Antioxidant and pro-oxidant properties of ascorbic acid and gallic acid

A novel ruthenium(ii) gallic acid complex disrupts the actin cytoskeleton and inhibits migration, invasion and adhesion of triple negative breast tumor cells

This work describes the synthesis of three new ruthenium(ii) complexes with gallic acid and derivatives of the general formula [Ru(L)(dppb)(bipy)]PF₆, where L = gallate (GAC), benzoate (BAC), and esterified-gallate (EGA), bipy = 2,2'-bipyridine and dppb = 1,4-bis(diphenylphosphino)butane. The complexes were characterized by elemental analysis, molar conductivity, NMR, cyclic voltammetry, UV-vis and IR spectroscopy, and two of them by X-ray crystallography. Cell viability assays show promising results, indicating higher cytotoxicity of the complexes in MDA-MB-231 cells, a triple-negative breast cancer (TNBC) cell line, compared with the hormone-dependent MCF-7 cell line. Studies in vitro with the MDA-MB-231 cell line showed that only Ru(BAC) and Ru(GAC) interacted with BSA. Besides that, the Ru(GAC) complex, which has a polyphenolic acid, interacted in an apo-Tf structure and function dependent manner and it was able to inhibit the formation of reactive oxygen species. Ru(GAC) was able to cause damage to the cellular cytoskeleton leading to inhibition of some cellular processes of TNBC cells, such as invasion, migration, and adhesion.

Medicinal potential of mycelium and fruiting bodies of an arboreal mushroom Fomitopsis officinalis in therapy of lifestyle diseases

Fomitopsis officinalis is a medicinal mushroom used in traditional European eighteenth and nineteenth century folk medicine. Fruiting bodies of F. officinalis were collected from the natural environment of Świętokrzyskie Province with the consent of the General Director for Environmental Protection in Warsaw. Mycelial cultures were obtained from fragments of F. officinalis fruiting bodies. The taxonomic position of the mushroom mycelium was confirmed using the PCR method. The presence of organic compounds was determined by HPLC–DAD analysis. Bioelements were determined by AF-AAS. The biochemical composition of the tested mushroom material was confirmed with the FTIR method. Antioxidant properties were determined using the DPPH method, and the antiproliferative activity was assessed with the use of the MTT test. The presence of indole compounds (l-tryptophan, 6-methyl-d,l-tryptophan, melatonin, 5-hydroxy-l-tryptophan), phenolic compounds (p-hydroxybenzoic acid, gallic acid, catechin, phenylalanine), and sterols (ergosterol, ergosterol peroxide) as well as trace elements was confirmed in the mycelium and fruiting bodies of F. officinalis. Importantly, a high level of 5-hydroxy-l-tryptophan in in vitro mycelium cultures (517.99 mg/100 g d.w) was recorded for the first time. The tested mushroom extracts also showed antioxidant and antiproliferative effects on the A549 lung cancer cell line, the DU145 prostate cancer cell line, and the A375 melanoma cell line.

Phenolic profile (HPLC-UV) analysis and biological activities of two organic extracts from Echinops spinosissimus Turra roots growing in Tunisia

Echinops spinosissimus Turra subsp. roots was investigated, after extraction with two different solvents: ethanol and ethyl acetate, for its phenolic profile as well as biological activities. Echinops spinosissimus Turra subsp. spinosus roots ethanolic extract was characterized by the highest content of total polyphenols (19.3 mg GAE/100 g of DW). In addition, the phenolic profiles of the two studied extracts were analysed using HPLC-UV, where p-coumaric (8.59 mg/kg of DW) and cinnamic acids (4.68 mg/kg of DW) were detected as the most abundant phenolic acids, and kaempferol was the predominant flavonoids (30.37 mg/kg of DM) followed by quercetin and rutin in the ethanolic extract. While, only p-coumaric acid, epicatechin, kaempferol and quercetin were identified and quantified in ethyl acetate roots extract. All tested extracts exhibited an antimicrobial effect against Gram-positive and Gram-negative bacteria. These findings indicate that Echinops spinosissimus Turra subsp. spinosus roots can be regarded as a new source of edible oil having health benefits and nutritional properties.

Four active monomers from Moutan Cortex exert inhibitory effects against oxidative stress by activating Nrf2/Keap1 signaling pathway

Paeonol, quercetin, β-sitosterol, and gallic acid extracted from Moutan Cortex had been reported to possess anti-oxidative, anti-inflammatory, and antitumor activities. This work aimed to illustrate the potential anti-oxidative mechanism of monomers in human liver hepatocellular carcinoma (HepG2) cells-induced by hydrogen peroxide (H2O2) and to evaluate whether the hepatoprotective effect of monomers was independence or synergy in mice stimulated by carbon tetrachloride (CCl4). Monomers protected against oxidative stress in HepG2 cells in a doseresponse manner by inhibiting the generation of reactive oxygen species, increasing total antioxidant capacity, catalase and superoxide dismutase (SOD) activities, and activating the antioxidative pathway of nuclear factor E2-related factor 2/Kelchlike ECH-associated protein 1 (Nrf2/Keap1) signaling pathway. We found that the in vitro antioxidant capacities of paeonol and quercetin were better than those of β-sitosterol and gallic acid. Furthermore, paeonol apparently diminished the levels of alanine transaminase and aspartate aminotransferase, augmented the contents of glutathione and SOD, promoted the expressions of Nrf2 and heme oxygenase-1 proteins in mice stimulated by CCl4. In HepG2 cells, paeonol, quercetin, β-sitosterol, and gallic acid play a defensive role against H2O2-induced oxidative stress through activating Nrf2/Keap1 pathway, indicating that these monomers have anti-oxidative properties. Totally, paeonol and quercetin exerted anti-oxidative and hepatoprotective effects, which is independent rather than synergy.

Recurrent Indoor Environmental Pollution and Its Impact on Health and Oxidative Stress of the Textile Workers in Bangladesh

Perennial indoor environmental pollution in the textile industrial area is a potential health hazard for workers engaged in this line of work, resulting in mental aberration to severe health risks. This study was designed to investigate the indoor environmental quality of textile industries and correlate its effect on the occupational health and well-being of the textile workers by measuring plasma oxidative stress status in textile workers and healthy control subjects. Environmental samples were collected from 15 textile industries located in Dhaka division, and 30 volunteer textile workers and 30 volunteer office workers (control) aged 18 to 57 years participated in the study. The concentration of plasma ascorbic acid (P-ASC), plasma malondialdehyde (P-MDA), and plasma conjugated diene (P-CD) was measured in both groups. The noise level (78.0 ± 0.68 dB) and the formaldehyde level (141.80 ± 4.47 µg/m³) were found to be significantly higher in the indoor environmental area compared with those in the control area (70.17 ± 0.25 dB and 108.0 ± 0.76 µg/m³, respectively). Furthermore, the daily average concentration of suspended particulate matters (PMs), that is, PM_2.5 (322.2 ± 13.46 µg/m³) and PM₁₀ (411.0 ± 17.57 µg/m³), was also found to be significantly higher in the indoor environmental air compared with that in the control area (78.59 ± 1.66 and 174.0 ± 2.33 µg/m³, respectively). The levels of P-MDA (0.37 ± 0.03 nmol/L) and P-CD (14.74 ± 0.61 nmol/L) were significantly increased, whereas the level of P-ASC level (0.46 ± 0.04 mg/dL) was markedly decreased in the textile workers compared with the healthy control subjects (0.18 ± 0.01 nmol/L of P-MDA, 10.04 ± 0.44 nmol/L of P-CD, and 1.29 ± 0.06 mg/dL of P-ASC). The textile plants were found to have significantly elevated levels of indoor environmental pollutants compared with those in the control area, and the textile workers were significantly exposed to oxidative stresses compared with the control subjects. The use of noise pads and high-efficiency air filters is perhaps highly instrumental to put an end to this prevailing situation. Moreover, to overcome the oxidative stresses among workers, supplementation of antioxidant vitamins (ie, ascorbic acid and/or vitamin E) may be beneficial. In addition, to prevent serious health-related issues, proper precautions should be taken to protect the occupational health of the textile workers.

Antibacterial tragacanth gum-based nanocomposite films carrying ascorbic acid antioxidant for bioactive food packaging

Food packaging has a pivotal share to improve protection, safety and shelf-life time of foods and bioproducts. Herein, we prepared bioactive nanocomposite films that composed of tragacanth (TG), polyvinyl alcohol, ZnO nanoparticles (NPs) and ascorbic acid (AA) using glycerol as a plasticizer and citric acid as a cross-linker for food packaging. The SEM images showed a homogenous distribution of ZnO NPs with low aggregation in nanocomposite films. The water solubility of nanocomposite films reduced from 15.65 % to 10.81 with increasing of TG and ZnO NPs contents. The incorporation of AA and ZnO NPs into nanocomposite films improved antioxidant activity from 50 % to 66 % in 95 % ethanolic solution. Also, the nanocomposite films showed good antibacterial activity against Gram-negative and -positive bacteria. Soil degradation rate of nanocomposite films increased from 80 % to 91.46 as the wt% of TG increased. Therefore, prepared nanocomposite films could be employed as a promising candidate for food packaging applications.

99mTc-gallic-gold nanoparticles as a new imaging platform for tumor targeting

Early and accurate detection of tumor assists in identifying more effective therapies. Gold nanoparticles (GNPs) were synthesized by green synthesis method using gallic acid (GA) then characterized and labeled with technetium-99m. This new platform was biologically evaluated in both normal and solid tumor bearing mice. The in-vivo study of [^99mTc]Tc-gallic-GNPs via both I.V. and I.T injecton showed a high accumulation in tumor site. As a result, [^99mTc]Tc-gallic-GNPs can be afforded as a potential nano-platform for tumor imaging.

Effects of treatment temperatures on redox potential and sensory evaluation of different spices and herbs applied to cooked pork sausages

BACKGROUND

This study aimed to investigate the effects of treatment temperatures (22, 78, 100 °C) on the antioxidant activity of 13 types of dried ground spices and herbs (black mustard, black pepper, blackberries, onion, cumin, galangal, lemon balm, lovage, marjoram, oregano, parsley, rosemary and watercress) through measurements of redox potential. Four different combinations of spices and herbs were created and applied to cooked pork sausages, then sensory evaluation was carried out.

RESULTS

The redox potential was temperature dependent. A temperature of 78 °C was chosen to produce the cooked pork sausages with the addition of the spice and herb combinations. The combinations were black mustard, onion, and cumin (at a 1:1:1 ratio); onion, marjoram, and parsley (at a 1:1:1 ratio); black pepper, lemon balm, and parsley (at a 1:2.35:1.65 ratio) and black pepper, cumin, and lovage (at a 1:2:2 ratio). In pork sausages cooked at 78 °C, the variants at 12 g kg^-1 had a more intense aroma and taste than those at 6 g kg^-1 spice and herb combinations, and received a superior sensory evaluation in total.

CONCLUSIONS

The most desirable treatment temperature possibly applied in food products was 78 °C as it gave the highest number of negative results in redox potential of water extracts. The addition of the tested spice and herb combinations contributed to the increase of antioxidant possibility of 78 °C-cooked pork sausages. Further investigation of the redox potential in other meat products (raw meat products at 22 °C, sausages from cooked meat at 100 °C) with the addition of the current spice and herb combinations will be undertaken in subsequent research. © 2020 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Vincetoxicum arnottianum ameliorate inflammation by suppressing oxidative stress and pro-inflammatory mediators in rat

ETHNOPHARMACOLOGICAL RELEVANCE

Aerial parts of Vincetoxicum arnottianum (Wight) Wight (Family Apocynaceae) are used by local communities for inflammation, healing of wound and injuries and also for urticaria.

AIM OF STUDY

Extract/fractions of V. arnottianum were evaluated for potential anti-inflammatory activity in rat.

METHODS

Methanol extract of aerial parts of V. arnottianum (VAM) was partitioned on polarity for n-hexane (VAH), ethyl acetate (VAE), butanol (VAB) and aqueous (VAA) fractions. The extract/fractions were evaluated during in vitro assay for protection against heat induced protein denaturation and Carrageenan induced paw inflammation in rat. VAM and VAE were evaluated for anti-inflammatory potential against formalin and Freund's complete adjuvant (FCA) induced inflammation in paw of rat while croton oil induced inflammation in ear of rat, respectively. The level of inflammatory mediators; IL-17, IL-1β, IL-6, TNF-α and nitric oxide (NO) was estimated in serum of rat.

RESULTS

All the extract/fractions used in this study exhibited anti-inflammatory activity. However, VAE (300 mg/kg) exhibited potential anti-inflammatory activity in carrageenan (78.06 ± 4.6%), formalin (54.71 ± 0.34%) and croton oil (73.12 ± 1.9%) induced edema in rat. In FCA induced inflammation model VAM and VAE showed admiring proficiencies against alteration of body weight and organ weight indices, paw edema and histological studies. In serum increased level of pro-inflammatory cytokines (IL-1β, TNF-α, IL-6, IL-17) and NO during adjuvant-induced inflammation were more efficiently restored with VAE treatment to rat. Presence of polyphenolics; rutin, gallic acid, caffeic acid, apigenin, myricetin and quercetin was indicated in VAE.

CONCLUSION

The results suggest the presence of anti-inflammatory constituents in V. arnottianum.

Pectin Degradation is an Important Determinant for Alfalfa Silage Fermentation through the Rescheduling of the Bacterial Community

This study aimed to evaluate the effects of the four kinds of additives on the silage quality and the relevant bacterial community diversity by Illumina HiSeq 16S rRNA sequencing. The four kinds of additives were Lactobacillus plantarum (LP), organic acids including gallic acid (GA) and phenyllactic acid (PA), pectin (PEC), and enzymes including pectinase (PEE) and cellulase (CE). After 30 d of fermentation, the pH value was shown to have the lowest value in the PEE and PEC groups, followed by the PA group, and then in CE and GA groups; the highest value of pH was found in both LP and control groups. The ammonia nitrogen concentration was lower in the PEE group compared to the other groups except for the PA group. In the comparisons among the seven groups, Lactobacillus was higher in the LP group, Paracoccus was higher in the GA group, Weissella was higher in the PA group, Leuconostoc was higher in the PEC group, Bacillus, Aeromonas, and Curvibacter were higher in the PEE group, and Coriobacteriaceae_UCG_002 was higher in the CE group compared to the other groups. This study proposed that the addition of PEC and PEE improved the fermentation quality of alfalfa silage compared to other additives by improving the bacterial community of Leuconostoc, and Bacillus and Aeromonas, respectively. Moreover, the enhanced fermentation quality of alfalfa silage by the supplementation of PEC and PEE might be attributed to other unclassified genera. This study provides an implication that pectin degradation is an important determinant for alfalfa silage fermentation through the rescheduling of bacterial community diversity.

A comparative study on the structures of Grifola frondosa polysaccharides obtained by different decolourization methods and their in vitro antioxidant activities

Decolourization of polysaccharides is one of the crucial procedures that affects their structure, which is closely related to their bioactivity. Here, Grifola frondosa polysaccharide (GFP) was decolourized with H2O2 and AB-8 macroporous resin. Then, two main fractions, named DGFP and SGFP, were obtained by purification with Sepharose CL-4B. The molecular weights of these two polysaccharides were determined to be 6.306 × 106 (±0.410%) Da and 1.174 × 107 (±0.299%) Da by HPSEC. Monosaccharide analysis indicated that DGFP was composed of glucose, mannose, and galactose (32.20 : 1.00 : 1.75), while SGFP consisted entirely of glucose. Despite a backbone →4)-α-Glcp-(1→ in two polysaccharides, reducing ends Rα →3)-α-Glcp and Rβ →4)-β-Glcp were observed in DGFP by 1D/2D NMR. The results suggested that decolourization with low concentrations of H2O2 might alter the structure of GFP and generate new reducing ends. In vitro antioxidant results implied that DGFP exhibited a higher ability to scavenge DPPH and hydroxyl radicals and reduced the over-generated ROS levels in a concentration-dependent manner. These results suggested that the antioxidant effects of GFP could be activated by decolourization with H2O2. Therefore, DGFP might be a more promising natural antioxidant than SGFP.

Evaluation of the genotoxic, DNA-protective and antioxidant profile of synthetic alkyl gallates and gallotannins using in vitro assays

New gallotanins, methyl 2,3,4,6-tetra-O-galloyl-α-D-glucoside (G₄Glc), methyl 2,3,4,6-tetra-O-galloyl-α-D-mannoside (G₄Man), and methyl 2,3,4-tri-O-galloyl-α-L-rhamnoside (G₃Rham), have been synthesized in order to study the protective effects of synthetic polyphenols that are structurally related with natural compounds. Apart from spectral analysis, examination of antioxidant ability and protective efficiency showed the differences among newly prepared compounds and commercial antioxidants - gallic acid (GA), methyl gallate (MG), and octyl gallate (OG) applying radical scavenging 1,1-diphenyl-2-picryl-hydrazyl (DPPH), reducing power and iron-chelating assays. The genotoxicity and DNA-protective potential of tested compounds on human peripheral blood mononuclear cells (PBMCs) were evaluated using the single-cell gel electrophoresis (comet assay) and DNA-topology assay. Experimental data revealed that gallotannins G₃Rham, G₄Man, and G₄Glc possess significant radical scavenging/antioxidant activities and manifest very low genotoxic effect on human PBMCs. Moreover, tested compounds considerably reduce the level of DNA damage induced by hydrogen peroxide or Fe²⁺-ions. The results imply that new synthetic gallotannins can be considered as nontoxic agents for subsequent design of new antioxidants with potential biomedical applications.

Identification of functional compounds in baru (Dipteryx alata Vog.) nuts: Nutritional value, volatile and phenolic composition, antioxidant activity and antiproliferative effect

This work aimed to contribute to the nutritional and functional characterization of roasted baru nuts, a seed widely consumed and produced in Brazil. Baru nut was characterized in terms of its nutritional value and volatile composition (SPME-GC-MS analysis). The ultrasound assisted extraction was used to extract free and bound phenolic compounds that were identified by LC-DAD-ESI-MS/MS method. Bioactivity assays were carried out to evaluate the antioxidant activity (ORAC and HOSC assay) and anticancer effect (inhibition of HT29 cell growth and targeting of cancer stemness) of baru nut extracts and phenolic compounds. Results showed that baru is a good source of protein and monounsaturated fatty acids, specifically oleic acid (47.20 g/100 g). The predominant volatile compounds are hexanal (71.18%) and 2,5-dimethyl-pyrazine (9.43%). The main phenolic compounds identified were gallic acid and its derivatives, such as gallic acid esters and gallotannins. Among all, gallic acid and methyl gallate seemed to be the main compounds responsible for the high antioxidant activity. The antiproliferative effect evaluated of baru extracts in HT29 cell line showed ability to impair cell growth in both monolayer and spheroid cultures and to reduce ALDH+ population. These results supply new information about the functional compounds presents in baru nut, which are important sources of natural antioxidants and antiproliferative compounds.

Effect of Ultrafiltration of Pitaya Extract (Stenocereus thurberi) on Its Phytochemical Content, Antioxidant Capacity, and UPLC-DAD-MS Profile

Stenocereus thurberi is an endemic species in northwestern Mexico. It produces colorful fruits called pitayas that have an edible pulp. They have phytochemical compounds associated with biological activities. Ultrafiltration is a widely used method for the clarification of fruit juices and the recovery of phytochemicals. However, its effect has not been extensively studied in extracts. Therefore, the objective of this work is to study the effect of the ultrafiltration of pitaya extract (Stenocereus thurberi) on its phytochemical content, antioxidant capacity, and identification of phenolic compounds by UPLC-DAD-MS, providing greater knowledge about the pitaya. In this study, two extracts were analyzed, the unclarified extract (UE) and the clarified extract (CE). The antioxidant capacity was higher in the CE with 15.93 ± 0.42 mM TE/g, DPPH and 18.37 ± 0.016 mM TE/g, ABTS. The UPLC-MS analysis indicated the decrease in phenolic compounds in the CE and the presence of gallic acid and resorcinol, compounds that had not been identified in other species of Stenocereus spp. The correlation analysis indicated that all the phytochemicals present in the pitaya contribute significantly to the antioxidant capacity. The ultrafiltration process could be a viable option to improve the biological activity of the natural extracts.

Amide–imine conjugate involving gallic acid and naphthalene for nano-molar detection, enrichment and cancer cell imaging of La3+: studies on the catalytic activity of the La3+ complex

A single crystal X-ray structurally characterized amide–imine conjugate (GAN) derived from gallic acid and naphthalene selectively recognizes La³⁺ ion via TURN ON fluorescence through ESIPT and CHEF mechanisms.

Tannic and gallic acids alter redox-parameters of the medium and modulate biofilm formation

Tannic (TA) and gallic (GA) acids are known to have both anti- and prooxidant properties however recently they have been described as potential anti-biofilm agents although their mechanisms of action on bacterial cells remain obscure. The aim of our research was to elucidate the role of prooxidant actions of these plant phenolic compounds in bactericidal effects and biofilm formation. In our experiments, both compounds demonstrated strong oxidative properties that altered activity of stress regulons and contributed to decrease of CFU and ability of cells to maintain membrane potential. Stimulation of biofilm formation was observed in all the strains with the exception of the strains deficient in flagella synthesis. Both compounds demonstrated bactericidal effect which was weakened in biofilms. TA efficiently killed bacteria in the bioflms of pgaA mutant which pointed out an important role of poly-beta-1,6-N-acetyl-D-glucosamine (PGA) polysaccharide in matrix formation. Similar effects of TA in recA mutant indicate involvement of SOS-response into reaction towards exposure with TA. Gallic acid-induced killing was more pronounced in the biofilms of csgA mutant revealing role of curli in protection against GA toxicity.

Performance and structural comparison of hydrogels made from wheat bran arabinoxylan using enzymatic and coacervation methods as micro-and nano- encapsulation and delivery devices

This study evaluated the structural and performance differences between arabinoglucuronoxylan micro-hydrogels that were enzymatically produced from alkaline-extracted wheat bran arabinoglucuronoxylans using recombinant α-L-arabinofuranosidase (AbfB) that selectively removes arabinose side chains, and chemically through coacervation process, as delivery devices for bioactive substances. The encapsulations of model bioactive substance, gallic acid (GA), in the hydrogels, were done either in-situ or ex-situ to identify the most effective encapsulation and delivery method. The hydrogels particle size distribution, polydispersity index, GA encapsulation efficiency, retention and release of functional GA (based on antioxidant activity) were assessed. The hydrogels formed in both coacervation and enzymatic processes had particle size ranges of 469-678 nm, which classify them as micro-hydrogels. However, the latter were monodispersed with polydispersity index (PdI) < 0.4 compared to the former with PdI > 0.7. In addition, enzymatically produced hydrogels attained higher zeta potential (-8.8 mV) and retained and released GA with higher anti-oxidant capacity (91%) than chemically formed micro-hydrogels (zeta potential = - 3.3 mV and antioxidant capacity = 80%). However, GA encapsulation efficiencies (72% in-situ and 68% ex-situ) were higher in chemically formed micro-hydrogels than enzymatically produced micro-hydrogels (59% in-situ and 52% ex-situ). The in-situ encapsulated GA experienced less initial burst during sustained release of 8 h compared to ex-situ encapsulation. Overall, enzymatic modification process and in-situ encapsulation were the most effective methods for production of arabinoglucuronoxylan micro-hydrogels delivery devices and for encapsulation of the GA, respectively, because of maintaining functional GA upon release and having the potential to customize the structural and functional properties of the micro-hydrogels.

Phytochemical analysis of crude extract of Delphinium brunonianum and its effect on hypertension and metabolic perturbations in fructose fed rats

The present study aims at phytochemical profiling and valuating the effect of crude extract of Delphinium brunonianum on fructose mediated rise in blood pressure and metabolic abnormalities in rats. Therefore, rats were fed on fructose (10%w/v) for 6 weeks. Rats in treatment groups received amlodipine 250, 500 and 1000 mg/kg of DB-Cr separately in concurrent to fructose. Various parameters of metabolic perturbations were assessed at the end of study. Further, DB-Cr was analyzed using LC-MS technique. DB-Cr exerted remarkable antihypertensive effect whereas, sympathetic hyperactivity and hyperinsulinemia in these rats was significantly blunted, further, endothelium functionality was successfully restored. LC-MS analysis of DB-Cr revealed the presence of a variety of chemical constituents (41) including quinic acid, scopolin, gingerol, Robinetin 3-rutinoside, KAPA and maleic acid. In conclusion, D. brunonianum possess the potential to combat the fructose mediated hypertension and metabolic perturbations, which may partially be due to its chemical constituents.

Gallic Acid-Dextran Conjugate: Green Synthesis of a Novel Antioxidant Molecule

A novel derivative of dextran, dextran–gallic acid (Dex–Gal), obtained from simple conjugation with gallic acid, was synthesized by an efficient free radical-mediated method. To verify the synthesis of Dex–Gal, 1H-nuclear magnetic resonance (1H-NMR), Fourier transform infrared (FTIR) spectrometry, and high-performance size-exclusion chromatography (HPSEC) were employed. The results revealed the conjugation of gallic acid with the 15.5 kDa dextran from Leuconostoc mesenteroides. Dex–Gal had a molecular weight of 11.2 kDa, indicating that the conjugation reaction was accompanied by a minor degradation of Dex–Gal. In addition, Dex–Gal contained 36.8 ± 1.4 mg gallic acid per gram dextran. These molecules were also evaluated as antioxidants using total antioxidant capacity (TAC), reducing power, ferric chelation, and superoxide radical-scavenging assays. Both polysaccharides had no ferric chelation activity. In addition, Dex–Gal was more efficient as an antioxidant agent in TAC (13 times) and was more efficient than dextran in superoxide radical-scavenging (60 times) and reducing power (90 times) assays. These data demonstrate that Dex–Gal is a natural-compound-based antioxidant with potential applications in the pharmaceutical, cosmetic, and food industries.

A novel gold nanocluster-based fluorometric biosensor for measuring prooxidant activity with a large Stokes shift

A chicken egg white protein-protected gold nanocluster (CEW-AuNC) based fluorogenic biosensor, where protein was used as both reducing and protecting agent, was developed to determine the Cu(II)-induced prooxidant activity of natural antioxidants abundant in food and biological samples. Gold nanoclusters, prepared using egg white proteins, exhibited strong fluorescence. The prooxidant activity of the tested antioxidants was indirectly measured by their reducing action on Cu(II) to Cu(I), and the reduced cuprous ion was bound to the thiol groups in the CEW-AuNC structure, causing a decrease in fluorescence intensity. Epicatechin, catechin, epigallocatechin gallate, morin, rutin, quercetin, gallic, chlorogenic, and rosmarinic acids, glutathione, cysteine, N-acetyl cysteine, bilirubin, resveratrol, and α-tocopherol were studied as natural antioxidants. A fluorometric method showing a large Stokes shift with excitation/emission maxima at 360∕640 nm was developed to sensitively measure the decrease in the fluorescence of CEW-AuNC associated with the binding of copper(I) to the protein structure. Total prooxidant activities of the binary, ternary, and quaternary synthetic mixtures and of some food and synthetic serum samples were determined. The biosensor response was statistically compared to that of its spectrophotometric counterpart. This method can be used for the control of the oxidative stability of foods with a prolonged shelf life.

Effects of Tannase and Ultrasound Treatment on the Bioactive Compounds and Antioxidant Activity of Green Tea Extract

The present study investigated the effects of tannase and ultrasound treatment on the bioactive compounds and antioxidant activity of green tea extract. The single-factor experiments and the response surface methodology were conducted to study the effects of parameters on antioxidant activity of green tea extract. The highest antioxidant activity was found under the optimal condition with the buffer solution pH value of 4.62, ultrasonic temperature of 44.12 °C, ultrasonic time of 12.17 min, tannase concentration of 1 mg/mL, and ultrasonic power of 360 W. Furthermore, phenolic profiles of the extracts were identified and quantified by high-performance liquid chromatography. Overall, it was found that tannase led to an increase in gallic acid and a decrease in epigallocatechin gallate, and ultrasounds could also enhance the efficiency of enzymatic reaction.

Regulation of the levels of health promoting compounds: lupeol, mangiferin and phenolic acids in the pulp and peel of mango fruit: a review

There is a demand for feasible methodologies that can increase/maintain the levels of health-promoting phytochemicals in horticultural produce, due to strong evidence that these compounds can reduce risk of chronic diseases. Mango (Mangifera indica L.), ranks fifth among the most cultivated fruit crops in the world, is naturally rich in phytochemicals such as lupeol, mangiferin and phenolic acids (e.g. gallic acid, chlorogenic acid and vanillic acid). Yet, there is still much scope for up-regulating the levels of these compounds in mango fruit through manipulation of different preharvest and postharvest practices that affect their biosynthesis and degradation. The process of ripening, harvest maturity, physical and chemical elicitor treatments such as low temperature stress, methyl jasmonate (MeJA), salicylic acid (SA) and nitric oxide (NO) and the availability of enzyme cofactors (Mg²⁺ , Mn²⁺ and Fe²⁺ ) required in terpenoid biosynthesis were identified as potential determinants of the concentration of health-promoting compounds in mango fruit. The effectiveness of these preharvest and postharvest approaches in regulating the levels of lupeol, mangiferin and phenolic acids in the pulp and peel of mango fruit will be discussed. In general spray application of 0.2% iron(II) sulphate (FeSO₄ ) 30 days before harvest, harvest at sprung stage, storage of mature green fruit at 5 °C for 12 days prior to ripening, fumigation of mature green fruit with 10^-5  mol L^-1 and/or 10^-4  mol L^-1 MeJA for 24 h or 20 and/or 40 µL L^-1 NO for 2 h upregulate the levels of lupeol, mangiferin and phenolic acids in pulp and peel of ripe mango fruit. © 2019 Society of Chemical Industry.

Gallic Acid-Chitosan Conjugate Inhibits the Formation of Calcium Oxalate Crystals

It has recently been shown that chitosan (Chit) induces the formation of calcium oxalate (CaOx) crystals, which are mainly responsible for the appearance of kidney stones, and this might limit the use of Chit in vivo. Here, Chit was conjugated with gallic acid (Chit-Gal) to decrease the formation of CaOx crystal. This conjugation was confirmed by FTIR and NMR analyses. Chit-Gal contains 10.2 ± 1.5 mg GA per g of Chit. Compared to the control group, Chit increased the number of crystals by six-fold, mainly in the number of monohydrated CaOx crystals, which are the most harmful CaOx crystals. In addition, Chit increased the zeta potential (ζ) of CaOx crystals by three-fold, indicating that Chit was associated with the crystals. These alterations were abolished when Chit-gal was used in these tests. As oxidative stress is related to renal calculus formation, Chit and Chit-Gal were also evaluated as antioxidants using total antioxidant Capacity (TAC), reducing power, ferrous chelation, and copper chelation tests. Chit-gal was more efficient antioxidant agent in TAC (2 times), in ferrous chelation (90 times), and in reducing Power (5 times) than Chit. Overall, Chit-gal has higher antioxidant activity than Chit, does not induce the formation of CaOx crystals. Thus, Chit-Gal has potential to be used as a chit substitute.

Protective effect of gallic acid on apoptosis of sperm and in vitro fertilization in adult male mice treated with cyclophosphamide

BACKGROUND

Alteration of free radicals (reactive oxygen species) causes mammals' sperm damage. Gallic acid (GA) is known as an antioxidant which is effective against oxidative stress. The purpose of this study was to evaluate the antioxidant effects of GA on the sperm apoptosis and in vitro fertilization (IVF) in adult male mice treated with cyclophosphamide (CP).

MATERIALS AND METHODS

Following a pilot study to find the dose responses of GA, 40 adult male naval medical research institute (NMRI) mice (32 ± 3 g) were divided into five groups (n = 8): control, sham (normal saline, NS: 0.2 mL per day), CP (15 mg kg^-1 per week; intraperitoneal, IP), GA (12.5 mg kg ^-1 per day; IP), and GA+CP. After the treatment, sperm parameters were analyzed. The apoptosis of sperm was measured by Annexin-PI staining method followed by flow cytometry detection. Fertility was assessed by IVF method among the groups.

RESULTS

The difference in sperm parameter and fertility rate between the control (% 80.05 ± 6.53) and cyclophosphomide groups (% 51.82 ± 10.78) was significant (P < .001) but GA plus CP (% 78.16 ± 5.71) restored the fertilization rate (P < .001). Also, a remarkable increase was noted regarding apoptotic sperm in CP group vs the control group. The comparison in the five groups shows that GA cotreatment was significantly effective in reducing the apoptosis rate caused by cyclophosphamide (P < .05).

CONCLUSION

It was ultimately attained that GA has a potent antioxidant effect which could inhibit the detrimental effect of CP on the apoptosis and fertility rate of sperm in the mouse.