where it was not detected. Contents in hesperidin ranged from 83 ± 0.06 to 234 ± 1.73 mg/g FW. Poncirin, didymin, diosmin, isorhoifolin and narirutin were also present in all extracts whereas naringin was present only in one mandarin variety. The nine flavedo extracts exhibited good DNA protecting ability in the cuphen assay with IC₅₀ values ranging from 6.3 ± 0.46 to 23.0 ± 0.48 mg FW/mL. Essentially the flavedos were able to chelate metal ions however, tangor was most effective with an IC₅₀ value of 9.1 ± 0.08 mg FW/mL. The flavedo extracts of citrus fruits represent a significant source of phenolic antioxidants with potential prophylactic properties for the development of functional foods.     

Antioxidant and antibacterial activities of the leaf essential oils of Himalayan Lauraceae species

The leaf essential oils from seven Himalayan Lauraceae species viz. Neolitsea pallens, Lindera pulcherrima, Dodecadenia grandiflora, Persea duthiei, Persea odoratissima, Persea gamblei and Phoebe lanceolata exhibited potent antioxidant and antibacterial activities. The in vitro antioxidant activity was assessed by using β-carotene bleaching assay, reducing power, DPPH radical scavenging and inhibition of lipid peroxidation methods. The oils of D. grandiflora and L. pulcherrima showed a potent free radical scavenging activity as evidenced by low IC₅₀ value for DPPH radical (0.032 mg/ml and 0.087 mg/ml, respectively) and inhibition of lipid peroxidation (in between IC₅₀ = 0.44 mg/ml and IC₅₀ = 0.74 mg/ml, respectively). The oils were tested against three Gram negative (Escherichia coli, Salmonella enterica enterica and Pasturella multocida) and one Gram positive (Staphylococcus aureus) bacteria at different concentrations using disc diffusion and tube dilution methods. The inhibition zones (IZ) and MIC values for bacterial strains were in the range of 8.7–22.0 mm and 3.90–31.25 μl/ml, respectively.     

Antioxidant activities of leaf extract of Salvia miltiorrhiza Bunge and related phenolic constituents

Leaf of Salvia miltiorrhiza Bunge, the waste part during the root harvest, is rich in health-promoting phenolics and is a novel resource of natural antioxidants. The acetone and methanol extracts of leaves (AL and ML, respectively) of S. miltiorrhiza were evaluated by various in vitro antioxidant assays. The total phenolic contents of AL and ML were 39.0 ± 1.13 and 54.3 ± 1.1 mg gallic acid equivalents/g extract tested, respectively. EC₅₀ of ML was 7.0 ± 0.28 μg/mL in DPPH radical scavenging assay and 246.5 ± 10.35 μg/mL in superoxide radical quenching assay. It was also found that ML has prominent effects on the inhibition of linoleic acid oxidation (93.2%), which was equivalent to the positive control, butylated hydroxytoluene (BHT, p > 0.05), and was significantly higher than α-tocopherol (VE, p < 0.05). The reducing power of leaf extracts was as strong as roots (p > 0.05). HPLC and correlation analysis show that salvianolic acid B and rosmarinic acid constitute the most abundant phenolic compounds. They are the major contributors to antioxidant activities. The results suggested that S. miltiorrhiza leaves could be considered as a new potential source of natural phenolic antioxidants for food, pharmaceutical, cosmetics or nutraceutical industries.     

Purification of chicken breast protein hydrolysate and analysis of its antioxidant activity

Chicken breast protein was hydrolyzed by papain under optimal conditions. The antioxidant activity of the chicken breast protein hydrolysate was then evaluated in vitro and in vivo using different measurements, including reducing power and DPPH radical scavenging assays. The reducing power of the hydrolysate was 0.5 at 2.37 mg/mL. The DPPH radical scavenging assay showed that the EC₅₀ value of the hydrolysate was 1.28 mg/mL. In antioxidant assays in vivo, d-galactose-induced aging mice administrated the fraction peptides of chicken breast protein hydrolysate showed significantly increased antioxidant enzyme activities, while malondialdehyde levels decreased both in serums and livers. Under a transmission electron microscope (TEM), the ultramicrostructure of hepatic tissue was observed and we found that the hydrolysate may play a part in inhibiting oxidative stress in hepatocytes in vivo. Therefore, we concluded that chicken breast protein hydrolysate exhibits significant antioxidant activity.     

Polyphenolics from various extracts/fractions of red onion (Allium cepa) peel with potent antioxidant and antimutagenic activities

In order to determine antioxidant activity, the five extracts/fractions of red onion peel were studied for their total content of phenolics (TPC), flavonoids (TFC), antioxidant activity (AOA), free radical scavenging activity (FRSA), assayed by DPPH radical in the terms of anti-radical power (ARP) and reducing power (RP), expressed as ascorbic acid equivalents (ASE)/ml. High TPC (384.7 ± 5.0 mg GAE/g), TFC (165.2 ± 3.2 mg QE/g), AOA (97.4 ± 7.6%), ARP (75.3 ± 4.5) and RP (1.6 ± 0.3 ASE/ml) were found for the ethyl acetate (EA) fraction. EA fraction had markedly higher antioxidant capacity than butylated hydroxytoluene (BHT) in preventive or scavenging capacities against FeCl₃-induced lipid peroxidation, protein fragmentation, hydroxyl (site-specific and non-site-specific), superoxide anion and nitric oxide radicals. EA fraction also showed dose dependent antimutagenic activity by following the inhibition of tobacco-induced mutagenicity in Salmonella typhimurium strains (TA102) and hydroxyl radical-induced nicking in plasmid pUC18 DNA. HPLC and MS/MS analysis showed the presence of ferulic, gallic, protocatechuic acids, quercetin and kaempferol. The large amount of polyphenols contained in EA fraction may cause its strong antioxidant and antimutagenic properties. This information shows that EA fraction of red onion peel can be used as natural antioxidant in nutraceutical preparations.     

Insights into cholinesterase inhibitory and antioxidant activities of five Juniperus species

In vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory and antioxidant activities of the aqueous and ethanol extracts of the leaves, ripe fruits, and unripe fruits of Juniperus communis ssp. nana, Juniperus oxycedrus ssp. oxycedrus, Juniperus sabina, Juniperus foetidissima, and Juniperus excelsa were investigated in the present study. Cholinesterase inhibition of the extracts was screened using ELISA microplate reader. Antioxidant activity of the extracts was tested by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide radical scavenging, ferrous ion-chelating, and ferric-reducing antioxidant power (FRAP) assays. Total phenol and flavonoid contents of the extracts were determined spectrophotometrically. The extracts had low or no inhibition towards AChE, whereas the leaf aqueous extract of J. foetidissima showed the highest BChE inhibition (93.94 ± 0.01%). The leaf extracts usually exerted higher antioxidant activity. We herein describe the first study on anticholinesterase and antioxidant activity by the methods of ferrous ion-chelating, superoxide radical scavenging, and ferric-reducing antioxidant power (FRAP) assays of the mentioned Juniperus species.     

Essential oil composition and antioxidant activities of Curcuma aromatica Salisb.

The chemical composition of the hydro-distilled essential oil from leaves of Curcuma aromatica Salisb. was analysed by GC–MS. Twenty-three compounds representing 94.29% of the total oil were identified. The antioxidant activities of the oil and various extracts of C. aromatica were evaluated by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide radical-scavenging assays. The oil and methanol extract showed potent DPPH radical-scavenging activities (IC₅₀ = 14.45 and 16.58 μg/ml, respectively), which were higher than butylated hydroxyanisole (IC₅₀ = 18.27 μg/ml). The extracts also exhibited remarkable superoxide radical-scavenging activities (IC₅₀ = 22.6–45.27 μg/ml) and the activity in the methanol extract was superior to all other extracts (IC₅₀ = 22.6 μg/ml). Furthermore, the amount of total phenolic compounds was determined and its content in ethyl acetate extract was the highest as compared to other extracts. The results indicate that the oil and extracts of C. aromatica could serve as an important bio-resource of antioxidants for using in the food industries.     

Acetylcholinesterase inhibition,antioxidant activity and toxicity of Peumus boldus water extracts on HeLa and Caco-2 cell lines

This work aimed to study the inhibition on acetylcholinesterase activity (AChE), the antioxidant activity and the toxicity towards Caco-2 and HeLa cells of aqueous extracts of Peumus Boldus. An IC₅₀ value of 0.93 mg/mL, for AChE inhibition, and EC₅₀ of 18.7 μg/mL, for the antioxidant activity, was determined. This activity can be attributed to glycosylated flavonoid derivatives detected, which were the main compounds, although boldine and other aporphine derivatives were also present. No changes in the chemical composition or the biochemical activities were found after gastrointestinal digestion. Toxicity of P. boldus decoction gave an IC₅₀ value 0.66 mg/mL for HeLa cells, which caused significant changes in the cell proteome profile.     

Antioxidant and antidermatophytic activities of essential oil and extracts of Metasequoia glyptostroboides Miki ex Hu

This study was undertaken to assess the antioxidant and antidermatophytic potential of the essential oil and extracts (hexane, chloroform, ethyl acetate and methanol) of Metasequoia glyptostroboides Miki ex Hu. Antioxidant activity was evaluated by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The free radical scavenging activities of the oil and ethyl acetate extract were found to be superior (IC₅₀ = 9.1 and 14.24 μg/ml, respectively) as compared to butylatedhydroxyanisole (BHA), (IC₅₀ = 18.27 μg/ml). Also the ethyl acetate extract revealed the highest phenolic contents (93.26 mg/g of dry wt) as compared to the other extracts. Further, oil (1250 μg/disc) and extracts (1750 μg/disc) revealed 35.33–67.66 and 18.0–53.3% antidermatophytic effect, respectively, along with their respective MIC values (62.5–500 and 250–4000 μg/ml) against Trichophyton rubrum KCTC 6345, T. rubrum KCTC 6375, T. rubrum KCTC 6352, T. mentagrophytes KCTC 6085, T. mentagrophytes KCTC 6077, T. mentagrophytes KCTC 6316, Microsporum canis KCTC 6591, M. canis KCTC 6348 and M. canis KCTC 6349. The oil also had a strong detrimental effect on spore germination as well as concentration and time-dependent kinetic inhibition of M. canis KCTC 6591.     

Antioxidant activity and total phenolic content of ethanolic extract of Caesalpinia bonducella seeds

The aim of this study was to assess the in vitro potential of ethanolic extract of Caesalpinia bonducella seeds as a natural antioxidant. The DPPH activity of the extract (20, 40, 50, 100 and 200 μg/ml) was increased in a dose dependent manner, which was found in the range of 38.93–74.77% as compared to ascorbic acid (64.26–82.58%). The IC₅₀ values of ethanolic extract and ascorbic acid in DPPH radical scavenging assay were obtained to be 74.73 and 26.68 μg/ml, respectively. The ethanolic extract was also found to scavenge the superoxide generated by EDTA/NBT system. Measurement of total phenolic content of the ethanolic extract of C. bonducella was achieved using Folin–Ciocalteau reagent containing 62.50 mg/g of phenolic content, which was found significantly higher when compared to reference standard gallic acid. The ethanolic extract also inhibited the hydroxyl radical, nitric oxide, superoxide anions with IC₅₀ values of 109.85, 102.65 and 89.84 μg/ml, respectively. However, the IC₅₀ values for the standard ascorbic acid were noted to be 70.79, 65.98 and 36.68 μg/ml respectively. The results obtained in this study clearly indicate that C. bonducella has a significant potential to use as a natural antioxidant agent.     

Antioxidant activities of the essential oils and methanol extracts from myrtle (Myrtus communis var. italica L.) leaf,stem and flower

This study was designed to examine the chemical composition and antioxidant activity of the essential oils and methanol extracts of Myrtus communis var. italica L. leaf, stem and flower. Myrtle leaf and flower were the valuable organs for the essential oil production representing a yield of 0.61% and 0.30% (w/w), respectively. The essential oil composition of myrtle leaf and flower was characterized by high proportions of α-pinene, the main compound of monoterpene hydrocarbon class, with 58.05% for leaf and 17.53% for flower. Stem was rich in oxygenated monoterpenes, largely due to 1,8-cineole with 32.84%. The total phenol contents varied between different myrtle parts; leaf extract had higher total phenol content (33.67 mg GAE/g) than flower (15.70 mg GAE/g) and stem (11.11 mg GAE/g) extracts. Significant differences were also found in total tannin contents among different myrtle parts, representing 26.55 mg GAE/g in leaf, 11.95 mg GAE/g in flower, 3.33 mg GAE/g in stem. The highest contents of total flavonoids and condensed tannins were observed in stem (5.17 and 1.99 mg CE/g, respectively) and leaf (3 and 1.22 mg CE/g, respectively) extracts. The HPLC analysis indicated that the main phenolic class was hydrolysable tannins (gallotannins) in leaf (79.39%, 8.90 mg/g) and flower (60.00%, 3.50 mg/g) while the stem was characterized by the predominance of flavonoid class (61.38%, 1.86 mg/g) due to the high presence of catechin (36.91%, 1.12 mg/g). Antioxidant activities of the essential oil and the methanolic extract from different myrtle parts were evaluated by using DPPH radical scavenging, β-carotene-linoleic acid bleaching, reducing power and metal chelating activity assays. In all tests, methanolic extracts of different myrtle parts showed better antioxidant activity than essential oils.     

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.     

Biological activities of Portuguese propolis: Protection against free radical-induced erythrocyte damage and inhibition of human renal cancer cell growth in vitro

This study reports for the first time the biological properties of Portuguese propolis. The antioxidant potential of propolis samples from Bornes (Northeast) and Fundão (Centre) regions of Portugal was evaluated by their ability to inhibit the 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced oxidative hemolysis and lipid peroxidation in human erythrocytes. Bornes and Fundão propolis strongly protected the erythrocyte membrane from hemolysis (IC₅₀ of 6.3 ± 0.7 and 10.4 ± 2.7 μg/ml, respectively), in a time- and concentration-dependent manner. This effect was found to be significantly higher than that presented by ascorbic acid (IC₅₀ of 31.0 ± 5.6 μg/ml). In addition, human erythrocytes treated with propolis extracts showed concentration-dependent decrease in levels of malondialdehyde, a breakdown product of lipid peroxidation. Propolis extracts were also assayed for their anticancer properties on human renal cell carcinoma (RCC). Primary cultures of normal and cancerous renal cells derived from RCC patients, in addition to A-498 cell line, were treated with propolis extracts (0-100 μg/ml). Cytotoxic and antiproliferative effects were determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Propolis extracts exhibited selective toxicity against malignant cells compared to normal cells. In vitro RCC growth was strongly inhibited by Bornes and Fundão propolis in a concentration-dependent manner. Our results indicate that Portuguese propolis constitutes an excellent source of effective natural antioxidant and chemopreventive agents.