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Journal ArticleDOI: 10.1080/24701556.2020.1792495

Biosynthesis, characterization and antioxidant activity of oleuropein-mediated silver nanoparticles

04 Mar 2021-Inorganic and Nano-Metal Chemistry (Informa UK Limited)-Vol. 51, Iss: 3, pp 411-419
Abstract: In this study, oleuropein was isolated from olive leaves by chromatographic method and its structure was elucidated by spectroscopic analyses such as FTIR, 1H-NMR and 13CNMR. Silver nanoparticles (...

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Topics: Silver nanoparticle (59%), Oleuropein (57%)
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Open accessJournal ArticleDOI: 10.1007/S10904-021-02057-3
Esma Nur Gecer1Institutions (1)
Abstract: Salvia species have been used extensively in medicinal and food industries for years due to their significant secondary metabolites contents such as flavonoids and phenolic compounds. Silver nanoparticles capped and stabilized by Salvia aethiopis compounds are expected to reveal considerable biological effects. In this study, Salvia aethiopis L. was heated in distilled water for 2 h. After filtration, water extract was treated with silver nitrate for 2 h at 60 °C to yield the silver nanoparticles (Sa-AgNPs). The structure of silver nanoparticles was elucidated by spectroscopic methods such as Ultraviolet–Visible (UV–Vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscope (SEM), and zeta potential analyses. The maximum absorption in UV–Vis spectrum was observed at 508 nm. XRD pattern (2θ) at 38.1°, 44.3°, 64.4°, and 77.4° degrees can be assigned to the (111), (200), (220) and (311) Bragg’s reflections of the face-centered cubic crystalline structure. The average size of Sa-AgNPs was found as 74.09 nm by SEM analysis. The characteristic hydroxyl vibration signal appeared at 3222 cm−1. The zeta potential of Sa-AgNPs was found as − 20.3 mV displaying the stability of Sa-AgNPs. Antioxidant activity of extract and Sa-AgNPs were carried out using DPPH⋅, ABTS⋅+ FRAP assay. The Sa-AgNPs revealed a considerable ABTS⋅+ scavenging effect with the value of 4.93 (IC50, µg/mL) compared to BHT (IC50, µg/mL, 8.34). However, Sa-AgNPs displayed a lower DPPH⋅ activity (IC50, µg/mL, 24.37) than that of the standard BHT (IC50, µg/mL, 9.67). The reducing power activity of Sa-AgNPs was found as 4.52 (µmol TE/mg extract) while the standard BHT value was 488 (µmol TE/mg extract).

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Topics: Salvia aethiopis (56%), Silver nitrate (56%), Silver nanoparticle (55%)

1 Citations



Journal ArticleDOI: 10.1016/J.MTCOMM.2021.102316
Kadriye Ozlem Saygi1, Ercan Cacan1Institutions (1)
Abstract: In the past several years, the interest in synthesizing nanoparticles from plant extract has been increasing due to easy, low cost and being clean. In this study, Tilia cordata flower (Tcf) extract was used as bioreduction of silver nitrate to form silver nanoparticles (AgNPs). Visual formation of nanoparticles was confirmed by a color change from light yellow to brown. The structural properties and morphology of Tcf-AgNPs were confirmed by Ultraviolet-visible (UV–vis), Fourier transform infrared (FT-IR), Scanning electron microscope with Energy dispersive X-ray (SEM/EDX), High resolution transmission electron microscope (HR-TEM) and X-ray diffraction (XRD) spectroscopic techniques. The antioxidant capacity of AgNPs was investigated in vitro by ferric reducing antioxidant power (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazolibe-6-sulphonic acid) ABTS assays. DPPH activities were found as good as standard, BHT with the values of 9.40 (IC50, μg/mL) and 9.67 (IC50, μg/mL) respectively. The anti-tumor effect of Tcf-AgNPs was determined by MTT assays and the results indicate that Tcf-AgNPs have cytotoxic activities in a cell line and dose-dependent manner.

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Topics: Silver nanoparticle (56%), Silver nitrate (54%), DPPH (54%) ... read more

Open accessJournal ArticleDOI: 10.3390/MOLECULES26226892
16 Nov 2021-Molecules
Abstract: The aim of this study was to analyse the effect of spontaneous microbial maceration on the release and extraction of the flavonoids and phenolics from olive leaves. Bioprofiling based on thin-layer chromatography effect-directed detection followed by ATR-FTIR spectroscopy proved to be a reliable and convenient method for simultaneous comparison of the extracts. Results show that fermentation significantly enhances the extraction of phenolic compounds and flavonoids. The polyphenolic content was increased from 6.7 µg GAE (gallic acid equivalents) to 25.5 µg GAE, antioxidants from 10.3 µg GAE to 25.3 µg GAE, and flavonoid content from 42 µg RE (rutin equivalents) to 238 µg RE per 20 µL of extract. Increased antioxidant activity of fermented ethyl acetate extracts was attributed to the higher concentration of extracted flavonoids and phenolic terpenoids, while increased antioxidant activity in fermented ethanol extract was due to increased extraction of flavonoids as extraction of phenolic compounds was not improved. Lactic acid that is released during fermentation and glycine present in the olive leaves form a natural deep eutectic solvent (NADES) with significantly increased solubility for flavonoids.

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Topics: Gallic acid (52%), Polyphenol (51%), Maceration (wine) (51%) ... read more

Journal ArticleDOI: 10.1111/JFBC.13967
Masood Sadiq Butt, Urwa Tariq, Iahtisham-Ul-Haq1, Ambreen Naz2  +1 moreInstitutions (2)
Abstract: Neurological disorders are increasing at a faster pace due to oxidative stress, protein aggregation, excitotoxicity, and neuroinflammation. It is reported that the Mediterranean diet including olives as a major dietary component prevents and ameliorates neurological anomalies. Oleuropein is the major bioactive component in different parts of the Olive (Olea europaea L.) tree. Several mechanisms have been reported for the neuroprotective role of oleuropein including induction of apoptosis and autophagy, enhancing the antioxidant pool of the cerebral region, decreasing the unnecessary release of proinflammatory cytokines and chemokines by deactivating the microglia cells and astrocytes thus preventing the occurrence of neuroinflammation. Regular intake of oleuropein seems to be correlated with decreased risks of neural disorders including Alzheimer's, Parkinson's, strokes, depression, anxiety, epilepsy, and others. This review majorly discusses the chemistry, biosynthesis, and metabolism of oleuropein along with an updated vision of its neuroprotective role in counteracting the acute and chronic neurodegenerative and neuropsychiatric disorders. Moreover, mechanisms by which oleuropein may prevent neurodegeneration are reviewed. PRACTICAL APPLICATION: Neurological disorders are negatively affecting the health and life quality of individuals around the globe. Although various medicinal solutions are available to tackle such ailments, none has proven to fully cure and being deprived of side effects. In this respect, the prevention of such disorders using natural remedies may be an effective strategy to overcome the incidence of the increasing cases. Furthermore, the natural compounds provide a safer alternative to pharmaceutical drugs. Hence, oleuropein from olive tree products is found to be efficacious against neurological disorders. This review provides an updated insight on the positive effects of oleuropein against neurodegenerative and neuropsychiatric disorders. The diet practitioners and nutraceutical companies may benefit from the provided information to design and develop strategies to improve the mental health of suffering individuals.

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Topics: Oleuropein (52%), Neuroprotection (52%)
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30 results found


Journal ArticleDOI: 10.1016/S0891-5849(98)00315-3
Abstract: A method for the screening of antioxidant activity is reported as a decolorization assay applicable to both lipophilic and hydrophilic antioxidants, including flavonoids, hydroxycinnamates, carotenoids, and plasma antioxidants. The pre-formed radical monocation of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS*+) is generated by oxidation of ABTS with potassium persulfate and is reduced in the presence of such hydrogen-donating antioxidants. The influences of both the concentration of antioxidant and duration of reaction on the inhibition of the radical cation absorption are taken into account when determining the antioxidant activity. This assay clearly improves the original TEAC assay (the ferryl myoglobin/ABTS assay) for the determination of antioxidant activity in a number of ways. First, the chemistry involves the direct generation of the ABTS radical monocation with no involvement of an intermediary radical. Second, it is a decolorization assay; thus the radical cation is pre-formed prior to addition of antioxidant test systems, rather than the generation of the radical taking place continually in the presence of the antioxidant. Hence the results obtained with the improved system may not always be directly comparable with those obtained using the original TEAC assay. Third, it is applicable to both aqueous and lipophilic systems.

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16,566 Citations


Journal ArticleDOI: 10.1038/1811199A0
Marsden S. Blois1Institutions (1)
01 Apr 1958-Nature
Abstract: METHODS for measuring antioxidants and appraising antioxidant activity appear to be of two general types. If the chemical nature of the antioxidant is known, one may strive for a test specific for the compound or group of interest; for example, the nitroprusside test for sulphydryl groups. Alternatively one may observe the inhibition of some natural oxidative process such as the β-oxidation of fats, as a function of the added antioxidant.

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Topics: Antioxidant (51%), Metal chelating activity (51%)

9,416 Citations


Open accessJournal ArticleDOI: 10.5264/EIYOGAKUZASHI.44.307
Abstract: グルコサミン塩酸塩を遊離形にし, 37℃インキュベーターで0日から30日間放置褐変した褐変グルコサミン (BGA) の抗酸化性, 還元力, 褐変度, アミノ糖の残存量, pH, 水分量, 全窒素量を, 放置0日から5日間は毎日, 以後5日間の間隔で30日間測定した。一方, 0, 15, 30日間放置褐変したBGAをセファデックスG-15で分画し, 抗酸化性, 還元力, 褐変度, pHについて測定して, 次のような結果を得た。1) 遊離グルコサミンは, 3日間放置後より白色粉末状から褐色ペースト状に急激な変化を示した。2) 最も強い抗酸化性は, 25日間と30日間放置褐変したBGAで認められた。3) BGAのリノール酸に対する抗酸化性は, 褐変度と深い関係を示した。4) 長く放置褐変したBGAは, 分子量が比較的高い領域の褐変生成物質と, 比較的低い領域の褐変生成物質に分画された。5) 長く放置褐変したBGAでは, 高分子の褐変生成物質のフラクションと, 低分子の褐変生成物質のフラクションの中間フラクションに抗酸化性を認めた。

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6,282 Citations


Journal ArticleDOI: 10.1016/J.BIOTECHADV.2008.09.002
Mahendra Rai1, Alka Yadav1, Aniket Gade1Institutions (1)
Abstract: Silver has been in use since time immemorial in the form of metallic silver, silver nitrate, silver sulfadiazine for the treatment of burns, wounds and several bacterial infections. But due to the emergence of several antibiotics the use of these silver compounds has been declined remarkably. Nanotechnology is gaining tremendous impetus in the present century due to its capability of modulating metals into their nanosize, which drastically changes the chemical, physical and optical properties of metals. Metallic silver in the form of silver nanoparticles has made a remarkable comeback as a potential antimicrobial agent. The use of silver nanoparticles is also important, as several pathogenic bacteria have developed resistance against various antibiotics. Hence, silver nanoparticles have emerged up with diverse medical applications ranging from silver based dressings, silver coated medicinal devices, such as nanogels, nanolotions, etc.

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Topics: Silver nitrate (69%), Silver nanoparticle (69%), Fungal-derived nanoparticles (60%) ... read more

4,505 Citations


Journal ArticleDOI: 10.1016/S1383-5718(02)00128-6
Abstract: We determined the genotoxicity of 39 chemicals currently in use as food additives. They fell into six categories—dyes, color fixatives and preservatives, preservatives, antioxidants, fungicides, and sweeteners. We tested groups of four male ddY mice once orally with each additive at up to 0.5×LD50 or the limit dose (2000 mg/kg) and performed the comet assay on the glandular stomach, colon, liver, kidney, urinary bladder, lung, brain, and bone marrow 3 and 24 h after treatment. Of all the additives, dyes were the most genotoxic. Amaranth, Allura Red, New Coccine, Tartrazine, Erythrosine, Phloxine, and Rose Bengal induced dose-related DNA damage in the glandular stomach, colon, and/or urinary bladder. All seven dyes induced DNA damage in the gastrointestinal organs at a low dose (10 or 100 mg/kg). Among them, Amaranth, Allura Red, New Coccine, and Tartrazine induced DNA damage in the colon at close to the acceptable daily intakes (ADIs). Two antioxidants (butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT)), three fungicides (biphenyl, sodium o-phenylphenol, and thiabendazole), and four sweeteners (sodium cyclamate, saccharin, sodium saccharin, and sucralose) also induced DNA damage in gastrointestinal organs. Based on these results, we believe that more extensive assessment of food additives in current use is warranted.

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Topics: Butylated hydroxyanisole (55%), Sodium cyclamate (54%), Butylated hydroxytoluene (53%) ... read more

563 Citations


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20215