Goniothalamus velutinus Airy Shaw belongs to the family Annonaceae which is known to have anticancer, antitumor and many other bioactivities. Natives of Sabah and Sarawak use root decoction of G. ...velutinus for the treatment of headache and food poisoning while the bark was used as a mosquito repellent. Bark and leaf extracts of this plant, obtained from Brunei Darussalam, were tested for phytochemical and antioxidant activities. Phytochemical screening of plant extracts revealed the presence of alkaloids, steroids, terpenoids and cardiac glycosides. Quantitative determination of total phenolics, total flavonoids, and various in vitro antioxidant activities (DPPH, ABTS and FRAP) of methanolic extract was carried out using colorimetric methods. The total phenolic content, expressed as mg of gallic acid equivalent (GAE) per gram of extract, was found to be 68mgGAE/g and 78mgGAE/g for bark and leaves respectively. The radical scavenging activity measurement, expressed in terms of EC50 (effective concentration of extract in μg/mL that reduces DPPH absorbance to 50% as compared to negative control), for leaf and bark extracts was found to be 155μg/mL and 204μg/mL respectively. Standards trolox and ascorbic acid show EC50 value of 5μg/mL and 4μg/mL respectively. Trolox equivalent antioxidant capacity (TEAC) was measured using the ABTS and FRAP method. Result for bark and leaf extracts was 79mg and 106mg trolox equivalent (TE)/g respectively for the ABTS method. For FRAP assay, results for bark and leaf extracts were 80 and 89mgTE/g respectively.
•Kinetic and endpoint analysis were combined for reliable comparison of antioxidants activities.•Parameter k2′ offers a better understanding of the antioxidant’s kinetic behavior.•Parameters k2max′, ...IC100 and n can be used to compare antioxidants potential.•The kinetic analysis was applied to compare antioxidant activity of 3 natural beverages.
The antioxidant activities of three beverages, coffee, black tea and green tea, along with their major components, were investigated in terms of their reaction with the stable radical 2,2′-diphenyl-2-picrylhydrazyl (DPPH). We used a kinetic approach in parallel with quantification methods based on a fixed end-point to determine the scavenging efficiency of compounds abundant in these beverages during their reaction with DPPH using a stopped-flow spectrophotometer-based method. Ascorbic acid, (+)-catechin, (−)-epigallocatechin, tannic acid, and caffeic acid were selected as model antioxidants to study in coffee, black tea and green tea. We applied a second-order model to demonstrate similarities in the kinetics behavior of beverages and related compounds. Our findings showed the slopes k2′((mol/L)-1s-1) and k2max′((mol/L)1s-1) exhibited similar and correlated values; we suggest the variation in k2′ as a function of time is more informative about antioxidant properties than reaction with DPPH alone. We also used IC100 to test the reliability of the relative stoichiometry using a new comparative parameter “n”, which was calculated as: n=c0DPPHIC100 (mol/L(mol/L)−1, (mol/L)mlmg−1 or molg−1).
•Determination of formation constants between estragole and cyclodextrins.•Formation of 1:1 inclusion complexes in solution.•Physicochemical characterization of the freeze–dried solid inclusion ...complexes.•Determination of the encapsulation efficiencies of CDs.•Increase of photostability, controlled release and radical scavenging activity.
Inclusion complexes of estragole (ES) as pure compound and as main component of basil and tarragon essential oils (EOs) with α-cyclodextrin (α-CD), β-cyclodextrin (β-CD), hydroxypropyl-β-cyclodextrin (HP-β-CD), randomly methylated-β-cyclodextrin (RAMEB), a low methylated-β-cyclodextrin (CRYSMEB) and γ-cyclodextrin (γ-CD) were characterized. Formation constants (Kf) of the complexes were determined in aqueous solution by nonlinear regression analysis using static headspace gas chromatography (SH-GC) and UV–visible spectroscopy. Solid inclusion complexes were prepared by the freeze-drying method for different CD:ES molar ratios and were characterized by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR). Inclusion complexes formation allowed the controlled release of ES. Moreover, increased DPPH radical scavenging activity and photostability of ES and ES containing EOs (ESEOs) were observed in the presence of CDs. These findings suggest that encapsulation with CDs could be an efficient tool to improve the use of ES and ESEOs in aromatherapy, cosmetic and food fields.
•Batch-injection analysis (BIA) with amperometric detection of DPPH consumption.•Antioxidant capacity measurement (EC50 value) based on DPPH consumption.•BIA and spectrophotometry methods agree ...statistically for antioxidants.•BIA method provided comparable EC50 measurements to plant and tea samples.
This work proposes the application of batch-injection analysis with amperometric detection to determine the antioxidant capacity of real samples based on the measurement of DPPH radical consumption. The efficient concentration or EC50 value corresponds to the concentration of sample or standard required to scavenge 50% DPPH radicals. For the accurate determination of EC50, samples were incubated with DPPH radical for 1h because many polyphenolic compounds typically found in plants and responsible for the antioxidant activity exhibit slow kinetics. The BIA system with amperometric detection using a glassy-carbon electrode presented high precision (RSD=0.7%, n=12), low detection limit (1μmolL−1) and selective detection of DPPH (free of interferences from antioxidants). These contributed to low detection limits for the antioxidant (0.015 and 0.19μmolL−1 for gallic acid and butylated hydroxytoluene, respectively). Moreover, BIA methods show great promise for portable analysis because battery-powered instrumentation (electronic micropipette and potentiostats) is commercially available.
•Synthesis of water soluble cobalt and copper complexes of tyrosine using encapsulation in β-cyclodextrin.•The prepared complexes were non-cytotoxic and exhibited radical scavenging ...ability.•Environmentally friendly and cost effective antioxidant.
In this study, the cobalt and copper complexes of tyrosine (Tyr) were encapsulated in β-cyclodextrin (βCD) to improve their water solubility. The resulting inclusion complexes (Co-Tyr/βCD and Cu-Tyr/βCD) were characterized by FT-IR, UV–vis, EDX, ICP-OES, TGA, Cyclic Voltammetry (CV), and Photoluminescence (PL). TGA results indicated that approximately 35 wt.% and 41 wt.% of (Co+Tyr) and (Cu+Tyr) were encapsulated within the βCD cavity. The antioxidant activity of the samples was determined using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging method. Co-Tyr/βCD was found to have better antioxidant activity than Cu-Tyr/βCD. The non-cytotoxic nature of the prepared samples was confirmed by the MTT assay.
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The aim of the research was to evaluate the antioxidant activity of 23 LAB strains isolated from raw fermented meat products. The methodology was based on in vitro tests in which the ability of ...antioxidants to deactivate free radicals was used. The greatest ability to scavenge the DPPH radicals was observed in Pediococcus pentosaceus KL14 and KL10, to scavenge ABTS radicals was in Pd. pentosaceus KL11 and KL14. The highest activity of superoxide dismutase (SOD) was found in Pd. pentosaceus BAL6 and BAL3. The Pd. pentosaceus BAL6, KL14 strains were able to produce H2O2. The highest resistance to superoxide anions was found in Pd. pentosaceus KL14 whereas the hydroxyl radicals was observed in Lactiplantibacillus plantarum SCH1 and Pd. pentosaceus BAL6. All of the strains were catalase-negative. The resistance to H2O2 was observed in Pd. pentosaceus KL14 and BAL5. Furthermore, the highest antioxidant activity was found in strains Pediococcus pentosaceus KL14, BAL6 and Lactiplantibacillus plantarum SCH1. Moreover, we identified 15 strains of LAB with high antioxidant activity comparable to probiotic L. rhamnosus GG. The use of natural antioxidant activity can be used in meat processing to limit the use of chemical antioxidants.
•The 23 LAB isolated from meat products were examined to the antioxidant activity.•The highest antioxidant activity was found in KL14, BAL6 and SCH1 strains.•LAB strains can be used as starters for meat to increase antioxidant potential.
Free new ligand 6-MBTADB and metal complexes have been synthesized. Spectroscopy experiments, DFT calculations, antibacterial properties against Gram-positive and Gram-negative bacteria, antifungal, ...molecular docking, antioxidant and anticancer were performed.
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•New free ligand (6-MBTADB) and metal complexes were synthesized and characterized using various methods.•Calculations of energy gaps and other key theoretical parameters were performed using DFT.•Synthesized compounds were evaluated for antibacterial efficacy against Gram positive, Gram negative, and fungi.•The dock mechanism and binding preferences of compounds with different receptors are being studied.•DPPH radical scavenging was used for antioxidant activity assay.•MCF-7 and normal HUVECs are investigated for their anticancer activity in vitro.
A novel tridentate azo dye ligand, 2-2′-(6-methoxybenzothiazolyl)azo-5-dimethylamino benzoic acid (6-MBTADB) and its Pt(IV) and Au(III) metal complexes have been synthesized. The proposed structures were defined from elemental analysis, molar conductivity, magnetic susceptibility, atomic absorption spectrophotometry,1H NMR, 13C NMR, FT-IR, UV–Vis, mass spectra, X-ray diffraction analysis (XRD), thermal analysis (TGA/DTA) and field emission scanning electron microscopy (FE-SEM). Based on analytical and spectroscopic data, suitable geometry has been suggested for all complexes. The 6-MBTADB ligand acts as a tridentate via NNO donors towards the metal ions inside octahedral geometry with Pt(IV), and square planner with Au(III) ion. Quantum chemical calculations were performed on the compounds using density functional theory DFT/B3LYP, 6–311G (d,p), and LanL2DZ basis sets. Moreover, the synthesized compounds showed greater antimicrobial activity when tested biologically against Escherichia coli, Staphylococcus aureus, and Aspergillus niger. The results of their tests show that the metal complexes are more effective against several bacterial and fungal strains. Further, the free radical scavenging activity of the free ligand and metal complexes has been determined by their interaction with the stable DPPH free radical. The combined molecular docking study evaluates the binding energies of anticancer agents, providing the binding property with the receptor. The results of the molecular docking show that the ligand and its complexes have a good affinity with the protein kinase (1HK7). Finally, all the compounds exhibited significant antiproliferative activity against the human breast cancer (MCF-7) and normal HUVECs cell lines, showing that Pt(IV) chelate the most potent against MCF-7 cell line based on IC50 and selective indices (SI) values. This research may provide knowledge that is an excellent backdrop for the rational design of promising drugs.
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