The effects of covalent binding of protocatechuic acid (PA) and gallic acid (GA) to lactoferrin (LF) on the structure, functional, and antioxidant properties of the protein conjugate were investigated. These protein-phenolic conjugates were produced by laccase cross-linking and ultrasound-assisted free radical grafting, which were characterized using turbidity, particle size, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analyses. Structural changes in conjugates were monitored by endogenous fluorescence spectroscopy, fourier transform infrared spectroscopy (FTIR), and circular dichroism (CD). The antioxidant capacities and pH stability were determined using DPPH, ABTS, FRAP, and potentiometric analysis. The enzymatic cross-linking and free radical grafting yielded LF-PA/GA conjugates with altered hydrodynamic diameter and zeta-potential. Spectroscopic and chromatographic analyses revealed that binding to PA/GA altered the molecular structure of LF, with a decrease in LF isoelectric point post binding to PA/GA, without affecting antioxidant activities. In conclusion, LF-PA/GA conjugates present potential applications in the food industry.
Free radicals and reactive oxygen species (ROS) have been implicated in contributing to the processes of aging and disease. In an effort to combat free radical activity, scientists are studying the effects of increasing individuals' antioxidant levels through diet and dietary supplements. Honey appears to act as an antioxidant in more ways than one. In the body, honey can mop up free radicals and contribute to better health. Various antioxidant activity methods have been used to measure and compare the antioxidant activity of honey. In recent years, DPPH (Diphenyl-1-picrylhydrazyl), FRAP (Ferric Reducing Antioxidant Power), ORAC (The Oxygen Radical Absorbance Capacity), ABTS [2, 2-azinobis (3ehtylbenzothiazoline-6-sulfonic acid) diamonium salt], TEAC [6-hydroxy-2, 5, 7, 8-tetramethylchroman-2-carboxylic acid (Trolox)-equivalent antioxidant capacity] assays have been used to evaluate antioxidant activity of honey. The antioxidant activity of honey is also measured by ascorbic acid content and different enzyme assays like Catalase (CAT), Glutathione Peroxidase (GPO), Superoxide Dismutase (SOD). Among the different methods available, methods that have been validated, standardized and widely reported are recommended.
The present study was conducted to determine the effect of air (AD), oven (OD) and freeze drying (FD) on the free radical scavenging activity and total phenolic content (TPC) of Cosmos caudatus and the effect of storage time by the comparison with a fresh sample (FS). Among the three drying methods that were used, AD resulted in the highest free radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) (IC50 = 0.0223 mg/mL) and total phenolic content (27.4 g GAE/100 g), whereas OD produced the lowest scavenging activity and TPC value. After three months of storage, the dried samples showed a high and consistent free radical scavenging activity when compared to stored fresh material. The drying methods could preserve the quality of C. caudatus during storage and the stability of its bioactive components can be maintained.
This research aimed to determine the total antioxidant activity and total phenolic content of the papaya
seeds. These papaya seeds then were introduced into the prepared ice cream to determine the effect of the
papaya seeds to the physicochemical and the acceptability of ice cream by making four different
formulations (Control, 1.0%, 2.0%, and 3.0% of papaya seeds). Two methods namely free radical
scavenging assay (DPPH) and ferric reducing antioxidant power (FRAP) were used to determine the total
antioxidant activity of the papaya seeds, whereas total phenolic content was determined by FolinCiocalteu’s method (TPC). The papaya seeds showed high total phenolic content in the TPC analysis result.
Furthermore, DPPH and FRAP showed high antioxidant activity of the papaya seeds. Acceptability of the
ice cream was conducted by sensory evaluation and the results showed that the control (0.0%) papaya seeds
ice cream formulation was the most favorable by the panelists followed by 1.0%, 2.0%, and 3.0% papaya
seeds formulation. In conclusion, the papaya seeds are proven to contain antioxidants by the results given
in DPPH, FRAP, and TPC tests. Surprisingly, the papaya seeds also did not affect the physicochemical of
the ice cream and the ice cream was accepted by the panelists.
In this work, the bioactive compounds which was obtained by extracting Quercus infectoria via two extraction methods; Soxhlet and supercritical carbon dioxide (SC-CO2) extraction, were analyzed using total phenolic content and DPPH (2,2-diphenyl-1-picryl hydrazyl) free radical scavenging activity analysis. The aim of this study is to compare the total phenolic content and antioxidant activity of Quercus infectoria extract acquired from SC-CO2 extraction with those from Soxhlet extraction method. The results showed the used of SC-CO2 extraction give the lowest extraction yield as compared to Soxhlet extraction. The selectivity of Q. infectoria extracts using SC-CO2 extraction was better which in contrast with Soxhlet extraction method since it shows higher total phenolic content (143.75 ± 1.06 mg GAE/g sample). This study also revealed that the extracts from both extraction methods can posses’ antioxidant activity and comparable to those obtained from commercial antioxidant.
The generation of free radicals is the key to the photocatalytic efficiency. In this study, the degradation mechanism of photoelectrocatalysis (PEC) membrane could be adequately explained by exploring the generation pathway of different free radicals. The PEC membrane was prepared by gas phase polymerization of poly (3, 4-ethylene dioxythiophene) (PEDOT) on non-woven fabric, industrial filter cloth, ceramic membrane and polyvinylidene fluoride (PVDF) membrane, respectively. Three-dimensional fluorescence test showed that the optimal degradation of mixed or monomer contamination (bovine serum protein, sodium humate, and sodium alginate) was achieved by modified ceramic membrane under PEC condition. As for self-cleaning experiment, the membrane resistance decreased 65.7% when the reaction conditions changed from dark to PEC for 30 min. Combined with the characterization results, PEDOT as photocapacitance extended electron lifetime and promoted free radical generation. This system was mainly dependent on superoxide free radicals (0.01 mmol/L) and singlet oxygen (0.10 mmol/L), which came from energy and electron transfer. Oxygen vacancy could adsorb oxygen to produce superoxide radicals, which was further oxidized to singlet oxygen. In addition, the π-electron conjugated system of PEDOT accelerated the hole transfer and the separation of electrons and holes. Also, this study provided a new view of reactive oxygen species generation mechanism from PEDOT modified membrane.
Functional property changes in Phaleria macrocarpa fruit during ripening on tree were studied. Results showed that juice extracted from fruit flesh had low acidity and soluble solid content. Fruit acidity decreased but soluble solids increased as the fruit ripened. In terms of antioxidant content, ascorbic acid, DPPH free radical scavenging activities and total phenolic content were, however, the lowest in fully ripe fruit flesh while the unripe fruit flesh had the highest. High percentage of these antioxidants was water soluble. This study suggests that the unripe fruits should be harvested for valuable medicinal product development instead of the fully ripe fruits.
Using two different hydrosilylation methods, low temperature thermal and UV initiation, silicon (111) hydrogenated surfaces were functionalized in presence of an OH-terminated alkyne, a CF3-terminated alkyne and a mixed equimolar ratio of the two alkynes. XPS studies revealed that in the absence of premeditated surface radical through low temperature hydrosilylation, the surface grafting proceeded to form a Si-O-C linkage via nucleophilic reaction through the OH group of the alkyne. This led to a small increase in surface roughness as well as an increase in hydrophobicity and this effect was attributed to the surficial etching of silicon to form nanosize pores (~1-3 nm) by residual water/oxygen as a result of changes to surface polarity from the grafting. Furthermore in the radical-free thermal environment, a mix in equimolar of these two short alkynes can achieve a high contact angle of ~102°, comparable to long alkyl chains grafting reported in literature although surface roughness was relatively mild (rms = ~1 nm). On the other hand, UV initiation on silicon totally reversed the chemical linkages to predominantly Si-C without further compromising the surface roughness, highlighting the importance of surface radicals determining the reactivity of the silicon surface to the selected alkynes.
Nutritional value of cooked food has been considered to be lower compared to the fresh produce. However, many reports showed that processed fruits and vegetables including mushrooms may retain antioxidant activity. Pleurotus spp. as one of the edible mushroom are in great demand globally and become one of the most popular mushrooms grown worldwide with 25-fold increase in production from 1960-2009. The effects of three different cooking methods (boiling, microwave and pressure cooking) on the antioxidant activities of six different types of oyster mushrooms (Pleurotus eryngii, P citrinopileatus, P. cystidiosus P. flabellatus, P. floridanus and P. pulmonarius) were assessed. Free radical scavenging (DPPH) and reducing power (TEAC) were used to evaluate the antioxidant activities and the total phenolic contents were determined by Folin-Ciocalteu reagent. Pressure cooking improved the scavenging abilities of P. floridanus (>200 %), P. flabellatus (117.6 %), and P. pulmonarius (49.1 %) compared to the uncooked samples. On the other hand, the microwaved Pleurotus eryngii showed 17 % higher in the TEAC value when compared to the uncooked sample. There was, however, no correlation between total phenolic content and antioxidant activities. There could be presence of other bioactive components in the processed mushrooms that may have contributed to the antioxidant activity. These results suggested that customized cooking method can be used to enhance the nutritional value of mushrooms and promote good health.
Introduction: Piper sarmentosum is one of the herbaceous plants that has been used as natural antioxidant to source to treat diseases. This study was conducted to determine the total phenolic contents (TPC) and free radical scavenging capacity in free and bound (soluble and insoluble) of P. sarmentosum. Methods: Free phenolic extract was acquired through direct methanol extraction while acidic and alkaline hydrolyses were adopted to release the bound phenolic acids. The TPC was determined by using Folin-Ciocalteu assay and is expressed as Gallic Acid equivalent (GAE) in miligrams per gram of extracts. The antioxidant scavenging capacity was determined by using DPPH (2, 2-diphenyl-1-picrylhydrazyl) assay. Results: Insoluble bound phenolic extract of P. sarmentosum showed the highest TPC value (1.54 ± 0.04 mg GAE/g DW) followed by soluble phenolic extract and free extract (1.13 ± 0.10 and 0.57 ± 0.06 mg GAE/g DW, respectively). The soluble phenolic fraction has expressed the highest free radical scavenging capacity (76.57± 4.12%) followed by insoluble (69.79± 2.33 %) and free extracts (58.15± 4.44 %). The IC50 values for free, soluble and insoluble bound phenolic were 24.05 ± 3.81, 16.17 ± 1.84 and 18.49 ± 1.92 mg/ml, respectively. Conclusions: The significant differences between all the extracts and antioxidant inhibition in this present study suggested that different forms (free and bound) of extracts did influence the radical scavenging capacity as a whole.
The study was aimed to determine the antioxidant and α-glucosidase inhibition activities of
the stem and leaf of five different traditional medicinal plants. The studied plants exhibited
varied antioxidant and α-glucosidase inhibition activities. The antioxidant activities of the
plants were determined through their free radical scavenging capabilities using DPPH assay.
The most potent antioxidant activity was demonstrated by Neptunia oleracea with an IC50 of
35.45 and 29.72 μg/mL for leaf and stem, respectively. For α-glucosidase inhibition activity,
Neptunia oleracea exhibited potential α-glucosidase inhibition activity with IC50 value of
19.09 and 19.74 μg/mL for leaf and stem, respectively. The highest total phenolic content
(TPC) was also marked in Neptunia oleracea leaf and stem with value of 40.88 and 21.21 mg
GAE/g dry weight, respectively. The results also showed that Strobilanthes crispus collected
from two different locations possessed different levels of phenolic content, antioxidant and
α-glucosidase inhibition activities. The study revealed that phenolic compounds could be the
main contributors to the antioxidant and α-glucosidase inhibition activities with R values of 78.9
and 67.4%, respectively. In addition, antioxidant and α-glucosidase were positively correlated
(R = 81.9%). Neptunia oleracea could be suggested as a potential natural source of antioxidant
and antidiabetic compounds that can be used for the prevention or treatment of diabetes.
Antioxidants in seaweeds have attracted increasing interest for its role in protecting human health. Therefore, the aim of this study was to assess the Total phenolic content (TPC) values and antioxidant activities in red seaweeds Kappaphycus alvarezii and Kappaphycus striatum of different solvent extracts. Total phenolic content (TPC) and antioxidant activities (DPPH scavenging assay and Trolox equivalent antioxidant capacity assay, TEAC) for both K. alvarezii and K. striatum extracts were determined using different solvents at different concentrations (ethanol: 50%, 70%, 100%; acetone: 50%, 70%, 100%; methanol: 50%, 70%, 100%). The TPC value was measured using the Folin-Ciocalteu’s method. The antioxidant activities were measured by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay and Trolox Equivalent Antioxidant Capacity (TEAC) assay. The highest TPC value of K. alvarezii antioxidant extract was obtained by 50% ethanol extracts while for K. striatum obtained by 50% methanol extract. The highest percentage of DPPH free radical inhibition for K. alvarezii was shown by 50% acetone extract while K. striatum was shown using 50% methanol extract. The highest TEAC value for K. alvarezii was shown by 50% acetone while K. striatum extract was shown by 50% ethanol extract. The TPC values and antioxidant activities of all solvent extracts of K. striatum were significantly higher (p< 0.05) than K. alvarezii antioxidant extracts. The TPC values showed strong correlation (r = 0.797) with TEAC values for K. alvarezii antioxidant extract (p< 0.01). The TEAC values also showed strong correlation (r = 0.735) with percentage of DPPH free radical inhibition for K. alvarezii (p< 0.01). The TPC value, DPPH free radical scavenging assay and TEAC assay for K. striatum extracts showed strong correlation (r> 0.8) with each other (p< 0.01). In summary, K. striatum showed better antioxidant activity and higher TPC value than K. alvarezii.
Ultrasound-assisted extraction (UAE) was applied for the extraction of bioactive valuable compounds from winter melon (Benincasa hispida) seeds. Effects of amplitude (25-75%), temperature (40-60°C) and sonication time (20-60 min) on crude extraction yield (CEY) and radical scavenging activities (RSA, % inhibition of DPPH˙ and ABTS˙+ free radicals) of extracts were determined using complete randomised design (CRD). The results showed that the CEY and RSA of extracts significantly affected by independent variables. The maximum value of CEY (97.14±0.36 mgg-1), scavenging of DPPH˙ radicals (32.12 ± 0.38%) and scavenging of ABTS˙+ radicals (40.52±0.73%) were obtained at the combined treatment conditions of 75%, 55°C and 40 min. The UAE results obtained were compared with those achieved by using conventional Soxhlet extraction (CSE) method. It was found UAE allowed extraction at lower temperature and the extracts obtained posses higher quality compare with CSE. UAE is a promising environment friendly technique for the extraction of bioactive compounds from winter melon (Benincasa hispida) seeds.
The effects of sodium chloride (NaCl) (3.5%) solution and polysaccharides, such as carboxymethyl cellulose (CMC) (0.1, 0.3 and 0.5%) and gum arabic (5, 10 and 15%), on the physicochemical properties, antioxidant capacity and sensory characteristics of bitter gourd juice were investigated. An increase in the concentration of CMC and gum arabic significantly was observed to increase the lightness (L value) and the viscosity (mPas) of bitter gourd juice at all levels. Increased concentrations of gum arabic significantly increased the total soluble solids. The bitter gourd fruit treated with NaCl solution produced the highest lightness (L value) and scavenging activity of free radical 2,2-diphenyl-1-picrylhydrazyl of bitter gourd juice. Increased concentration of gum arabic up to 15% significantly increased the total phenolic content. The addition of 5% gum arabic effectively reduced the bitterness of the bitter gourd juice. Viscosity of the juice resulted in negative correlation for bitterness.
Polymers and organic materials that are exposed to sunlight undergo photooxidation, which leads to deterioration of their physical properties. To allow adequate performance under outdoor conditions, synthetic polymers require additives such as antioxidants and UV absorbers. A major problem with optimising polymer formulations to maximise their working life span is that accelerated weathering tests are empirical. The conditions differ significantly from real weathering situations, and samples require lengthy irradiation period. Degradation may not be apparent in the early stages of exposure, although this is when products such as hydroperoxides are formed which later cause acceleration of oxidation. A simple way of quantifying the number of free radicals presents in organic materials following exposure to light or heat is by measuring chemiluminescence (CL) emission. Most polymers emit CL when they undergo oxidative degradation, and it originates from the bimolecular reaction of macroperoxy radicals which creates an excited carbonyl.
The present study was carried out to determine the antioxidant activity and total phenolic content of Ocimum basilicum collected from different regions of the world. The accession V1 is from Sudan, V2 from Iraq, V3 from Germany, V4 from Thailand, V5 from Russia and V6 from Maldives. The extracts from six basil accessions were analysed for their DPPH free radical scavenging activity and their total phenolic content (TPC). The results suggest that the highest antioxidant activity was found in V6 (from Maldives) and the lowest antioxidant activity was found in V4 (from Thailand). The highest amount of phenolic content was found in V6 (from Maldives) and the lowest phenolic content was found inV4 (from Thailand). This study shows that basil is a good source of free-radical scavenging compounds that have their traditional medicinal applications.
In this study, we propose an innovative, bio-based, environmentally friendly approach for the covalent functionalization of multi-walled carbon nanotubes using clove buds. This approach is innovative because we do not use toxic and hazardous acids which are typically used in common carbon nanomaterial functionalization procedures. The MWCNTs are functionalized in one pot using a free radical grafting reaction. The clove-functionalized MWCNTs (CMWCNTs) are then dispersed in distilled water (DI water), producing a highly stable CMWCNT aqueous suspension. The CMWCNTs are characterized using Raman spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. The electrostatic interactions between the CMWCNT colloidal particles in DI water are verified via zeta potential measurements. UV-vis spectroscopy is also used to examine the stability of the CMWCNTs in the base fluid. The thermo-physical properties of the CMWCNT nano-fluids are examined experimentally and indeed, this nano-fluid shows remarkably improved thermo-physical properties, indicating its superb potential for various thermal applications.
Ganoderma lucidum has been recognized as a precious fungus in both Chinese and Japanese traditional medicine for
centuries. It contains many bioactive ingredients such as triterpenoids and polysaccharides. The present study used
supercritical carbon dioxide (SC-CO2
) fractionation to fractionate Ganoderma lucidum extract into four fractions (R,
F1, F2, & F3) and evaluate the correlation between the content of functional components and their antioxidant ability.
Relatively high concentrations of the three types of bioactive constituents were simultaneously partitioned into different
fractionation collecting vessels. The free radical scavenging ability was greatest in F1. The IC50 of DPPH scavenging ability
was 0.90 mg/mL and that of ABTS radicals scavenging activity was 0.45 mg/mL. The correlation analysis of antioxidant
ability with total triterpenoids and total polyphenols showed a positive relationship. In conclusion, this study showed
that fractionation of Ganoderma lucidum extract using SC-CO2 fractionation technology was able to effectively partition
its bioactive components including triterpenoids, polysaccharides and phenolic compounds and also to increase the
antioxidant activities of the fractions.
In this paper, the synthesis and characterisation of caffeine-imprinted polymers are described. The polymers were prepared in monolithic form via both reversible addition-fragmentation chain-transfer (RAFT) polymerisation and conventional free radical polymerisation, using methacrylic acid and ethylene glycol dimethacrylate as the functional monomer and crosslinking agent, respectively. The potential benefits in applying RAFT polymerisation techniques towards the synthesis of molecularly imprinted polymers (MIPs) are explored and elucidated. The pore structures of the polymers produced were characterised by nitrogen sorption porosimetry and the molecular recognition properties of representative products were evaluated in high-performance liquid chromatography (HPLC) mode. Molecular imprinting effects were confirmed by analysing the relative retentions of analytes on imprinted and non-imprinted HPLC
stationary phases. It was found that a caffeine-imprinted polymer synthesised by RAFT polymerisation was superior to a polymer prepared using a conventional synthetic approach; the imprinting factor and column efficiency were found to be higher for the former material.