Sub-acute effects of diazinon on biochemical indices and specific biomarkers in rats: Protective effects of crocin and safranal

In this study, the effects of crocin and safranal were studied against sub-acute toxicity of diazinon (DZN) on specific biomarkers, biochemical indices and enzymes levels in rats. Vitamin E (200 IU/kg), safranal at doses 0.025, 0.05 and 0.1 ml/kg and crocin at doses 50, 100 and 200 mg/kg were injected intraperitoneally three times per week alone or with DZN (20 mg/kg/day, orally) for 4 weeks. The parameters were evaluated at the end of 4 weeks. Diazinon did not change serum urea, creatinine, cholesterol, triglyceride, total and direct bilirubin levels. Total protein and albumin concentrations were decreased by diazinon. Crocin, safranal and vitamin E prevented the effect of diazinon on some biochemical indices and enzymes levels. The levels of serum TNF-α, direct 8-iso-prostaglandin F_2α and soluble protein-100 β (S100β) were increased significantly by diazinon. The augmentation of direct 8-iso-prostaglandin F_2α and S100β levels by diazinon was significantly decreased by crocin, safranal and vitamin E. TNF-α level was significantly decreased in diazinon plus crocin 50 and 100 mg/kg treated groups compared to the diazinon group. This study showed that vitamin E, safranal and crocin could prevent diazinon induced enzymes elevation and augmentation of some specific biomarkers.     

Cinnamon (Cinnamomum zeylanicum) as an antidote or a protective agent against natural or chemical toxicities: a review

Cinnamon (Cinnamomum zeylanicum, Lauraceae) is a food additive greatly used for its taste. However, recently this medicinal plant has been brought to attention due to its medical effects. Cinnamon has constituents such as cinnamaldehyde and cinnamic acid that offers some health benefits including antioxidant and free-radical scavenging properties, lowering of blood glucose, anti-cholesterolemic, analgesic, antimicrobial, anti-inflammatory, anti-yeast, anti-secretagogue, and anti-gastric ulcer effects. This review summarizes various in vitro and animal studies on the protective effects of cinnamon against natural and chemical toxins. These studies consider the antidotal and/or protective effects of cinnamon and its major constituents against natural toxins and chemical-induced toxicities. It has been mentioned that cinnamon and its main constituents can ameliorate the toxicity of chemical toxins in liver, kidney, blood, brain, embryo, reproductive system, heart, spleen in part through antioxidant effect, radical scavenging, reducing lipid peroxidation, anti-inflammatory, fungistatic and fungicidal activities, modulation of CK-MB, LDH, TNF-α, IL-6, mitogen-activated protein kinase (MAPK), and nuclear factor-?B (NF-?B) signaling pathways.     

Affinity-based target deconvolution of safranal

Background and the purpose of the study

Affinity-based target deconvolution is an emerging method for the identification of interactions between drugs/drug candidates and cellular proteins, and helps to predict potential activities and side effects of a given compound. In the present study, we hypothesized that a part of safranal pharmacological effects, one of the major constituent of Crocus sativus L., relies on its physical interaction with target proteins.

Methods

Affinity chromatography solid support was prepared by covalent attachment of safranal to agarose beads. After passing tissue lysate through the column, safranal-bound proteins were isolated and separated on SDS-PAGE or two-dimensional gel electrophoresis. Proteins were identified using MALDI-TOF/TOF mass spectrometry and Mascot software.

Results and major conclusion

Data showed that safranal physically binds to beta actin, cytochrome b-c1 complex sub-unit 1, trifunctional enzyme sub-unit beta and ATP synthase sub-unit alpha and beta. These interactions may explain part of safranal’s pharmacological effects. However, phenotypic and/or biological relevance of these interactions remains to be elucidated by future pharmacological studies.     

A new validated SPE-HPLC method for monitoring crocetin in human plasma--application after saffron tea consumption

Saffron (stigmas of Crocus sativus L.) is a well-known spice with many attributed therapeutic uses throughout centuries. Although studies have demonstrated that crocetin and crocins from saffron have various biological functions, issues concerning the route and way of saffron administration, the absorption and metabolism of saffron carotenoids in humans have not been answered yet. In the present study, an isocratic reversed-phase liquid chromatographic method was developed and validated for the determination of crocetin in plasma. Samples were pre-treated by solid phase extraction (recoveries >72%) and were chromatographed on a Luna C-18 column (4.6mm×250mm, 5μm) with a mobile phase consisting of methanol-water-trifluoroacetic acid (75.0:24.5:0.5, v/v/v) at a flow rate of 1.0mLmin(-1). The HPLC method developed resulted in sharp peaks at 10.7 (trans-crocetin) and 18.6min (cis-crocetin), whereas the calibration curve of total crocetin in plasma displayed a good linearity for concentrations of 0.020-20μM (R(2)=0.999). Specificity, precision, accuracy and stability were studied with spiked plasma samples and were acceptable. The developed method was applied to the determination of crocetin levels in plasma of four healthy human volunteers before and after consumption of one cup of saffron tea (200mg of saffron in 80°C water for 5min). Results showed that the concentration of crocetin was high after 2h (1.24-3.67μM) and still determined after 24h (0.10-0.24). Interestingly, the percentage of the cis-isomer ranges from 25 to 50%, suggesting in vivo isomerization.     

Proteomic screening of molecular targets of crocin

Background

Traditional drug discovery approaches are mainly relied on the observed phenotypic changes following administration of a plant extract, drug candidate or natural product. Recently, target-based approaches are becoming more popular. The present study aimed to identify the cellular targets of crocin, the bioactive dietary carotenoid present in saffron, using an affinity-based method.

Methods

Heart, kidney and brain tissues of BALB/c mice were homogenized and extracted for the experiments. Target deconvolution was carried out by first passing cell lysate through an affinity column prepared by covalently attaching crocin to agarose beads. Isolated proteins were separated on a 2D gel, trypsinized in situ and identified by MALDI-TOF/TOF mass spectrometry. MASCOT search engine was used to analyze Mass Data.

Results

Part of proteome that physically interacts with crocin was found to consist of beta-actin-like protein 2, cytochrome b-c1 complex subunit 1, ATP synthase subunit beta, tubulin beta-3 chain, tubulin beta-6 chain, 14-3-3 protein beta/alpha, V-type proton ATPase catalytic subunitA, 60 kDa heat shock protein, creatine kinase b-type, peroxiredoxin-2, cytochrome b-c1 complex subunit 2, acetyl-coA acetyltransferase, cytochrome c1, proteasome subunit alpha type-6 and proteasome subunit alpha type-4.

Conclusion

The present findings revealed that crocin physically binds to a wide range of cellular proteins such as structural proteins, membrane transporters, and enzymes involved in ATP and redox homeostasis and signal transduction.     

Isolation and chemical characterization of a toxin isolated from the venom of the sea snake, Hydrophis torquatus aagardi

Sea snakes (family: Hydrophiidae) are serpents found in the coastal areas of the Indian and Pacific Oceans. There are two subfamilies in Hydrophiidae: Hydrophiinae and Laticaudinae. A toxin, aagardi toxin, was isolated from the venom of the Hydrophiinae snake, Hydrophis torquatus aagardi and its chemical properties such as molecular weight, isoelectric point, importance of disulfide bonds, lack of enzymatic activity and amino acid sequence were determined. The amino acid sequence indicated a close relationship to the primary structure of other Hydrophiinae toxins and a significant difference from Laticaudinae toxins, confirming that primary toxin structure is closely related to sea snake phylogenecity.     

Boswellia serrata, a potential antiinflammatory agent: an overview

The resin of Boswellia species has been used as incense in religious and cultural ceremonies and in medicines since time immemorial. Boswellia serrata (Salai/Salai guggul), is a moderate to large sized branching tree of family Burseraceae (Genus Boswellia), grows in dry mountainous regions of India, Northern Africa and Middle East. Oleo gum-resin is tapped from the incision made on the trunk of the tree and is then stored in specially made bamboo basket for removal of oil content and getting the resin solidified. After processing, the gum-resin is then graded according to its flavour, colour, shape and size. In India, the States of Andhra Pradesh, Gujarat, Madhya Pradesh, Jharkhand and Chhattisgarh are the main source of Boswellia serrata. Regionally, it is also known by different names. The oleo gum-resins contain 30-60% resin, 5-10% essential oils, which are soluble in the organic solvents, and the rest is made up of polysaccharides. Gum-resin extracts of Boswellia serrata have been traditionally used in folk medicine for centuries to treat various chronic inflammatory diseases. The resinous part of Boswellia serrata possesses monoterpenes, diterpenes, triterpenes, tetracyclic triterpenic acids and four major pentacyclic triterpenic acids i.e. β-boswellic acid, acetyl-β-boswellic acid, 11-keto-β-boswellic acid and acetyl-11-keto-β-boswellic acid, responsible for inhibition of pro-inflammatory enzymes. Out of these four boswellic acids, acetyl-11-keto-β-boswellic acid is the most potent inhibitor of 5-lipoxygenase, an enzyme responsible for inflammation.     

Evaluation of Cynanchum otophyllum glucan sulfate against human immunodeficiency virus and herpes simplex virus as a microbicide agent

Objective:

The root of Cynanchum otophyllum—also known as Qing Yang Sheng—is a traditional ethnical Chinese medicine. The objective of this study was to evaluate in vitro activities and safety of C. otophyllum glucan sulfate (PS20) against Human Immunodeficiency Virus (HIV) and Herpes Simplex Virus (HSV).

Materials and Methods:

Anti-HIV activity was detected with syncytial formation assay and quantitative P24 Enzyme-Linked Immunosorbent Assay (ELISA). Anti-HSV activity was detected with plaque reduction assay; cytotoxicity was tested with MTT colorimetric assay; and anti-bacterial activity was tested with microdilution method. Anti-HIV mechanism was investigated with fusion inhibition, time of addition, and pretreatment.

Results:

The 50% Inhibition Concentration (IC₅₀) of PS20 for HIV-1_IIIB, HIV-_Ada-M, HIV-1_Bal, HSV-I, and -II were 0.26 ± 0.02 mM, 0.46 ± 0.02 mM, 0.90 ± 0.04 mM, 3.45 ± 0.85 μM, and 0.70 ± 0.22 mM, respectively. Selectivity Indices (SI) were 653, 50, 39, 85, and 362, respectively. Studies on anti-HIV mechanism of PS20 showed that the target molecule should be the envelope protein. The 50% Cytotoxicity Concentrations (CC₅₀) of PS20 for HeLa and ME-180 cell lines and human foreskin fibroblast cells was more than 70 μM. The Minimum Inhibitory Concentration (MIC) for vaginal lactobacilli was more than 1000 μM.

Conclusion:

PS20 possesses anti-HIV and HSV effect and low cytotoxicity to epithelium cells and vaginal lactobacilli. It may be considered as a potential microbicide agent for further investigation.     

Preparation of herbal tea as infusion or by maceration at room temperature using mistletoe tea as an example

Herbal tea can be prepared by infusion or maceration at room temperature resulting in different compositions of extractable constituents, which possibly influences the mode of action or safety profile. Knowledge on this topic is limited. The aim of this study was to investigate the substantial differences between infusion and maceration as recommended preparation methods for the preparation of herbal mistletoe tea, a traditional remedy against cardiovascular diseases. No active substances are known but analytical marker substances such as proteins, triterpenoids, phenylpropane derivatives and flavonoids can be quantified within the herb and the different herbal tea preparations. Whereas phenylpropane derivatives were completely extracted by infusion and maceration, neither method dissolved viscotoxins. 43% of mistletoe lectins were extracted by maceration, whereas by infusion they are inactivated by thermal degradation. By contrast, oleanolic acid and betulinic acid are present in higher concentrations in infusates compared with macerates, but even infusion extracted less than 2%. Infusion extracted 43% of flavonoid-like substances and maceration only 31%. In conclusion this study determines some differences between both extraction methods on the profile of solved substances. The relevance of it should be determined in studies dealing with the efficacy of herbal mistletoe tea.     

First-in-class cardiolipin-protective compound as a therapeutic agent to restore mitochondrial bioenergetics

A decline in energy is common in aging, and the restoration of mitochondrial bioenergetics may offer a common approach for the treatment of numerous age-associated diseases. Cardiolipin is a unique phospholipid that is exclusively expressed on the inner mitochondrial membrane where it plays an important structural role in cristae formation and the organization of the respiratory complexes into supercomplexes for optimal oxidative phosphorylation. The interaction between cardiolipin and cytochrome c determines whether cytochrome c acts as an electron carrier or peroxidase. Cardiolipin peroxidation and depletion have been reported in a variety of pathological conditions associated with energy deficiency, and cardiolipin has been identified as a target for drug development. This review focuses on the discovery and development of the first cardiolipin-protective compound as a therapeutic agent. SS-31 is a member of the Szeto-Schiller (SS) peptides known to selectively target the inner mitochondrial membrane. SS-31 binds selectively to cardiolipin via electrostatic and hydrophobic interactions. By interacting with cardiolipin, SS-31 prevents cardiolipin from converting cytochrome c into a peroxidase while protecting its electron carrying function. As a result, SS-31 protects the structure of mitochondrial cristae and promotes oxidative phosphorylation. SS-31 represents a new class of compounds that can recharge the cellular powerhouse and restore bioenergetics. Extensive animal studies have shown that targeting such a fundamental mechanism can benefit highly complex diseases that share a common pathogenesis of bioenergetics failure. This review summarizes the mechanisms of action and therapeutic potential of SS-31 and provides an update of its clinical development programme.

LINKED ARTICLES

This article is part of a themed issue on Mitochondrial Pharmacology: Energy, Injury & Beyond. To view the other articles in this issue visit http://dx.doi.org/10.1111/bph.2014.171.issue-8     

Black bean (Phaseolus vulgaris L.) as a protective agent against DNA damage in mice

This study was designed to evaluate the toxicogenetic or protective effect of cooked and dehydrated black beans (Phaseolus vulgaris L.) in bone marrow and peripheral blood cells of exposed mice. The frequency of micronuclei detected using the bone marrow erythrocyte micronucleus test and level of DNA lesions detected by the comet assay were chosen as end-points reflecting mutagenic and genotoxic damage, respectively. Initially, Swiss male mice were fed with a 20% black bean diet in order to detect mutagenic and genotoxic activity. However, no increase in the frequency of bone marrow micronucleated polychromatic erythrocytes (MN PCEs) or DNA lesion in leukocytes was observed. In contrast, received diets containing 1, 10 or 20% of black beans, a clear, but not dose-dependent reduction in the frequency of MN PCEs were observed in animals simultaneously treated with cyclophosphamide, an indirect acting mutagen. Similar results were observed in leukocytes by the comet assay. Commercial anthocyanin was also tested in an attempt to identify the bean components responsible for this protective effect. However, instead of being protective, the flavonoid, at the highest dose administered (50 mg/kg bw), induced primary DNA lesion, as detected by the comet assay. These data indicate the importance of food components in preventing genetic damage induced by chemical mutagens, and also reinforce the role of toxicogenetic techniques in protecting human health.     

Potential therapeutic effect of Allium cepa L. and quercetin in a murine model of Blomia tropicalis induced asthma

Background

Asthma is an inflammatory condition characterized by airway hyperresponsiveness and chronic inflammation. The resolution of inflammation is an essential process to treat this condition. In this study we investigated the effect of Allium cepa L. extract (AcE) and quercetin (Qt) on cytokine and on smooth muscle contraction in vitro and its therapeutic potential in a murine model of asthma.

Methods

AcE was obtained by maceration of Allium cepa L. and it was standardized in terms of quercetin concentration using high performance liquid chromatography (HPLC). In vitro, using AcE 10, 100 or 1000 μg/ml or Qt 3.5, 7.5, 15 μg/ml, we measured the concentration of cytokines in spleen cell culture supernatants, and the ability to relax tracheal smooth muscle from A/J mice. In vivo, Blomia tropicalis (BT)-sensitized A/J mice were treated with AcE 100, 1000 mg/kg or 30 mg/kg Qt. We measured cell influx in bronchoalveolar lavage (BAL), eosinophil peroxidase (EPO) in lungs, serum levels of Bt-specific IgE, cytokines levels in BAL, and lung histology.

Results

We observed a reduction in the production of inflammatory cytokines, a relaxation of tracheal rings, and a reduction in total number of cells in BAL and EPO in lungs by treatment with AcE or Qt.

Conclusion

AcE and Qt have potential as antiasthmatic drugs, as they possess both immunomodulatory and bronchodilatory properties.     

Role of the Rosa canina L. leaf extract as an antidiarrheal drug in rodents

Objectives:

The objective of the study was to investigate the effect of the leaf extract of Rosa canina L. against experimental diarrhea induced by castor oil in rodents.

Materials and Methods:

The methanol extract of Rosa canina L. (30 and 60 mg/kg body weight) was administered orally to two groups of mice (five animals per group) in order to evaluate the activity of the extract against the castor oil-induced diarrhea model in mice. Two other groups received normal saline and diphenoxylate (5 mg/kg) as positive control. The effect of the extract on intestinal transit and castor oil-induced intestinal fluid accumulation (enteropooling) was assessed. The effects of the extract on the isolated rabbit jejunum and on the isolated rat ileum were studied.

Results:

The preliminary phytochemical screening of the leaf extract of Rosa Canina L. revealed the presence of alkaloids, flavonoids, glycosides, saponins, and volatile oil. Intraperitoneal LD50 of the extract was found to be 455.19 ± 23 mg/kg in mice. The antidiarrheal effect of the methanolic extract exhibited a concentration-dependent inhibition of the spontaneous pendular movement of the isolated rabbit jejunum and inhibited acetylcholine-induced contraction of the rat ileum. A dose-dependent decrease in gastrointestinal transit was observed with extracts (30 and 60 mg/kg), which also protected mice against castor oil-induced diarrhea and castor oil-induced fluid accumulation, respectively.

Conclusions:

The presence of some of the phytochemicals in the leaf extract may be responsible for the observed effects, and also the basis for its use in traditional medicine as an antidiarrheal drug.     

Dimerumic acid as an antioxidant from the mold, Monascus anka: the inhibition mechanisms against lipid peroxidation and hemeprotein-mediated oxidation

This study aimed to investigate the antioxidant mechanism of dimerumic acid isolated as the active component with a radical scavenging action from the mold Monascus anka, traditionally used for the fermentation of foods. Dimerumic acid inhibited NADPH- and iron(II)-dependent lipid peroxidation (LPO) of rat liver microsomes at 20 and 200 microM, respectively. When ferrylmyoglobin was incubated with dimerumic acid, the myoglobin was scavenged and an electron spin resonance (ESR) signal with nine peaks was observed. The spin adduct was identified as a nitroxide radical by analysis of hyperfine structure. Similar ESR signal was also detected by incubation of dimerumic acid with peroxyl radicals. Thus, it was clarified that the antioxidant action of dimerumic acid is due to one electron donation of the hydroxamic acid group in the dimerumic acid molecule toward oxidants resulting in formation of nitroxide radical.     

LASSBio-881: an N-acylhydrazone transient receptor potential vanilloid subfamily type 1 antagonist orally effective against the hypernociception induced by capsaicin or partial sciatic ligation

Background and purpose:

Compound LASSBio-881 is an orally effective antinociceptive that binds to cannabinoid receptors and is active mainly on the neurogenic component of pain models. We investigated whether transient receptor potential vanilloid subfamily type 1 (TRPV1) channels are involved in the effects of LASSBio-881.

Experimental approach:

Modulation of capsaicin (CAP)- and low pH-induced currents was evaluated in TRPV1-expressing Xenopus oocytes. In vivo effects were evaluated in CAP-induced acute and inflammatory changes in nociception, as well as in partial sciatic ligation-induced thermal hypernociception.

Key results:

LASSBio-881 inhibited TRPV1 currents elicited by CAP with an IC₅₀ of 14 µM, and inhibited proton-gated currents by 70% at 20 µM. Functional interaction with CAP was surmountable. Locally applied LASSBio-881 decreased time spent in CAP-elicited nocifensive behaviour by 30%, and given orally it reduced measures of CAP- or carrageenan-evoked thermal hypernociception by 60 and 40% respectively. In addition, LASSBio-881 decreased the paw withdrawal responses to thermal stimuli of animals with sciatic neuropathy 7–11 days after nerve ligation, at a dose of 300 µmol·kg⁻¹·day⁻¹ p.o. At this dose, hyperthermia was not observed within 4 h following oral administration.

Conclusions and implications:

LASSBio-881 is a TRPV1 antagonist that apparently competes with CAP. Accordingly, LASSBio-881 inhibited nociception in models of acute, inflammatory and neuropathic pain presumed to involve TRPV1 signalling. These in vivo actions were not hindered by hyperthermia, a common side effect of other TRPV1 antagonists. We propose that the antinociceptive properties of LASSBio-881 are due to TRPV1 antagonism, although other molecular interactions may contribute to the effects of this multi-target drug candidate.     

N-arachidonoyl glycine, an endogenous lipid that acts as a vasorelaxant via nitric oxide and large conductance calcium-activated potassium channels

Background and purpose:

N-arachidonoyl glycine (NAGly) is an endogenous lipid that is structurally similar to the endocannabinoid, N-arachidonoyl ethanolamide (anandamide). While NAGly does not activate cannabinoid receptors, it exerts cannabimimetic effects in pain regulation. Here, we have determined if NAGly, like anandamide, modulates vascular tone.

Experimental approach:

In rat isolated small mesenteric arteries, the relaxant responses to NAGly were characterized. Effects of N-arachidonoyl serine and N-arachidonoyl γ-aminobutyric acid were also examined.

Key results:

In endothelium-intact arteries, NAGly-induced relaxation (pEC_50%= 5.7 ± 0.2; relaxation at 30 µM = 98 ± 1%) was attenuated by l-NAME (a nitric oxide synthase inhibitor) or iberiotoxin [selective blocker of large conductance Ca²⁺-activated K⁺ channels (BK_Ca)], and abolished by high extracellular K⁺ concentration. Endothelial removal reduced the potency of NAGly, and the resultant relaxation was inhibited by iberiotoxin, but not l-NAME. NAGly responses were sensitive to the novel cannabinoid receptor antagonist O-1918 independently of endothelial integrity, whereas pertussis toxin, which uncouples G_i/o proteins, attenuated NAGly relaxation only in endothelium-intact arteries. Treatments with antagonists for CB₁, CB₂ and TRPV1 receptors, or inhibitors of fatty acid amide hydrolase and COX had no effect. The two other arachidonoyl amino acids also induced iberiotoxin- and L-NAME-sensitive relaxations.

Conclusion and implications:

NAGly acts as a vasorelaxant predominantly via activation of BK_Ca in rat small mesenteric arteries. We suggest that NAGly activates an unknown G_i/o-coupled receptor, stimulating endothelial release of nitric oxide which in turn activates BK_Ca in the smooth muscle. In addition, NAGly might also activate BK_Ca through G_i/o- and nitric oxide-independent mechanisms.     

Diazoxide acts more as a PKC-epsilon activator, and indirectly activates the mitochondrial K(ATP) channel conferring cardioprotection against hypoxic injury

BACKGROUND AND PURPOSE: Diazoxide, a well-known opener of the mitochondrial ATP-sensitive potassium (mitoK(ATP)) channel, has been demonstrated to exert cardioprotective effect against ischemic injury through the mitoK(ATP) channel and protein kinase C (PKC). We aimed to clarify the role of PKC isoforms and the relationship between the PKC isoforms and the mitoK(ATP) channel in diazoxide-induced cardioprotection. EXPERIMENTAL APPROACH: In H9c2 cells and neonatal rat cardiomyocytes, PKC-epsilon activation was examined by Western blotting and kinase assay. Flavoprotein fluorescence, mitochondrial Ca(2+) and mitochondrial membrane potential were measured by confocal microscopy. Cell death was determined by TUNEL assay. KEY RESULTS: Diazoxide (100 microM) induced translocation of PKC-epsilon from the cytosolic to the mitochondrial fraction. Specific blockade of PKC-epsilon by either epsilonV1-2 or dominant negative mutant PKC-epsilon (PKC-epsilon KR) abolished the anti-apoptotic effect of diazoxide. Diazoxide-induced flavoprotein oxidation was inhibited by either epsilonV1-2 or PKC-epsilon KR transfection. Treatment with 5-hydroxydecanoate (5-HD) did not affect translocation and activation of PKC-epsilon induced by diazoxide. Transfection with wild type PKC-epsilon mimicked the flavoprotein-oxidizing effect of diazoxide, and this effect was completely blocked by epsilonV1-2 or 5-HD. Diazoxide prevented the increase in mitochondrial Ca(2+), mitochondrial depolarization and cytochrome c release induced by hypoxia and all these effects of diazoxide were blocked by epsilonV1-2 or 5-HD. CONCLUSIONS AND IMPLICATIONS: Diazoxide induced isoform-specific translocation of PKC-epsilon as an upstream signaling molecule for the mitoK(ATP) channel, rendering cardiomyocytes resistant to hypoxic injury through inhibition of the mitochondrial death pathway.     

Polysaccharides as a protective response against microcystin-induced oxidative stress in <Emphasis Type="Italic">Chlorella vulgaris</Emphasis> and <Emphasis Type="Italic">Scenedesmus quadricauda</Emphasis> and their possible significance in the aquatic ecosystem

Toxic cyanobacteria occur worldwide in aquatic ecosystem, and their toxins have adverse effects on most aquatic organisms. However, some species of green algae can grow and flourish at environmentally relevant concentrations of microcystins (MCYSTs). Therefore, the present study aimed to investigate the possible adaptive response of two representatives of green algae, Chlorella vulgaris and Scenedesmus quadricauda to these toxins. Growth and antioxidative biomarkers of these algae were studied over a 14-day exposure to different concentrations of pure microcystin-LR (MCYST-LR) and crude MCYSTs. Both pure and crude MCYSTs significantly decreased the growth of the two algae compared to control cultures during the first 3 days of incubation. Meanwhile, increases in glutathione-S-transferase (GST), glutathione peroxidase (GPX) and lipid peroxidation, and decreases in glutathione (GSH) were also observed in toxin-treated cultures. All growth and biochemical variables were restored to control levels after 3 days of incubation and remained at levels near to those of control cultures during the remaining period of experiment. The changes in these variables correlated with polysaccharide contents of toxin-treated cultures, indicating the involvement of these polysaccharides in protecting the algal cells against MCYST-induced oxidative stress. The results of in vitro assay of antioxidant activity revealed that these polysaccharides had different activities, depending on their sulfate contents. This study provides an evidence for the first time that polysaccharides play a protective role in some microalgae against MCYST-induced oxidative stress.     

Development of a selective S1P1 receptor agonist,Syl930, as a potential therapeutic agent for autoimmune encephalitis

Sphingosine-1-phosphate receptor subtype 1 (S1P₁) is essential for lymphocyte egress from secondary lymphoid organs and is a validated drug target for the treatment of autoimmune disorders. However, during the preclinical and clinical trials of S1P₁ modulators, the undesired activation of S1P₃, a subtype of sphingosine 1-phosphate (S1P) receptors family, by S1P₁ modulators often results in bradycardia in patients. Thus, we designed and synthesized a new series of selective S1P₁ agonists. One of them, Syl930 (the prodrug), is preference to activate S1P₁ but not S1P₃. In this study, we further investigated the therapeutic potential of Syl930 on an experimental autoimmune encephalomyelitis (EAE) model in Lewis rats. We found that Syl930 can activate and internalize S1P₁ receptors and effectively decreased the periphery blood lymphocytes (PBL) in SD rats, and subsequently rendered PBL insensitive to egress signal from secondary lymphoid organs (SLO). Intriguingly, the treatment of Syl930 did not bring any side effect on heart rate of the tested rats. Furthermore, the suppressed PBL caused by Syl930 was able to recover within 3 days after the last dose of treatment, which is correlated to the relatively short elimination half-life of Syl930. In the rat EAE model, therapeutic treatment with Syl930 significantly inhibited the progression of EAE and EAE-associated histological changes in brain and spinal cord of Lewis rats. These results illustrate that, as a selective S1P₁ agonist, Syl930 exhibits a profound and rapidly reversible suppression of lymphocyte trafficking and it has the potential to serve as a therapeutic agent for autoimmune encephalitis.