Redox properties of tea polyphenols and related biological activities

An efficient protocol for extracting thylakoid membranes and total leaf proteins from Posidonia oceanica and other polyphenol-rich plants

BACKGROUND

The extraction of thylakoids is an essential step in studying the structure of photosynthetic complexes and several other aspects of the photosynthetic process in plants. Conventional protocols have been developed for selected land plants grown in controlled conditions. Plants accumulate defensive chemical compounds such as polyphenols to cope with environmental stresses. When the polyphenol levels are high, their oxidation and cross-linking properties prevent thylakoid extraction.

RESULTS

In this study, we developed a method to counteract the hindering effects of polyphenols by modifying the grinding buffer with the addition of both vitamin C (VitC) and polyethylene glycol (PEG4000). This protocol was first applied to the marine plant Posidonia oceanica and then extended to other plants synthesizing substantial amounts of polyphenols, such as Quercus pubescens (oak) and Vitis vinifera (grapevine). Native gel analysis showed that photosynthetic complexes (PSII, PSI, and LHCII) can be extracted from purified membranes and fractionated comparably to those extracted from the model plant Arabidopsis thaliana. Moreover, total protein extraction from frozen P. oceanica leaves was also efficiently carried out using a denaturing buffer containing PEG and VitC.

CONCLUSIONS

Our work shows that the use of PEG and VitC significantly improves the isolation of native thylakoids, native photosynthetic complexes, and total proteins from plants containing high amounts of polyphenols and thus enables studies on photosynthesis in various plant species grown in natural conditions.

Catechin Bioavailability Following Consumption of a Green Tea Extract Confection Is Reduced in Obese Persons without Affecting Gut Microbial-Derived Valerolactones

Obesity-related cardiometabolic disorders are driven by inflammation, oxidative stress, and gut dysbiosis. Green tea catechins protect against cardiometabolic disorders by anti-inflammatory, antioxidant, and prebiotic activities. However, whether obesity alters catechin bioavailability remains unknown. We hypothesized that obesity would decrease catechin bioavailability due to altered gut microbiota composition. Obese and healthy persons completed a pharmacokinetics trial in which a confection formulated with green tea extract (GTE; 58% epigallocatechin gallate, 17% epigallocatechin, 8% epicatechin, 6% epicatechin gallate) was ingested before collecting plasma and urine at timed intervals for up to 24 h. Stool samples were collected prior to confection ingestion. Catechins and γ-valerolactones were assessed by LC-MS. Obesity reduced plasma area under the curve (AUC_0-12h) by 24-27% and maximum plasma concentrations by 18-36% for all catechins. Plasma AUC_0-12h for 5'-(3',4'-dihydroxyphenyl)-γ-valerolactone and 5'-(3',4',5'-trihydroxyphenyl)-γ-valerolactone, as well as total urinary elimination of all catechins and valerolactones, were unaffected. ⍺-Diversity in obese persons was lower, while Slackia was the only catechin-metabolizing bacteria that was altered by obesity. Ascorbic acid and diversity metrics were correlated with catechin/valerolactone bioavailability. These findings indicate that obesity reduces catechin bioavailability without affecting valerolactone generation, urinary catechin elimination, or substantially altered gut microbiota populations, suggesting a gut-level mechanism that limits catechin absorption.

Pressurized Liquid Extraction as a Novel Technique for the Isolation of Laurus nobilis L. Leaf Polyphenols

Laurus nobilis L., known as laurel or bay leaf, is a Mediterranean plant which has been long known for exhibiting various health-beneficial effects that can largely be attributed to the polyphenolic content of the leaves. Pressurized liquid extraction (PLE) is a green extraction technique that enables the efficient isolation of polyphenols from different plant materials. Hence, the aim of this research was to determine optimal conditions for PLE (solvent, temperature, number of extraction cycles and static extraction time) of laurel leaf polyphenols and to assess the polyphenolic profile of the optimal extract by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) as well as to evaluate the antioxidant activity determined by FRAP, DPPH and ORAC assays. The optimal PLE conditions were 50% ethanol, 150 °C, one extraction cycle and 5 min static time. The polyphenolic extract obtained at optimal PLE conditions comprised 29 identified compounds, among which flavonols (rutin and quercetin-3-glucoside) were the most abundant. The results of antioxidant activity assays demonstrated that PLE is an efficient green technique for obtaining polyphenol-rich laurel leaf extracts with relatively high antioxidant activity.

Green Tea Catechins, (-)-Catechin Gallate, and (-)-Gallocatechin Gallate are Potent Inhibitors of ABA-Induced Stomatal Closure

Stomatal movement is indispensable for plant growth and survival in response to environmental stimuli. Cytosolic Ca2+ elevation plays a crucial role in ABA-induced stomatal closure during drought stress; however, to what extent the Ca2+ movement across the plasma membrane from the apoplast to the cytosol contributes to this process still needs clarification. Here the authors identify (-)-catechin gallate (CG) and (-)-gallocatechin gallate (GCG), components of green tea, as inhibitors of voltage-dependent K+ channels which regulate K+ fluxes in Arabidopsis thaliana guard cells. In Arabidopsis guard cells CG/GCG prevent ABA-induced: i) membrane depolarization; ii) activation of Ca2+ permeable cation (ICa ) channels; and iii) cytosolic Ca2+ transients. In whole Arabidopsis plants co-treatment with CG/GCG and ABA suppressed ABA-induced stomatal closure and surface temperature increase. Similar to ABA, CG/GCG inhibited stomatal closure is elicited by the elicitor peptide, flg22 but has no impact on dark-induced stomatal closure or light- and fusicoccin-induced stomatal opening, suggesting that the inhibitory effect of CG/GCG is associated with Ca2+ -related signaling pathways. This study further supports the crucial role of ICa channels of the plasma membrane in ABA-induced stomatal closure. Moreover, CG and GCG represent a new tool for the study of abiotic or biotic stress-induced signal transduction pathways.

The Oxidation Mechanism of Flavan-3-ols by an Enzymatic Reaction Using Liquid Chromatography-Mass Spectrometry-Based Metabolomics Combined with Captured o-Quinone Intermediates of Flavan-3-ols by o-Phenylenediamine

During the enzymatic oxidation of black tea, flavan-3-ols undergo a complicated chemical transformation and generate theaflavins and thearubigins. So far, the oxidation mechanism of flavan-3-ols has not been clarified. Liquid chromatography-tandem mass spectrometry-based metabolomics combined with o-quinone intermediates captured by o-phenylenediamine was developed and successfully applied in the liquid incubation of fresh tea homogenates. During the oxidation, the contents of catechins continuously decreased, while theaflavins increased first but decreased subsequently at the end of incubation. Meanwhile, the content of thearubigins greatly increased at the late stage of incubation. Dehydrotheasinensins were accumulated at the end of oxidation along with the decrease of theasinensins. Through o-phenylenediamine derivation, several adducts of (-)-epigallocatechin gallate, (-)-epigallocatechin, theasinensins A, B, C, and D, and corresponding dehydrotheasinensins were identified, which were considered as the substrates of thearubigins. These results suggested that theaflavins and these oxidation products contributed to the formation of thearubigins.

Polyphenolic Characterization and Antioxidant Capacity of Laurus nobilis L. Leaf Extracts Obtained by Green and Conventional Extraction Techniques

Laurus nobilis L. is an evergreen Mediterranean shrub whose leaves have been known for various health-promoting effects mainly attributed to polyphenols. Microwave- (MAE) and ultrasound-assisted extraction (UAE) are green extraction techniques that enable effective isolation of polyphenols from plant material. Therefore, the aim of this research was to optimize the extraction conditions of MAE (ethanol percentage, temperature, extraction time, microwave power) and UAE (ethanol percentage, extraction time, amplitude) of polyphenols from Laurus nobilis L. leaves and to assess their polyphenolic profile by ultra performance liquid chromatography- tandem mass spectrometry (UPLC-MS/MS) and antioxidant capacity by oxygen radical absorbance capacity (ORAC) assay. Optimal MAE conditions were 50% ethanol, 80 °C, 10 min and 400 W. Optimal UAE conditions were 70% ethanol, 10 min and 50% amplitude. Spectrophotometric analysis showed the highest total phenolic content in the extracts was obtained by MAE, compared to conventional heat-reflux extraction (CRE) and UAE. The polyphenolic profile of all obtained extracts included 29 compounds, with kaempferol and quercetin glycosides being the most abundant. UPLC-MS/MS showed the highest total phenolic content in the extracts obtained by CRE. ORAC assay showed the highest antioxidant capacity in extracts obtained by CRE, which is in agreement with the polyphenolic profile determined by UPLC-MS/MS.

On the Development of a Cutaneous Flavonoid Delivery System: Advances and Limitations

Flavonoids are one of the vital classes of natural polyphenolic compounds abundantly found in plants. Due to their wide range of therapeutic properties, which include antioxidant, anti-inflammatory, photoprotective, and depigmentation effects, flavonoids have been demonstrated to be promising agents in the treatment of several skin disorders. However, their lipophilic nature and poor water solubility invariably lead to limited oral bioavailability. In addition, they are rapidly degraded and metabolized in the human body, hindering their potential contribution to the prevention and treatment of many disorders. Thus, to overcome these challenges, several cutaneous delivery systems have been extensively studied. Topical drug delivery besides offering an alternative administration route also ensures a sustained release of the active compound at the desired site of action. Incorporation into lipid or polymer-based nanoparticles appears to be a highly effective approach for cutaneous delivery of flavonoids with good encapsulation potential and reduced toxicity. This review focuses on currently available formulations used to administer either topically or systemically different classes of flavonoids in the skin, highlighting their potential application as therapeutic and preventive agents.

The Role of Selected Natural Biomolecules in Sperm Production and Functionality

Emerging evidence from in vivo as well as in vitro studies indicates that natural biomolecules may play important roles in the prevention or management of a wide array of chronic diseases. Furthermore, the use of natural compounds in the treatment of male sub- or infertility has been proposed as a potential alternative to conventional therapeutic options. As such, we aimed to evaluate the effects of selected natural biomolecules on the sperm production, structural integrity, and functional activity. At the same time, we reviewed their possible beneficial or adverse effects on male reproductive health. Using relevant keywords, a literature search was performed to collect currently available information regarding molecular mechanisms by which selected natural biomolecules exhibit their biological effects in the context of male reproductive dysfunction. Evidence gathered from clinical trials, in vitro experiments and in vivo studies suggest that the selected natural compounds affect key targets related to sperm mitochondrial metabolism and motion behavior, oxidative stress, inflammation, DNA integrity and cell death. The majority of reports emphasize on ameliorative, stimulating and protective effects of natural biomolecules on the sperm function. Nevertheless, possible adverse and toxic behavior of natural compounds has been indicated as well, pointing out to a possible dose-dependent impact of natural biomolecules on the sperm survival and functionality. As such, further research leading to a deeper understanding of the beneficial or adverse roles of natural compounds is necessary before these can be employed for the management of male reproductive dysfunction.

Goji berry (Lycium barbarum L.) juice reduces lifespan and premature aging of Caenorhabditis elegans: Is it safe to consume it?

Goji berry fruit is considered a healthy food. However, studies on its effects on aging and safety are rare. This study is the first to evaluate the effects of goji berry juice (GBJ) on oxidative stress, metabolic markers, and lifespan of Caenorhabditis elegans. GBJ caused toxicity, reduced the lifespan of C. elegans by 50%, and increased the reactive oxygen species (ROS) production by 45-50% at all tested concentrations (1-20 mg/µL) of GBJ. Moreover, the highest concentration of GBJ increased lipid peroxidation by 80% and altered the antioxidant enzymes. These effects could be attributed to a pro-oxidant effect induced by GBJ polyphenols and carotenoids. Moreover, GBJ increased lipofuscin, glucose levels, number of apoptotic bodies, and lipase activity. The use of mutant strains demonstrated that these effects observed in the worms treated with GBJ were not associated with the Daf-16/FOXO or SKN-1 pathways. Our findings revealed that GBJ (mainly the highest concentration) exerted toxic effects and promoted premature aging in C. elegans. Therefore, its consumption should be carefully considered until further studies in mammals are conducted.

Amelioration of pulmonary aflatoxicosis by green tea extract: An in vivo study

Aflatoxins (AFB₁) are mycotoxins known to be associated with human and animal diseases. The lung is a at risk from AFB₁exposure either via inhalation or circulation. Green tea consumption is increasing over time due to widespread popularity as antioxidants, anti-inflammatory, and cytoprotective agents. Therefore, we attempted to study the lung toxicity caused by AFB₁ and the possible ameliorating effect of green tea extract. Forty adult male albino rats were divided into five groups; Group I: Untreated control group, Group II (vehicle): Each rat received 1 ml of olive oil, Group III (GTE): Each rat received Camellia sinensis, green tea extract (30 mg/kg/day), Group IV(AFB₁): Each rat received (50 μg/kg/day of AFB₁). Group V (AFB₁+ GTE): Each rat received the same previously mentioned doses of AFB1 in addition to GTE concomitantly. All treatments were orally gavaged for 8 weeks then rats were sacrificed. Serum levels of pro-inflammatory (IL-1β, TNF-α, IL-6) and anti-inflammatory (IL-10) cytokines were measured, lung tissues' oxidative stress indices were also measured in addition to the histopathological study which was performed by using hematoxylin & eosin and Masson trichrome stains. Morphometric and statistical analyses were also performed. Oral gavage of AFB₁ resulted in significant histopathological changes in the lung tissues, in the form of variable degrees of congestion, hemorrhage, interstitial inflammation with infiltration by chronic inflammatory cells, interstitial fibrosis, bronchitis, vasculitis and fibrous thickening of arterial walls. Inflammation was evident by elevated levels of pro-inflammatory cytokines and a declined level of anti-inflammatory cytokines. Also, oxidative stress was evident by increased levels of Malondialdehyde (MDA), Myeloperoxidase (MPO), and decreased levels of total glutathione (tGSH) and Catalase (CAT). The histopathological changes, inflammatory cytokines, and oxidative stress markers were significantly decreased during concomitant administration of green tea extract in (AFB₁+ GTE) group. Aflatoxin B₁ has deleterious effects on the lung tissue that could be minimized by concomitant administration of Green tea extract owing to its anti-inflammatory, antioxidant, and protective properties.

Epicatechin Provides Antioxidant Protection to Bovine Spermatozoa Subjected to Induced Oxidative Stress

Epicatechin (EPI) is a natural flavonoid with antibacterial, anti-inflammatory and anti-cancer properties. Furthermore, the molecule exhibits powerful reactive oxygen species (ROS) scavenging and metal-chelating properties. In this study, we assessed the efficiency of EPI to reverse ROS-mediated alterations to the motility, viability, DNA integrity and oxidative profile of bovine spermatozoa. For the first experiment, spermatozoa were washed out of fresh semen and exposed to 12.5 μmol/L EPI, 25 μmol/L EPI, 50 μmol/L EPI and 100 μmol/L EPI in the presence of ferrous ascorbate (FeAA) during a 6 h in vitro culture. For the second experiment, the ejaculates were split into aliquots and cryopreserved with a commercial semen extender supplemented with 12.5 μmol/L EPI, 25 μmol/L EPI, 50 μmol/L EPI, 100 μmol/L EPI or containing no supplement. Sperm motility was assessed using the computer-aided sperm analysis and the cell viability was studied with the metabolic activity test. ROS production was quantified using luminometry, and DNA fragmentation was evaluated using the chromatin dispersion test. Cell lysates were prepared at the end of the culture in order to assess the concentration of protein carbonyls and malondialdehyde. Exposure to FeAA led to a significantly reduced sperm motility (p < 0.001), mitochondrial activity (p < 0.001), but increased the generation of ROS (p < 0.001), as well as oxidative damage to proteins (p < 0.001), DNA (p < 0.001) and lipids (p < 0.001). EPI supplementation, particularly at a concentration range of 50–100 μmol/L, resulted in higher preservation of the spermatozoa vitality (p < 0.001). Furthermore, 50–100 μmol/L EPI were significantly effective in the prevention of oxidative damage to sperm proteins (p < 0.001), lipids (p < 0.001) and DNA (p < 0.01 in relation to 50 μmol/L EPI; p < 0.001 with respect to 100 μmol/L EPI). In the case of the cryopreserved spermatozoa, the administration of 50–100 μmol/L EPI resulted in higher sperm motility (p < 0.001) and mitochondrial activity (p < 0.001). ROS production, the number of protein carbonyls, lipid peroxidation as well as oxidative DNA damage were found to be significantly decreased particularly in samples cryopreserved in the presence of 100 μmol/L EPI (p < 0.001). Our results suggest that EPI could behave as an effective antioxidant which may prevent oxidative insults to spermatozoa, and thus, preserve their vitality and functionality. Nevertheless, its potential to achieve higher fertilization rates in reproductive technologies needs to be validated.

Structure activity relationship (SAR) and quantitative structure activity relationship (QSAR) studies showed plant flavonoids as potential inhibitors of dengue NS2B-NS3 protease

Background

Due to dengue virus disease, half of the world population is at severe health risk. Viral encoded NS2B-NS3 protease complex causes cleavage in the nonstructural region of the viral polyprotein. The cleavage is essentially required for fully functional viral protein. It has already been reported that if function of NS2B-NS3 complex is disrupted, viral replication is inhibited. Therefore, the NS2B-NS3 is a well-characterized target for designing antiviral drug.

Results

In this study docking analysis was performed with active site of dengue NS2B-NS3 protein with selected plant flavonoids. More than 100 flavonoids were used for docking analysis. On the basis of docking results 10 flavonoids might be considered as the best inhibitors of NS2B-NS3 protein. The interaction studies showed resilient interactions between ligand and receptor atoms. Furthermore, QSAR and SAR studies were conducted on the basis of NS2B-NS3 protease complex docking results. The value of correlation coefficient (r) 0.95 shows that there was a good correlation between flavonoid structures and selected properties.

Conclusion

We hereby suggest that plant flavonoids could be used as potent inhibitors of dengue NS2B-NS3 protein and can be used as antiviral agents against dengue virus. Out of more than hundred plant flavonoids, ten flavonoid structures are presented in this study. On the basis of best docking results, QSAR and SAR studies were performed. These flavonoids can directly work as anti-dengue drug or with little modifications in their structures.

Tea polyphenol epigallocatechin gallate inhibits Escherichia coli by increasing endogenous oxidative stress

The antibacterial effects of tea polyphenol epigallocatechin gallate (EGCG), a common phytochemical with a number of potential health benefits, are well known. However, the mechanism of its bactericidal action remains unclear. Using E. coli as a model organism, it is argued here that H2O2 synthesis by EGCG is not attributed to its inhibitory effects. In contrast, the bactericidal action of EGCG was a result of increased intracellular reactive oxygen species and blunted adaptive oxidative stress response in E. coli due to the co-administration of antioxidant N-acetylcysteine, and not on account of exogenous catalase. Furthermore, we noted a synergistic bactericidal effect for EGCG when combined with paraquat. However, under anaerobic conditions, the inhibitory effect of EGCG was prevented. In conclusion, EGCG caused an increase in endogenous oxidative stress in E. coli, thereby inhibiting its growth, and hence the use of EGCG as a prooxidant is supported by this study.

Ameliorative Influence of Green Tea Extract on Copper Nanoparticle-Induced Hepatotoxicity in Rats

The potential toxicity of copper nanoparticles (CNPs) to the human health and environment remains a critical issue. In the present study, we investigated the protective influence of an aqueous extract of green tea leaves (GTE) against CNPs-induced (20-30 nm) hepatotoxicity. Four different groups of rats were used: group I was the control, group II received CNPs (40 mg/kg BW), group III received CNPs plus GTE, and group IV received GTE alone. We highlighted the hepatoprotective effect of GTE against CNPs toxicity through monitoring the alteration of liver enzyme activity, antioxidant defense mechanism, histopathological alterations, and DNA damage evaluation. The rats that were given CNPs only had a highly significant elevation in liver enzymes, alteration in oxidant-antioxidant balance, and severe pathological changes. In addition, we detected a significant elevation of DNA fragmentation percentage, marked DNA laddering, and significance over expression of both caspase-3 and Bax proteins. The findings for group III clarify the efficacy of GTE as a hepatoprotectant on CNPs through improving the liver enzyme activity, antioxidant status, as well as suppressing DNA fragmentation and the expression of the caspase-3 and Bax proteins. In conclusion, GTE was proved to be a potential hepatoprotective additive as it significantly ameliorates the hepatotoxicity and apoptosis induced by CNPs.

The role of natural polyphenols in cell signaling and cytoprotection against cancer development

The cytoprotective and anticancer action of dietary in-taken natural polyphenols has for long been attributed only to their direct radical scavenging activities. Currently it is well supported that those compounds display a broad spectrum of biological and pharmacological outcomes mediated by their complex metabolism, interaction with gut microbiota as well as direct interactions of their metabolites with key cellular signaling proteins. The beneficial effects of natural polyphenols and their synthetic derivatives are extensively studied in context of cancer prophylaxis and therapy. Herein we focus on cell signaling to explain the beneficial role of polyphenols at the three stages of cancer development: we review the recent proceedings about the impact of polyphenols on the cytoprotective antioxidant response and their proapoptotic action at the premalignant stage, and finally we present data showing how phenolic acids (e.g., caffeic, chlorogenic acids) and flavonols (e.g., quercetin) hamper the development of metastatic cancer.

Polyphenols from marine brown algae target radiotherapy-coordinated EMT and stemness-maintenance in residual pancreatic cancer

INTRODUCTION

Therapy-associated onset of stemness-maintenance in surviving tumor-cells dictates tumor relapse/recurrence. Recently, we recognized the anti-pancreatic cancer (PC) potential of seaweed polyphenol manifolds and narrowed down three superior drug-deliverables that could serve as adjuvants and benefit PC cure. Utilizing the PC- cancer stem cells (PC-CSCs) grown ex vivo and mouse model of residual-PC, we investigated the benefits of seaweed polyphenols in regulating stemness-maintenance.

METHODS

ALDH(+)CD44(+)CD24(+) PC-CSCs from Panc-1, Panc-3.27, MiaPaCa-2, or BxPC-3 cells-derived xenografts grown ex vivo were either mock-irradiated, exposed to fractionated irradiation (FIR, 2Gy/D for 5 days), treated with polyphenols (100 μg/ml) of Hormophysa triquerta (HT-EA), Spatoglossum asperum (SA-EA) or Padina tetrastromatica (PT-EA) with/without FIR were examined for cell viability, transcription of 93 stem-cell-related molecules (QPCR profiling). Polyphenol-dependent regulation of FIR-transactivated Oct4, Zic3, EIF4C, Nanog, and LIF (QPCR) and functional translation of Nanog, SOX2, and OCT3/4 (immunoblotting) were examined in Panc-1/Panc-3.27/MiaPaCa-2/BxPC-3-xenografts derived PC-CSCs. Effect of seaweed-polyphenols in the regulation of EMT (N-Cadherin), pluripotency- (SOX2, OCT3/4, Nanog) and stemness-maintenance (PI3KR1, LIF, CD44) in therapy (FIR, 2Gy/D for 5D/wk for 3-weeks) resistant residual tumors were examined by tissue microarray construction and automated immunohistochemistry.

RESULTS

Ex vivo exposure of PC-CSCs to SA-EA, PT-EA and HT-EA exhibit dose-dependent inhibition of cell viability. FIR amplified the transcription of 69, 80, 74 and 77 stem-cell related genes in MiaPaCa-2-, Panc-1-, Panc-3.27- and BXPC3-established xenograft-derived ALDH(+)CD44(+)CD24(+)PC-CSCs. Treatment with SA-EA, PT-EA, or HT-EA completely suppressed FIR-activated stem-cell transcriptional machinery in ALDH(+)CD44(+)CD24(+)PC-CSCs established from MiaPaCa-2, Panc-1, Panc-3.27 and BXPC3 xenografts. QPCR validated EIF4C, OCT3/4, Nanog, LIF, and ZIC3 transcriptional profile outcomes. Nanog, Sox2, and OCT3/4 immunoblotting affirmed the PC-CSC radiosensitizing benefit of seaweed polyphenols. Residual-PC tissues microarrayed and immunostained after in vivo treatments recognized complete regulation of FIR-induced SOX2, OCT3/4, Nanog, LIF, CD44, PIK3R1, N-Cadherin, and E-Cadherin with SA-EA, PT-EA, and HT-EA.

CONCLUSIONS

These data, for the first time, documented the EMT/stemness-maintenance in therapy-resistant PC-CSCs. Further, the data suggest that seaweed polyphenols may inhibit PC relapse/recurrence by targeting therapy-orchestrated stem-cell signaling in residual cells.

Influence of green tea extract on oxidative damage and apoptosis induced by deltamethrin in rat brain

In the present study, we investigated the protective effect of an aqueous extract of green tea leaves (GTE) against neurotoxicity and oxidative damage induced by deltamethrin (DM) in male rats. Four different groups of rats were used: the 1st group was the vehicle treated control group, the 2nd group received DM (0.6 mg/kg BW), the 3rd group received DM plus GTE, and the 4th received GTE alone (25 mg/kg BW). The brain tissues were collected at the end of the experimental regimen for subsequent investigation. Rats that were given DM had a highly significant elevation in MDA content, nitric oxide concentration, DNA fragmentation and expression level of apoptotic genes, TP53 and COX2. Additionally, a significant reduction in the total antioxidant capacity in the second group was detected. The findings for the 3rd group highlight the efficacy of GTE as a neuro-protectant in DM-induced neurotoxicity through improving the oxidative status and DNA fragmentation as well as suppressing the expression of the TP53 and COX2 genes. In conclusion, GTE, at a concentration of 25mg/kg/day, protected against DM-induced neurotoxicity through its antioxidant and antiapoptotic influence; therefore, it can be used as a protective natural product against DM-induced neurotoxicity.

Phytochemicals as Anticancer and Chemopreventive Topoisomerase II Poisons

Phytochemicals are a rich source of anticancer drugs and chemopreventive agents. Several of these chemicals appear to exert at least some of their effects through interactions with topoisomerase II, an essential enzyme that regulates DNA supercoiling and removes knots and tangles from the genome. Topoisomerase II-active phytochemicals function by stabilizing covalent protein-cleaved DNA complexes that are intermediates in the catalytic cycle of the enzyme. As a result, these compounds convert topoisomerase II to a cellular toxin that fragments the genome. Because of their mode of action, they are referred to as topoisomerase II poisons as opposed to catalytic inhibitors. The first sections of this article discuss DNA topology, the catalytic cycle of topoisomerase II, and the two mechanisms (interfacial vs. covalent) by which different classes of topoisomerase II poisons alter enzyme activity. Subsequent sections discuss the effects of several phytochemicals on the type II enzyme, including demethyl-epipodophyllotoxins (semisynthetic anticancer drugs) as well as flavones, flavonols, isoflavones, catechins, isothiocyanates, and curcumin (dietary chemopreventive agents). Finally, the leukemogenic potential of topoisomerase II-targeted phytochemicals is described.

Epigallocatechin-3-gallate, a DYRK1A inhibitor, rescues cognitive deficits in Down syndrome mouse models and in humans

SCOPE

Trisomy for human chromosome 21 results in Down syndrome (DS), which is among the most complex genetic perturbations leading to intellectual disability. Accumulating data suggest that overexpression of the dual-specificity tyrosine-(Y)-phosphorylation regulated kinase 1A (DYRK1A), is a critical pathogenic mechanisms in the intellectual deficit.

METHODS AND RESULTS

Here we show that the green tea flavonol epigallocatechin-gallate (EGCG), a DYRK1A inhibitor, rescues the cognitive deficits of both segmental trisomy 16 (Ts65Dn) and transgenic mice overexpressing Dyrk1A in a trisomic or disomic genetic background, respectively. It also significantly reverses cognitive deficits in a pilot study in DS individuals with effects on memory recognition, working memory and quality of life. We used the mouse models to ensure that EGCG was able to reduce DYRK1A kinase activity in the hippocampus and found that it also induced significant changes in plasma homocysteine levels, which were correlated with Dyrk1A expression levels. Thus, we could use plasma homocysteine levels as an efficacy biomarker in our human study.

CONCLUSION

We conclude that EGCG is a promising therapeutic tool for cognitive enhancement in DS, and its efficacy may depend of Dyrk1A inhibition.

Detection of electrophile-sensitive proteins

BACKGROUND

Redox signaling is an important emerging mechanism of cellular function. Dysfunctional redox signaling is increasingly implicated in numerous pathologies, including atherosclerosis, diabetes, and cancer. The molecular messengers in this type of signaling are reactive species which can mediate the post-translational modification of specific groups of proteins, thereby effecting functional changes in the modified proteins. Electrophilic compounds comprise one class of reactive species which can participate in redox signaling. Electrophiles modulate cell function via formation of covalent adducts with proteins, particularly cysteine residues.

SCOPE OF REVIEW

This review will discuss the commonly used methods of detection for electrophile-sensitive proteins, and will highlight the importance of identifying these proteins for studying redox signaling and developing novel therapeutics.

MAJOR CONCLUSIONS

There are several methods which can be used to detect electrophile-sensitive proteins. These include the use of tagged model electrophiles, as well as derivatization of endogenous electrophile-protein adducts.

GENERAL SIGNIFICANCE

In order to understand the mechanisms by which electrophiles mediate redox signaling, it is necessary to identify electrophile-sensitive proteins and quantitatively assess adduct formation. Strengths and limitations of these methods will be discussed. This article is part of a Special Issue entitled Current methods to study reactive oxygen species - pros and cons and biophysics of membrane proteins. Guest Editor: Christine Winterbourn.

Epimerization of green tea catechins during brewing does not affect the ability to poison human type II topoisomerases

(-)-Epigallocatechin gallate (EGCG) is the most abundant and biologically active polyphenol in green tea (Camellia sinensis) leaves, and many of its cellular effects are consistent with its actions as a topoisomerase II poison. In contrast to genistein and several related bioflavonoids that act as interfacial poisons, EGCG was the first bioflavonoid shown to act as a covalent topoisomerase II poison. Although studies routinely examine the effects of dietary phytochemicals on enzyme and cellular systems, they often fail to consider that many compounds are altered during cooking or cellular metabolism. To this point, the majority of EGCG and related catechins in green tea leaves are epimerized during the brewing process. Epimerization inverts the stereochemistry of the bond that bridges the B- and C-rings and converts EGCG to (-)-gallocatechin gallate (GCG). Consequently, a significant proportion of EGCG that is ingested during the consumption of green tea is actually GCG. Therefore, the effects of GCG and related epimerized green tea catechins on human topoisomerase IIα and IIβ were characterized. GCG increased levels of DNA cleavage mediated by both enzyme isoforms with an activity that was similar to that of EGCG. GCG acted primarily by inhibiting the ability of topoisomerase IIα and IIβ to ligate cleaved DNA. Several lines of evidence indicate that GCG functions as a covalent topoisomerase II poison that adducts the enzyme. Finally, epimerization did not affect the reactivity of the chemical substituents (the three hydroxyl groups on the B-ring) that were required for enzyme poisoning. Thus, the activity of covalent topoisomerase II poisons appears to be less sensitive to stereochemical changes than interfacial poisons.

The flavonoid content and antiproliferative, hypoglycaemic, anti-inflammatory and free radical scavenging activities of Annona dioica St. Hill

Background

Annona dioica St. Hill (Annonacaeae) is a Brazilian plant used in folk medicine for the treatment of several types of rheumatisms and diarrhoea. The focus of this work was to evaluate the in vitro antiproliferative and antioxidant activity and the in vivo hypoglycaemic and anti-inflammatory activity of A. dioica and identify the principal constituents of this plant.

Methods

The crude methanol extract (EAD) and hexane (HF), chloroform (CF), ethyl acetate (EAF) and hydromethanol fractions (HMF) were evaluated for free radical scavenging activity using the DPPH assay. The EAD and EAF were assayed for hypoglycaemic activity in rats. The EAD was tested in an antiproliferation assay and for anti-inflammatory effects in paw oedema, in addition to myeloperoxidase activity induced by carrageenan (Cg) in mice. The EAF was assayed using chromatographic methods.

Results

The fractionation of the EAF through chromatographic methods identified derivatives of the flavonoids quercetin and kaempferol. Among all the tested fractions, the ethyl acetate and hydromethanol fractions were the most potent, exhibiting an IC₅₀ of 8.53 and 10.57 μg/mL, respectively, which is comparable to that of the commercial antioxidant butylated hydroxytoluene (BHT). The oral administration of the EAD (100 mg/kg) and EAF (15 mg/kg) inhibited the increase of glucose levels, resulting in a hypoglycaemic effect. The EAD (30 to 300 mg/kg) exhibited an anti-oedematogenic effect in Cg-induced paw oedema in a time- and dose-dependent manner. The results showed a reduction of MPO activity by A. dioica 6 h after the induction of paw oedema at all doses tested with maximal inhibition at 300 mg/kg.

Conclusions

Our results reveal for the first time that compounds contained in the A. dioica leaves exert anti-inflammatory, hypoglycaemic, antiproliferative, and antioxidant effects. The antioxidant activity may be associated with the presence of flavonoids.

Oxidative metabolites of curcumin poison human type II topoisomerases

The polyphenol curcumin is the principal flavor and color component of the spice turmeric. Beyond its culinary uses, curcumin is believed to positively impact human health and displays antioxidant, anti-inflammatory, antibacterial, and chemopreventive properties. It also is in clinical trials as an anticancer agent. In aqueous solution at physiological pH, curcumin undergoes spontaneous autoxidation that is enhanced by oxidizing agents. The reaction proceeds through a series of quinone methide and other reactive intermediates to form a final dioxygenated bicyclopentadione product. Several naturally occurring polyphenols that can form quinones have been shown to act as topoisomerase II poisons (i.e., they increase levels of topoisomerase II-mediated DNA cleavage). Because several of these compounds have chemopreventive properties, we determined the effects of curcumin, its oxidative metabolites, and structurally related degradation products (vanillin, ferulic acid, and feruloylmethane) on the DNA cleavage activities of human topoisomerase IIα and IIβ. Intermediates in the curcumin oxidation pathway increased the level of DNA scission mediated by both enzymes ~4-5-fold. In contrast, curcumin and the bicyclopentadione, as well as vanillin, ferulic acid, and feruloylmethane, had no effect on DNA cleavage. As found for other quinone-based compounds, curcumin oxidation intermediates acted as redox-dependent (as opposed to interfacial) topoisomerase II poisons. Finally, under conditions that promote oxidation, the dietary spice turmeric enhanced topoisomerase II-mediated DNA cleavage. Thus, even within the more complex spice formulation, oxidized curcumin intermediates appear to function as topoisomerase II poisons.

Quercetin modulates activities of Taiwan cobra phospholipase A2 via its effects on membrane structure and membrane-bound mode of phospholipase A2

The goal of the present study is to elucidate the mechanism of quercetin on modulating Naja naja atra phospholipase A2 (PLA2) activities. Sphingomyelin inhibited PLA2 enzymatic activity and membrane-damaging activity against egg yolk phosphatidylcholine (EYPC), while cholesterol and quercetin abrogated the sphingomeyelin inhibitory effect. Quercetin incorporation led to a reduction in PLA2 enzymatic activity and membrane-damaging activity toward EYPC/sphingomyelin/cholesterol vesicles. Both cholesterol and quercetin increased detergent resistance and reduced membrane fluidity of EYPC/sphingomyelin vesicles. Quercetin reduced detergent insolubility but increased ordered lipid packing of EYPC/sphingomyelin/cholesterol vesicles. Acrylamide quenching studies and trinitrophenylation of Lys residues revealed that quercetin altered the membrane-bound mode of PLA2 differently upon absorption onto the membrane bilayers of different lipid compositions. However, 8-anilinonaphthalene sulphonate-binding assay revealed that quercetin marginally affected the interaction between active site of PLA2 with phospholipid vesicles. Collectively, our data indicate that membrane-inserted quercetin modulates PLA2 interfacial activity and membrane-damaging activity via its effects on membrane structure and membrane-bound mode of PLA2.

Antiarrhythmic effects of (-)-epicatechin-3-gallate, a novel sodium channel agonist in cultured neonatal rat ventricular myocytes

(-)-Epicatechin-3-gallate (ECG), a polyphenol extracted from green tea, has been proposed as an effective compound for improving cardiac contractility. However, the therapeutic potential of ECG on the treatment of arrhythmia remains unknown. We investigated the direct actions of ECG on the modulation of ion currents and cardiac cell excitability in the primary culture of neonatal rat ventricular myocyte (NRVM), which is considered a hypertrophic model for analysis of myocardial arrhythmias. By using the whole-cell patch-clamp configurations, we found ECG enhanced the slowly inactivating component of voltage-gated Na(+) currents (I(Na)) in a concentration-dependent manner (0.1-100 μM) with an EC(50) value of 3.8 μM. ECG not only shifted the current-voltage relationship of peak I(Na) to the hyperpolarizing direction but also accelerated I(Na) recovery kinetics. Working at a concentration level of I(Na) enhancement, ECG has no notable effect on voltage-gated K(+) currents and L-type Ca(2+) currents. With culture time increment, the firing rate of spontaneous action potential (sAP) in NRVMs was gradually decreased until spontaneous early after-depolarization (EAD) was observed after about one week culture. ECG increased the firing rate of normal sAP about two-fold without waveform alteration. Interestingly, the bradycardia-dependent EAD could be significantly restored by ECG in fast firing rate to normal sAP waveform. The expression of dominant cardiac sodium channel subunit, Nav1.5, was consistently detected throughout the culture periods. Our results reveal how ECG, the novel I(Na) agonist, may act as a promising candidate in clinical applications on cardiac arrhythmias.

Inhibition of the intracellular Ca(2+) transporter SERCA (Sarco-Endoplasmic Reticulum Ca(2+)-ATPase) by the natural polyphenol epigallocatechin-3-gallate

The use of a microsomal preparation from skeletal muscle revealed that both Ca(2+) transport and Ca(2+)-dependent ATP hydrolysis linked to Sarco-Endoplasmic Reticulum Ca(2+)-ATPase are inhibited by epigallocatechin-3-gallate (EGCG). A half-maximal effect was achieved at approx. 12 μM. The presence of the galloyl group was essential for the inhibitory effect of the catechin. The relative inhibition of the Ca(2+)-ATPase activity decreased when the Ca(2+) concentration was raised but not when the ATP concentration was elevated. Data on the catalytic cycle indicated inhibition of maximal Ca(2+) binding and a decrease in Ca(2+) binding affinity when measured in the absence of ATP. Moreover, the addition of ATP to samples in the presence of EGCG and Ca(2+) led to an early increase in phosphoenzyme followed by a time-dependent decay that was faster when the drug concentration was raised. However, phosphorylation following the addition of ATP plus Ca(2+) led to a slow rate of phosphoenzyme accumulation that was also dependent on EGCG concentration. The results are consistent with retention of the transporter conformation in the Ca(2+)-free state, thus impeding Ca(2+) binding and therefore the subsequent steps when ATP is added to trigger the Ca(2+) transport process. Furthermore, phosphorylation by inorganic phosphate in the absence of Ca(2+) was partially inhibited by EGCG, suggesting alteration of the native Ca(2+)-free conformation at the catalytic site.

Hamamelitannin from witch hazel (Hamamelis virginiana) displays specific cytotoxic activity against colon cancer cells

Hamamelis virginiana (witch hazel) bark is a rich source of condensed and hydrolyzable tannins reported to exert a protective action against colon cancer. The present study characterizes different witch hazel tannins as selective cytotoxic agents against colon cancer. To cover the structural diversity of the tannins that occur in H. virginiana bark, the hydrolyzable tannins, hamamelitannin and pentagalloylglucose, together with a proanthocyanidin-rich fraction (F800H4) were selected for the study. Treatment with these compounds reduced tumor viability and induced apoptosis, necrosis, and S-phase arrest in the cell cycle of HT29 cells, with hamamelitannin being the most efficient. Owing to polyphenol-mediated H(2)O(2) formation in the incubation media, the antiproliferative effect was determined in the presence and absence of catalase to rule out any such interference. The presence of catalase significantly changed the IC(50) only for F800H4. Furthermore, at concentrations that inhibit the growth of HT29 cells by 50%, hamamelitannin had no harmful effects on NCM460 normal colonocytes, whereas pentagalloylglucose inhibited both cancerous and normal cell growth. Using the TNPTM assay, we identified a highly reactive phenolic position in hamamelitannin, which may explain its efficacy at inhibiting colon cancer growth.

Comparative studies on antioxidant activities of extracts and fractions from the leaves and stem of Epimedium koreanum Nakai

The antioxidant potency of various extracts and fractions from the leaves and stem of Epimedium koreanum Nakai was evaluated using three esteblished methods, specifically the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radica-scavenging activity assay, the inhibitory effect on lipid peroxidation induced by Fe(2+)/ascorbate (MDA) assay and the ferric reducing power (FRP) assay. The amounts of total phenolics and total flavonoids in the extracts and fractions were determined by spectrophotometric methods and the content of icariin was determined by HPLC. The results showed that all the extracts and fractions exhibited antioxidant activities at different magnitudes of potency. The leaf extract and fractions demonstrated superior antioxidant activity in most of the assays. The decreasing order of antioxidant activities among the extracts/fractions assayed through the three methods were found to be n-BuOH fraction>ethyl acetate fraction>ethanol extract>petroleum ether fraction>water fraction. A positive correlation was found between the amounts of total phenolics, total flavonoids and icariin and DPPH radical scavenging activity (R(2) = 0.9935, 0.9944 and 0.9997, respectively) and inhibitory activity on lipid peroxidation (R(2) = 0.9987, 0.9830 and 0.9886, respectively). The results suggested that Icariin was one of the main constituents contribute to the antioxidant activity of Epimedium koreanum Nakai and the n-BuOH fractions of leaf extract might be valuable antioxidant natural sources.

EGCG-meditated cyto- and genotoxicity in HaCat keratinocytes is impaired by cell-mediated clearance of auto-oxidation-derived H2O2: an algorithm for experimental setting correction

Several lines of evidence suggest that besides antioxidant also prooxidant properties are crucially involved in cytotoxic and protective activities of the major green tea catechin epigallocatechin-3-gallate (EGCG) in vitro (Elbling et al., 2011). Furthermore recent data suggest that EGCG induces oxidative stress also in vivo (Li et al., 2010). Here we set out to identify factors modulating cellular effects of EGCG in vitro. Using the HaCat keratinocytes model, we demonstrate that the cytotoxic, genotoxic and signal-activating effects of EGCG are significantly dependent on the ratio of cell number to working volume. Treatment with identical EGCG concentrations at altered experimental settings resulted in IC(50) values differing up to orders of magnitude and could even exert contradictory effects. This effect was based on cell-mediated clearance of autooxidation-derived H(2)O(2) from the supernatant. In order to estimate EGCG/H(2)O(2) concentrations equally effective under different settings, we have rationally derived and experimentally verified a simple algorithm relating concentration, working volume, cell number and - indirectly - exposure time. Algorithm application resulted in similar H(2)O(2) clearance curves from cell supernatants as well as comparable EGCG/H(2)O(2) effects at different settings. Our results demonstrate the importance of standardized experimental settings when investigating cytotoxic and/or beneficial effects of autooxidizing compounds.

Mitigation of DMBA-induced mammary carcinoma in experimental rats by antiangiogenic property of Kalpaamruthaa

Extra cellular matrix (ECM) and basement membrane (BM) are important layers that regulate cell structure, cell migration, and cellular proliferation. Degradation of both ECM and BM mediated by proteases favors the tumor invasion and promotes angiogenesis. Female Sprague-Dawley rats weighing 180 ± 10 g were categorized into 6 groups. Group-1 animals served as vehicle control. Group-2 to Group-4 animals were administered with 7,12-dimethylbenz(a)anthracene (25 mg/rat dissolved in olive oil, orally) on day 1 of experimental period to induce mammary carcinoma. (After 90 days, mammary carcinoma was confirmed by histopathological examination). Group-3 and Group-4 rats were subsequently treated with Semecarpus anacardium nut milk extract (SA) and Kalpaamruthaa (KA), respectively. Group-5 and Group-6 animals served as drug control for SA and KA, respectively. Pro-angiogenic factors like proteases, cyclooxygenase-2, and vascular endothelial growth factor were elevated in tumor-bearing animals and decreased in SA- and KA-supplemented rats. Increased levels of these angiogenic factors in tumor-bearing rats indicate the progression of mammary tumor. The decreased levels of these angiogenic in SA- and KA-treated rats may be due to the ameliorative effect of phenolic compounds such as flavonoids, tannins, and other compounds present in the drug.

Plant polyphenols: chemical properties, biological activities, and synthesis

Eating five servings of fruits and vegetables per day! This is what is highly recommended and heavily advertised nowadays to the general public to stay fit and healthy! Drinking green tea on a regular basis, eating chocolate from time to time, as well as savoring a couple of glasses of red wine per day have been claimed to increase life expectancy even further! Why? The answer is in fact still under scientific scrutiny, but a particular class of compounds naturally occurring in fruits and vegetables is considered to be crucial for the expression of such human health benefits: the polyphenols! What are these plant products really? What are their physicochemical properties? How do they express their biological activity? Are they really valuable for disease prevention? Can they be used to develop new pharmaceutical drugs? What recent progress has been made toward their preparation by organic synthesis? This Review gives answers from a chemical perspective, summarizes the state of the art, and highlights the most significant advances in the field of polyphenol research.

Green tea polyphenol epigallocatechin-3-gallate (EGCG) induced intermolecular cross-linking of membrane proteins

Increasing evidence has demonstrated that EGCG possesses prooxidant potential in biological systems, including modifying proteins, breaking DNA strands and inducing the generation of reactive oxygen species. In the present study, the prooxidant effect of EGCG on erythrocyte membranes was investigated. SDS-PAGE and NBT-staining assay were utilized to detect the catechol-protein adducts that generated upon treating the membranes with EGCG. The results indicated that EGCG was able to bind covalently to sulfhydryl groups of membrane proteins, leading to the formation of protein aggregates with intermolecular cross-linking. We suggested that the catechol-quinone originated from the oxidation of EGCG acted as a cross-linker on which peptide chains were combined through thiol-S-alkylation at the C2- and C6-sites of the gallyl ring. EGC showed similar effects as EGCG on the ghost membranes, whereas ECG and EC did not, suggesting that a structure with a gallyl moiety is a prerequisite for a catechin to induce the aggregation of membrane proteins and to deplete membrane sulfhydryls. EDTA and ascorbic acid inhibited the EGCG-induced aggregation of membrane proteins by blocking the formation of catechol-quinone. The information of the present study may provide a fresh insight into the prooxidant effect and cytotoxicity of tea catechins.

Biological rationale for the use of DNA methyltransferase inhibitors as new strategy for modulation of tumor response to chemotherapy and radiation

Epigenetic modifications play a key role in the patho-physiology of many tumors and the current use of agents targeting epigenetic changes has become a topic of intense interest in cancer research. DNA methyltransferase (DNMT) inhibitors represent a promising class of epigenetic modulators. Research performed yielded promising anti-tumorigenic activity for these agents in vitro and in vivo against a variety of hematologic and solid tumors. These epigenetic modulators cause cell cycle and growth arrest, differentiation and apoptosis. Rationale for combining these agents with cytotoxic therapy or radiation is straightforward since the use of DNMT inhibitor offers greatly improved access for cytotoxic agents or radiation for targeting DNA-protein complex. The positive results obtained with these combined approaches in preclinical cancer models demonstrate the potential impact DNMT inhibitors may have in treatments of different cancer types. Therefore, as the emerging interest in use of DNMT inhibitors as a potential chemo- or radiation sensitizers is constantly increasing, further clinical investigations are inevitable in order to finalize and confirm the consistency of current observations.The present article will provide a brief review of the biological significance and rationale for the clinical potential of DNMT inhibitors in combination with other chemotherapeutics or ionizing radiation. The molecular basis and mechanisms of action for these combined treatments will be discussed herein.

Green tea catechins are potent sensitizers of ryanodine receptor type 1 (RyR1)

Catechins, polyphenols extracted from green tea leaves, have a broad range of biological activities although the specific molecular mechanisms responsible are not known. At the high experimental concentrations typically used polyphenols bind to membrane phospholipid and also are easily auto-oxidized to generate superoxide anion and semiquinones, and can adduct to protein thiols. We report that the type 1 ryanodine receptor (RyR1) is a molecular target that responds to nanomolar (-)-epigallocatechin-3-gallate (EGCG) and (-)-epicatechin-3-gallate (ECG). Single channel analyses demonstrate EGCG (5-10nM) increases channel open probability (Po) twofold, by lengthening open dwell time. The degree of channel activation is concentration-dependent and is rapidly and fully reversible. Four related catechins, EGCG, ECG, EGC ((-)-epigallocatechin) and EC ((-)-epicatechin) showed a rank order of activity toward RyR1 (EGCG>ECG>>EGC>>>EC). EGCG and ECG enhance the sensitivity of RyR1 to activation by < or =100microM cytoplasmic Ca(2+) without altering inhibitory potency by >100microM Ca(2+). EGCG as high as 10microM in the extracellular medium potentiated Ca(2+) transient amplitudes evoked by electrical stimuli applied to intact myotubes and adult FDB fibers, without eliciting spontaneous Ca(2+) release or slowing Ca(2+) transient recovery. The results identify RyR1 as a sensitive target for the major tea catechins EGCG and ECG, and this interaction is likely to contribute to their observed biological activities.