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.
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.
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.
Hundreds of fruit-bearing trees are native to Southeast Asia, but many of them are considered as indigenous or underutilized. These species can be categorized as indigenous tropical fruits with potential for commercial development and those possible for commercial development. Many of these fruits are considered as underutilized unless the commercialization is being realized despite the fact that they have the developmental potential. This review discusses seven indigenous tropical fruits from 15 species that have been identified, in which their fruits are having potential for commercial development. As they are not as popular as the commercially available fruits, limited information is found. This paper is the first initiative to provide information on the phytochemicals and potential medicinal uses of these fruits. Phytochemicals detected in these fruits are mainly the phenolic compounds, carotenoids, and other terpenoids. Most of these phytochemicals are potent antioxidants and have corresponded to the free radical scavenging activities and other biological activities of the fruits. The scientific research that covered a broad range of in vitro to in vivo studies on the medicinal potentials of these fruits is also discussed in detail. The current review is an update for researchers to have a better understanding of the species, which simultaneously can provide awareness to enhance their commercial value and promote their utilization for better biodiversity conservation.
Indigenous southern Thai non-glutinous rice varieties Kaab Dum, Khai Mod Rin, Yar Ko, Yoom Noon, and Look Lai made under four different processing conditions, white rice, brown rice, germinated brown rice, and rice grass, were assessed for antioxidant components and in vitro antioxidative activities. According to the findings, rice’s antioxidant components and antioxidant activity were considerably impacted by both variety and processing. High levels of total extractable phenolic compounds (164−314 mg gallic acid equivalent (GAE)/kg, dry weight (dw)) and carotenoid (0.92−8.65 mg/100 g, dw) were found in all rice varieties, especially in rice grass and germinated brown rice, indicating that milling to generate white rice had an adverse effect on those components. Additionally, after germination, a higher γ-oryzanol concentration (9−14 mg/100 g, dw) was found. All rice varieties had higher ascorbic acid, phenolic compound, and carotenoid contents after sprouting. Overall, Yoom Noon rice grass had the highest total extractable phenolic content (p < 0.05). The rice grass from Yoom Noon/Look Lai/Kaab Dum had the highest ascorbic acid content (p < 0.05). The total carotenoid concentration of Look Lai rice grass was the highest, and Yoom Noon’s germinated brown rice had the highest γ-oryzanol content (p < 0.05). All rice varieties’ aqueous extracts had remarkable ABTS free radical scavenging activity, with Khai Mod Rin reaching the highest maximum value of 42.56 mmol Trolox equivalent/kg dw. Other antioxidant mechanisms, however, were quite low. Compared to germinated brown rice, brown rice, and white rice, rice grass often tended to have stronger antioxidant activity. Yar Ko rice grass was found to have the highest DPPH free radical scavenging activity (3.8 mmol Trolox equivalent/kg dw) and ferric reducing antioxidant power (FRAP) (4.6 mmol Trolox equivalent/kg dw) (p < 0.05). Khai Mod Rice grass had the most pronounced metal chelation activity (1.14 mmol EDTA equivalent/kg dw) (p < 0.05). The rice variety and processing conditions, therefore, influenced the antioxidant compounds and antioxidative properties of Thai indigenous rice. The results can be used as a guide to select the optimal rice variety and primary processing in order to satisfy the needs of farmers who want to produce rice as a functional ingredient and to promote the consumption of indigenous rice by health-conscious consumers.
A new poly(methacrylamide) grafted crosslinked chitosan was prepared for removal of lead, Pb(II) ion from aqueous solution. Crosslinked chitosan, in beads form, was grafted with methacrylamide (MAm) using ammonium persulfate (APS) as free radical initiator. Evidence of grafting was determined by comparing FTIR, TGA, SEM and (13)C NMR analyses of chitosan and graft copolymer. The optimal conditions for grafting reaction were as follow: crosslinked chitosan beads (1g), MAm (17.62×10(-1)M), APS (2.63×10(-1)M), reaction time (3h) and temperature (60°C). The modified chitosan bead was then used in laboratory batch experiments to evaluate the removal of Pb(II) ion from water samples. The Langmuir and Freundlich adsorption models were also applied to describe the equilibrium isotherms. The results revealed that the adsorption of Pb(II) ions onto the beads fitted very well with the Langmuir model with the maximum capacity (qmax) of 250mgg(-1).
The n-butyramido, isobutyramido, benzamido, and furancarboxamido functions profoundly modulate the electronics of the stilbene olefinic and NH groups and the corresponding radical cations in ways that influence the efficiency of the cyclization due presumably to conformational and stereoelectronic factors. For example, isobutyramido- stilbene undergoes FeCl(3) promoted cyclization to produce only indoline, while n-butyramidostilbene, under the same conditions, produces both indoline and bisindoline.
Ultrasound-assisted extraction (UAE) with ethanol was used to extract the compounds responsible for the antioxidant activities of Misai Kucing (Orthosiphon stamineus). Response surface methodology (RSM) was used to optimize four independent variables: ethanol concentration (%), amplitude (%), duty cycle (W/s) and extraction time (min). Antioxidant compounds were determined by total phenolic content and total flavonoid content to be 1.4 g gallic acid equivalent/100 g DW and 45 g catechin equivalent/100 g DW, respectively. Antioxidant activities were evaluated using the 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+) radical scavenging capacity assay and the 2,2-diphenyl-1-picrylhydrazyl (DPPH•) radical scavenging capacity assay to be 1,961.3 and 2,423.3 µmol Trolox Equivalent Antioxidant Capacity (TEAC)/100 g DW, respectively. Based on the optimal conditions, experimental values were reported to be close to the predicted value by RSM modeling (p>0.05), indicating the suitability of UAE for extracting the antioxidants of Misai Kucing. Rosmarinic acid, kaempferol-rutinoside and sinesetine were identified by high performance liquid chromatography-mass spectrometry.
Honey is a good source of several important chemical compounds and antioxidants and is harvested throughout the year. However, no study has determined how their contents change over the years. The aim of the present research was to investigate the changes in the phenolics, flavonoids and antioxidant properties, as well as other physicochemical properties, of Malaysian acacia honey collected during different months during a two year period. The DPPH (1,1-diphenyl-2-picrylhydrazyl) and FRAP (ferric reducing antioxidant power) methods were used to determine the total antioxidant activity of the honey samples. Generally, honey samples collected in the beginning and the middle of the year tended to have higher sugar content, which may be attributed to its high acidic nature and low moisture content. There was a gradual increase in the phenolic content of the acacia honey samples collected between September 2010 and December 2010. The honey sample collected at the beginning of the year (January) showed the highest color intensity and was dark amber in color. It also contained the highest concentration of phenolic compounds (341.67 ± 2.94 mg(gallic acid)/kg), the highest flavonoid content (113.06 ± 6.18 mg(catechin)/kg) and the highest percentage of DPPH inhibition and the highest FRAP value, confirming its high antioxidant potential. There was a positive correlation between DPPH and total phenolic content, suggesting that phenolic compounds are the strongest contributing factor to the radical scavenging activity of Malaysian acacia honeys. Overall, our results indicated that there were significant seasonal variations in the antioxidant potentials of honey over the two year period and the time of honey collection affects its physicochemical properties. Therefore, acacia honey from Malaysia should ideally be collected during the dry season, particularly in the months of January, May and June.
A series of six novel heterocyclic chalcone analogues 4(a-f) has been synthesized by condensing 2-acetyl-5-chlorothiophene with benzaldehyde derivatives in methanol at room temperature using a catalytic amount of sodium hydroxide. The newly synthesized compounds are characterized by IR, mass spectra, elemental analysis and melting point. Subsequently; the structures of these compounds were determined using single crystal X-ray diffraction. All the synthesized compounds were screened for their antioxidant potential by employing various in vitro models such as DPPH free radical scavenging assay, ABTS radical scavenging assay, ferric reducing antioxidant power and cupric ion reducing antioxidant capacity. Results reflect the structural impact on the antioxidant ability of the compounds. The IC₀ values illustrate the mild to good antioxidant activities of the reported compounds. Among them, 4f with a p-methoxy substituent was found to be more potent as antioxidant agent.
A new series of multipotent antioxidants (MPAOs), namely Schiff base-1,2,4-triazoles attached to the oxygen-derived free radical scavenging moiety butylated hydroxytoluene (BHT) were designed and subsequently synthesized. The structure-activity relationship (SAR) of the designed antioxidants was established alongside the prediction of activity spectra for substances (PASS). The antioxidant activities of the synthesized compounds 4-10 were tested by the DPPH bioassay. The synthesized compounds 4-10 inhibited stable DPPH free radicals at a level that is 10(-4) M more than the well-known standard antioxidant BHT. Compounds 8-10 with para-substituents were less active than compounds 4 and 5 with trimethoxy substituents compared to those with a second BHT moiety (compounds 6 and 7). With an IC50 of 46.13 ± 0.31 µM, compound 6 exhibited the most promising in vitro inhibition at 89%. Therefore, novel MPAOs containing active triazole rings, thioethers, Schiff bases, and BHT moieties are suggested as potential antioxidants for inhibiting oxidative stress processes and scavenging free radicals, hence, this combination of functions is anticipated to play a vital role in repairing cellular damage, preventing various human diseases and in medical therapeutic applications.
Microwave extraction of phytochemicals from medicinal plant materials has generated tremendous research interest and shown great potential. This research highlights the importance of microwave extraction in the analysis of flavonoids, isoflavonoid and phenolics and the antioxidant properties of extracts from three varieties of the Malaysian medicinal herb, Labisia pumila Benth. High and fast extraction performance ability, equal or higher extraction efficiencies than other methods, and the need for small samples and reagent volumes are some of the attractive features of this new promising microwave assisted extraction (MAE) technique. The aims of the present research were to determine the foliar phenolics and flavonoids contents of extracts of three varieties of L. pumila obtained by a microwave extraction method while flavonoid, isoflavonoid and phenolic compounds were analyzed using RP-HPLC. Furthermore, the antioxidant activities were measured by the DPPH and FRAP methods and finally, the chemical composition of the crude methanolic extracts of the leaves of all three varieties were analyzed by GS-MS.
A new neolignan, 3,4-dimethoxy-3',4'-methylenedioxy-2,9-epoxy-6,7-cyclo-1,8-neolign-11-en-5(5H)-one, which has been named (+)-kunstlerone (1), together with six known alkaloids: (+)-norboldine (2), (+)-N-methylisococlaurine (3), (+)-cassythicine (4), (+)-laurotetanine (5), (+)-boldine (6) and (-)-pallidine (7), were isolated from the leaves of Beilschmiedia kunstleri. The structures were established through various spectroscopic methods notably 1D- and 2D-NMR, UV, IR and LCMS-IT-TOF. (+)- Kunstlerone (1) showed a strong antioxidant activity, with an SC(50) of 20.0 µg/mL.
Among athletes, endurance is one of the key elements to victory. In addition to
training, athletes normally used supplement to prevent fatigue during the event. With
prolonged and intense activity, our body started to experience decrease in muscle
performance due to several factors such as oxidative stress, dehydration and
accumulation of lactic acid in the body fluids. The free radicals generated during
intense exercise will expose the cells to oxidative damages. In the event of
dehydration, there will be significant losses of water and functional electrolytes during
intense exercise which affected the body fluid balance. Fatigue will also occur during
reduced oxygen in aerobic metabolism which later caused accumulation of lactic acid
in the muscle. This will change the pH balance toward more acidic and caused the
muscles to lose contractile efficiency. In addition, fatigue can also be studied using rats
as model organism. Results from this activity can be useful to analyse cellular
metabolism and physiology effects of the tested rats toward physical exercise.
Therefore, this review aims to discuss the causes of fatigue through oxidative stress,
dehydration and lactic acid accumulation. In addition, the effectiveness of using rats as
a model system in measuring fatigue is also included in illustrating examples on fatigue
assessment in vivo.
Impaired wound healing is one of the serious problems among the diabetic patients. Currently, available treatments are limited due to side effects and cost effectiveness. In line with that, we attempted to use a natural source to study its potential towards the wound healing process. Therefore, Alternanthera sessilis (A. sessilis), an edible and medicinal plant, was chosen as the target sample for the study. During this investigation, the wound closure properties using stem extract of A. sessilis were analyzed. Accordingly, we analyzed the extract on free radical scavenging capacity and the cell migration of two most prominent cell types on the skin, human dermal fibroblast (NHDF), keratinocytes (HaCaT), and diabetic human dermal fibroblast (HDF-D) to mimic the wound healing in diabetic patients. The bioactive compounds were identified using gas chromatography-mass spectrometry (GC-MS). We discovered that the analysis exhibited a remarkable antioxidant, proliferative, and migratory rate in NHDF, HaCaT, and HDF-D in dose-dependent manner, which supports wound healing process, due to the presence of wound healing associated phytocompounds such as Hexadecanoic acid. This study suggested that the stem extract of A. sessilis might be a potential therapeutic agent for skin wound healing, supporting its traditional medicinal uses.
Bioactive compounds from plant sources are generally categorized as natural antioxidants with well-known health benefits. The health-promoting characteristics of natural antioxidants include anti-inflammatory, anti-diabetic, and hepatic effects as well as free radical scavenging. Herein, a comprehensive and comparative review are presented about the effects of conventional (thermal and mechanical) and relatively new (non-thermal) processing methods on phytochemicals and discussed the importance of implementing the use of those methods that could be of very helpful retaining the quality of the bioactive compounds in plant-based foods. Plant-based foods rich in phenolics, vitamin C, carotenoids, and other compounds undergo a range of processing operations before they are consumed. Most of these methods involve thermal treatments of fruits, stems, leaves, and roots. These techniques have varying effects on bioactive compounds and their activities, and the magnitude of these effects depends on process parameters such as temperature, time, and the food matrix. Thermal processing can be detrimental to bioactive compounds while nonthermal procedures may not cause significant deterioration of important health-promoting phytochemicals and in some cases can improve their bio-activity and bio-availability. The detrimental effects of conventional processing on the quality of natural antioxidants have been compared to the effects of innovative nonthermal food treatments such as gamma and ultraviolet irradiation, ultraviolet light, pulsed electric fields, and high hydrostatic pressure.
Therapeutic application of metallic nanoparticles such as gold nanoparticles have been extensively investigated and intriguing finding have been reported. Superparamagnetic iron oxide nanoparticles (SPION) could also potentially have therapeutic properties that can be exploited to enhance radiotherapy outcome. In this study, investigations on the dose enhancement effects inflicted by SPIONs under irradiation with megavoltage photon beam radiotherapy were conducted. T24 human bladder cancer cell lines were pretreated with 1 mMol/L of SPION and irradiated with 6 MV and 10 MV photon beam at different doses.The non-treated cells irradiation was used as a control. Clonogenic assay was performed to determine the cell survival. Linear quadratic (LQ) model are used as fitting curve and does enhancement factors (DEF) were extrapolated from the curves. The cytotoxicity indicated cell growth normally after 72 hours and no long term cytotoxicity effects of SPIONs towards the cells were observed. The dose enhancement effects were observed for both 6 MV and 10 MV photon beam with DEF obtained 1.71 and 2.50, respectively. This reduction of cell colonies growth could be resulted from the interaction that induced free radical and reactive oxygen species (ROS) by megavoltage photon beams. The SPIONs were therefore act as multifunction nanoparticle both in diagnostic agent and radiotherapy as radiation dose enhancer, thus clearly qualified as future theranostic agents.
Osteoarthritis is a debilitating disease of the joint involving cartilage degeneration and chondrocytes apoptosis. Oxidative stress is one of the many proposed mechanisms underpinning joint degeneration in osteoarthritis. The current pharmacotherapies emphasize pain and symptomatic management of the patients but do not alter the biological processes underlying the cartilage degeneration. Vitamin E is a potential agent to prevent or treat osteoarthritis due to its antioxidant and anti-inflammatory effects. This review aims to summarize the current evidence on the relationship between vitamin E and osteoarthritis derived from preclinical and human studies. Cellular studies showed that vitamin E mitigated oxidative stress in cartilage explants or chondrocyte culture invoked by mechanical stress or free radicals. Animal studies suggested that vitamin E treatment prevented cartilage degeneration and improve oxidative status in animal models of osteoarthritis. Low circulating or synovial vitamin E was observed in human osteoarthritic patients compared to healthy controls. Observational studies also demonstrated that vitamin E was related to induction or progression of osteoarthritis in the general population. Vitamin E supplementation might improve the outcomes in patients with osteoarthritis, but negative results were also reported. Different isomers of vitamin E might possess distinct anti-osteoarthritic effects. As a conclusion, vitamin E may retard the progression of osteoarthritis by ameliorating oxidative stress and inflammation of the joint. Further studies are warranted to develop vitamin E as an anti-osteoarthritis agent to reduce the global burden of this disease.