Inhibition of free radical induced oxidative hemolysis of red blood cells by green tea polyphenols

The Effects of Laurencia caspica Algae Extract on Hemato-Immunological Parameters, Antioxidant Defense, and Resistance against Streptococcus agalactiae in Nile tilapia (Oreochromis niloticus)

Natural immune stimulants are among the most effective chemicals for boosting immunity and fish welfare. This study aims to investigate the effects of red macroalgae extract (Laurencia caspica) on hematological, immunological, antioxidant, biochemical, and disease resistance against S. agalactiae in Nile tilapia for 50 days. For this purpose, fishes were assigned to four dietary treatments group in which the base meal was supplemented with 0.5%, 1%, and 2% of L. caspica extract. On days 25 and 50 of the experiment, samples were taken to investigate the hematological, immunological, biochemical, and antioxidant parameters. The white blood cells (WBCs), hemoglobin, and neutrophils significantly increased after 50 days of feeding with the L. caspica extract, but until the 25th day, no significant difference was observed among the treatments except for hemoglobin. Immunological parameters (including Immunoglobulin M [IgM] and complement 3 [C3]) were significantly higher in treated groups compared to control both 25 days and 50 days posttreatment. However, on the 25th day, no significant difference was noticed between treatments and control in the case of lysozyme activity. Alkaline phosphatase (ALP) and alanine aminotransferase (ALT) considerably increased in comparison to the control group on the 50th day, but no significant difference was observed on the 25th day. In addition, feeding with L. caspica significantly increased the antioxidant enzyme activities on the 25th day (L. caspica 1% and 2% in peroxidase [POD] and superoxide dismutase [SOD] in all groups) and 50th day (catalase [CAT], SOD and L. caspica 1% and 2% in POD) in the spleen. The survival rate of fish challenged with Streptococcus agalactiae was considerably greater than the control group. Finally, it can be concluded that L. caspica extract is an immunological stimulant that induces fish resistance to S. agalactiae.

Bioactivity, bioavailability, and gut microbiota transformations of dietary phenolic compounds: implications for COVID-19

The outbreak of mysterious pneumonia at the end of 2019 is associated with widespread research interest worldwide. The coronavirus disease-19 (COVID-19) targets multiple organs through inflammatory, immune, and redox mechanisms, and no effective drug for its prophylaxis or treatment has been identified until now. The use of dietary bioactive compounds, such as phenolic compounds (PC), has emerged as a putative nutritional or therapeutic adjunct approach for COVID-19. In the present study, scientific data on the mechanisms underlying the bioactivity of PC and their usefulness in COVID-19 mitigation are reviewed. In addition, antioxidant, antiviral, anti-inflammatory, and immunomodulatory effects of dietary PC are studied. Moreover, the implications of digestion on the putative benefits of dietary PC against COVID-19 are presented by addressing the bioavailability and biotransformation of PC by the gut microbiota. Lastly, safety issues and possible drug interactions of PC and their implications in COVID-19 therapeutics are discussed.

Dietary peppermint (Mentha piperita) powder affects growth performance, hematological indices, skin mucosal immune parameters, and expression of growth and stress-related genes in Caspian roach (Rutilus caspicus)

Peppermint is a popular herbal medicine due to its several pharmaceutical applications. In this study, peppermint powder was used as a feed additive to evaluate growth performance, hematological parameters, protein profile of skin mucus, and immune parameters, as well as growth hormone (GH), insulin-like growth factor (IGF), and 70 kDa heat shock protein (HSP70) gene expression in Caspian roach (Rutilus caspicus). The fingerlings (average weight of 2.40 ± 0.12 g) were fed with diet containing 0 (control), 2, 3, and 4 g/kg peppermint for 8 weeks. The addition of peppermint significantly enhanced the growth parameters and decreased the food conversion ratio. Hematological indices of fish fed with peppermint-supplemented diets were significantly different from the control group (P < 0.05). Soluble protein, alkaline phosphatase, and lysozyme enzyme activity in mucus samples showed an incremental trend by increasing the peppermint levels in the diet. Evaluation of mucosal immunity indicated a remarkable difference between the protein profile in treatments fed with peppermint-supplemented diets and the control group. A new protein band (approximately 27 kDa) was also found in the skin mucus of fish fed with the diet containing 4 g/kg peppermint, and the highest band density was observed in this treatment. The highest IGF and GH gene expression were observed in 4 g/kg peppermint treatment. There was a significant difference in HSP70 expression between the fish fed with peppermint powder and the control group (P < 0.05). Overall, the results showed that dietary oral administration of peppermint at 4 g/kg of feed can act as a growth promoter and immunostimulant.

Tea and Its Components Prevent Cancer: A Review of the Redox-Related Mechanism

Cancer is a worldwide epidemic and represents a major threat to human health and survival. Reactive oxygen species (ROS) play a dual role in cancer cells, which includes both promoting and inhibiting carcinogenesis. Tea remains one of the most prevalent beverages consumed due in part to its anti- or pro-oxidative properties. The active compounds in tea, particularly tea polyphenols, can directly or indirectly scavenge ROS to reduce oncogenesis and cancerometastasis. Interestingly, the excessive levels of ROS induced by consuming tea could induce programmed cell death (PCD) or non-PCD of cancer cells. On the basis of illustrating the relationship between ROS and cancer, the current review discusses the composition and efficacy of tea including the redox-relative (including anti-oxidative and pro-oxidative activity) mechanisms and their role along with other components in preventing and treating cancer. This information will highlight the basis for the clinical utilization of tea extracts in the prevention or treatment of cancer in the future.

Semi-synthesis of Twelve Known 20Z/E Pseudo-Ginsenosides and Their Comparative Study of Antioxidative Activity in Free Radical Induced Hemolysis of Rabbit Erythrocytes

Twelve pseudo-ginsenosides were synthesized under a mild condition, via a simple three-step called acetylation, elimination-addition and saponification. The inhibitory effects of these twelve pseudo-ginsenosides were screened on the hemolysis of rabbit erythrocytes caused by 2,2'-azobis (2-amidinopropane hydrochloride) (AAPH). It was found that the IC₅₀ values followed the sequence of (20Z) pseudo-protopanaxatriol (pseudo-PPT)<(20Z) pseudo-protopanaxadiol (pseudo-PPD)<(20Z) pseudo-Rh2<(20E) pseudo-PPT<(20E) pseudo-PPD<(20E) pseudo-Rh2<(20Z) pseudo-Rg2<(20E) pseudo-Rg2<Rb1<(20Z) pseudo-Rh1<Rg2<(20E) pseudo-Rh1. These compounds can be divided into three groups: accelerate the hemolysis group (7, 8), weak group (2, 11, 12) and strong group (others). Moreover, we also find that most of the Z configuration has better antioxidative activity than E configuration and the number and type of sugar moieties to the ring of triterpene dammarane influence the antioxidative activity.

Effect of polyphenols extracted from tamarind (Tamarindus indica L.) seed coat on pathophysiological changes and red blood cell glutathione peroxidase activity in heat-stressed broilers

The purpose of this study was to determine the effect of polyphenols extracted from the tamarind seed coat (PETSC) on glutathione peroxidase (GPx) activity, red blood cell parameters and bilirubin in heat-stressed broilers. One hundred forty-seven broilers, 18-days old were divided into two groups. In group 1, broilers were maintained at an environmental temperature of 26 ± 2 °C throughout the experimental period. In group 2, the broilers were maintained at 38 ± 2 °C (cyclic temperature: 26 ± 2 °C; -38 ± 2 °C; and -26 ± 2 °C, and broilers were maintained at 38 ± 2 °C for 6 h/ day) and received PETSC at a concentration of 0, 100, 200, 300, 400 or 500 mg/kg in their diet ad libitum. Parameters were investigated on days 1, 7, 14 and 21 of the experimental period. Results showed that GPx activity of heat-stressed broilers that received 100 mg/kg of PETSC in their diet was lower (P < 0.05) than that in broilers fed the other concentrations. The mean total red blood cell count and hemoglobin concentration of heat-stressed broilers that received 100 mg/kg PETSC was higher (P < 0.05) than those in broilers in group 1 and those fed the other concentrations. The mean bilirubin level in the excreta of heat-stressed broilers that received 100 mg/kg of PETSC was lower (P < 0.05) than that in broilers that received 0, 300, 400 and 500 mg/kg of PETSC. This showed that PETSC could reduce GPx activity and bilirubin in feces, and increase red blood cell parameters in heat-stressed broilers.

Haematological and biochemical toxicity induced by methanol in rats: Ameliorative effects of Opuntia vulgaris fruit extract

The ameliorative effects of Opuntia vulgaris fruit extract (OE) were evaluated against methanol-induced haematological and biochemical toxicity in rats. The methanol-induced haematological and biochemical perturbation significantly decreased the levels of red blood cell (RBC), haemoglobin (Hb), haematocrit (Ht), serum total protein and increased glucose, cholesterol, and triglyceride levels in serum. Treatment of rats with methanol significantly increased lipid peroxidation (LPO) level and decreased the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) in erythrocytes. OE treatment could increase significantly the levels of RBC, Hb, Ht and total protein, and decrease glucose, cholesterol and triglyceride levels in serum, and increase the activities of SOD, CAT and GPx in erythrocytes, when compared with methanol-treated group. Spleen histopathology showed that OE could significantly reduce the incidence of spleen lesion induced by methanol. These results suggested that OE could exhibit a potential source of natural antioxidants against methanol-induced haematological and biochemical disruption in rats. The protective effects of OE may be due to the modulation of antioxidant enzymes activities and inhibition of LPO.

Epigallocatechin-3-gallate (EGCG) affects the antioxidant and immune defense of the rainbow trout, Oncorhynchus mykiss

Epigallocatechin-3-gallate (EGCG), a very potent antioxidant derived from green tea, was compared with vitamin E in terms of its effects on antioxidant defense and immune response of rainbow trout, by means of a feeding trial of eight weeks. Two of the experimental diets were supplemented with EGCG at either 20 or 100 mg kg(-1) diet (which contained only 30% of the intended levels) and the third was provided with 100 mg kg(-1) vitamin E but not EGCG. The control diet was not supplemented with the test components. Observation of tissue levels indicated that the high amount of EGCG helped to increase the availability of the lipid-soluble antioxidant vitamin E. The lower levels of lipid hydroperoxide in the liver of fish fed the higher amount of EGCG suggested that it was an effective antioxidant. Considering the immune indices, EGCG and vitamin E at 100 mg (actual amounts 31.9 and 94.1 mg kg(-1) diet, respectively) had identical capabilities in improving phagocytic activity and controlling hydrogen peroxide production by leucocytes. However, EGCG could possibly be more effective at enhancing serum lysozyme activity and the alternative complement activity. This work revealed the potential of EGCG as an antioxidant and an immunostimulant for rainbow trout, at least at the inclusion level of 32 mg kg(-1) diet.

Evaluation of the free-radical-scavenging activity of diclofenac acid on the free-radical-induced haemolysis of human erythrocytes

Free-radical-induced peroxidation in-vivo is regarded as the aetiology of some diseases and free-radical-scavenging drugs, also called antioxidants (AH), have been widely used to overcome oxidative stress. An in-vitro experimental method, 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH)-induced haemolysis of human erythrocytes can be applied to assess the free-radical-scavenging activity of a drug. The major objectives of this work were focused on three aspects. Firstly, introduction of the chemical kinetic deduction of free-radical-initiating reaction to AAPH-induced haemolysis of human erythrocytes, by which the number of free radicals trapped by an antioxidant, n, can be obtained after finding the quantitative relationship between the inhibition period (t(inh)) and the concentration of the antioxidant, t(inh) = (n/Ri) [AH]. Ri, the free-radical-initiating rate, was initially confirmed by using alpha-tocopherol (VE) whose n was taken as 2. Secondly, the free-radical-scavenging activity of diclofenac acid (DaH) and its sodium salt (DaNaH) was assessed. It has been found that DaH and DaNaH protect human erythrocytes against AAPH-induced haemolysis dose-dependently. In particular, the n values of DaH and DaNaH (4.96 and 3.60) were much higher than some traditional antioxidants, such as 6-hydroxyl-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox, a water-soluble structural analogue of VE, n = 0.30) and L-ascorbic acid (VC, n = 0.25), and L-ascorbyl-6-laurate (VC-12, a lipophilic structural analogue of VC, n = 1.11). Moreover, the free-radical-scavenging activity of lipophilic antioxidants is higher than the corresponding water-soluble species. Thirdly, the free-radical-scavenging activity of mixed antioxidants, VE + DaH, VC-12 + DaH, Trolox + DaNaH and VC + DaNaH, was revealed. The n value of VC, VC-12, VE and Trolox increase in the case of mixed usage with DaH and DaNaH, implying that diclofenac acid can repair the radical of these antioxidants. Thus, a mutual antioxidant effect between diclofenac acid and these antioxidants prolongs the lifespan of VC, VC-12, VE and Trolox, respectively.

Protective effects of flavonols and their glycosides against free radical-induced oxidative hemolysis of red blood cells

The in vitro oxidative hemolysis of human red blood cells (RBCs) was used as a model to study the free radical-induced damage of biological membranes and the protective effect of flavonols and their glycosides (FOHs), i.e., myricetin (MY), quercetin (Q), morin (MO), kaempferol (K), rutin (R), quercetin galactopyranoside (QG), quercetin rhamnopyranoside (QR), and kaempferol glucopyranoside (KG). The hemolysis of RBCs was induced by a water-soluble free radical initiator 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH). It was found that addition of AAPH at 37 degrees C to the suspension of RBCs caused fast hemolysis after a short period of inhibition period, and addition of FOHs significantly suppressed the hemolysis. The FOHs (MY, Q, R, QG and QR) which bears an ortho-dihydroxyl functionality showed much more effective anti-hemolysis activity than that of the other FOHs (MO, K and KG) bearing no such functionality.

Antioxidative Effects of Flavonols and Their Glycosides against the Free-Radical-Induced Peroxidation of Linoleic Acid in Solution and in Micelles

The antioxidative effect of flavonols and their glycosides against the peroxidation of linoleic acid has been studied in homogeneous solution (tBuOH/H(2)O, 3:2) and in sodium dodecyl sulfate and cetyl trimethylammonium bromide micelles. The peroxidation was initiated thermally by the water-soluble initiator 2,2'-azobis(2-methylpropionamidine) dihydrochloride, and the reaction kinetics were studied by monitoring the formation of linoleic acid hydroperoxides. The synergistic antioxidant effect of the flavonols with alpha-tocopherol (vitamin E) was also studied by following the decay kinetics of alpha-tocopherol and the alpha-tocopheroxyl radical. Kinetic analysis of the antioxidative process demonstrates that the flavonols are effective antioxidants in solution and in micelles, either alone or in combination with alpha-tocopherol. The antioxidative action involves trapping the initiating radicals in solution or in the bulk-water phase of the micelles, trapping the propagating lipid peroxyl radicals on the surface of the micelles, and regenerating alpha-tocopherol by reducing the alpha-tocopheroxyl radical. It was found that the antioxidant activity of the flavonols and their glycosides depends significantly on the position and number of the hydroxy groups, the oxidation potential of the molecule, and the reaction medium. The flavonols bearing ortho-dihydroxy groups possess significantly higher antioxidative activity than those without such functionalities, and the glycosides are less active than their parent aglycones. The activity of the flavonols is higher in micelles than in solution, while the activity of alpha-tocopherol is lower in micelles than in solution. This is because the predominant factor for controlling the activity is the hydrogen-bonding interaction of the antioxidant with the micellar surface in the case of hydrophilic flavonols, while it is the inter- and intramicellar diffusion in the case of lipophilic alpha-tocopherol.

Strictinin as an efficient antioxidant in lipid peroxidation

The antioxidant effect of strictinin (SOH), which was extracted from green tea leaves, against the peroxidation of linoleic acid in sodium dodecyl sulfate (SDS) and cetyl trimethylammonium (CTAB) micelles, against the peroxidation of low-density lipoprotein (LDL) and against oxidative hemolysis of human red blood cells (RBCs), has been studied. The peroxidation of linoleic acid and LDL, and oxidative hemolysis of RBCs were initiated thermally by a water-soluble azo initiator 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH), and the reaction kinetics in micelles and LDL were monitored by uptake of oxygen. The synergistic antioxidant effect of SOH with alpha-tocopherol (Vitamin E) was also studied by following the decay kinetics of alpha-tocopherol. Kinetic analysis of the antioxidation process demonstrates that SOH, used either alone or in combination with alpha-tocopherol, is an effective antioxidant against lipid peroxidation, but its effects significantly depend on the reaction medium.

Antioxidative and free radical scavenging effects of ecdysteroids from Serratula strangulata

The antioxidative and free radical scavenging effects of four ecdysteroids, 20-hydroxyecdysone (E1), 25-deoxy-11,20-dihydroxyecdysone (E2), 24-(2-hydroxyethyl)-20-hydroxyecdysone (E3), and 20-hydroxyecdysone-20,22-monoacetonide (E4), isolated from the Chinese herb Serratula strangulata have been investigated in vitro. These ecdysteroids could protect human erythrocytes against oxidative hemolysis induced by a water-soluble azo initiator 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH). They could also inhibit the peroxidation of rat liver microsomes induced by hydroxyl radicals, as monitored by the formation of thiobarbituric acid reactive substances (TBARS), and prevent radical-induced decrease of membrane fluidity as determined by fluorescence polarization. They reacted with galvinoxyl radicals in homogeneous solution, and the pseudo-first-order rate constants were determined spectrophotometrically by following the disappearance of galvinoxyl radicals. Compounds E1 and (or) E3 were the most active in both antioxidative and radical-scavenging reactions.

Can ginsenosides protect human erythrocytes against free-radical-induced hemolysis?

Many studies have focused on the free-radical-initiated peroxidation of membrane lipid, which is associated with a variety of pathological events. Panax ginseng is used in traditional Chinese medicine to enhance stamina and capacity to deal with fatigue and physical stress. Many reports have been devoted to the effects of ginsenosides, the major active components in P. ginseng, on the lipid metabolism, immune function and cardiovascular system. The results, however, are usually contradictory since the usage of mixture of ginsenosides cannot identify the function of every individual ginsenosides on the experimental system. On the other hand, every individual ginsenosides is not compared under the same experimental condition. These facts motivate us to evaluate the antioxidant effect of various individual ginsenosides on the experimental system of free-radical-initiated peroxidation: the hemolysis of human erythrocyte induced thermally by water-soluble initiator, 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH). The inhibitory concentration of 50% inhibition (IC(50)) of AAPH-induced hemolysis of the erythrocyte has been studied firstly and found that the order of IC(50) is Rb3 - Rb1<<Rg2<Re<Rg1 - Rc<Rh1<R1. Rb1, Rc and Rg2, as antioxidants, can prolong the lag time of hemolysis. Contrarily, Rg3, Rd and Rh1, together with high concentration of Rb3, Rg1 and Rh2, function as prooxidants to accelerate AAPH-induced hemolysis. The addition of Re does not influence the lag time of hemolysis. The R1 with the concentration ranging from 10 to 20 microM decreases the lag time of hemolysis. These results suggest that there is a mutual interaction that existed in the molecule of ginsenosides since the difference of the structure of ginsenosides is only due to the connective position and type of sugar moieties to the ring of a triterpene dammarane. Moreover, the synergistic antioxidative properties of various individual ginsenosides with alpha-tocopherol (TOH) are also discussed, and it was found that the order of synergistic antioxidative properties with TOH is Rb1>Rc>Re>Rh1>R1>Rg2>Rb3. Rg3, Rd and Rh2, however, act as synergistic prooxidants in the above experimental system. Rg1 does not show any synergistic antioxidative property. Although the antioxidative and prooxidative mechanism of various ginsenosides with or without TOH in AAPH-induced hemolysis of human erythrocytes will be further studied in detail, this information may be useful in the clinical usage of ginsenosides.

Antioxidative or prooxidative effect of 4-hydroxyquinoline derivatives on free-radical-initiated hemolysis of erythrocytes is due to its distributive status

7-Chloro-4-hydroxyquinoline (CQ) is an antitumor drug but its efficiency is not very satisfactory. This fact motivates us to study the relationship between the structure of 4-hydroxyquinoline with various substituent and its antioxidant effect against free-radical-initiated peroxidation: the hemolysis of human erythrocyte initiated thermally by water-soluble initiator, 2,2'-azobis (2-amidinopropane hydrochloride) (AAPH), acts as an experimental system. 7-Fluoro-4-hydroxyquinoline (FQ) and CQ can be synthesized by decarboxylation of 7-fluoro-4-hydroxyquinoline-3-carboxylic acid (FQCA) and 7-chloro-4-hydroxyquinoline-3-carboxylic acid (CQCA), respectively, and FQCA and CQCA are prepared by hydrolysis of ethyl 7-fluoro-4-hydroxyquinoline-3-carboxylate (FQCE) and ethyl 7-chloro-4-hydroxyquinoline-3-carboxylate (CQCE), respectively. The inhibitory concentration of 50% inhibition (IC(50)) of AAPH-induced hemolysis of the erythrocyte has been studied and found that all these chemicals dissolved in dimethyl sulfoxide (DMSO) can inhibit the free-radical-induced peroxidation. To clarify the relationship between the distributive status of the chemicals and their antioxidant effect, the chemical has been dissolved in the vesicle of dipalmitoyl phosphatidylcholine (DPPC) by sonication and suspended in the reaction system. It is found that FQCE, CQCE, FQCA and CQCA act as prooxidants either used alone or used in combination with alpha-tocopherol (TOH), demonstrating that FQCE, CQCE, FQCA and CQCA play a prooxidative role when they are packaged in the DPPC vesicle. This can be understood that the electron-attracting group, i.e. -COOC(2)H(5), -COOH, at the ortho position to the hydroxy group of quinoline makes the phenoxy radical of quinoline derivatives active by attracting negative charge from the electron-deficient radical site. These unstable free radicals preserved in DPPC vesicle can initiate additional propagation of lipid peroxidation and cause hemolysis. However, FQ and CQ without electron-attracting group are antioxidants even in DPPC vesicle either used alone, or mixed with TOH. Moreover, the antioxidative activity of FQ is much better than CQ either used alone or in combination with TOH, indicating that FQ has the potential to replace CQ to be an antioxidant drug. Therefore, the antioxidant/prooxidant effect is not only correlated with the molecular structure but also the distributive status in the reaction system.