A novel antioxidant flavonoid (IdB 1031) affecting molecular mechanisms of cellular activation

Clinical development and informatics analysis of natural and semi-synthetic flavonoid drugs: A critical review

BACKGROUND

Flavonoids are one of the most important metabolites with vast structural diversity and a plethora of potential pharmacological applications, which have drawn considerable attention in the laboratory. Nevertheless, it remains uncertain how many candidates were progressed to clinical application.

AIM OF REVIEW

We carried out a critical review of natural and semi-synthetic flavonoid drugs and candidates undergoing different clinical phases worldwide by applying an adequate search method and conducted a brief cheminformatic and bioinformatic analysis. It was expected that the obtained results might narrow the screening scope and reduce the cost of drug research and development.

KEY SCIENTIFIC CONCEPTS OF REVIEW

To our knowledge, this is the most systematic summarization of flavonoid-based drugs and clinical candidates to date. It was found that a total of 19 flavonoid-based drugs have been approved for the market, and of these, natural flavonoids accounted for 52.6%. Besides, a total of 36 flavonoid-based clinical candidates are undergoing or suspended in different phases, and of these, natural flavonoids account for 44.4%. Thus, natural flavonoids remain the best option for finding novel agents/active templates, and when investigated in conjunction with synthetic chemicals and biologicals, they offer the potential to discover novel structures that can lead to effective agents against a variety of human diseases. Additionally, flavonoid-based marketed drugs have been successful in cardiovascular treatment, and the related drugs account for more than 30% of marketed drugs. However, the use of flavonoids as antineoplastic and immunomodulating agents is not likely for approximately 50% of the candidates suspended in the clinical stage. Interestingly, the marketed drugs covered a broader range of chemical spaces based on size, polarity, and three-dimensional structure compared to the clinical candidates. In addition, flavonoid glycosides with poor oral bioavailability account for 36.8% of the marketed drugs, and thus, they could be thoroughly investigated.

Protective effect of quercetin and thymoquinone against genotoxicity and oxidative stress induced by ZnO nanoparticles in the Wistar rat model

Zinc oxide nanoparticles (ZnO-NPs) are increasingly used in a variety of consumer and other commercial products. Hence, man faces the risk of exposure to ZnO-NPs and the consequent adverse health effects. Mitigation/prevention of such effects using natural products has drawn the attention of scientists. Therefore, the aim of the present study has been to find the toxic effects associated with exposure to ZnO-NPs, and the protective role of the phytochemicals thymoquinone (TQ) and quercetin (QCT) in the rat model. ZnO-NPs were administered to male Wistar rats through oral route; TQ / QCT was concurrently administered through intra-peritoneal route. The response in the animal was analyzed adopting chromosomal aberration test, micronucleus test, and comet assay of bone marrow cells to assess the genotoxicity, and biochemical assays of superoxide dismutase (SOD), catalase (CAT), lipid peroxidation (LPO), total extractable protein of liver, and reduced glutathione (GSH) of liver homogenate to monitor the changes in the antioxidant defense mechanism in response to the oxidative stress. Treatment of 300 mg/kg body weight (bw) of ZnO-NPs produced adverse effects on all aspects analyzed viz., structural chromosomal aberrations, micronuclei formation, DNA damage, SOD, catalase, lipid peroxidation, GSH, and extractable total protein of liver. Co-treatment of TQ / QCT offered protection against the toxicity induced by ZnO-NPs. The most optimum doses of TQ and QCT that offered the best protection were 18 mg/kg bw and 500 mg/kg bw, respectively. The study reveals that TQ / QCT supplementation is beneficial in the context of toxic effects of ZnO-NPs.

Underutilized legumes, Cajanus cajan and Glycine max may bring about antisickling effect in sickle cell disease by modulation of redox homeostasis in sickled erythrocytes and alteration of its functional chemistry

The antisickling and anti-oxidative effect of the Cajanus cajan, Glycine max, and their blends were investigated in sickled erythrocytes. The powdered samples were analyzed for their nutritional and anti-nutritional constituents. Their aqueous extracts were analyzed for in vitro antioxidant activities. The extracts were incubated with sickled erythrocytes at 37°C for 6 hours and the antisickling effect examined via microscopic analysis. The blend was the most active and its incubated cells were subjected to anti-oxidative analysis which covers for GSH, SOD, catalase, and lipid peroxidation (LPO). Chemical functional group of the treated cells was analyzed with FTIR spectroscopy. The in silico binding of the predominant amino acid to hemoglobin was also investigated. An increased concentration of leucine was observed in the blend compared to that of C. cajan and G. max, respectively. Vitamins C, B6, and B9 were the only vitamins observed in the blend. Phytate and oxalate were present in all samples. All extracts displayed significant (p < .05) scavenging activities. Treatment with the blend exacerbated SOD and catalase activities as well as the GSH level, while suppressing LPO. FTIR analysis of the treated cells showed the presence of hydrophobic functional groups. Leucine was the predominant amino acid, and it showed a potent molecular interaction with HIS-87 residue of the alpha chain of 1HCO. C. cajan and G. max blend inhibited sickling activities of sickle erythrocytes, while concomitantly exacerbating their endogenous antioxidant enzymes activity and modification of the functional chemistry. PRACTICAL APPLICATIONS: Cajanus cajan and Glycine max are among the common underutilized legumes in Nigeria. Aside their nutritional properties, these legumes have been used from time immemorial for the treatment and management of various ailments. Sickle cell anemia is a class of hemoglobinopathy common in Sub-Saharan Africa. There have been concerns about its treatment owing to the increasing scourge of the disease coupled to the financial burden of its management. This study reports the ability of the potentials of the legumes to prevent sickling activities of sickled erythrocytes and the possible biochemical mechanism involved.

Ethanol- and Cigarette Smoke-Related Alternations in Oral Redox Homeostasis

Alcohol abuse as well as smoking cigarettes has been proven to negatively affect the oral environment. The aim of this work was to provide a systematic review of the literature on the influence of ethanol and cigarette smoking on oral redox homeostasis. A search was performed for scientific articles indexed in the PubMed, Medline and Web of Science databases. We identified 32,300 articles, of which 54 were used for the final review, including the results from 2000 to 2021. Among the publications used to write this article, n = 14 were related to the influence of alcohol consumption (clinical studies n = 6, experimental studies n = 8) and n = 40 were related to the influence of smoking (clinical studies n = 33, experimental studies n = 7) on oral redox homeostasis. The reviewed literature indicates that alcohol abusers and smokers are more likely to suffer from salivary gland dysfunction, as well as develop precancerous lesions due to DNA damage. Compared to alcohol abstainers and non-smokers, alcohol drinkers and smokers are also characterized by a deterioration in periodontal health measured by various indicators of periodontal status. In summary, alcohol abuse and smoking are associated with disrupted oral redox homeostasis, which may lead not only to tooth loss, but also contribute to various adverse effects related to mental health, digestive processes and chronic inflammation throughout the human body.

Oxidative Stress and Cellular Senescence: The Key Tumor-promoting Factors in Colon Cancer and Beneficial Effects of Polyphenols in Colon Cancer Prevention

Background:

Colon cancer is the third leading cause of cancer-related deaths worldwide. Colon tumorigenesis is a sequential process called “Adenoma-carcinoma sequence”. The alimentary habits, obesity, heavy alcohol consumption, inflammatory bowel diseases, family history of colon cancer, oxidative stress, and cellular senescence are the major risk factor influencing colon cancer development. Senescence contributes to the aging process as well as the development and progression of colon cancer. However, the precise mechanism underlying the aging-related progress of colon cancer is yet to be answered. Recent studies proposed that the senescent cell secretes Senescence-Associated Secretory Phenotype (SASP) includes pro-inflammatory cytokines, interleukins, growth factors, and proteases actively involved in the creation of pro-tumorigenic microenvironment.

Objective:

This review aims to provide an overview of ROS influence cellular senescence and colon cancer development as well as summarize the antioxidant and antiaging activity of natural flavonoids. Many of the studies had reported that pro-aging genes suppress cancer and various ‘markers’ are used to identify senescent cells in vitro and in vivo. The SASP of the cells may act as a link between senescence and cancer.

Conclusion:

This review facilitates a better understanding and might contribute to diagnostic and prognostic systems as well as to find out the novel and targeted therapeutic approaches. Additionally, we focused on the potential role of natural flavonoids in colon cancer therapies and highlighting the flavonoid-based treatments as innovative immunomodulatory strategies to inhibit the growth of colon cancer.

Antioxidant Activity of Synthetic Polymers of Phenolic Compounds

In recent years, developing potent antioxidants has been a very active area of research. In this context, phenolic compounds have been evaluated for their antioxidant activity. However, the use of phenolic compounds has also been limited by poor antioxidant activity in several in vivo studies. Polymeric phenols have received much attention owing to their potent antioxidant properties and increased stability in aqueous systems. To be truly effective in biological applications, it is important that these polymers be synthesized using benign methods. In this context, enzyme catalyzed synthesis of polymeric phenols has been explored as an environmentally friendly and safer approach. This review summarizes work in enzymatic syntheses of polymers of phenols. Several assays have been developed to determine the antioxidant potency of these polymeric phenols. These assays are discussed in detail along with structure-property relationships. A deeper understanding of factors affecting antioxidant activity would provide an opportunity for the design of versatile, high performing polymers with enhanced antioxidant activity.

Antioxidant and Anti-Inflammatory Activities of Kigelia africana (Lam.) Benth

Kigelia africana is used to manage inflammation among indigenous communities. We hypothesized that K. africana extracts contain phytoconstituents with good antioxidant and anti-inflammatory activities. The methanolic extract of K. africana fruits and Spathodea campanulata leaves (SPK04), K. africana aqueous fruit extract (KFM02), and K. africana acetone fruit extract (KFM05) were subjected to antioxidant and anti-inflammatory assays. Antioxidant activity was evaluated using the ABTS radical scavenging assay, and the MTT cell viability assay was used for cytotoxicity. The extracts were preincubated with enzymes and assayed for 15-LOX and COX-2 enzyme activity using an ELISA method. Nitric oxide (NO) inhibitory effect of the extracts was evaluated and measurement of proinflammatory cytokines (IL-1β, TNF-α, and IL-6) and the anti-inflammatory cytokine (IL-10) was done using ELISA kits. SPK04 had the highest antioxidant activity with a mean inhibition of 99.37 ± 0.56% and an IC50 of 4.28 µg/mL. SPK04 and KFM05 did not inhibit 15-LOX as their IC50 values were >1000 μg/mL. All extracts were safe on Vero cells at the highest concentration (200 µg/mL) tested. KFM02 was the best inhibitor of NO production and had the highest cell viability at both the lowest (50 µg/mL) and highest concentrations (200 µg/mL). SPK04 was the best COX-2 inhibitor while KFM05 expressed the strongest suppression effect for IL-β and IL-6. KFM02 did not inhibit IL-6 at the highest concentration (200 µg/mL). The order of suppression of TNF-α by the extracts differed across concentrations, KFM05 > SPK04 > KFM02 at 200 µg/mL, KFM02 > SPK04 > KFM05 at 100 µg/mL, and SPK04 > KFM02 > KFM05 at 50 µg/mL. All the tested extracts had no inhibitory effect against IL-10. SPK04, KFM05, and KFM02 had good antioxidant and anti-inflammatory activity and this supports their use as potential anti-inflammatory therapies. This study presents for the first time the antioxidant and anti-inflammatory activity of K. africana and S. campanulata polyherbal extract. It is also among the very few studies that have reported the inhibitory effect of cytokines IL-1β, TNF-α, IL-6, and IL-10 by K. africana.

Nkadimeng S, Lall N, Kabasa JD, J. McGaw L. Ethnobotany, Phytochemistry and Pharmacological Activity of Kigelia africana (Lam.) Benth. (Bignoniaceae)

Kigelia africana has been used in the management of human ailments since time immemorial. Ethnobotanists have documented the traditional uses of K. africana, which include treatment of skin disorders, cancer and gynecological complaints, among others. This has interested scientists, who have examined K. africana plant parts for their bioactivity. This review provides an insightful understanding on the ethnobotany, phytochemistry and pharmacology of K. africana. Web search engines Google and Google Scholar, as well as the databases of PubMed, Scopus, JSTOR, HINARI, SID, AJOL and Springer Link, were exhaustively searched using key words and phrases. Institutional reports and conference papers were also consulted. A total of 125 relevant international literature sources meeting the inclusion criteria were included. Kigelia africana has biologically active phytochemicals, many of which have been isolated. Whilst the fruits are most often cited in pharmacological studies, other plant parts are also used in herbal preparations. Commercially available products have been formulated from K. africana, though many have not been fully standardized. Despite many efforts by researchers to scientifically validate traditional uses of K. africana, many remain merely claims, thus the need to conduct more research, scientifically validate other traditional uses, isolate new bioactive phytochemicals and standardize K. africana products.

Nutritional Composition of Apis mellifera Drones from Korea and Denmark as a Potential Sustainable Alternative Food Source: Comparison Between Developmental Stages

We compared nutrient compositions of honey bee (Apis mellifera) drones of different developmental stages from two different populations-the Italian honey bee reared in Korea and Buckfast bees from Denmark. Analyses included amino acid, fatty acid, and mineral content as well as evaluations of antioxidant properties and haemolysis activities. The compositions of total amino acids, and thus protein content of the insects, increased with development. A similar trend was observed for minerals presumably due to the consumption of food in the adult stage. In contrast, total fatty acid amounts decreased with development. Altogether, seventeen amino acids, including all the essential ones, except tryptophan, were determined. Saturated fatty acids dominated over monounsaturated fatty acids in the pupae, but the reverse held true for the adults. Drones were found to be rich in minerals and the particularly high iron as well as K/Na ratio was indicative of the nutritional value of these insects. Among the three developmental stages, adult Buckfast drones exhibited the highest antioxidant activity. Bearing in mind the overall high nutritional value, i.e., high amino acids, minerals and less fatty acids, late pupae and adult drones can be useful for human consumption while the larvae or early pupal stage can be recommended as feed. However, owing to their relatively high haemolysis activity, we advocate processing prior to the consumption of these insects.

Assessment of the antioxidant, cytotoxic, and genotoxic potential of the Annona muricata leaves and their influence on genomic stability

The popular use of Annona muricata L. is based upon a range of medicinal purposes, and the plant exhibits biological activities including antihyperglycemic, antiparasitic, and antitumor activities. The objectives of this study were to examine the antioxidant, cytotoxic, and genotoxic potential of the hydroalcoholic extract of A. muricata leaves (AMEs), as well as its effects on genotoxicity induced by methyl methanesulfonate (MMS) and hydrogen peroxide (H₂O₂). The results using 2,2-diphenyl-1-picrylhydrazyl assay showed that AME was able to scavenge 44.71% of free radicals. The extract significantly reduced the viability of V79 cells in the clonogenic assay at concentrations ≥8 µg/ml. No significant differences in micronucleus (MN) frequency were observed between V79 cell cultures treated with different concentrations of the extract (0.125, 0.25, 0.5, and 1 µg/ml) and negative control. When AME concentrations were combined with MMS, data revealed no marked differences from mutagen alone. In contrast, significant reductions in the frequencies of MN were noted in cultures treated with AME combined with H₂O₂ compared to H₂O₂ alone. In vivo studies found no significant differences in the frequencies of micronucleated polychromatic erythrocytes (MNPCEs) between animals treated with different AME doses compared to control. Animals treated with AME doses of 125 and 250 mg/kg and MMS exhibited significantly higher frequencies of MNPCE compared to mutagen alone. In conclusion, under current experimental conditions, AME was not genotoxic and exerted a modulatory effect on DNA damage depending upon the experimental conditions. The extract did not influence markedly MMS-induced genotoxicity in in vitro test system. However, the extract increased DNA damage induced by mutagen in mice. In V79 cells, AME reduced the genotoxicity produced by H₂O₂, and this protective effect was attributed in part to the antioxidant activity of AME.

Neuro-Preventive Effect and Elevation of Cellular Adenosine Triphosphate by PUFAs from Pteleiosis suberosa Stem Bark on Mercury Sub-Acute Exposed Rats

OBJECTIVES

Occupational/industrial exposure and experimental intoxication of mercury can produce neurological effects but Pteleiosis suberosa stem bark extract (PTSSBE) might be useful in the treatment of brain disorders because it's anti-ulcer, anti-inflammatory and antioxidant effects had been documented.

METHODS

The present study was therefore designed to investigate some phenolic constituents, evaluate its antioxidant properties and examine its reversal effects of PTSSBE on sub-acute mercury-induced brain toxicity. Rats were divided into five groups of 10 animals each. Group I was given distilled water; group II, III, IV and V was orally administered with mercury at a dose of 3.75 mg/kg body weight. Group III, IV and V were co-treated with PTSSBE of 25, 50 and 100 mg/ kg body weight respectively, for 10 days.

RESULTS

The results revealed that the stem bark extract exhibited high presence of antioxidants. Experimental exposure of rats to mercury significantly decreased the activities of catalase (CAT), lactate dehydrogenase (LDH), and the level of reduced glutathione (GSH), while the activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and the formation of malondialdehyde (MDA) were increased. These effects were reversed by co-administration with PTSSBE in mercury-induced brain toxicity in rats.

CONCLUSION

The protective effects of Pteleiosis suberosa, during mercury exposure suggest that these phenolics and PUFAs may be helpful in treating neurological disorders and other related cerebral toxicity implicated in depleted cellular ATP and oxidative stress.

Flavonoids as important molecules of plant interactions with the environment

Flavonoids are small molecular secondary metabolites synthesized by plants with various biological activities. Due to their physical and biochemical properties, they are capable of participating in plants' interactions with other organisms (microorganisms, animals and other plants) and their reactions to environmental stresses. The majority of their functions result from their strong antioxidative properties. Although an increasing number of studies focus on the application of flavonoids in medicine or the food industry, their relevance for the plants themselves also deserves extensive investigations. This review summarizes the current knowledge on the functions of flavonoids in the physiology of plants and their relations with the environment.

Substituent effects on in vitro antioxidizing properties, stability, and solubility in flavonoids

Antioxidants are widely used by humans, both as dietary supplements and as additives to different types of products. The desired properties of an antioxidant often include a balance between the antioxidizing capacity, stability, and solubility. This review focuses on flavonoids, which are naturally occurring antioxidants, and different common substituent groups on flavonoids and how these affect the properties of the molecules in vitro. Hydroxyl groups on flavonoids are both important for the antioxidizing capacity and key points for further modification resulting in O-methylation, -glycosylation, -sulfation, or -acylation. The effects of O-glycosylation and acylation are discussed as these types of substitutions have been most explored in vitro concerning antioxidizing properties as well as stability and solubility. Possibilities to control the properties by enzymatic acylation and glycosylation are also reviewed, showing that depending on the choice of enzyme and substrate, regioselective results can be obtained, introducing possibilities for more targeted production of antioxidants with predesigned properties.

Novel quercetin derivatives in treatment of peroxynitrite-oxidized SERCA1

Sarco/endoplasmic reticulum calcium ATP-ase (SERCA) is regulated by low concentrations of peroxynitrite and inhibited by high levels, as indicated in human diseases. We studied quercetin (Q) and its novel derivatives monochloropivaloylquercetin (MPQ) and chloronaphthoquinonequercetin (CHQ) as agents with expected preventive properties against peroxynitrite-induced SERCA impairment. Q and MPQ protected the SERCA1 against peroxynitrite induced activity decrease, while CHQ potentiated the inhibitory effect of peroxynitrite. Quercetin derivatives were found to be weaker antioxidants compared with Q, as indicated by their ability to scavenge peroxynitrite and prevent of SERCA1 carbonylation, both decreasing in the order (Q > MPQ > CHQ). Quantum-chemical values of theoretical parameter E HOMO also indicated lower antioxidant capacities for MPQ and CHQ. Prooxidant properties estimated by calculations of frontier molecular orbitals (E LUMO) correlated with experimentally determined SH-group decrease induced by the compounds studied. Both methods showed a decrease of prooxidant properties as follows: CHQ > MPQ > Q. In addition, experimentally measured half-wave potentials indicated stronger prooxidant properties of quercetin derivatives as compared to Q. More expressive alterations of conformation in the transmembrane region of SERCA1 induced by quercetin derivatives, as compared with Q, may at least partially correlate with their higher lipophilicities. The protective effects of Q and MPQ on different isoforms of SERCA activity may be useful in prevention and treatment of inflammation or muscle diseases. The inhibitory effect of CHQ on SERCA isoforms may be beneficial in therapeutic approaches aimed at anti-tumor treatment.

Antioxidant effects of quercetin and naringenin are associated with impaired neutrophil microbicidal activity

Naringenin and quercetin are considered antioxidant compounds with promising activity against oxidative damage in human cells. However, no reports have described their effects on reactive oxygen species (ROS) production by phagocytes during microbicidal activity. Thus, the present study evaluated the effects of naringenin and quercetin on ROS production, specifically hypochlorous acid (HOCl), and their involvement in the microbicidal activity of neutrophils. Naringenin and quercetin inhibited HOCl production through different systems, but this inhibition was more pronounced for quercetin, even in the cell-free systems. With regard to the microbicidal activity of neutrophils, both naringenin and quercetin completely inhibited the killing of Staphylococcus aureus. Altogether, these data indicate that the decrease in the oxidant activity of neutrophils induced by these compounds directly impaired the microbicidal activity of neutrophils. Naringenin and quercetin exerted their effects by controlling the effector mechanisms of ROS production, with both positive and negative effects of these antioxidant agents in oxidative stress conditions and on ROS in the microbicidal activity of phagocytes. The present results challenge the traditional view of antioxidants as improvers of pathological conditions.

Hibiscus sabdariffa leaf polyphenolic extract inhibits LDL oxidation and foam cell formation involving up-regulation of LXRα/ABCA1 pathway

The oxidative modification of low-density lipoprotein (LDL) is involved in the pathogenesis of atherosclerotic lesions through the formation of macrophage-derived foam cells. In the present study, we aimed to investigate the anti-atherosclerotic effect of Hibiscus sabdariffa leaf polyphenolic extract (HLP), which is rich in flavonoid. The inhibitory effect of HLP on oxidation and lipid peroxidation of LDL was defined in vitro. HLP showed potential in reducing foam cell formation and intracellular lipid accumulation in oxidised-LDL (ox-LDL)-induced macrophage J774A.1 cells under non-cytotoxic concentrations. Molecular data showed these influences of HLP might be mediated via liver-X receptor α (LXRα)/ATP-binding cassette transporter A1 (ABCA1) pathway, as demonstrated by the transfection of LXRα siRNA. Our data implied that HLP up-regulated the LXRα/ABCA1 pathway, which in turn led to stimulation of cholesterol removal from macrophages and delay atherosclerosis. These results suggested that HLP potentially could be developed as an anti-atherosclerotic agent.

Antioxidant and Hepatoprotective Properties of Tofu (Curdle Soymilk) against Acetaminophen-Induced Liver Damage in Rats

The antioxidant and hepatoprotective properties of tofu using acetaminophen to induce liver damage in albino rats were evaluated. Tofus were prepared using calcium chloride, alum, and steep water as coagulants. The polyphenols of tofu were extracted and their antioxidant properties were determined. The weight gain and feed intake of the rats were measured. The analysis of serum alanine aminotransferase (ALT), alkaline phosphatase (ALP), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) activities and the concentrations of albumin, total protein, cholesterol, and bilirubin were analyzed. The result reveals that the antioxidant property of both soluble and bound polyphenolic extracts was significantly higher in all tofus, but the steep water coagulated tofu was recorded higher. Rats fed with various tofus and acetaminophen had their serum ALP, ALT, AST, and LDH activities; total cholesterol; and bilirubin levels significantly (P < 0.05) reduced, and total protein and albumin concentrations increased when compared with basal diet and acetaminophen administered group. Therefore, all tofus curdled with various coagulants could be used to prevent liver damage caused by oxidative stress.

Polyphenol derivatives - potential regulators of neutrophil activity

The study provides new information on the effect of natural polyphenols (derivatives of stilbene - resveratrol, pterostilbene, pinosylvin and piceatannol and derivatives of ferulic acid - curcumin, N-feruloylserotonin) on the activity of human neutrophils in influencing oxidative burst. All the polyphenols tested were found to reduce markedly the production of reactive oxygen species released by human neutrophils on extra-and intracellular levels as well as in cell free system. Moreover, pinosylvin, curcumin, N-feruloylserotonin and resveratrol decreased protein kinase C activity involved in neutrophil signalling and reactive oxygen species production. Our results suggest that due to their anti-neutrophil activity, the polyphenols tested might be attractive candidates in therapeutic development.

Natural polyphenols against neurodegenerative disorders: potentials and pitfalls

Within the last years, a rapidly growing number of polyphenolic compounds with neuroprotective effects have been described. Many efforts have been made to explore the mechanisms behind the neuroprotective action of polyphenols. However, many pathways and mechanisms considered for mediating these effects are rather general than specific. Moreover, despite the beneficial effects of polyphenols in experimental treatment of neurodegeneration, little has been achieved in bringing them into routine clinical applications. In this review, we have summarized the protective effects of polyphenols against neurodegeneration, and we have also discussed some of the barricades in translating these biochemical compounds, into relevant therapeutics for neurodegenerative diseases.

Effects of morin-5′-sulfonic acid sodium salt (NaMSA) on cyclophosphamide-induced changes in oxido-redox state in rat liver and kidney

Cyclophosphamide (CPX) is an anticancer drug with immunosuppressive properties. Its adverse effects are partly connected to the induction of oxidative stress. Some studies indicate that water-soluble derivative of morin—morin-5′-sulfonic acid sodium salt (NaMSA) exhibits strong antioxidant activity. The aim of present study was to evaluate the effect of NaMSA on CPX-induced changes in oxido-redox state in rat. Experiment was carried out on Wistar rats divided in three experimental groups ( N = 12) receiving: 0.9% saline, CPX (15 mg/kg) or CPX (15 mg/kg) + NaMSA (100 mg/kg), respectively, and were given intragastrically for 10 days. Malondialdehyde (MDA) and glutathione (GSH) concentrations and superoxide dismutase (SOD) activity were determined in liver and kidneys. Catalase (CAT) activity was assessed only in liver. Treatment with CPX resulted in significant decrease in MDA level in both tissues, which was completely reversed by NaMSA treatment only in liver. In comparison to the control group significant decrease in SOD activity were observed in both tissues of CPX receiving group. In kidneys this parameter was fully restored by NaMSA administration. CPX evoked significant decrease in GSH concentration in kidneys, which was completely reversed by NaMSA treatment. No significant changes were seen in GSH levels and CAT activity between all groups in liver. Results of our study suggest that CPX may exert significant impact on oxido-redox state in both organs. NaMSA fully reversed the CPX-induced changes, especially MDA level in liver, SOD activity and GSH concentration in kidneys and it may be done by enhancement of activity/concentration of endogenous antioxidants.

Biochemical basis for functional ingredient design from fruits

Functional food ingredients (nutraceuticals) in fruits range from small molecular components, such as the secondary plant products, to macromolecular entities, e.g., pectin and cellulose, that provide several health benefits. In fruits, the most visible functional ingredients are the color components anthocyanins and carotenoids. In addition, several other secondary plant products, including terpenes, show health beneficial activities. A common feature of several functional ingredients is their antioxidant function. For example, reactive oxygen species (ROS) can be oxidized and stabilized by flavonoid components, and the flavonoid radical can undergo electron rearrangement stabilizing the flavonoid radical. Compounds that possess an orthodihydroxy or quinone structure can interact with cellular proteins in the Keap1/Nrf2/ARE pathway to activate the gene transcription of antioxidant enzymes. Carotenoids and flavonoids can also exert their action by modulating the signal transduction and gene expression within the cell. Recent results suggest that these activities are primarily responsible for the health benefits associated with the consumption of fruits and vegetables.

In vitro antioxidant and antimicrobial activities of two Hawaiian marine Limu: Ulva fasciata (Chlorophyta) and Gracilaria salicornia (Rhodophyta)

The antioxidant and antimicrobial properties of two Hawaiian marine algae (Ulva fasciata and Gracilaria salicornia) were evaluated. Ethanolic extracts of these two algae exhibited intracellular reactive 1,1-diphenyl-2-picrylhydrazyl, 2,2'-azino-bis(3-ethylbenzthiazoline)-6-sulfonic radical, nitric oxide, superoxide radical, and hydroxyl radical scavenging activities. In addition to the antioxidant activity these algae possessed appreciable antimicrobial activity and total phenolic contents. The overall results have established that these two marine algae could be used to derive bioactive compounds for a possible role as nutraceutical agents.

Mulberry leaf polyphenols possess antiatherogenesis effect via inhibiting LDL oxidation and foam cell formation

Oxidized low-density lipoprotein (ox-LDL) and its uptake by machrophage are the hallmark in atherogenesis. In the present study, we aimed to investigate the antiatherogenic effect of mulberry leaf extracts (MLE) and the polyphenolic extracts (MLPE), which contained polyphenols including quercetin (11.70%), naringenin (9.01%) and gallocatechin gallate (10.02%). Both MLE and MLPE inhibited the oxidation and lipid peroxidation of LDL, while MLPE was shown to be more potent. As 1.0 mg/mL MLE reduced 30% of ox-LDL-generated ROS, 0.5 mg/mL MLPE decreased 46% of the ROS and was shown to be more potent on elevating SOD-1 and GPx in macrophages. At the same dose of 0.5 mg/mL, MLPE exhibited 1.5-fold potency than MLE in decreasing the formation of foam cells. Both MLE and MLPE reduced the expression of PPARγ, CD36 and SR-A, implicating the molecular regulation on ox-LDL uptake. These results suggested that MLPE potentially could be developed as an antiatherogenic agent and deserve further investigation.

Antioxidant and prooxidant properties of flavonoids

The interest in possible health benefits of flavonoids has increased owing to their potent antioxidant and free radical scavenging activities observed in vitro. Nevertheless, the antioxidant efficacy of flavonoids in vivo is less documented and their prooxidant properties have been actually described in vivo. Due to their prooxidant properties, they are able to cause oxidative damage by reacting with various biomolecules, such as lipids, proteins and DNA. Hence, the aim of this review is to discuss both the antioxidant and prooxidant effects of flavonoids.

Antioxidant activity and hepatoprotective property of leaf extracts of Boerhaavia diffusa Linn against acetaminophen-induced liver damage in rats

Extracts of Boerhaavia diffusa leaves were evaluated for antioxidant and hepatoprotective properties in the acetaminophen-induced liver damage model. Antioxidative evaluation of ethanolic extract gave total phenolic content, total flavonoid content, vitamin C content and vitamin E content and the levels of selenium and zinc as 6.6+/-0.2mg/g tannic acid equivalent, 0.092+/-0.003 mg/g quercetin equivalent, 0.21+/-0.03 mg/g, 0.054+/-0.002 mg/g, 0.52+/-0.05 ppm and 9.28+/-0.16 ppm, respectively. The DPPH scavenging capacity and the reductive potential were 78.32+/-2.41% and 0.65+/-0.02 mg/g ascorbic acid, respectively. Pretreatment with aqueous and ethanolic extracts decreased the activities of alkaline phosphatase, lactate dehydrogenase, alanine aminotransferase, aspartate aminotransferase, and the level of bilirubin in the serum that were elevated by acetaminophen. The two extracts also ameliorated the elevation in the activities of the enzymes in the liver. Acetaminophen intoxication led to reduction in serum and liver albumin levels which were not significantly increased by pretreatment with the extracts. The extracts also protected against acetaminophen induced lipid peroxidation. These results indicated that leaf extracts from B. diffusa possess hepatoprotective property against acetaminophen-induced liver damage which may be mediated through augmentation of antioxidant defenses.

Changes in Polyphenols Distribution and Antioxidant Activity during Fermentation of Some Underutilized Legumes

The effect of fermentation on the polyphenol distribution and antioxidant activity of four underutilized legumes [Cajanus cajan L. Millsp (Pigeon pea), Vigna subterranea L. Verdc (Bambara groundnut), Sphenostylis stenocarpa Harms (African yam bean), and Phaseolus vulgaris L. (Kidney bean)] were investigated. The beans were cooked (12 h), soaked in boiled water (12 h), dehulled, and then cooked again (2 h). The cotyledons were drained, wrapped in jute sacks and left to ferment at 37°C (4 days) to produce condiments. The distribution of free and bound phenolic compounds in the fermented and unfermented beans was determined; thereafter the free radical scavenging ability, reducing power, and the ability of the free and bound phenolic compounds of the fermented and unfermented beans to inhibit lipid peroxidation were determined. The results of the study revealed that fermentation caused a significant increase (p<0.05) in the free soluble phenol content of the legumes, while there was a significant decrease (p<0.05) in the bound phenol content of the legumes. Free soluble phenol from both the fermented and unfermented legumes had a significantly (p<0.05) higher reducing power (except C. cajan), free radical scavenging ability (except C. cajan) and inhibition of lipid peroxidation than bound phenolic extract. However, free soluble phenolic compounds from the fermented beans had a significantly higher (p<0.05) reducing power, free radical scavenging ability, and inhibition of lipid peroxidation than free soluble phenols from unfermented beans. Hence, it was concluded that, fermentation could increase the free soluble phenolic content of the underutilized legumes tested and consequently enhance the antioxidant activities of the legumes; fermented V. subterranea was found to be the most promising condiment with antioxidant activity.

Elevated ozone alters soybean-virus interaction

Increasing concentrations of ozone (O(3)) in the troposphere affect many organisms and their interactions with each other. To analyze the changes in a plant-pathogen interaction, soybean plants were infected with Soybean mosaic virus (SMV) while they were fumigated with O(3). In otherwise natural field conditions, elevated O(3) treatment slowed systemic infection and disease development by inducing a nonspecific resistance against SMV for a period of 3 weeks. During this period, the negative effect of virus infection on light-saturated carbon assimilation rate was prevented by elevated O(3) exposure. To identify the molecular basis of a soybean nonspecific defense response, high-throughput gene expression analysis was performed in a controlled environment. Transcripts of fungal, bacterial, and viral defense-related genes, including PR-1, PR-5, PR-10, and EDS1, as well as genes of the flavonoid biosynthesis pathways (and concentrations of their end products, quercetin and kaempherol derivatives) increased in response to elevated O(3). The drastic changes in soybean basal defense response under altered atmospheric conditions suggest that one of the elements of global change may alter the ecological consequences and, eventually, coevolutionary relationship of plant-pathogen interactions in the future.

Food for thought: the role of dietary flavonoids in enhancing human memory, learning and neuro-cognitive performance

Emerging evidence suggests that dietary-derived flavonoids have the potential to improve human memory and neuro-cognitive performance via their ability to protect vulnerable neurons, enhance existing neuronal function and stimulate neuronal regeneration. Long-term potentiation (LTP) is widely considered to be one of the major mechanisms underlying memory acquisition, consolidation and storage in the brain and is known to be controlled at the molecular level by the activation of a number of neuronal signalling pathways. These pathways include the phosphatidylinositol-3 kinase/protein kinase B/Akt (Akt), protein kinase C, protein kinase A, Ca-calmodulin kinase and mitogen-activated protein kinase pathways. Growing evidence suggests that flavonoids exert effects on LTP, and consequently memory and cognitive performance, through their interactions with these signalling pathways. Of particular interest is the ability of flavonoids to activate the extracellular signal-regulated kinase and the Akt signalling pathways leading to the activation of the cAMP-response element-binding protein, a transcription factor responsible for increasing the expression of a number of neurotrophins important in LTP and long-term memory. One such neurotrophin is brain-derived neurotrophic factor, which is known to be crucial in controlling synapse growth, in promoting an increase in dendritic spine density and in enhancing synaptic receptor density. The present review explores the potential of flavonoids and their metabolite forms to promote memory and learning through their interactions with neuronal signalling pathways pivotal in controlling LTP and memory in human subjects.

Flavonoids: modulators of brain function?

Emerging evidence suggests that dietary phytochemicals, in particular flavonoids, may exert beneficial effects on the central nervous system by protecting neurons against stress-induced injury, by suppressing neuroinflammation and by improving cognitive function. It is likely that flavonoids exert such effects, through selective actions on different components of a number of protein kinase and lipid kinase signalling cascades, such as the phosphatidylinositol-3 kinase (PI3K)/Akt, protein kinase C and mitogen-activated protein kinase (MAPK) pathways. This review explores the potential inhibitory or stimulatory actions of flavonoids within these pathways, and describes how such interactions are likely to underlie neurological effects through their ability to affect the activation state of target molecules and/or by modulating gene expression. Future research directions are outlined in relation to the precise site(s) of action of flavonoids within signalling pathways and the sequence of events that allow them to regulate neuronal function.

Protective effects of puerarin on carbon tetrachloride-induced hepatotoxicity

Puerarin, the main isoflavone glycoside found in the root of Pueraria lobata, has been used for various medicinal purposes in traditional Chinese medicine for thousands of years. The purpose of this study was to investigate the protective effects of puerarin against hepatotoxicity induced by carbon tetrachloride (CCl4) and the mechanism of its hepatoprotective effect. In mice, pretreatment with puerarin prior to the administration of CCl4 significantly prevented the increased serum enzymatic activity of alanine aspartate aminotransferase and hepatic malondialdehyde formation in a dose-dependent manner. In addition, pretreatment with puerarin significantly prevented both the depletion of reduced glutathione (GSH) content and the decrease in glutathione S-transferase (GST) activity in the liver of CCl4-intoxicated mice. Hepatic GSH levels and GST activity were increased by treatment with puerarin alone. CCl4-induced hepatotoxicity was also prevented, as indicated by liver histopathology. The effects of puerarin on cytochrome P450 (CYP) 2E1, the major isozyme involved in CCl4 bioactivation, were also investigated. Treatment of the mice with puerarin resulted in a significant decrease in the CYP2E1-dependent aniline hydroxylation in a dose-dependent manner. Consistent with these observations, the CYP2E1 protein levels were also lowered. Puerarin exhibited anti-oxidant effects on FeCl2-ascorbate induced lipid peroxidation in mouse liver homogenates, and on superoxide radical scavenging activity. These results suggest that the protective effects of puerarin against the CCl4-induced hepatotoxicity possibly involve mechanisms related to its ability to block CYP-mediated CCl4 bioactivation, induction of GST activity and free radical scavenging effects.

The interactions of flavonoids within neuronal signalling pathways

Emerging evidence suggests that dietary phytochemicals, in particular flavonoids, may exert beneficial effects in the central nervous system by protecting neurons against stress-induced injury, by suppressing neuroinflammation and by promoting neurocognitive performance, through changes in synaptic plasticity. It is likely that flavonoids exert such effects in neurons, through selective actions on different components within a number of protein kinase and lipid kinase signalling cascades, such as phosphatidylinositol-3 kinase (PI3K)/Akt, protein kinase C and mitogen-activated protein kinase. This review details the potential inhibitory or stimulatory actions of flavonoids within these pathways, and describes how such interactions are likely to affect cellular function through changes in the activation state of target molecules and/or by modulating gene expression. Although, precise sites of action are presently unknown, their abilities to: (1) bind to ATP binding sites on enzymes and receptors; (2) modulate the activity of kinases directly; (3) affect the function of important phosphatases; (4) preserve neuronal Ca(2+) homeostasis; and (5) modulate signalling cascades lying downstream of kinases, are explored. Future research directions are outlined in relation to their precise site(s) of action within the signalling pathways and the sequence of events that allow them to regulate neuronal function in the central nervous system.

Antioxidant and hepatoprotective properties of polyphenol extracts from Telfairia occidentalis (fluted pumpkin) leaves on acetaminophen induced liver damage

In this study the antioxidant and hepatoprotective properties of free and bound polyphenols from Telfairia occidentalis (darkish green leafy vegetable popularly used in soup and folk medicine for the management of many diseases in Nigeria) leaves were compared. Free soluble polyphenols were extracted with 80% acetone, while the bound polyphenols were extracted from the acid and alkaline hydrolyzed residue of the leaf from free soluble polyphenols using ethyl acetate. The total phenol, DPPH free radical scavenging ability and reducing property were determined; subsequently the ability of the extracts to prevent acetaminophen (megadose) induced liver damage in rats were also assessed. Change in serum Glutamate Oxaloacetate Transaminase (GOT), Glutamate Pyruvate Transaminase (GPT), alkaline phosphatase (ALP), albumin, total protein and bilirubin were also determined. The results of the study revealed that the free soluble polyphenols content in the vegetable were significantly higher (p<0.05) than the bound polyphenols. Also, the free soluble polyphenols had a significantly higher antioxidant activity as typified by their higher reducing Power (0.28 OD700) and free radical scavenging ability (83.3%) than the bound polyphenols [reducing power (0.22 OD700), free radical scavenging ability (66.6%)]. Daily intubation of wistar strain albino rat's with 100 mg/mL/day for 7 days caused a significant increase (p<0.05) in serum alkaline phosphatase (ALP), Glutamate Oxaloacetate Transaminase (GOT) and Glutamate Pyruvate Transaminase (GPT), while there was no significant change (p>0.05) in serum bilirubin, albumin, globulin and total proteins in the rats. However, simultaneous intubations of some of the rat with 10 mg or 20 mg mL(-1) of T. occidentalis leaf extract (free soluble or bound polyphenols) along side with the acetaminophen caused a significant decrease (p<0.05) in serum ALP, GOT and GPT (except those intubated with bound polyphenols). Free soluble polyphenols had higher protective effect on the liver than the bound polyphenols; however there action were not dose-dependent. It could be inferred that both soluble free and bound polyphenols extracts of T. occidentails leaf have antioxidant and hepatoprotective properties, however soluble free polyphenols had significantly higher antioxidant and hepatoprotective properties than the bound polyphenols.

Opening the calcium-activated potassium channel participates in the cardioprotective effect of puerarin

The aim of the present study was to determine whether the effective cardioprotection conferred by puerarin against ischemia and reperfusion is mediated by the calcium-activated potassium channel. Hearts isolated from male Sprague-Dawley rats were perfused on a Langendorff apparatus and subjected to 30 min of global ischemia followed by 120 min of reperfusion. The production of formazan, which provides an index of myocardial viability, was measured by absorbance at 550 nm, and the level of lactate dehydrogenase (LDH) in the coronary effluent was determined. Pretreatment with puerarin at 0.24 mmol/l for 5 min before ischemia increased myocardial formazan content and reduced LDH release during reperfusion. Administration of paxilline (1 micromol/l), an antagonist of the calcium-activated potassium channel, attenuated the protective effects of puerarin. In isolated ventricular myocytes, pretreatment with puerarin prevented simulated ischemia and reperfusion injury, hydrogen peroxide-induced cell death and the release of reactive oxygen species. Paxilline and chelerythrine (a protein kinase C inhibitor) both attenuated the effects of puerarin. These findings indicate that puerarin protects the myocardium against ischemia and reperfusion injury via opening the calcium-activated potassium channel and activating protein kinase C.

Effect of chronic treatments with GH, melatonin, estrogens, and phytoestrogens on oxidative stress parameters in liver from aged female rats

The aging theory postulates that this process may be due to the accumulation of oxidative damage in cells and molecules. The present study has investigated the effect of castration in old female rats on various parameters related to the antioxidant properties of several cellular fractions obtained from the liver, and the influence of several chronic treatments on it, both in intact and castrated animals. Sixty-one 22-month-old Wistar female rats, were used. About 21 intact animals were divided into three groups and treated for 10 weeks with GH, melatonin or saline, and 40 ovariectomized (at 12 months of age) animals were divided into five groups and treated for the same time with GH, melatonin, estrogens (Eos), phytoestrogens (Phyt) or saline. All animals were sacrificed at 24 months of age by decapitation. The activity of glutathione peroxidase (GPx) in cytosolic fraction, glutathione-S-transferase (GST) in cytosol and microsomal fractions, and the levels of nitric oxide (NO) and cytochrome C in mitochondrial and cytosol fractions of liver were determined. A decrease in GST activity was detected in cytosol and in the microsomal fraction in ovariectomized animals as compared to intact rats. The activity of GPx was also decreased in ovariectomized as compared with the intact group. NO level was increased and cytochrome C decreased in the mitochondrial fraction of the liver in ovariectomized females as compared with the intact group, respectively. No significant changes after melatonin or GH treatments were found in GPx, GST activity and NO level in mitochondrial fraction in the intact group. Administration of GH, melatonin, Eos and Phyt in the ovariectomized groups significantly increased the GPx, and GST activity in the cytosol and microsomal fraction and decreased the level of NO in the mitochondrial fraction as compared with the untreated rats. A significant increase in the level of cytochrome C in the mitochondrial fraction and a decrease in the cytosol fraction were also found with all treatments. The administration of GH, melatonin, Eos and Phyt to castrated females seem to reduce oxidative changes in the liver from old ovariectomized rats.

Protective effect of Operculina turpethum against 7,12-dimethyl benz(a)anthracene induced oxidative stress with reference to breast cancer in experimental rats

Reactive oxygen species (ROS) directly or indirectly involves in multistage process of carcinogenesis. Antioxidant activity of methanolic extract of Operculina turpethum stems (MEOT) on 7,12 dimethylbenz(a)anthracene (DMBA) induced breast cancer was investigated in female Sprague-Dawley rats. Changes in the levels of lipid peroxidation and antioxidants system was evaluated in addition to tumour development. Twenty four female rats were divided into four groups: control, DMBA, DMBA+MEOT and MEOT. In the DMBA group, rats were intragastrically administered with 20 mg of DMBA using corn oil as vehicle. Animals of DMBA+MEOT group received a single dose of 20 mg of DMBA dissolved in corn oil intragastrically followed by O. turpethum extract (100 mg/kg body weight), while MEOT group received O. turpethum extract (100 mg/kg body weight) intragastrically daily for a period of 45 days. After the experimental period of 45 days, oxidative stress parameters were assessed in serum, liver and breast of both control and experimental groups. In addition to this, tumour weight of breast was also assessed. A significant increase in lipid peroxidation levels were observed in the tested samples of cancer induced rats while the activities of enzymic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and non-enzymic antioxidants like glutathione (GSH), ascorbic acid (Vitamin C) and alpha-tocopherol (Vitamin E) were decreased in cancer-bearing animals when compared to control animals. A significant (P<0.05) increase in the tumour weight was observed in the breast of DMBA group and the breast tumour weight decreased significantly (P<0.05) in the DMBA+MEOT groups. Oral administration of MEOT remarkably reduced the lipid peroxidation activity and increased the antioxidants level in drug treated animals and decreased the tumour weight significantly (P<0.05). This result suggests that MEOT shows antioxidant activity and play a protective role against DMBA induced breast cancer.