Oxidants and Antioxidants in Clinical Medicine: Past, Present and Future Potential

Comparative Study of the Antioxidant Constituents, Activities and the GC-MS Quantification and Identification of Fatty Acids of Four Selected Helichrysum Species

Helichrysum Mill. (Asteraceae) is a plant genus comprising distinctively of aromatic plants of about 500–600 species. Since most of these plants have not been previously studied, extensive profiling helps to validate their folkloric uses and determine their potential value as sources of plant-derived drug candidates. This study, therefore, aims to investigate the antioxidant activity (DPPH, NO, FRAP); total antioxidant capacity, total phenolic, total flavonoid, and fatty acid compositions of the aqueous acetone extracts from four Helichrysum plants namely, Helichrysum pandurifolium, Helichrysum foetidum, Helichrysum petiolare, and Helichrysum cymocum. The results obtained showed that the H. cymocum extract had the best DPPH radical scavenging activity (IC50 = 11.85 ± 3.20 µg/mL) and H. petiolare extract had the best nitric oxide scavenging activity (IC50 = 20.81 ± 3.73 µg/mL), while H. pandurifolium Schrank extract (0.636 ± 0.005 µg/mL) demonstrated the best ferrous reducing power, all of which are comparable with results from ascorbic acid used as the standard. The IC50 values of the radical scavenging activity ranged from 11.85–41.13 µg/mL (DPPH), 20.81–36.19 µg/mL (NO), and 0.505–0.636 µg/mL (FRAP), for all the plants studied. The H. petiolare has the highest total antioxidant capacity (48.50 ± 1.55 mg/g), highest total phenolic content (54.69 ± 0.23 mg/g), and highest total flavonoid content (56.19 ± 1.01 mg/g) compared with other species. The fatty acid methyl esters were analysed using gas chromatography-mass spectrometry (GC-MS). The results obtained showed variations in the fatty acid composition of the plant extracts, with H. petiolare having the highest saturated fatty acid (SFA) content (7184 µg/g) and polyunsaturated fatty acid (PUFA) content (7005.5 µg/g). In addition, H. foetidum had the highest monounsaturated fatty acid (MUFA) content (1150.3 µg/g), while H. cymocum had the highest PUFA:SFA ratio of 1.202. In conclusion, the findings from this study revealed that H. pandurifolium Schrank, H. foetidum, H. petiolare, and H. cymocum are repositories of natural bioactive compounds with potential health-promoting benefits that need to be investigated, for both their antioxidant activity in a number of disease conditions and for further exploration in drug discovery and development projects.

The medicinal chemistry of mitochondrial dysfunction: a critical overview of efforts to modulate mitochondrial health

Mitochondria are subcellular organelles that perform a variety of critical biological functions, including ATP production and acting as hubs of immune and apoptotic signalling. Mitochondrial dysfunction has been extensively linked to the pathology of multiple neurodegenerative disorders, resulting in significant investment from the drug discovery community. Despite extensive efforts, there remains no disease modifying therapies for neurodegenerative disorders. This manuscript aims to review the compounds historically used to modulate the mitochondrial network through the lens of modern medicinal chemistry, and to offer a perspective on the evidence that relevant exposure was achieved in a representative model and that exposure was likely to result in target binding and engagement of pharmacology. We hope this manuscript will aid the community in identifying those targets and mechanisms which have been convincingly (in)validated with high quality chemical matter, and those for which an opportunity exists to explore in greater depth.

Marine-Derived Compounds with Potential Use as Cosmeceuticals and Nutricosmetics

The cosmetic industry is among the fastest growing industries in the last decade. As the beauty concepts have been revolutionized, many terms have been coined to accompany the innovation of this industry, since the beauty products are not just confined to those that are applied to protect and enhance the appearance of the human body. Consequently, the terms such as cosmeceuticals and nutricosmetics have emerged to give a notion of the health benefits of the products that create the beauty from inside to outside. In the past years, natural products-based cosmeceuticals have gained a huge amount of attention not only from researchers but also from the public due to the general belief that they are harmless. Notably, in recent years, the demand for cosmeceuticals from the marine resources has been exponentially on the rise due to their unique chemical and biological properties that are not found in terrestrial resources. Therefore, the present review addresses the importance of marine-derived compounds, stressing new chemical entities with cosmeceutical potential from the marine natural resources and their mechanisms of action by which these compounds exert on the body functions as well as their related health benefits. Marine environments are the most important reservoir of biodiversity that provide biologically active substances whose potential is still to be discovered for application as pharmaceuticals, nutraceuticals, and cosmeceuticals. Marine organisms are not only an important renewable source of valuable bulk compounds used in cosmetic industry such as agar and carrageenan, which are used as gelling and thickening agents to increase the viscosity of cosmetic formulations, but also of small molecules such as ectoine (to promote skin hydration), trichodin A (to prevent product alteration caused by microbial contamination), and mytiloxanthin (as a coloring agent). Marine-derived molecules can also function as active ingredients, being the main compounds that determine the function of cosmeceuticals such as anti-tyrosinase (kojic acid), antiacne (sargafuran), whitening (chrysophanol), UV protection (scytonemin, mycosporine-like amino acids (MAAs)), antioxidants, and anti-wrinkle (astaxanthin and PUFAs).

Garcinia xanthochymus extract protects PC12 cells from H2O2-induced apoptosis through modulation of PI3K/AKT and NRF2/HO-1 pathways

The aim of the present study was to investigate the protective effects and underlying mechanisms of Garcinia xanthochymus, a perennial medicinal plant native to Yunnan, China, against H₂O₂-induced oxidative damage in rat pheochromacytoma PC12 cells. Preincubation of PC12 cells with fruit EtOAc fraction (fruit-EFr., 12.5-50 µmol·L^-1) of G. xanthochymus for 24 h prior to H₂O₂ exposure markedly improved cell viability and increased the activities of antioxidant enzymes (superoxide dismutase, catalase, and heme oxygenase-1 [HO-1]), prevented lactate dehydrogenase release and lipid peroxidation malondialdehyde production, attenuated the decrease of matrix metalloproteinases (MMP), and scavenged reactive oxygen species (ROS). Fruit-EFr. also reduced BAX and cytochrome C expression and improved BCL-2 expression, thereby decreasing the ratio of BAX to BCL-2. Fruit-EFr. activated the nuclear translocation of NRF2 to increase HO-1 and induced the phosphorylation of AKT. Its cytoprotective effect was abolished by LY294002, a specific inhibitor of PI3K. Taken together, the above findings suggested that fruit-EFr.of G. xanthochymus could enhance cellular antioxidant defense capacity, at least in part, through upregulating HO-1 expression and activating the PI3K/AKT pathway and that it could suppress H₂O₂-induced oxidative damage via PI3K/AKT and NRF2/HO-1 signaling pathways.

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.

Antioxidant properties of diverse cereal grains: A review on in vitro and in vivo studies

Cereal grains and products have gained popularity in contributing to healthy eating behavior because of their antioxidant properties associated with protection against chronic diseases. In this review, notable studies on the in vitro and in vivo antioxidant activity of commonly consumed cereal grains are summarized. Cereals contain phytochemicals or certain minor components with antioxidant properties. The antioxidant potential of cereals depends on their bioaccessibility, absorption in the gastrointestinal and their bioavailability utilization in vivo. The in vitro gastrointestinal digestion and fermentation of cereals increased their antioxidant potentials which are significantly correlated with their total phenolic contents. Most studies performed in vivo have been concerned with the antioxidant properties of colored rice, wheat bran and rye products. There are inadequate in vitro and in vivo studies on antioxidative potentials of fermented versus unfermented cereals. Therefore, further studies are necessary to maximize possible health benefits of cereal antioxidative phytochemicals.

Synergistic effect of Se-methylselenocysteine and vitamin E in ameliorating the acute ethanol-induced oxidative damage in rat

The present study was conduced to investigate the synergistic effects of combined treatments with Se-methylselenocysteine (SeMSC) and vitamin E (Vit E) in reversing oxidative stress induced by ethanol in serum and different tissues of rats. Sixty female rats were randomly divided into six groups for 30 days' consecutive pretreatments as followed: control (I), physiological saline (II), 2.8μgkg(-1) Se as SeMSC (III), 2.8μgkg(-1) Se as sodium selenite (Na2SeO3, IV), 5mgkg(-1) α-tocopherol as α-tocopherol acetate (Vit E, V), 5mgkg(-1) α-tocopherol as α-tocopherol acetate and 2.8μgkg(-1) Se as SeMSC (VI). All animals in groups II-VI were treated by ethanol treatment to cause oxidative stress. After 6h of ethanol treatment, the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), the contents of total antioxidant capacity (T-AOC), malondialdehyde (MDA), glutathione (GSH) and carbonyl protein (CP) in the serum, liver, heart and kidney were measured. The result showed that the individual SeSMC, Na2SeO3 and vitamin E could effectively increase the SOD, T-AOC, GSH-Px and GSH contents as well as significantly decrease the MDA and CP concentrations in the tissues of ethanol-induced rats. At the same dose on different forms of Se, SeMSC showed greater antioxidant activity than Na2SeO3. Moreover, group VI (SeMSC and α-tocopherol acetate) showed much better antioxidant activity than individual group III (SeMSC) and V (α-tocopherol acetate) due to the synergistic effect.

Antioxidant enzyme activity and malondialdehyde levels can be modulated by Piper betle, tocotrienol rich fraction and Chlorella vulgaris in aging C57BL/6 mice

OBJECTIVE

The aim of this study was to determine the erythrocyte antioxidant enzyme activity and the superoxide dismutase, catalase, glutathione peroxidase, and plasma malondialdehyde levels in aging mice and to evaluate how these measures are modulated by potential antioxidants, including the tocotrienol-rich fraction, Piper betle, and Chlorella vulgaris.

METHOD

One hundred and twenty male C57BL/6 inbred mice were divided into three age groups: young (6 months old), middle-aged (12 months old), and old (18 months old). Each age group consisted of two control groups (distilled water and olive oil) and three treatment groups: Piper betle (50 mg/kg body weight), tocotrienol-rich fraction (30 mg/kg), and Chlorella vulgaris (50 mg/kg). The duration of treatment for all three age groups was two months. Blood was withdrawn from the orbital sinus to determine the antioxidant enzyme activity and the malondialdehyde level.

RESULTS

Piper betle increased the activities of catalase, glutathione peroxidase, and superoxide dismutase in the young, middle, and old age groups, respectively, when compared to control. The tocotrienol-rich fraction decreased the superoxide dismutase activity in the middle and the old age groups but had no effect on catalase or glutathione peroxidase activity for all age groups. Chlorella vulgaris had no effect on superoxide dismutase activity for all age groups but increased glutathione peroxidase and decreased catalase activity in the middle and the young age groups, respectively. Chlorella vulgaris reduced lipid peroxidation (malondialdehyde levels) in all age groups, but no significant changes were observed with the tocotrienol-rich fraction and the Piper betle treatments.

CONCLUSION

We found equivocal age-related changes in erythrocyte antioxidant enzyme activity when mice were treated with Piper betle, the tocotrienol-rich fraction, and Chlorella vulgaris. However, Piper betle treatment showed increased antioxidant enzymes activity during aging.

Impaired hepatic function and central dopaminergic denervation in a rodent model of Parkinson's disease: a self-perpetuating crosstalk?

In Parkinson's disease (PD), aside from the central lesion, involvement of visceral organs has been proposed as part of the complex clinical picture of the disease. The issue is still poorly understood and relatively unexplored. In this study we used a classic rodent model of nigrostriatal degeneration, induced by the intrastriatal injection of 6-hydroxydopamine (6-OHDA), to investigate whether and how a PD-like central dopaminergic denervation may influence hepatic functions. Rats received an intrastriatal injection of 6-OHDA or saline (sham), and blood, cerebrospinal fluid, liver and brain samples were obtained for up to 8 weeks after surgery. Specimens were analyzed for changes in cytokine and thyroid hormone levels, as well as liver mitochondrial alterations. Hepatic mitochondria isolated from animals bearing extended nigrostriatal lesion displayed increased ROS production, while membrane potential (ΔΨ) and ATP production were significantly decreased. Reduced ATP production correlated with nigral neuronal loss. Thyroid hormone levels were significantly increased in serum of PD rats compared to sham animals while steady expression of selected cytokines was detected in all groups. Hepatic enzyme functions were comparable in all animals. Our study indicates for the first time that in a rodent model of PD, hepatic mitochondria dysfunctions arise as a consequence of nigrostriatal degeneration, and that thyroid hormone represents a key interface in this CNS-liver interaction. Liver plays a fundamental detoxifying function and a better understanding of PD-related hepatic mitochondrial alterations, which might further promote neurodegeneration, may represent an important step for the development of novel therapeutic strategies.

The antioxidative effect of icariin in human erythrocytes against free-radical-induced haemolysis

Icariin (2-(4′-methoxyl phenyl)-3-rhamnosido-5-hydroxyl-7-glucosido-8-(3′-methyl-2-butylenyl)-4-chromanone) is the major component in Herba Epimedii used in traditional Chinese medicine for the treatment of atherosclerosis. This work focuses on the antioxidative effect of icariin on free-radical-induced haemolysis of human erythrocytes, in which the initial free radical derives from the decomposition of 2,2′-azobis(2-amidinopropane hydrochloride) (AAPH) at physiological temperature. To reveal the structure-activity relationship of icariin, the antioxidant effects of two structural analogues of icariin, acacetin (2-(4′-methoxylphenyl)-5,7-dihydroxylchromone) and norwogonin (2-phenyl-5,7,8-trihydroxylchromone), on the same experimental system were examined as well. It was found that all these chromone derivatives (Chm-OHs) dose-dependently protected human erythrocytes against free-radical-induced haemolysis. The order of antioxidative activity was norwogonin&gt;acacetin&gt;icariin by the analysis of the relationship between the concentration of Chm-OHs and the prolongation percentage of the lag time of haemolysis (PP%). It was also proved that the phenyl hydroxyl group attached to the chromone ring at 7-position cannot trap the free radical. On the contrary, phenyl hydroxyl groups at the 5- and 8-position in norwogonin made it a significant antioxidant in AAPH-induced haemolysis. The more hydroxyl groups attached to the chromone ring, the higher the antioxidative activity in protecting erythrocytes against free-radical-induced peroxidation.

Chemical and molecular mechanisms of antioxidants: experimental approaches and model systems

Free radicals derived from oxygen, nitrogen and sulphur molecules in the biological system are highly active to react with other molecules due to their unpaired electrons. These radicals are important part of groups of molecules called reactive oxygen/nitrogen species (ROS/RNS), which are produced during cellular metabolism and functional activities and have important roles in cell signalling, apoptosis, gene expression and ion transportation. However, excessive ROS attack bases in nucleic acids, amino acid side chains in proteins and double bonds in unsaturated fatty acids, and cause oxidative stress, which can damage DNA, RNA, proteins and lipids resulting in an increased risk for cardiovascular disease, cancer, autism and other diseases. Intracellular antioxidant enzymes and intake of dietary antioxidants may help to maintain an adequate antioxidant status in the body. In the past decades, new molecular techniques, cell cultures and animal models have been established to study the effects and mechanisms of antioxidants on ROS. The chemical and molecular approaches have been used to study the mechanism and kinetics of antioxidants and to identify new potent antioxidants. Antioxidants can decrease the oxidative damage directly via reacting with free radicals or indirectly by inhibiting the activity or expression of free radical generating enzymes or enhancing the activity or expression of intracellular antioxidant enzymes. The new chemical and cell-free biological system has been applied in dissecting the molecular action of antioxidants. This review focuses on the research approaches that have been used to study oxidative stress and antioxidants in lipid peroxidation, DNA damage, protein modification as well as enzyme activity, with emphasis on the chemical and cell-free biological system.

Unusual antioxidant behavior of alpha- and gamma-terpinene in protecting methyl linoleate, DNA, and erythrocyte

The antioxidant effects of alpha-terpinene (alpha-TH) and gamma-terpinene (gamma-TH) on the oxidation of methyl linoleate (LH), DNA, and erythrocytes induced by 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH) were investigated. The results from erythrocytes and DNA were treated by means of chemical kinetic equations. It was found that either alpha- or gamma-TH was able to scavenge approximately 0.4 radicals when they protected DNA. alpha-TH can trap approximately 0.7 radicals when protecting erythrocytes and can trap approximately 0.5 radicals when protecting LH. gamma-TH can trap approximately 1.2 radicals when protecting erythrocytes and LH. Therefore, the antioxidant effectiveness of gamma-TH was higher than alpha-TH. gamma-TH contained a nonconjugated diene, and the diene in alpha-TH was conjugated. The obtained results implied that the nonconjugated diene benefited for antioxidant capacity more than a conjugated diene. Moreover, the reactions of alpha- and gamma-TH with 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) cation radical (ABTS(+) (*)) and 2,2'-diphenyl-1-picrylhydrazyl (DPPH) implicated that alpha- and gamma-TH were able to scavenge radicals directly. However, alpha- and gamma-TH promoted AAPH-induced hemolysis with a high concentration employed.

Potential cytoprotection: antioxidant defence by caffeic acid phenethyl ester against free radical-induced damage of lipids, DNA, and proteins

Oxidative stress is considered to be a major cause of cellular injuries in a variety of chronic health problems, such as carcinogenesis and neurodegenerative disorders. Caffeic acid phenethyl ester (CAPE), derived from the propolis of honeybee hives, possesses a variety of biological and pharmacological properties including antioxidant and anticancer activity. In the present study, we focused on the diverse antioxidative functionalities of CAPE and its related polyphenolic acid esters on cellular macromolecules in vitro. The effects on human erythrocyte membrane ghost lipid peroxidation, plasmid pBR322 DNA, and protein damage initiated by the water-soluble initiator 2,2′-azobis(2-amidinopropane) hydrochloride (AAPH) and hydrogen peroxide (H2O2) were monitored by formation of hydroperoxides and by DNA nicking assay, single-cell alkaline electrophoresis, and SDS-polyacrylamide gel electrophoresis. Our results showed that CAPE and its related polyphenolic acid esters elicited remarkable inhibitory effects on erythrocyte membrane lipid peroxidation, cellular DNA strand breakage, and protein fragmentation. The results suggest that CAPE is a potent exogenous cytoprotective and antigenotoxic agent against cell oxidative damage that could be used as a template for designing novel drugs to combat diseases induced by oxidative stress components, such as various types of cancer.

Potential Mechanisms for Altered Iron Metabolism in Human Immunodeficiency Virus Disease

Recently, anemia associated with human immunodeficiency virus (HIV) disease has received more attention as our understanding of the significance of anemia in this population has grown and more emphasis is placed on the quality of life of people living with HIV/AIDS. Although the diagnosis and treatment of anemia in HIV disease has been discussed in great detail, the prevalence and pathophysiology of the two most common forms of anemia, iron deficiency anemia (IDA) and the anemia of chronic disease (ACD), have not received much attention despite the difficulty and importance of differentiating between these two anemias. In addition, little attention has been given to iron overload, which has serious implications in individuals with HIV disease. This article proposes a model of altered iron metabolism in HIV disease as a basis for explaining the pathophysiology and implications of IDA, ACD, and iron overload in this population. Implications for clinical practice and recommendations for future research are discussed.

Lipid peroxidation inhibitory compounds from daylily (Hemerocallis fulva) leaves

Daylilies (Hemerocallis spp.) have been used as food and in traditional medicine for thousands of years in eastern Asia. The leaves of the plant are used in the treatment of inflammation and jaundice. In studies of the aqueous methanol extracts of fresh Hemerocallis fulva leaves, 1',2',3',4'-tetrahydro-5'-deoxy-pinnatanine (1), pinnatanine (2), roseoside (3), phlomuroside (4), lariciresinol (5), adenosine (6), quercetin 3-O-beta-D-glucoside (7), quercetin 3,7-O-beta-D-diglucopyranoside (8), quercetin 3-O-alpha-L-rhamnopyransol-(1-->6)-beta-D-glucopyranosol-7-O-beta-D-glucopyranoside (9), isorhamnetin-3-O-beta-D-6'-acetylglucopyranoside (10) and isorhamnetin-3-O-beta-D-6'-acetylgalactopyranoside (11) were isolated. All of these compounds were tested for their in vitro lipid peroxidation inhibitory activities. Compounds 3-5 and 7-11 were found to possess strong antioxidant properties, inhibiting lipid oxidation by 86.4, 72.7, 90.1, 79.7, 82.4, 89.3, 82.2, and 93.2%, respectively at 50 microg/mL. Compound 1 is novel and compounds 3-6 and 8-11 described here in are isolated for the first time from daylily leaves.

Endomorphins, endogenous opioid peptides, provide antioxidant defense in the brain against free radical-induced damage

Oxidative stress has been considered to be a major cause of cellular injuries in a variety of chronic health problems, such as carcinogenesis and neurodegenerative disorders. The brain appears to be more susceptible to oxidative damage than other organs. Therefore, the existence of antioxidants may be essential in brain protective systems. The antioxidative and free radical scavenging effects of endomorphin 1 (EM1) and endomorphin 2 (EM2), endogenous opioid peptides in the brain, have been investigated in vitro. The oxidative damage was initiated by a water-soluble initiator 2,2'-azobis(2-amidinopropane hydrocholoride) (AAPH) and hydrogen peroxide (H2O2). The linoleic acid peroxidation, DNA and protein damage were monitored by formation of hydroperoxides, by plasmid pBR 322 DNA nicking assay and single-cell alkaline electrophoresis, and by SDS-polyacrylamide gel electrophoresis. Endomorphins can inhibit lipid peroxidation, DNA strand breakage, and protein fragmentation induced by free radical. Endomorphins also reacted with galvinoxyl radicals in homogeneous solution, and the pseudo-first-order rate constants were determined spectrophotometrically by following the disappearance of galvinoxyl radicals. In all assay systems, EM1 was more potent than EM2 and GSH, a major intracellular water-soluble antioxidant. We propose that endomorphins are one of the protective systems against free radical-induced damage in the brain.

In vitro study of the relationship between the structure of ginsenoside and its antioxidative or prooxidative activity in free radical induced hemolysis of human erythrocytes

Ginsenoside, the major active component in Panax ginseng, which has been used in traditional Chinese medicine, contains a series of derivatives of the triterpene dammarane being attached by some sugar moieties. To clarify the relationship between the structure of ginsenoside and its properties, 11 individual ginsenosides, along with the central structures of ginsenoside, protopanaxadiol and protopanaxatriol, are used in 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH) induced hemolysis of human erythrocytes, a good experimental model to research free radical induced membrane damage and to evaluate the antioxidative or prooxidative activities of various antioxidants conveniently. It is found that the central structures of ginsenosides, either protopanaxadiol or protopanaxatriol, play a prooxidative role in AAPH-induced hemolysis of erythrocytes. As to the individual ginsenoside, if there are no sugar moieties attached to the 20-position of the triterpene dammarane, the ginsenoside acts as a prooxidant, that is, Rg3, Rh2, and Rg2. A glucose attached to the 6-position instead of the 20-position sugar moieties can make the ginsenoside an antioxidant, that is, Rh1. The antioxidants among ginsenosides follow two different mechanisms that can be expressed mathematically by the Boltzmann equation, that is, Rc and Rb1, and a polynomial equation, that is, Re, Rd, R1, Rg1, Rb3, and Rh1. The orders of antioxidative ability are Rc > Rb1 and Re > Rd > R1 > Rg1 > Rb3 > Rh1, respectively.

Changes in blood antioxidants and several lipid peroxidation products in women with age-related macular degeneration

PURPOSE

The aim of this study was to evaluate the ferric reducing ability of plasma (FRAP), selected enzymatic and non-enzymatic components of the antioxidative system, and the intensity of peroxidative processes in the blood of patients with age-related macular degeneration (AMD).

METHODS

In the peripheral blood, we evaluated FRAP; concentrations of vitamins C, A, and E; and of thiols. We assayed the activity of enzymatic components of the antioxidative system-superoxide dismutase, catalase, ceruloplasmin and the concentration of reduced glutathione as an indicator of glutathione peroxidase activity. In order to determine the intensity of lipid peroxidation, we measured the concentrations of malondialdehyde and hydroxyalkenales (MDA-HNA) and conjugated diens (CD).

RESULTS

We found a significant increase in FRAP in patients with AMD compared with the control group. The average concentrations of vitamins A and C were low and vitamins E and GSH were significantly higher in AMD than in the control group. The activity of almost all the antioxidative enzymes was high. We found a significant increase in MDA-HNA but no difference in CD.

CONCLUSIONS

The significantly higher concentration of lipid peroxidation products in patients with AMD indicates an important pathogenic role of oxido-reduction disturbance. The high FRAP concentration may be one of the protective mechanisms in oxidation stress. The adaptive increase of the antioxidant barrier mostly involves the enzymatic components.

Antioxidant effects of green tea polyphenols on free radical initiated peroxidation of rat liver microsomes

Antioxidative effects of the principal polyphenolic components extracted from green tea leaves, i.e. (-)-epicatechin (EC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin gallate (EGCG), (-)-epigallocatechin (EGC), and gallic acid (GA), against free radical initiated peroxidation of rat liver microsomes were studied. The peroxidation was initiated by a water-soluble azo compound 2,2'-azobis(2-amidinopropane hydrochloride (AAPH). The reaction kinetics was monitored by oxygen uptake and formation of malondialdehyde (MDA). Kinetic analysis of the antioxidation process demonstrates that these green tea polyphenols (GOHs), especially EC and ECG which bear ortho-dihydroxyl functionality, are good antioxidants for microsomal peroxidation. The antioxidant synergism of these GOHs with the endogenous alpha-tocopherol (TOH) (vitamin E) is also discussed.

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.

Isolation and characterization of stelladerol, a new antioxidant naphthalene glycoside, and other antioxidant glycosides from edible daylily (hemerocallis) flowers

Daylily (Hemerocallis spp.) flowers are utilized as an important ingredient in traditional Asian cuisine and are also valued for their reputed medicinal effects. In studies of the bioactive methanol and aqueous methanol extracts of lyophilized Hemerocallis cv. Stella de Oro flowers, kaempferol, quercetin, and isorhamnetin 3-O-glycosides (1-9), phenethyl beta-D-glucopyranoside (10), orcinol beta-D-glucopyranoside (11), phloretin 2'-O-beta-D-glucopyranoside (12), phloretin 2'-O-beta-D-xylopyranosyl-(1-->6)-beta-D-glucopyranoside (13), a new naphthalene glycoside, stelladerol (14), and an amino acid (longitubanine A) (15) have been isolated. All of these compounds were tested for their antioxidant and cyclooxygenase inhibitory activities. Stelladerol was found to possess strong antioxidant properties, inhibiting lipid oxidation by 94.6% +/- 1.4 at 10 microM in an in vitro assay. Several of the flavonol 3-O-glycoside isolates also demonstrated modest antioxidant activities at 10 microM. None of the isolates inhibited cyclooxygenase activity at 100 microM.

Electrochemical treatment of mouse Ehrlich tumor with direct electric current

Electrochemical treatment of cancer utilizes direct electric current (DEC) to produce direct alterations and chemical changes in tumors. However, the DEC treatment is not established and mechanisms are not well understood. In vivo studies were conducted to evaluate the effectiveness of DEC on animal tumor models. Ehrlich tumors were implanted subcutaneously in sixty male BALB/c mice. When the tumor volumes reached 850 mm(3), four platinum electrodes were inserted into the tumors. DEC of 4 mA was applied for 21 min to the treated group; the total charge was 5 C. The healthy and sick control groups were subjected to the same conditions but without DEC. Hematological and chemical parameters as well as histopathological and peritumoral findings were studied. After the electrochemical therapy it was observed that both tumor volume decrease and necrosis percentage increase were significant in the treated group. Moreover, 24 h after treatment an acute inflammatory response, as well as sodium ion decrease, and potassium ion and spleen weight increase were observed in this group. It was concluded that both electrochemical reactions (fundamentally those in which reactive oxygen species are involved), and immune system stimulation induced by cytotoxic action of the DEC could constitute the most important antitumor mechanisms.

Hemorrhage and renal ischemia-reperfusion upregulates the epidermal growth factor receptor in rabbit duodenum

To study the role of EGF-R in small intestinal adaptation to hemorrhage and I/R, anesthetized rabbits were implanted aseptically with arterial and venous catheters and bilateral renal artery Doppler flow probes and silastic occluders and allowed to recover. Rabbits were then randomly assigned to one of six groups: time control; hemorrhage (22.5 mL/kg) and 2.5 hours of renal occlusion (hemorrhage plus I/R); hemorrhage plus I/R and 2:1 LRS resuscitation; hemorrhage plus I/R and 3:1 LRS resuscitation; hemorrhage alone; or I/R alone. Rabbits were killed 48 hours after hemorrhage, and a section of duodenum was collected for analysis. Hemorrhage plus I/R induced a 2.5-fold increase in EGF-R tyrosine kinase activity compared with that found in the control group (P < .05), and this effect was not modified by either LRS resuscitation regimen. This increased activity was associated with similar Increases in EGF-R protein concentrations and approximately a 50% increase in EGF-R messenger (m)RNA levels compared with levels found in the control group. Further analysis of possible regulatory mechanisms for the increased EGF-R expression after hemorrhage plus I/R detected higher levels of EGF-R phosphorylation compared with those found in the control group but no significant increases in transforming growth factor-alpha mRNA levels. These data, coupled with a significant increase in duodenal thlobarbituric acid-reactive substance concentrations from rabbits in the hemorrhage plus I/R group, support the hypothesis that tyrosine kinase signal transduction pathways involving the EGF-R are activated in the small intestine after hemorrhage, renal I/R, or both, and this process may be mediated, at least in part, by oxidant stress.

Minimizing cancer risk using molecular techniques: a review

This review article summarizes molecular markers that can signal enhanced risk of cancer and provide clinicians with these clues in order to attempt the use of natural and synthetic compounds to intervene in the early precancerous stages of carcinogenesis before invasive disease begins. With an aim such as this in mind, we have begun to apply molecular techniques based on many research articles to look for biomarkers capable of signaling a greater risk of cancer. It is possible to attain relatively quick answers by monitoring selected signs and damage in the body which provide the environment for abnormal cell growth and differentiation. These molecular techniques aim to uncover critical precancerous events taking place inside the body and identify measurable biologic flags signaling their occurrence. For years now, scientists have understood that the onset of cancer is a gradual, step-wise process that may unfold over the course of decades, rather than a single, fixed event that can be dated in a pathologist's report. Carcinogenesis usually encompasses the prolonged accumulation of injuries at several different biological levels and includes both genetic and biochemical changes in cells. At each of these levels there is an opportunity for intervention-a chance to prevent, slow or even halt the gradual march of healthy cells toward malignancy. It is estimated that 75% of cancers are induced by chemicals; thus, if exposure to chemicals is avoided, cancer can be prevented. Also, depending on the individual's genetic background, the ability to metabolize chemicals is different among the population. This means that, "you and I can be exposed to exactly the same amount of a chemical," yet our response will differ because we metabolize carcinogens differently due to different rates of deoxyribonucleic acid (DNA) repair, apoptosis, and mitosis or different levels of Phase I and Phase II detoxification enzymes. This, along with a more or less efficient immune system, may promote tumor formation or destroy a cancer cell at its earliest stage of development. Therefore, measurement of the biologic markers such as DNA and protein adducts, DNA damage, programmed cell death, DNA repair system, mitosis, gene activation, levels of antioxidants and efficient immune function described in this chapter and summarized in Figures 2 and 10, are biological clues indicating that the body has been assaulted by toxic (or cancer-causing) agents. This early identification of biomarkers for special vulnerability to the effects of chemicals and detection of selected signs of precancerous damage in the body may culminate preventive measures and the saving of lives.