Free-radical acetoxy group migration: an E.P.R. spectral study

1971 ◽  
Vol 24 (10) ◽  
pp. 2099 ◽  
Author(s):  
ALJ Beckwith ◽  
PK Tindal
Keyword(s):  
Free Radical ◽  
Spectral Data ◽  
Spectral Study ◽  
Hyperfine Splitting ◽  
Butyl Acetate ◽  
Reducing Power ◽  
Flow Cell ◽  
Acetoxy Group ◽  
Cyclic Ethers ◽  
Group Migration

E.p.r. spectra have been recorded for a number of radicals generated in a flow cell from cyclic ethers, 1,3-dioxolans, 1,3-dioxans, and other cyclic and acyclic substrates. The cyclic radicals do not undergo detectable fragmentation, but the rearrangement of the radical (9) derived from t-butyl acetate has been observed. The mechanism of acetoxy group migration in radicals is discussed in the light of these results. ��� The spectral data, including, in some cases, values of 13C hyperfine splitting factors, indicate that there is considerable deviation from planarity at the radical, centres of some cyclic species, and this phenomenon is accompanied by a change in sign of α-proton splitting factors. The reducing power of radicals derived from cyclic ethers has been investigated.

Free-radical acetoxy group migration

1969 ◽  
Vol 91 (26) ◽  
pp. 7535-7537 ◽  
Author(s):  
Dennis D. Tanner ◽  
Francis C. P. Law
Keyword(s):  
Free Radical ◽  
Acetoxy Group ◽  
Group Migration

scholarly journals Antiradical and Cytotoxic Activities of Varying Polarity Extracts of the Aerial Part ofEuphorbia hirtaL.

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Shanmugapriya Perumal ◽  
Roziahanim Mahmud ◽  
Suthagar Pillai Piaru ◽  
Wei Cai Lee ◽  
Surash Ramanathan
Keyword(s):  
Linoleic Acid ◽  
Free Radical ◽  
Aerial Part ◽  
Radical Scavenging ◽  
Reducing Power ◽  
Free Radical Scavenging ◽  
Total Phenolic ◽  
Cytotoxic Activities ◽  
Uv Spectrophotometry ◽  
Etoh Extract

Euphorbia hirtais a well-known ethnomedicinal plant with diverse biological activities. The aim of the present study is to investigate the antiradical activities of various solvent extracts of the aerial part ofE. hirtaas well as to determine the possible cytotoxicity of these extracts. The aerial part ofE. hirtawas extracted with different solvent systems in order to increase polarity. The solvents used were hexane, dichloromethane (DCM), ethyl acetate (EA), ethanol (EtOH), and methanol (MeOH). The contents of total phenols and total flavonoids were analyzed by UV spectrophotometry, whereas the potential free radical-scavenging activities of the extracts were evaluated using the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH), theβ-carotene-linoleic acid bleaching system, and reducing power. The EtOH extract exhibited the highest total phenolic content (237.9±2.26 mg GAE/g), and DCM extract scored the highest total flavonoid content (121±0.15 mg CE/g). The MeOH extract showed a potent free radical-scavenging activity as evidenced by low EC50at 42.81 µg/mL. Interestingly, the EtOH extract demonstrated the highest reducing power activity with EC50value of 6.18 µg/mL. Inβ-carotene-linoleic acid assay, oxidation of linoleic acid was effectively inhibited by DCM extract with96.15±0.78%. All the extracts showed no cytotoxic activity against Vero cells.

scholarly journals EVALUATION OF ANTIOXIDANT AND FREE RADICAL SCAVENGING ACTIVITIES OF DIFFERENT SOLVENT EXTRACTS OF LEAVES OF PIPER UMBELLATUM

2017 ◽  
Vol 10 (2) ◽  
pp. 274
Author(s):  
Sethupandian Geetha ◽  
Kokkaiah Irulandi ◽  
Palanichamy Mehalingam
Keyword(s):  
Antioxidant Activity ◽  
Free Radical ◽  
Ethyl Acetate ◽  
Methanol Extract ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Reducing Power ◽  
Free Radical Scavenging ◽  
Frap Assay ◽  
Radical Scavenging Properties

Objective: This study was designed to determine the Total phenol, flavonoid content, antioxidant and free radical scavenging properties of different solvent extracts of Piper umbellatum.  Methods: Different solvent extracts evaluated with DPPH radical scavenging activity and Reducing power activity.Results: The presence of phenol and flavonoid showed highly in the methanol extracts than ethyl acetate and acetone extracts. All the extracts have various level of antioxidant activity. Methanol solvent extract have good extraction and show significant antioxidant activity. The effect of reducing power of methanol extract revealed good antioxidant activity compare with other tested extracts.Conclusion: On the basis of the above results we concluded that methanol extract of Piper umbellatum whole plant extracts shows significant antioxidant activity than ethyl acetate and acetone extracts.Keywords: Piper umbellatum, Antioxidant, DPPH, FRAP assay, Polar, Non polar solvents

scholarly journals Research antioxidant activity of chitooligosacchride by UV-VIS absorption spectrocopy

2020 ◽  
Vol 8 (1) ◽  
pp. 75-81
Author(s):  
Bui Van Hoai ◽  
Ngo Dai Nghiep ◽  
Dao An Quang ◽  
Nguyen Thi Nam Phuong
Keyword(s):  
Molecular Weight ◽  
Antioxidant Activity ◽  
Absorption Spectrum ◽  
Free Radical ◽  
Trichoderma Viride ◽  
Radical Scavenging ◽  
Reducing Power ◽  
Free Radical Scavenging ◽  
Degree Of Deacetylation ◽  
Radical Scavenging Ability

Chitosan with 80% degree of deacetylation was hydrolyzed by cellulase of Trichoderma viride to prepare chitooligosaccharides (COSs) by the fractionation of the COSs with ultrafiltration membrane. The antioxidant activities of the COSs were clarified in this study by reducing power and free radical scavenging ability assay by UV-VIS absorption spectrum. The results show that the COS 1 (10,000-5,000 Da), COS 2 (5,000-3,000 Da), COS 3 (3,000-1,000 Da) and COS 4 (less than1,000 Da) segments have antioxidant properties.The antioxidant activitives of the COSs increased with the increment of concentration, and they also depended on molecular weight.

scholarly journals Aktivitas Antioksidan Minuman Daun Beluntas Teh Hitam (Pluchea indica Less-Camelia sinensis)

2018 ◽  
Vol 38 (2) ◽  
pp. 200
Author(s):  
Paini Sri Widyawati ◽  
Tarsisius Dwi Wibawa Budianta ◽  
Yesiana Dwi Wahyu Werdani ◽  
Maria Olivia Halim
Keyword(s):  
Free Radical ◽  
Secondary Metabolites ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Reducing Power ◽  
Black Tea ◽  
Free Radical Scavenging ◽  
Free Radical Scavenging Activity ◽  
Scavenging Activity ◽  
Iron Ion

The research was conducted to explore the potency of pluchea leaves-black tea drink as antioxidant at various proportions. The research used a single factor randomized block design of pluchea leaves and black tea proportions, including 100:0; 75:25; 50:50; 25:75; and 0:100% (w/w). Each of it was repeated five times. The parameters observed in this study were secondary metabolites, total phenolic, total flavonoids, free radical DPPH scavenging activity, and iron reducing power. The data were statistically analyzed using Analysis of Variance (ANOVA) at α = 5%, if the analysis showed a significant effect then it was continued with Duncan's Multiple Range Test (DMRT). Data was stated as mean ± standard deviation. The results showed that the secondary metabolites containing in drink from pluchea leaves and black tea at various proportions were alkaloids, flavonoids, phenolics, saponins, tannins, and cardiac glycosides. The increasing of black tea proportion in samples added the intensity of alkaloids, phenolics, flavonoids, saponins, and cardiac glycosides compounds detected, but the tannins were decreased. These secondary metabolites were correlated with total phenolic content (TPC) and total flavonoid content (TFC). The increasing of black tea proportion in drink significantly decreased DPPH free radical scavenging activity and iron ion reducing power, except for 100% black tea proportion. Tannin compounds seems determining antioxidant activity.  Based on coefficient correlation between TPC or TFC and DPPH free radical scavenging activity or iron ion reducing power, the result showed that DPPH free radical scavenging activity was dominantly contributed by TPC and iron ion reducing power was determined by TPC and TFC. ABSTRAKPenelitian ini dilakukan untuk mengetahui potensi minuman daun beluntas teh hitam sebagai antioksidan pada berbagai proporsi. Penelitian ini menggunakan rancangan acak kelompok satu faktor, yaitu proporsi daun beluntas teh hitam meliputi 100:0; 75:25; 50:50; 25:75; dan 0:100% (b/b). Tiap faktor diulang sebanyak 5 kali. Parameter yang diamati pada penelitian ini meliputi kandungan metabolit sekunder, total fenolik (TPC), total flavonoid (TFC), kemampuan menangkal radikal bebas DPPH, dan kemampuan mereduksi ion besi. Data dianalisis secara statistik dengan Analysis of Variance (ANOVA) pada α = 5%, jika terdapat beda signifikan dilanjutkan dengan uji Duncan's Multiple Range Test (DMRT). Data dinyatakan dengan rata-rata ± standar deviasi.  Hasil menunjukkan bahwa metabolit sekunder yang terkandung dalam minuman daun beluntas teh hitam pada berbagai proporsi adalah alkaloid, flavonoid, fenolik, saponin, tannin, dan kardiak glikosida. Peningkatan proporsi teh hitam menambah intensitas senyawa alkaloid, fenolik, flavonoid, saponin, dan kardiak glikosida yang terdeteksi, tetapi kandungan senyawa tannin berkurang. Kandungan metabolit sekunder ini berkorelasi dengan total fenolik (TPC) dan total flavonoid (TFC). Peningkatan proporsi teh hitam dalam minuman menurunkan kemampuan menangkal radikal bebas DPPH dan kemampuan mereduksi ion besi, kecuali pada proporsi teh hitam 100%. Kandungan senyawa tannin dalam minuman menentukan aktivitas antioksidan. Berdasarkan koefisien korelasi antara TPC atau TFC dan kemampuan menangkal radikal bebas DPPH atau kemampuan mereduksi ion besi, hasil menunjukkan bahwa kemampuan menangkal radikal bebas DPPH dominan dikontribusi oleh TPC dan kemampuan mereduksi ion besi ditentukan oleh TPC dan TFC.

scholarly journals PHYTOCHEMICAL CHARACTERIZATION AND ANTIOXIDANT ACTIVITY OF THE NORTHERN MOROCCAN SPECIES: WITHANIA FRUTESCENS L.

2019 ◽  
pp. 276-279 ◽  
Author(s):  
ABDELFATTAH EL MOUSSAOUI ◽  
FATIMA ZAHRA JAWHARI ◽  
DALILA BOUSTA ◽  
AMINA BARI
Keyword(s):  
Antioxidant Activity ◽  
Free Radical ◽  
Antioxidant Capacity ◽  
Radical Scavenging ◽  
Reducing Power ◽  
Mineral Elements ◽  
Free Radical Scavenging ◽  
Butylated Hydroxytoluene ◽  
Phytochemical Analysis ◽  
Total Polyphenols

Objective: In this study, we were interested in qualitative, quantitative phytochemical characterization and evaluation of the antioxidant capacity of the total extracts of a plant from northern Morocco, the species selected for this study is Withania frutescens. Materials and Methods: Analysis of mineral elements by inductive coupling plasma-atomic absorption spectroscopy (ICP-AES), phytochemical screening, polyphenol and tannin assays, evaluation of antioxidant activity by the 1,2-diphenyl-β-picrylhydrazyl (DPPH) free radical scavenging method and reducing power. Results: The plant contains alkaloids, saponins, tannins, mucilages, and coumarins. It has a relatively high content of total polyphenols and tannins of 19.53±0.018 μg genetic generalized epilepsy/mg MS and 6.258±0.062 μg Eqcat/mg MS, respectively. The analysis of mineral elements by ICP-AES shows that our species is rich in mineral elements which are calcium, magnesium, and sodium, and it is devoid of metallic elements such as nickel, lead, cadmium, and cobalt. The evaluation of antioxidant activity by the DPPH free radical scavenging method shows that the half maximal inhibitory concentration of the tested extracts has an antiradical activity of about 0.056±0.008 μg/ml for the ethanol extract and 0.213±0.004 μg/ml for the methanol extract compared to the butylated hydroxytoluene value of 0.009±0.0004 μg/ml which was used as a reference. The reducing capacity test shows that methanolic extract has a high antioxidant capacity (0.213±0.006) compared to ethanolic extract (0.043±0.004) but remains low compared to ascorbic acid (0.003±0.0004) which was used as reference. Conclusion: Phytochemical analysis of W. frutescens shows that this plant is rich in high quantities of alkaloids, saponins, mucilage, tannins, and coumarins. It contains an average amount of total polyphenols and tannins that confer significant antioxidant activity to the plant studied.

scholarly journals Bijayasaline: A New C-Glucosyl-α-hydroxydihydrochalcone from the Heartwood of Bijayasal (Pterocarpus marsupium)

2014 ◽  
Vol 9 (6) ◽  
pp. 1934578X1400900
Author(s):  
Khem Raj Joshi ◽  
Hari Prasad Devkota ◽  
Shoji Yahara
Keyword(s):  
Circular Dichroism ◽  
Free Radical ◽  
Spectral Data ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Free Radical Scavenging ◽  
Free Radical Scavenging Activity ◽  
Scavenging Activity ◽  
Pterocarpus Marsupium ◽  
Circular Dichroïsm

A new C-glucosyl-α-hydroxydihydrochalcone derivative, (α S)-3′- C-β-glucopyranosyl-α,3,4,2′4′-pentahydroxydihydrochalcone, named as bijayasaline (1) was isolated from the heartwood of Bijayasal (Pterocarpus marsupium) and characterized on the basis of NMR and circular dichroism (CD) spectral data. Bijayasaline (1) showed potent DPPH free radical scavenging activity.

scholarly journals Effect of the Solvent on Propolis Phenolic Profile and its Antifungal, Antioxidant, and In Vitro Cytoprotective Activity in Human Erythrocytes Under Oxidative Stress

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4266
Author(s):  
Magdalena Woźniak ◽  
Lucyna Mrówczyńska ◽  
Patrycja Kwaśniewska-Sip ◽  
Agnieszka Waśkiewicz ◽  
Piotr Nowak ◽  
...  
Keyword(s):  
Free Radical ◽  
Antifungal Activity ◽  
Biological Effects ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Reducing Power ◽  
Human Erythrocytes ◽  
Antioxidant Potential ◽  
Phenolic Profile ◽  
Cytoprotective Activity

Propolis is a natural bee product with various beneficial biological effects. The health-promoting properties of propolis depend on its chemical composition, particularly the presence of phenolic compounds. The aim of this study was to evaluate the relationship between extraction solvent (acetone 100%, ethanol 70% and 96%) and the antifungal, antioxidant, and cytoprotective activity of the extracts obtained from propolis. Concentrations of flavonoids and phenolic acids in the propolis extracts were determined using ultrahigh-performance liquid chromatography. The antioxidant potential of different extracts was assessed on the basis of 2,2-diphenyl-1-picrylhydrazyl (DPPH·) free-radical-scavenging activity, Fe3+-reducing power, and ferrous ion (Fe2+)-chelating activity assays. The ability of the extracts to protect human red blood cell membranes against free-radical-induced damage and their antifungal activity was also determined. The results showed that the concentration of flavonoids in the propolis extracts was dependent on the solvent used in the extraction process and pinocembrin, chrysin, galangin, and coumaric acid were the most abundant phenols. All extracts exhibited high antioxidant potential and significantly protected human erythrocytes against oxidative damage. On the other hand, the antifungal activity of the propolis extracts depended on the solvent used in extraction and the fungal strains tested. It needs to be stressed that, to the best of our knowledge, there is no study relating the effect of solvent used for extraction of Polish propolis to its phenolic profile, and its antifungal, antioxidant, and cytoprotective activity.

Evaluation of antioxidant activity of Melothria maderaspatana in vitro

2010 ◽  
Vol 5 (2) ◽  
pp. 224-230 ◽  
Author(s):  
Boobalan Raja ◽  
Kodukkur Pugalendi
Keyword(s):  
Hydrogen Peroxide ◽  
Antioxidant Activity ◽  
Free Radical ◽  
Hydroxyl Radical ◽  
Superoxide Anion ◽  
Radical Scavenging ◽  
Reducing Power ◽  
Free Radical Scavenging ◽  
Melothria Maderaspatana

AbstractIn this study, an aqueous extract of leaves from Melothria maderaspatana was tested for in vitro antioxidant activity. Free radical scavenging assays, such as hydroxyl radical, hydrogen peroxide, superoxide anion radical and 2,2-diphenyl-1-picryl hydrazyl (DPPH), 2,2’-azinobis-(3-ethyl-enzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, and reducing power assay, were studied. The extract effectively scavenged hydroxyl radical, hydrogen peroxide and superoxide anion radicals. It also scavenged DPPH and ABTS radicals. Furthermore, it was found to have reducing power. All concentrations of leaf extract exhibited free radical scavenging and antioxidant power, and the preventive effects were in a dose-dependent manner. The antioxidant activities of the above were compared to standard antioxidants such as butylated hydroxytoluene (BHT), ascorbic acid, and α-tocopherol. The results obtained in the present study indicate that the M. maderaspatana extract could be considered a potential source of natural antioxidant.

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