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1.  Antioxidant, antimicrobial, and theoretical studies of the thiosemicarbazone derivative Schiff base 2-(2-imino-1-methylimidazolidin-4-ylidene)hydrazinecarbothioamide (IMHC) 
Background
Adverse antimicrobial activities of thiosemicarbazone (TSC) and Schiff base derivatives have widely been studied by using different kinds of microbes, in addition different methods were used to assay the antioxidant activities using DPPH, peroxids, or ntrosyl methods. However, there are no studies describing the synthesis of TSC derived from creatinine.
Results
In this study, 2-(2-imino-1-methylimidazolidin-4-ylidene)hydrazinecarbothioamide (IMHC) was synthesized by the reaction of creatinine with thiosemicarbazide. The novel molecule was characterized by FT-IR, UV-VIS, and NMR spectra in addition of the elemental analysis. The free radical scavenging ability of the IMHC was determined by it interaction with the stable-free radical 2,2"-diphenyl-1-picrylhydrazyl (or nitric oxide or hydrogen peroxide) and showed encouraging antioxidant activities. Density functional theory calculations of the IMHC performed using molecular structures with optimized geometries. Molecular orbital calculations provide a detailed description of the orbitals, including spatial characteristics, nodal patterns, and the contributions of individual atoms. Highest occupied molecular orbital-lowest unoccupied molecular orbital energies and structures are shown.
Conclusions
IMHC shows considerable antibacterial and antifungal activities. The free radical scavenging activity of synthesized compound was screened for in vitro antioxidant activity.
doi:10.1186/2191-2858-2-4
PMCID: PMC3342846  PMID: 22373542
antibacterial; antioxidant; antifungal; creatinine; Schiff base; thiosemicarbazone
2.  Synthesis, Characterization, Theoretical Crystal Structure, and Antibacterial Activities of Some Transition Metal Complexes of the Thiosemicarbazone (Z)-2-(pyrrolidin-2-ylidene)hydrazinecarbothioamide 
Problem Statement. In Iraq like most third world countries, attempts discovered new antibiotic drugs derived from thiosemicarbazide and its metal complexes and developed the branch of applied in organic chemistry. Approach. New (Z)-2-(pyrrolidin-2-ylidene)hydrazinecarbothioamide (L) was synthesized in a good yield by the reaction of pyrrolidone with thiosemicarbazide. Co(II), Ni(II), and Cu(II) complexes of (L) were prepared and characterized by FT-IR, UV/visible spectra, 1HNMR, and CHN analyses. Moreover, charge, bond length, bond angle, twist angle, heat of formation, and steric energy were calculated by using of the ChemOffice program, and the DFT calculations for the complexes were done. The free ligand and its metal complexes were tested in vitro against several microorganisms (Staphylococcus aurous, E. coli, Proteus vulgaris, Pseudomonas, and Klebsiella pneumoniae) to assess their antimicrobial properties. Results. The study shows that these complexes have octahedral geometry; in addition, it has high activity against tested bacteria. Conclusion/Recommendations. Based on the reported results, it may be concluded that ligand acts as bidentate, neutral ligand, coordinating through one of the nitrogen and sulfur atoms.
doi:10.1155/2011/483101
PMCID: PMC3143429  PMID: 21804771
3.  Design and Synthesis of Metal Complexes of (2E)-2-[(2E)-3-Phenylprop-2-en-1-ylidene]hydrazinecarbothioamide and Their Photocatalytic Degradation of Methylene Blue 
The Scientific World Journal  2013;2013:828313.
The photocatalytic degradation has been considered to be an efficient process for the degradation of organic pollutants, which are present in the effluents released by industries. The photocatalytic bleaching of cationic dye methylene blue was carried out spectrometrically on irradiation of UV light using Cu(II), Ni(II), and Co(II) complexes of (2E)-2-[(2E)-3-phenylprop-2-en-1-ylidene]hydrazinecarbothioamide (HL). The effects of pH and metal ion were studied on the efficiency of the reaction. Cu(II) complex shows better catalytic activity and the highest percentage degradation (~88.8%) of methylene blue was observed at pH 12. A tentative mechanism has also been proposed for the photocatalytic degradation of methylene blue.
doi:10.1155/2013/828313
PMCID: PMC3865733  PMID: 24363623
4.  Bis{N-ethyl-2-[3-(hy­droxy­imino-κN)butan-2-yl­idene]hydrazinecarbothio­amide-κ2 N 2,S}nickel(II) dichloride 
In the title complex, [Ni(C7H14N4OS)2]Cl2, the NiII ion is six-coordinated in a distorted octa­hedral geometry by four N atoms from the two imine and two oxime groups, and two S atoms from the thione groups. Two chloride ions complete the asymmetric unit. In the crystal, mol­ecules are linked through N—H⋯Cl and O—H⋯Cl hydrogen bonds into an infinite chain propagating along [101].
doi:10.1107/S1600536811055383
PMCID: PMC3274909  PMID: 22346856
5.  Antioxidant and Antifungal Activity of Extracts of the Aerial Parts of Thymus capitatus (L.) Hoffmanns Against Four Phytopathogenic Fungi of Citrus sinensis 
Background:
Many medicinal plants from the Lamiaceae family can be easily found in Algeria. These plants have been used as traditional medicines by local ethnic groups. Thymus capitatus is known in Algeria as "Zaatar" and has been commonly used as a spice, and reported to have many biological effects.
Objectives:
This paper focused on the assessment of the antioxidant potential and antifungal activity of essential oil and solvent extracts of T. capitatus against the growth of certain fungi.
Materials and Methods:
Essential oil, ethanol and hexane extracts of T. capitatus were tested for their antioxidant and antifungal activities. The 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to determine the free radical quenching capacity. Antifungal activity was assessed using the radial growth technique.
Results:
DPPH free radical scavenging effect of the extracts was compared with standard antioxidant ascorbic acid and showed significant results. The ethanol extract showed high activity at the concentration of 80 g/mL, but less than the standard ascorbic acid. The essential oil was effective against all the fungi used in the experiment. The highest inhibitory effect on the growth of Aspergillus niger, Aspergillus oryzae, Penicillium digitatum, and Fusarium solani was exhibited by the essential oil at concentrations between 0.1 and 0.5 μg/mL.
Conclusions:
These findings demonstrated that ethanol extract obtained from T. capitatus is a potential source of natural antioxidant, while the essential oil extract can be exploited as an ideal alternative to synthetic fungicides for use in the treatment of many fungal phytopathogens.
PMCID: PMC3957143  PMID: 24644439
Antioxidants; Citrus sinensis; 2, 2-diphenyl-1-picrylhydrazyl; Lamiaceae
6.  Synthesis and Antioxidant Activities of Novel 5-Chlorocurcumin, Complemented by Semiempirical Calculations 
The novel curcumin derivative (1E,4Z,6E)-5-chloro-1,7-bis(4-hydroxy-3-methoxyphenyl)hepta-1,4,6-trien-3-one (5-chlorocurcumin) was prepared from natural curcumin. The newly synthesised compound was characterised by spectral studies (IR, 1H NMR, and 13C NMR). The free radical scavenging activity of 5-chlorocurcumin has been determined by measuring interaction with the stable free radical DPPH, and 5-chlorocurcumin has shown encouraging antioxidant activities. Theory calculations of the synthesised 5-chlorocurcumin were performed using molecular structures with optimised geometries. Molecular orbital calculations provided a detailed description of the orbitals, including spatial characteristics, nodal patterns, and the contributions of individual atoms.
doi:10.1155/2013/354982
PMCID: PMC3793294  PMID: 24170994
7.  Synthesis, Characterization and Antioxidant Property of Quercetin-Tb(III) Complex 
Advanced Pharmaceutical Bulletin  2013;4(2):101-104.
Purpose: Nearly all of flavonoids are good metal chelators and can chelate many metal ions to form different complexes. This article describes a synthesis of Quercetin–Tb(III) in methanol, characterized by using elemental analysis, UV–visible and evaluation of its antioxidant properties.
Methods: The formation of complexes is realized from the UV–visible spectra which shows that the successive formation of Quercetin–Tb(III) occurs. To find out the antioxidant activity variation and the role of Tb(III) ion on the antioxidant activity of the complexes different radical scavenging methods such as: 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and 2,2′-azinobis 3-ethylbenzothiazoline-6-sulphonic acid (ABTS) were used.
Results: The results from DPPH, ABTS and FRAP methods showed that Quercetin and Quercetin–Tb(III) complex are capable of donating electron or hydrogen atom, and consequently could react with free radicals or terminate chain reactions in a time- and dose-dependent manner.
Conclusion: This study showed that the chelation of metal ions by Quercetin decrease the redox potential of Quercetin-metal complex.
doi:10.5681/apb.2014.016
PMCID: PMC3915808  PMID: 24511472
Flavonoid; Antioxidant; Quercetin–Tb(III) complex; DPPH; FRAP; ABTS
8.  Synthesis, Characterization, Antimicrobial, DNA Cleavage, and Antioxidant Studies of Some Metal Complexes Derived from Schiff Base Containing Indole and Quinoline Moieties 
A new Schiff base of 5-chloro-3-phenyl-1H-indole-2-carboxyhydrazide and 3-formyl-2-hydroxy-1H-quinoline (HL), and its Cu(II), Co(II), Ni(II), Zn(II), Cd(II), and Hg(II) complexes have been synthesized and characterized in the light of microanalytical, IR, H1 NMR, UV-Vis, FAB-mass, ESR, XRD, and TGA spectral studies. The magnetic susceptibility measurements and low conductivity data provide evidence for monomeric and neutral nature of the complexes. On the basis of spectral studies and analytical data, it is evident that the Schiff base acts as tridentate ligand. The Cu(II), Co(II), and Ni(II) complexes were octahedral, whereas Zn(II), Cd(II), and Hg(II) complexes were tetrahedral in nature. The redox behavior of the Cu(II) complex was investigated by electrochemical method using cyclic voltammetry. In order to evaluate the effect of metal ions upon chelation, both the ligand and its metal complexes were screened for their antibacterial and antifungal activities by minimum inhibitory concentration (MIC) method. The DNA cleavage experiment performed using agarose gel electrophoresis method showed the cleavage of DNA by all the metal complexes. The free radical scavenging activity of newly synthesized compounds has been determined at a different concentration range by means of their interaction with the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH).
doi:10.1155/2013/315972
PMCID: PMC3806341  PMID: 24194692
9.  Antioxidant and anti-inflammatory activities of selected medicinal plants and fungi containing phenolic and flavonoid compounds 
Chinese Medicine  2012;7:26.
Background
This study aims to determine the relationship between the antioxidant and anti-inflammatory activities of the thirteen herbs and two fungi extracts, and their total phenolic and flavonoid contents.
Methods
Antioxidant activities were evaluated by four assays: an antioxidant activity assay using Saccharomyces cerevisiae, a DPPH ((2, 2-diphenyl-1-picrylhydrazyl) assay to assess free radical scavenging, an assay assessing ferrous ions or iron (II) chelating ability, and a ferric reducing antioxidant power (FRAP) assay. Total phenolic and flavonoid contents were determined using the Folin-Ciocalteu and aluminium chloride methods, respectively. Anti-inflammatory activities were determined by measuring the inhibition of nitric oxide and TNF-α production in lipopolysaccharide- and interferon-γ-activated J774A.1 macrophages. Their cytotoxicities against macrophages were determined by MTT assay.
Results
A positive linear correlation between antioxidant activities and the total phenolic and flavonoid content of the plant extracts was found. The plant extracts with high phenolic and flavonoid content also exhibited significant anti-inflammatory activity with good cell viability.
Conclusion
The selected herbs could be a rich source of antioxidants and free radical scavenging compounds. The levels of phenolic and flavonoid compounds were correlated with the antioxidant and anti-inflammatory activities of the extracts from the herbs.
doi:10.1186/1749-8546-7-26
PMCID: PMC3577437  PMID: 23176585
10.  In vitro Antioxidant and Antibacterial Activities of Methanol Extract of Kyllinga nemoralis 
The present study was designed to evaluate the antioxidant and antibacterial activity of methanol extract of Kyllinga nemoralis. Six different in vitro antioxidant assays including 2,2-diphenyl-1-picrylhydrazyl, hydroxyl radical, superoxide anion radical, hydrogen peroxide radical, ferric reducing antioxidant power assay and reducing power were carried out to ensure the scavenging effect of the plant on free radicals. In addition, total antioxidant capacity assay, total phenolic contents, tannins, flavonoids and flavonol contents of the plant were also analysed by the standard protocols. Kyllinga nemoralis exhibited high antioxidant activity on 2,2-diphenyl-1-picrylhydrazyl assay (IC50= 90 μg/ml), superoxide radical scavenging assay (IC50= 180 μg/ml) and hydrogen peroxide radical scavenging assay (IC50= 200 μg/ml), compared with standards. These observations provide comprehensible supporting evidence for the antioxidant potential of the plant extract. Reducing power (IC50= 213.16 μg/ml) and hydroxyl radical scavenging activity (IC50= 223 μg/ml) of the plant extract was remarkable. The methanol extract of K. nemoralis exhibited significant antimicrobial activity against Gram-positive human pathogenic bacteria. Standard in vitro antioxidant assays assessed the electron donating ability of the plant extract in scavenging free radicals. The inhibitory effect of the plant extract against bacterial pathogens may be due to the presence of phytochemicals. Thus, the results suggest that Kyllinga nemoralis is a potential source of antioxidants and could serve as the base for drug development.
PMCID: PMC4023288  PMID: 24843192
Antioxidant activity; antimicrobial activity; Kyllinga nemoralis; phenolics; flavonoids
11.  Crystal structure of the charge-transfer complex 2-(1,2,3,4-tetra­hydro­naph­thal­en-1-yl­idene)hydrazinecarbo­thio­amide–pyrazine-2,3,5,6-tetra­carbo­nitrile (2/1) 
The reaction of 2-(1,2,3,4-tetra­hydro­napthalen-1-yl­idene)hydrazinecarbo­thio­amide (TTSC) with pyrazine-2,3,5,6-tetra­carbo­nitrile (tetra­cyano­pyrazine, TCNP) yields the title 2:1 charge-transfer adduct, 2C11H12N3S·C6N8. The complete TCNP mol­ecule is generated by a crystallographic inversion centre and the non-aromatic ring in the TTSC mol­ecule adopts an envelope conformation with a methyl­ene C atom as the flap. In the crystal, the thio­semicarbazone mol­ecules are connected through inversion-related pairs of N—H⋯S inter­actions, building a polymeric chain along the b-axis direction. The TCNP mol­ecules are embedded in the structure, forming TTSC–TCNP–TTSC stacks with the aromatic rings of TTSC and the mol­ecular plane of TCNP in a parallel arrangement [centroid–centroid distance = 3.5558 (14) Å]. Charge-transfer (CT) via π-stacking is indicated by a CT band around 550 cm−1 in the single-crystal absorption spectrum.
doi:10.1107/S1600536814019795
PMCID: PMC4257178  PMID: 25484688
charge-transfer composite compound; tetra­cyano­pyrazine; thio­semicarbazone; crystal structure
12.  Potent Antioxidant Dendrimers Lacking Pro-oxidant Activity 
Free radical biology & medicine  2010;50(8):918-925.
It is well known that antioxidants have protective effects against oxidative stress. Unfortunately, in the presence of transition metals, antioxidants including polyphenols with potent antioxidant activities may also exhibit pro-oxidant effects, which may irreversibly damage DNA. Therefore, antioxidants with strong free radical scavenging abilities and devoid of pro-oxidant effects would be of immense biological importance. We report two antioxidant dendrimers with a surface rich in multiple phenolic hydroxyl groups, benzylic hydrogens and electron donating ring substituents that contribute to their potent free radical quenching property. In order to minimize their pro-oxidant effects, the dendrimers were designed with a metal chelating tris(2-aminoethyl)amine (TREN) core. The dendritic antioxidants were prepared by attachment of six syringaldehyde or vanillin molecules to TREN by reductive amination. They exhibited potent radical scavenging properties: 5 times stronger than quercetin and 15 times more potent than Trolox according to the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The antioxidant dendrimers also protected low-density lipoprotein, lysozyme and DNA against 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced free radical damage. More importantly, unlike quercetin and Trolox, the two TREN antioxidant dendrimers did not damage DNA via their pro-oxidant effects when incubated with physiological amounts of copper ions. The dendrimers also showed no cytotoxicity towards Chinese hamster ovary cells.
doi:10.1016/j.freeradbiomed.2010.10.699
PMCID: PMC3047602  PMID: 20977937
Polyphenolic dendrimer; antioxidant; pro-oxidant; lipoprotein; lysozyme; DNA
13.  Synthesis and Structure-Activity Correlation Studies of Metal Complexes of α-N-heterocyclic Carboxaldehyde Thiosemicarbazones in Shewanella oneidensis 
This investigation involved the synthesis of metal complexes to test the hypothesis that structural changes and metal coordination in pyridine thiosemicarbazones affect cell growth and cell proliferation in vitro. Thiosemicarbazones are well known to possess antitumor, antiviral, antibacterial, antimalarial, and other activities. Extensive research has been carried out on aliphatic, aromatic, heterocyclic and other types of thiosemicarbazones and their metal complexes. Due to the pronounced reactivity exhibited by metal complexes of heterocyclic thiosemicarbazones, synthesis and structural characterization of di-2-pyridylketone 4N-phenyl thiosemicarbazone and diphenyl tin (Sn) and platinum (Pt) complexes were undertaken. Shewanella oneidensis MR-1, a metal ion-reducing bacterium, was used as a model organism to explore the biological activity under aerobic conditions. A comparision of the cytotoxic potential of selected ligand and metal-complex thiosemicarbazones on cell growth in wild type MR-1 and mutant DSP-010 Shewanella oneidensis strains at various concentrations (0, 5, 10, 15, 20 or 25 ppm) was performed. The wild type (MR-1) grown in the presence of increasing concentrations of Sn- thiosemicarbazone complexes was comparatively more sensitive (mean cell number = 4.8 × 108 ± 4.3 × 107 SD) than the DSP-010, a spontaneous rifampicillin derivative of the parent strain (mean cell number = 5.6 × 108 ± 6.4 × 107 SD) under comparable aerobic conditions (p=0.0004). No differences were observed in the sensitivity of the wild and mutant types when exposed to various concentrations of diphenyl Pt- thiosemicarbazone complex (p= 0.425) or the thiosemicarbazone ligand (p=0.313). Growth of MR-1 in the presence of diphenyl Sn- thiosemicarbazone was significantly different among treatment groups (p=0.012). MR-1 cell numbers were significantly higher at 5ppm than at 10 to 20ppm (p = 0.05). The mean number of DSP-010 variant strain cells also differed among diphenyl Sn- thiosemicarbazone complex treated groups (p=0.051). In general, there was an increasing trend in the number of cells from about 5.0 × 108 cells (methanol control group) to about 6.0 × 108 cells (25ppm). The number of cells in methanol control group was significantly lower than cell numbers at 20ppm and 25ppm (p = 0.05), and numbers at 5ppm treatment were lower than at 20 and 25ppm (p = 0.05). Furthermore, a marginally significant difference in the number of MR-1 cells was observed among diphenyl Pt- thiosemicarbazone complex treatment groups (p = 0.077), and an increasing trend in the number of cells was noted from ~5.0 × 108 cells (methanol control group) to ~5.8 × 108 cells (20ppm). In contrast, the DSP-010 variant strain showed no significant differences in cell numbers when treated with various concentrations of diphenyl Pt- thiosemicarbazone complex (p = 0.251). Differences in response to Sn- metal complex between MR-1 and DSP-010 growing cultures indicate that biological activity to thiosemicarbazone metal complexes may be strain specific.
PMCID: PMC3814712  PMID: 16705815
α-N-heterocyclic carboxaldehyde thiosemicarbazones; biological activity; metal complexes and Shewanella oneidensis
14.  Free radical scavenging activities of Cnidium officinale Makino and Ligusticum chuanxiong Hort. methanolic extracts 
Pharmacognosy Magazine  2010;6(24):323-330.
Background:
Antioxidants from natural resources possess multifaceted and importance of the activities provides substantial scope in neurodegenerative diseases. The aim of this study was to assess and compare the free radical scavenging activities of Cnidium officinale and Ligusticum chuanxiong, which are closely related species.
Materials and Methods:
The scavenging activities of plant materials were evaluated using Trolox equivalent antioxidant capacity (TEAC), oxygen radical absorbance capacity (ORAC) and 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide radical (O2·-), hydrogen peroxide (H2O2), hydroxyl (OH·), nitric oxide radical (NO·) and metal chelation. In addition, the cell viability and nitric oxide release were assayed using Neuro-2a (N2a) cells.
Results:
The methanolic extracts of C. officinale and L. chuanxiong showed scavenging activities of free radicals with an additional antioxidant capacity. Moreover, the efficacy on the cell viability and nitric oxide release in cell culture model has been established.
Conclusion:
Results of the present study suggests that the extracts of C. officinale and L. chuanxiong have comparatively similar free radical scavenging activities in vitro and may have important health effects.
doi:10.4103/0973-1296.71794
PMCID: PMC2992148  PMID: 21120037
Antioxidant; Cnidium officinale; free radical scavenging; Ligusticum chuanxiong; Umbelliferae
15.  Scavenging effects of methanolic extracts of broad beans on free-radical species 
This report describes the antioxidant characteristics of methanolic extracts from broad beans (Vicia fava). The methanolic extracts of broad beans (MEBB) exhibited a marked scavenging effect on superoxide. MEBB also exerted scavenging activities on hydrogen peroxide and 1, 1-diphenyl-2-picrylhydrazyl radical. The radical scavenging activity of MEBB was highest when the scavenging effect of MEBB on Superoxide (IC50 = 0.15 mg/ml) was examined. These results suggest that MEBB have effective activities both as a radical scavenger and as a hydrogen donor. The chelating activity of MEBB (0.70 mg/ml) on Fe2+ and Cu2+ was 31.2% and 28.5%, respectively. The antioxidant effect of MEBB on lipid peroxidation might be attributed to their properties of scavenging free-radical species and their chelating activity on metal ions. The antioxidant activity of MEBB against tert-butyl hydroperoxide (BHP)-induced oxidative stress in WI-38 cells was assessed. The activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase, and glutathione peroxidase (GSH-Px) were measured as indices of oxidative stress. WI-38 cells incubated with 0.1 mM BHP for 2 hr exhibited the increase of SOD, catalase and GSH-Px activities over the control. When the cells incubated in MEBB (45–450 μg/ml) for 18 hr were subjected to a BHP challenge test, SOD activity returned to its control value or lower at all levels tested. When catalase activity was determined, a similar trend occurred except in the cells incubated in 112.5 μ g/ml MEBB. These results imply that MEBB inhibit oxidative stress in WI-38 cells.
doi:10.1007/BF02931232
PMCID: PMC2723265  PMID: 21432501
Vicia fava; Broad beans; Methanolic extracts; Free radicals; Oxidative stress
16.  Antioxidant and antifungal activities of essential oil of Alpinia calcarata Roscoe rhizomes 
Antioxidant and antifungal activity were determined for the essential oil of Alpinia calcarata Roscoe (Zingiberaceae) rhizomes. Its antioxidant properties were investigated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay and thiobarbituric acid reactive substances (TBARS) assay. Butylated hydroxy toluene (BHT) and vitamin E served as positive controls. Antifungal activities were investigated against crop pathogens Curvularia spp. and Colletorichum spp. using the agar plate method. Fifty percent effective concentration (EC50) and % antioxidant index of the essential oil were 45 ± 0.4 and 16.1 ± 0.2 for DPPH and TBARS assays, respectively. The degree of, the essential oil’s inhibition of the growth of crop pathogens Curvularia spp. and Colletorichum spp. varied with time period its effects were higher than greater than for the positive control, daconil. In conclusion, the essential oil of A. calcarata rhizomes possess moderate antioxidant property and promising antifungal activity.
doi:10.4103/0975-9476.72621
PMCID: PMC3087359  PMID: 21547048
Alpinia calcarata; antifungal activity; antioxidant power; essential oil
17.  Antioxidant activity and free radical-scavenging capacity of Gynura divaricata leaf extracts at different temperatures 
Pharmacognosy Magazine  2011;7(25):40-45.
Background:
Extraction temperature influences the total phenolic content (TPC), total flavonoid content (TFC) of medicinal plant extracts to a great extend. TPC and TFC are the principle activity constituents present in the plant. The effects of extraction temperature on TPC, TFC and free radical-scavenging capacity of Gynura divaricata leaf extracts are worth to study.
Materials and Methods:
Folin–Ciocalteu and aluminum chloride colorimetric assay were used to determine the TPC and TFC of Gynura divaricata leaf extracts at different temperatures. The antioxidant and free radical-scavenging activity were measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) and phosphomolybdenum methods.
Results:
TPC and TFC were significantly elevated with increasing extraction temperature (from 40°C to 100°C). However, TPC and TFC were not significantly different (P > 0.05) at the extraction temperatures 90°C and 100°C. Also, the extracts obtained at a higher temperature exhibited a significant free radical-scavenging activity compared with extraction at lower temperatures (P < 0.05). The TPCs (13.95-36.68 mg gallic acid equivalent/g dry material) were highly correlated with DPPH (R2 = 0.9229), ABTS (R2 = 0.9951) free radical-scavenging capacity, and total antioxidant activity (R2 = 0.9872) evaluated by phosphomolybdenum method.
Conclusion:
The TPC and TFC of G. divaricata leaf was significantly influenced by the extraction temperatures, which were the main antioxidant constituents present in the G. divaricata plant.
doi:10.4103/0973-1296.75900
PMCID: PMC3065156  PMID: 21472078
Antioxidant activity; extraction temperature; Gynura divaricata; total phenolic content; total flavonoid content
18.  Antioxidant Activity and Protection from DNA Damage by Water Extract from Pine (Pinus densiflora) Bark 
Water extract from Pinus densiflora (WPD) was investigated for its antioxidant activity and its ability to provide protection from DNA damage. A series of antioxidant assays, including a 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging assay, a reducing power assay, a metal-chelating assay, a superoxide radical scavenging assay, and a nitrite scavenging ability, as well as a DNA damage protection assay were performed. Total phenolic content was found to be 211.32 mg Tan/g WPD. The extract scavenged 50% DPPH free radical at a concentration of 21.35 μg/mL. At that same concentration, the reducing power ability of WPD was higher than that of α-tocopherol. The extract chelated 68.9% ferrous ion at the concentration of 4 mg/mL. WPD showed better nitrite scavenging effect at the lower pH. Meanwhile, WPD exhibited a strong capability for DNA damage protection at 1 mg/mL concentration. Taken together, these data suggest water extract from Pinus densiflora could be used as a suitable natural antioxidant.
doi:10.3746/pnf.2012.17.2.116
PMCID: PMC3866746  PMID: 24471072
antioxidant; DNA damage; phenolic content; reactive oxygen species
19.  Oxygen Radical Scavenger Activity, EPR, NMR, Molecular Mechanics and Extended-Hückel Molecular Orbital Investigation of the Bis(Piroxicam)Copper(II) Complex 
Metal-Based Drugs  1995;2(1):43-56.
The oxygen radical scavenger activity (ORSA) of [CuII(Pir)2] (HPir = Piroxicam = 4-hydroxy -2- methyl -N-2- pyridyl -2H- 1,2-benzothiazine -3- carboxamide 1,1-dioxide) was determined by chemiluminescence of samples obtained by mixing human neutrophils (from healthy subjects) and [CuII(Pir)2(DMF)2] (DMF = N,N -dimethylformammide) in DMSO/GLY/PBS (2:1:2, v/v) solution (DMSO = dimethylsulfoxide, GLY = 1,2,3-propantriol, PBS = Dulbecco’s buffer salt solution). The ratio of the residual radicals, for the HPir (1.02·10−4M) and [CuII(Pir)2(DMF)2] (1.08·10−5M)/HPir (8.01·10−−5M) systems was higher than 12 (not stimulated) [excess of piroxicam was added (Cu/Pir molar ratio ≈1:10) in order to have most of the metal complexed as bischelate]. In contrast, the ratio of residual radicals for the CuCl2 (1.00·10−5M) and [CuII(Pir)2(DMF)2] (1.08·10−5M)/Hpir (8.01·10−5M)system was 5. The [CuII(Pir)2] compound is therefore a stronger radical scavenger than either HPir or CuCl2. A molecular mechanics (MM) analysis of the gas phase structures of neutral HPir, its zwitterionic (HPir+-) and anionic (Pir-) forms, and some CuII-piroxicam complexes based on X-ray structures allowed calculation of force constants. The most stable structure for HPir has a ZZZ conformation similar to that found in the CuII (and CdII complexes) in the solid state as well as in the gas phase. The structure is stabilized by a strong H bond which involves the N(amide)-H and O(enolic) groups. The MM simulation for the [CuII(Pir)2(DMF)2] complex showed that two high repulsive intramolecular contacts exist between a pyridyl hydrogen atom of one Pir- molecule with the O donor of the other ligand. These interactions activate a transition toward a pseudo-tetrahedral geometry, in the case the apical ligands are removed. On refluxing a suspension of [CuII(Pir)2(DMF)2] in acetone a brown microcystalline solid with the Cu(Pir)2·0.5DMF stoichiometry was in fact prepared. 13C spin-lattice relaxation rates of neutral, zwitterionic and anionic piroxicam, in DMSO solution are explained by the thermal equilibrium between the three most stable structures of the three forms, thus confirming the high quality of the force field. The EPR spectrum of [CuII(Pir)2(DMF)2] (DMSO/GLY, 2:1, v/v, 298 and 110 K) agrees with a N2O2+O2 pseudo-octahedral coordination geometry. The EPR spectrum of [CuII(Pir)2·0.5DMF agrees with a pseudo-tetrahedral coordination geometry. The parameters extracted from the room temperature spectra of the solution phases are in agreement with the data reported for powder and frozen solutions. The extended-Hückel calculations on minimum energy structures of [CuII(Pir)2(DMF)2] and [CuII(Pir)2] (square planar) revealed that the HOMOs have a relevant character of dx2−y2. On the other hand the HOMO of a computer generated structure for [CuII(Pir)2] (pseudo-tetrahedral) has a relevant character of dxy atomic orbital. A dxy orbital is better suited to allow a dπ-pπ interaction to the O2- anion. Therefore this work shows that the anti-inflammatory activity of piroxicam could be due in part to the formation of [CuII(Pir)2] chelates, which can exert a SOD-like activity.
doi:10.1155/MBD.1995.43
PMCID: PMC2364950  PMID: 18472745
20.  In Vitro Antioxidant Activity of Selected 4-Hydroxy-chromene-2-one Derivatives—SAR, QSAR and DFT Studies 
The series of fifteen synthesized 4-hydroxycoumarin derivatives was subjected to antioxidant activity evaluation in vitro, through total antioxidant capacity, 1,1-diphenyl-2-picryl-hydrazyl (DPPH), hydroxyl radical, lipid peroxide scavenging and chelating activity. The highest activity was detected during the radicals scavenging, with 2b, 6b, 2c, and 4c noticed as the most active. The antioxidant activity was further quantified by the quantitative structure-activity relationships (QSAR) studies. For this purpose, the structures were optimized using Paramethric Method 6 (PM6) semi-empirical and Density Functional Theory (DFT) B3LYP methods. Bond dissociation enthalpies of coumarin 4-OH, Natural Bond Orbital (NBO) gained hybridization of the oxygen, acidity of the hydrogen atom and various molecular descriptors obtained, were correlated with biological activity, after which we designed 20 new antioxidant structures, using the most favorable structural motifs, with much improved predicted activity in vitro.
doi:10.3390/ijms12052822
PMCID: PMC3116159  PMID: 21686153
4-hydroxycoumarins; antioxidant activity in vitro; DFT; BDEs; QSAR; design
21.  Antioxidant properties and electrochemical behavior of cultivated commercial Indian edible mushrooms 
Methanolic extracts of cap and stipe of commercially obtained mushrooms Agaricus bisporus, Hypsizygus ulmarius, and Calocybe indica were analyzed for their antioxidant activity in different chemical systems including reducing power, free radical scavenging, ferric reducing antioxidant power (FRAP), superoxide scavenging, peroxide scavenging, metal chelating activities and electrochemical behavior. Scavenging effects on 2,2-diphenyl-1-picrylhydrazyl radicals were moderate (43.5–59.0%) at 1.5 mg/ml. Chelating effects on ferrous ions were moderate to excellent (40.6–96.1%) at 20 mg/ml. At 12 mg/ml, the reducing powers were excellent (2.54–1.71). FRAP results were in the range 2.15–0.98 at 16 mg/ml. The ability to scavenge H2O2 was moderate to excellent (48.9–97.7%) at 1.5 mg/ml. At 10 mg/ml, Agaricus bisporus cap proved to be better at scavenging superoxide radicals than others. Similar electrochemical responses of all extracts suggested similar electroactive chemical composition. The total phenols in the extracts ranged from 14.73–26.72 mg/g.The total flavonoid content ranged from 1.12–2.17 μg/g.
doi:10.1007/s13197-011-0338-8
PMCID: PMC3550913  PMID: 24425920
Calocybe indica; Hypsizygus ulmarius; Agaricus bisporus; Antioxidant activity; Total phenol content; Total flavonoid content
22.  The Evaluation of Antibacterial, Antifungal and Antioxidant Activity of Methanolic Extract of Mindium Laevigatum (Vent.) Rech. F., From Central Part of Iran 
Background
Mindium laevigatum (Vent.) Rech. F. plant grows in central part of Iran. And used by local people as medical plant.
Objectives
The purpose of this study was to investigate the in vitro antibacterial, antifungal and antioxidant activities of the methanolic extracts of aerial and flower parts of plant.
Materials and Methods
The leaves and stem and flower of bark from M. laevigatum were separately collected, air-dried and powdered. Then the plant species extracts were prepared with methanol, water 80:20 and two polar and non-polar subfractions were realized. The antioxidant activity was evaluated by scavenging the radicals 1, 1-diphenyl-2-picrylhydrazyl radical (DPPH), β-Carotene linoleic acid assay and reducing power methods. The antifungal and antibacterial evaluation was performed by disc diffusion and minimum inhibitory concentration methods.
Results
The total phenolic analysis of subfractions found 182 ± 4.2 µg.gr-1 for polar and 158 ± 3.9 µg.gr-1 for non-polar extracts. The antifungal activity of the extracts against the various fungal varied from 14.0 to 34 mm. MIC values from 50 to 400 µg.mL-1 were satisfactory when compared with other plant products. The antibacterial results revealed that the subfraction extracts are mostly effective against Staphylococcus aureus. The antioxidant results showed polar subfraction has more activity against non-polar subfraction.
Conclusion
These findings demonstrated that the extract of Mindium laevigatum has remarkable in vitro antifungal and antioxidant activity.
PMCID: PMC3941880  PMID: 24624184
Methanolic Extract; Antioxidant; Antifungal; Antibacterial
23.  Antioxidant activities and phenolic contents of the methanol extracts of the stems of Acokanthera oppositifolia and Adenia gummifera 
Background
Acokanthera oppositifolia Lam (family: Apocynaceae) is a shrub or small tree with white latex, and the leaves of this plant are used in the form of a snuff to treat headaches and in infusions for abdominal pains and convulsions and septicaemia. Adenia gummifera Harv of the family Passifloraceae is a distinctive woody climber whose infusions are used as emetics and are said to help with some forms of depression. Lipid peroxidation has gained more importance today because of its involvement in pathogenesis of many diseases. Free radicals are the main agents in lipid peroxidation. Antioxidants thus play an important role of protecting the human body against damage by the free radicals. Plants containing phenolic compounds have been reported to possess strong antioxidant properties.
Methods
The antioxidant activities and phenolic contents of the methanol extracts of the stems of Acokanthera oppositifolia and Adenia gummifera were evaluated using in vitro standard procedures. Spectrophotometry was the basis for the determinations of total phenol, total flavonoids, flavonols, and proanthocyanidins. Tannins, quercetin and catechin equivalents were used for these parameters. The antioxidant activities of the stem extract of Acokanthera oppositifolia were determined by the 2,2'-azinobis-3- ethylbenzothiazoline-6-sulfonic acid (ABTS), 1,1-Diphenyl-2-picrylhydrazyl (DPPH), and ferrous reducing antioxidant property (FRAP) methods.
Results
The results from this study showed that the antioxidant activities of the stem extract of Acokanthera oppositifolia as determined by the 1,1-Diphenyl-2-picrylhydrazyl (DPPH), and ferrous reducing antioxidant property (FRAP) methods, were higher than that of Adenia gummifera. The levels of total phenols and flavonols for A. oppositifolia were also higher. On the other hand, the stem extract of Adenia gummifera had higher level of total flavonoids and proanthocyanidins than that of Acokanthera oppositifolia. The 2, 2'-azinobis-3- ethylbenzothiazoline-6-sulfonic acid (ABTS) activities of the 2 plant extracts were similar and comparable to that of BHT.
Conclusion
Thus, the present results indicate clearly that the extracts of Acokanthera oppositifolia and Adenia gummifera possess antioxidant properties and could serve as free radical inhibitors or scavengers, acting possibly as primary antioxidants. This study has to some extent validated the medicinal potential of the stems of Acokanthera oppositifolia and Adenia gummifera.
doi:10.1186/1472-6882-8-54
PMCID: PMC2566552  PMID: 18817535
24.  Evaluation of Abelmoschus moschatus extracts for antioxidant, free radical scavenging, antimicrobial and antiproliferative activities using in vitro assays 
Background
Abelmoschus moschatus Medik. leaves and seeds are considered as valuable traditional medicine. The aromatic seeds of this plant are aphrodisiac, ophthalmic, cardio tonic, antispasmodic and used in the treatment of intestinal complaints and check queasiness. To give a scientific basis for traditional usage of this medicinal plant, the seed and leaf extracts were evaluated for their antioxidant, free radical scavenging, antimicrobial and antiproliferative activities.
Methods
In this study, antioxidant, antimicrobial and antiproliferative activities of A. moschatus extracts were evaluated in a series of in vitro assay involving free radicals, reactive oxygen species and their IC50 values were also determined. The antioxidant activities of the seed and leaf extracts of A. moschatus were determined by total antioxidant, DPPH, and ferrous reducing antioxidant property (FRAP) methods. In addition, the antiproliferative activity was also evaluated using colorectal adenocarcinoma and retinoblastoma human cancer cell lines. Moreover, six bacterial reference strains, two gram-positive (Bacillus subtilis and Staphylococcus aureus), four gram-negative (Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris and Salmonella enterica paratyphi) and one fungal strain (Candida albicans) were used to evaluate its antimicrobial activity.
Results
The results from this study showed that the antioxidant activities of A. moschatus as determined by the total phenol, flavonoids, total antioxidant and FRAP methods were higher in leaf than that of the seed extracts. On the other hand, the aqueous overnight seed extract (AMS-I) has shown significant radical scavenging activity as in 1, 1- Diphenyl-2-picrylhydrazyl (DPPH), hydrogen peroxide, hydroxyl radical, superoxide and lipid peroxidation as compared to other seed and leaf extracts. The AMS-I and AML-IV have shown activity against six and seven microorganisms respectively. Simulteneously, AMS-IV and AML-IV have demonstrated potential antiproliferative activity against two human cell lines - Colorectal adenocarcinoma (COLO-205) and retinoblastoma (Y79).
Conclusion
The seed and leaf extracts of A. moschatus possess significant antioxidant activity and could serve as free radical inhibitors or scavenger, or substitute, probably as primary antioxidants. The plant possesses moderate antibacterial activity against bacterial strains used in this study. Hydroalcoholic seed and leaf extracts also exhibited antiproliferative activity against two human cancer cell lines. A. moschatus may therefore, be a good candidate for functional foods as well as pharmaceutics.
doi:10.1186/1472-6882-11-64
PMCID: PMC3201038  PMID: 21849051
25.  Antioxidant potential of hydro-methanolic extract of seed of Caesalpinia bonduc: An in vitro study 
It is well known that the over production of reactive oxygen species is harmful for living organisms and it damages major cellular constituents such as DNA, protein, and lipid. At present, searching of new plant sources having free radical scavenging activity is an important field of research in phytomedicine as natural products are safe and relatively low cost. In this respect, attention has been focused to evaluate the antioxidant potential of hydro-methanolic extract of seed of Caesalpinia bonduc (Caesalpenacae) using different in vitro models. To evaluate the antioxidant activity, extract was examined on 2, 2-diphenyl-1-picrylhydrazyl radical scavenging effect, scavenging of hydrogen peroxide, hydroxyl radical scavenging potential, and anti-lipid peroxidation activity by biochemical methods. Total phenol and flavonoids contents in the said extract were measured biochemically as per standard methods. Results were compared with butylated hydroxyl toluene and α-tocopherol. Results indicated that hydro-methanolic extract has strong scavenging activity on 2, 2-diphenyl-1-picrylhydrazyl radical with IC50 value 157.4 μg/ml, hydroxyl radical with IC50 value 61.9 μg/ml and hydrogen peroxide with IC50 value 64.32 μg/ml. Hydro-methanolic extract also showed notable inhibition in lipid peroxidation having IC50 value 58.87 μg/ml. Phytochemical study focused that the extract is rich in phenolic compounds (24.66 mg gallic acid equivalent/g dried extract) and flavonoids (136.65 mg quercetin equivalent/g dried extract). Findings of the experiment indicated that the hydro-methanolic extract of seed of Caesalpinia bonduc is a source of natural antioxidants.
doi:10.4103/2231-4040.90884
PMCID: PMC3255348  PMID: 22247894
Antioxidant; Caesalpinia bonduc; free radicals; lipid peroxidation

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