In Vitro Antioxidant Activity of Litsea martabanica Root Extract and Its Hepatoprotective Effect on Chlorpyrifos-Induced Toxicity in Rats.

In Thailand, people in the highland communities whose occupational exposure to pesticides used the root of Litsea martabanica as a detoxifying agent. However, the scientific data to support the traditional use of this plant are insufficient. This study aimed to evaluate the antioxidant activity and anti-pesticide potential of L. martabanica root extract. Antioxidant properties were investigated by 2,2'-diphenyl-1-picrylhydrazyl (DPPH) assay, superoxide radicals scavenging assay, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay, ferric reducing antioxidant power (FRAP), and total phenolic content determination. In all assays, L. martabanica extracts and their fractions exhibited high antioxidant activities differently. The water extract is traditionally used as a detoxifying agent. Therefore, it was chosen for in vivo experiments. The rats received the extract in a way that mimics the traditional methods of tribal communities followed by chlorpyrifos for 16 days. The results showed that acetylcholinesterase activity decreases in pesticide-exposed rats. Treatment with the extract caused increasing acetylcholinesterase activity in the rats. Therefore, L. martabanica extract may potentially be used as a detoxifying agent, especially for the chlorpyrifos pesticide. The antioxidant properties of L. martabanica may provide a beneficial effect by protecting liver cells from damage caused by free radicals. Histopathology results revealed no liver cell necrosis and showed the regeneration of liver cells in the treatment group. L. martabanica extract did not cause changes in behavior, liver weight, hematological and biochemical profiles of the rats.

Chemotaxonomy of the ethnic antidote Aristolochia indica for aristolochic acid content: Implications of anti-phospholipase activity and genotoxicity study.

ETHNOPHARMACOLOGICAL RELEVANCE: Aristolochia indica L. (Aristolochiaceae) is a common medicinal plant described in many traditional medicine as well as in Ayurveda used against snakebites. Besides, the plant has also been reported traditionally against fever, rheumatic arthritis, madness, liver ailments, dyspepsia, oedema, leishmaniasis, leprosy, dysmenorrhoea, sexual diseases etc. The plant is known to contain its major bioactive constituent aristolochic acid (AA) known for its anti-snake venom, abortifacient, antimicrobial and antioxidant properties. MATERIALS AND METHODS: This present work describes a validated, fast and reproducible high performance thin layer chromatography (HPTLC) method to estimate AA from the roots of 20 chemotypes of A. indica procured from 20 diverse geographical locations from the state of West Bengal, India. Further, an evidence-based approach was adopted to investigate the reported anti-venom activity of the aqueous extracts of the A. indica roots by assessing its phospholipase A2 (PLA2) inhibitory properties since PLA2 is a major component of many snake-venoms. Finally, the cytotoxicity and genotoxicity of the aqueous root extract of the Purulia (AI 1) chemotype were assessed at various concentrations using Allium cepa root meristematic cells. RESULTS: The highest amount of AA (7643.67 µg/g) was determined in the roots of A. indica chemotype collected from Purulia district followed by the chemotypes collected from Murshidabad, Jalpaiguri and Birbhum districts (7398.34, 7345.09 and 6809.97 µg/g respectively). This study not only determines AA in the plants to select pharmacologically elite chemotypes of A. indica, but it also identifies high AA producing A. indica for further domestication and propagation of the plants for pharmacological and industrial applications. The method was validated via analyzing inter-day and intra-day precision, repeatability, reproducibility, instrumental precision, limit of detection (LOD) and limit of quantification (LOQ) and specificity. Chemotypes with high AA content exhibited superior anti-PLA2 activity by selectively inhibiting human-group PLA2. Moreover, A. indica root extract significantly inhibited mitosis in Allium cepa root tips as a potent clastogen. CONCLUSIONS: The present quick, reproducible and validated HPTLC method provides an easy tool to determine AA in natural A. indica plant populations as well as in food and dietary supplements, a potential antivenin at one hand and a possible cause of aristolochic acid nephropathy (AAN) at another. Besides, the cytotoxic and mitotoxic properties of the root extracts should be used with caution especially for oral administration.

Milk thistle (Silybum Marianum) as an antidote or a protective agent against natural or chemical toxicities: a review.

Biological and chemical agents cause dangerous effects on human health via different exposing ways. Recently, herbal medicine is considered as a biological and safe treatment for toxicities. Silybum marianum (milk thistle), belongs to the Asteraceae family, possesses different effects such as hepatoprotective, cardioprotective, neuroprotective, anti-inflammatory and anti-carcinogenic activities. Several studies have demonstrated that this plant has protective properties against toxic agents. Herein, the protective effects of S. marianum and its main component, silymarin, which is the mixture of flavonolignans including silibinin, silydianin and silychristin acts against different biological (mycotoxins, snake venoms, and bacterial toxins) and chemical (metals, fluoride, pesticides, cardiotoxic, neurotoxic, hepatotoxic, and nephrotoxic agents) poisons have been summarized. This review reveals that main protective effects of milk thistle and its components are attributed to radical scavenging, anti-oxidative, chelating, anti-apoptotic properties, and regulating the inflammatory responses.

Medicinal plants and natural products in amelioration of arsenic toxicity: a short review.

CONTEXT: Chronic arsenic toxicity (arsenicosis) is considered a serious public health menace worldwide, as there is no specific, safe, and efficacious therapeutic management of arsenicosis. OBJECTIVES: To collate the studies on medicinal plants and natural products with arsenic toxicity ameliorative effect, active pre-clinically and/or clinically. METHODS: Literature survey was carried out by using Google, Scholar Google and Pub-Med. Only the scientific journal articles found on the internet for last two decades were considered. Minerals and semi-synthetic or synthetic analogs of natural products were excluded. RESULTS: Literature study revealed that 34 medicinal plants and 14 natural products exhibited significant protection from arsenic toxicity, mostly in preclinical trials and a few in clinical studies. CONCLUSION: This research could lead to development of a potentially useful agent in clinical management of arsenicosis in humans.

Determination of dimethyl trisulfide in rabbit blood using stir bar sorptive extraction gas chromatography-mass spectrometry.

Cyanide poisoning by accidental or intentional exposure poses a severe health risk. The current Food and Drug Administration approved antidotes for cyanide poisoning can be effective, but each suffers from specific major limitations concerning large effective dosage, delayed onset of action, or dependence on enzymes generally confined to specific organs. Dimethyl trisulfide (DMTS), a sulfur donor that detoxifies cyanide by converting it into thiocyanate (a relatively nontoxic cyanide metabolite), is a promising next generation cyanide antidote. Although a validated analytical method to analyze DMTS from any matrix is not currently available, one will be vital for the approval of DMTS as a therapeutic agent against cyanide poisoning. Hence, a stir bar sorptive extraction (SBSE) gas chromatography - mass spectrometry (GC-MS) method was developed and validated for the analysis of DMTS from rabbit whole blood. Following acid denaturation of blood, DMTS was extracted into a polydimethylsiloxane-coated stir bar. The DMTS was then thermally desorbed from the stir bar and analyzed by GC-MS. The limit of detection of DMTS using this method was 0.06µM with dynamic range from 0.5-100µM. For quality control standards, the precision, as measured by percent relative standard deviation, was below 10%, and the accuracy was within 15% of the nominal concentration. The method described here will allow further investigations of DMTS as a promising antidote for cyanide poisoning.

Pharmacological activity of Costus spicatus in experimental Bothrops atrox envenomation.

CONTEXT: Medicinal plants encompass a rich source of active compounds that can neutralize snake venoms or toxins. Costus spicatus (Jacq.) Sw. (Costaceae) is used by the Amazonian population to treat inflammation, pain and other pathological manifestations. OBJECTIVE: To evaluate the influence of C. spicatus aqueous extract on edema, peritonitis, nociception, coagulation, haemorrhage and indirect haemolytic activity induced by Bothrops atrox venom (BAV). MATERIALS AND METHODS: Dried and pulverized leaves were extracted with distilled water. Envenoming was induced by administration of B. atrox snake venom in Swiss Webster mice. The experimental groups consisted of BAV (at the minimum dose to induce measurable biological responses) and C. spicatus extract (CSE, 1.25, 2.5, 5.0, 7.5 and 10 mg/kg/25 µl phosphate-buffered saline) administered individually and in combination (BAVCSE). PBS was used as a control. In vitro assays were also conducted in order to evaluate phospholipase A2 coagulant activities (indirect haemolytic method). RESULTS: CSE significantly reduced the venom-induced edema and nociception at all concentrations tested and inhibited migration of inflammatory cells at the three least concentrations (5.0, 7.5 and 10 mg/kg/25 µl PBS). CSE was not effective in inhibiting coagulant, haemorrhagic and indirect haemolytic activities of the venom. DISCUSSION AND CONCLUSION: The data suggest that CSE could exhibit a central mechanism for pain inhibition, and may also inhibit prostaglandin synthesis. These findings corroborate the traditional administration of C. spicatus decoction to treat inflammatory disorders, including those caused by B. atrox envenomation.

Preclinical antitoxic properties of Spirulina (Arthrospira).

CONTEXT: Spirulina (Arthrospira) exerts a wide spectrum of pharmacological activities which are mainly attributed to its antioxidant effect. However, Spirulina has also been reported (both in preclinical and in clinical scenarios) to exhibit other bioactive effects, including an antitoxic potential. OBJECTIVE: We performed a systematic review of the literature, conducted in TOXNET, PubMed/MEDLINE, and Science Direct-Scopus; all available years were included. Searching criteria included the effects of Spirulina on experimental poisonings from arsenic, cadmium, carbon tetrachloride, deltamethrin, fluoride, hexachlorocyclohexane, iron, lead, lindane, and mercury. RESULTS: In all cases, it was established that the blue-green alga, and its isolated compounds, effectively counteracted these pollutants toxic effects on the exposed organisms. Some molecular mechanisms are proposed, although they have not been fully elucidated yet. CONCLUSION: Spirulina could be a useful coadjuvant agent within clinical practice for treatment of these or other pollutants poisonings.

Boletus edulis Nitrite Reductase Reduces Nitrite Content of Pickles and Mitigates Intoxication in Nitrite-intoxicated Mice.

Pickles are popular in China and exhibits health-promoting effects. However, nitrite produced during fermentation adversely affects health due to formation of methemoglobin and conversion to carcinogenic nitrosamine. Fruiting bodies of the mushroom Boletus edulis were capable of inhibiting nitrite production during pickle fermentation. A 90-kDa nitrite reductase (NiR), demonstrating peptide sequence homology to fungal nitrite reductase, was isolated from B. edulis fruiting bodies. The optimum temperature and pH of the enzyme was 45 °C and 6.8, respectively. B. edulis NiR was capable of prolonging the lifespan of nitrite-intoxicated mice, indicating that it had the action of an antidote. The enzyme could also eliminate nitrite from blood after intragastric administration of sodium nitrite, and after packaging into capsule, this nitrite-eliminating activity could persist for at least 120 minutes thus avoiding immediate gastric degradation. B. edulis NiR represents the first nitrite reductase purified from mushrooms and may facilitate subsequent applications.

In vitro exposure of Penicillium mycotoxins with or without a modified yeast cell wall extract (mYCW) on bovine macrophages (BoMacs).

Penicillium mycotoxins (PMs) are contaminants that are frequently found in grain or crop-based silage for animal feed. Previously, we have characterized the potential immunotoxicity of the following PMs: citrinin (CIT), ochratoxin A (OTA), patulin (PAT), mycophenolic acid (MPA), and penicillic acid (PA) by using a bovine macrophage cell line (BoMacs). In the present study, cell proliferation was used as a bioassay endpoint to evaluate the efficacy of a modified yeast cell wall extract (mYCW), for preventing PM toxicity under various in vitro conditions such as the following: pH (3, 5, 7), incubation time (1, 2, 4, 6 h), percentage of mYCW (0.05, 0.1, 0.2, 0.5, 1.0 %), and PM concentration. mYCW was most effective in preventing the toxicity of 12.88 and 25.8 µM OTA at pH 3.0 (p < 0.0001), regardless of incubation time (p < 0.0001) and the percentage of mYCW (p < 0.0001). An incubation time of 6 h (p < 0.05) or 0.5 and 1.0 % mYCW (p < 0.0001) significantly improved the efficacy of mYCW for preventing CIT toxicity. In contrast, 0.5 and 1.0 % of mYCW appeared to exacerbate the PAT toxicity (p < 0. 0001). This effect on PAT toxicity was constantly observed with higher PAT concentrations, and it reached significance at a concentration of 0.70 µM (p < 0.0001). mYCW had no effect on PA toxicity. These results suggest that mYCW may reduce OTA toxicity and, to some extent, CIT toxicity at pH 3.0. Although PAT toxicity was increased by mYCW treatment, PAT is readily degraded during heat treatment and may therefore be dealt with using other preventative measures.

Neutralizing effect of hemolymph from the shore crab, Thalamita crenata, on paralytic shellfish toxins.

Several species of crabs are resistant to paralytic shellfish toxins (PSTs) and/or pufferfish toxin, tetrodotoxin, regardless of toxification by the toxins. The shore crab Thalamita crenata, which inhabits Leizhou Peninsula, China, is tolerant to PST toxicity, and the hemolymph has neutralizing effects against the lethal activity of PST. In the present study, we investigated the PST neutralizing factors in the hemolymph from T. crenata and successfully separated PST-binding proteins by PST-ligand affinity chromatography. The neutralization factors, obtained in the fraction with a molecular weight over 10 kDa by ultrafiltration, were susceptible to proteases such as alcalase, animal complex proteases, pancreatin, and papain. The PST-binding protein had high dose-dependent neutralization effects on PST toxicity. The PST-binding activity of the protein was stable at 25 °C and then decreased with an increase in temperature; heating at 65 °C for 60 min eliminated the initial activity by two-thirds. The PST-binding activity was strongly inhibited in the presence of Mg(2+) and Ca(2+), but not Na(+) and K(+). The PST-binding capability of the protein differed among PST components in descending order of neosaxitoxin, gonyautoxins 1 and 4, saxitoxin, and gonyautoxins 2 and 3, suggesting a structure-activity relationship in PST binding.

Identification of a wide range of motifs inhibitory to shiga toxin by affinity-driven screening of customized divalent peptides synthesized on a membrane.

Shiga toxin (Stx), a major virulence factor of enterohemorrhagic Escherichia coli, binds to target cells through a multivalent interaction between its B-subunit pentamer and the cell surface receptor globotriaosylceramide, resulting in a remarkable increase in its binding affinity. This phenomenon is referred to as the "clustering effect." Previously, we developed a multivalent peptide library that can exert the clustering effect and identified Stx neutralizers with tetravalent peptides by screening this library for high-affinity binding to the specific receptor-binding site of the B subunit. However, this technique yielded only a limited number of binding motifs, with some redundancy in amino acid selectivity. In this study, we established a novel technique to synthesize up to 384 divalent peptides whose structures were customized to exert the clustering effect on the B subunit on a single cellulose membrane. By targeting Stx1a, a major Stx subtype, the customized divalent peptides were screened to identify high-affinity binding motifs. The sequences of the peptides were designed based on information obtained from the multivalent peptide library technique. A total of 64 candidate motifs were successfully identified, and 11 of these were selected to synthesize tetravalent forms of the peptides. All of the synthesized tetravalent peptides bound to the B subunit with high affinities and effectively inhibited the cytotoxicity of Stx1a in Vero cells. Thus, the combination of the two techniques results in greatly improved efficiency in identifying biologically active neutralizers of Stx.

Aqueous leaf extract of Jatropha gossypiifolia L. (Euphorbiaceae) inhibits enzymatic and biological actions of Bothrops jararaca snake venom.

Snakebites are a serious public health problem due their high morbi-mortality. The main available specific treatment is the antivenom serum therapy, which has some disadvantages, such as poor neutralization of local effects, risk of immunological reactions, high cost and difficult access in some regions. In this context, the search for alternative therapies is relevant. Therefore, the aim of this study was to evaluate the antiophidic properties of Jatropha gossypiifolia, a medicinal plant used in folk medicine to treat snakebites. The aqueous leaf extract of the plant was prepared by decoction and phytochemical analysis revealed the presence of sugars, alkaloids, flavonoids, tannins, terpenes and/or steroids and proteins. The extract was able to inhibit enzymatic and biologic activities induced by Bothrops jararaca snake venom in vitro and in vivo. The blood incoagulability was efficiently inhibited by the extract by oral route. The hemorrhagic and edematogenic local effects were also inhibited, the former by up to 56% and the latter by 100%, in animals treated with extract by oral and intraperitoneal routes, respectively. The inhibition of myotoxic action of B. jararaca reached almost 100%. According to enzymatic tests performed, it is possible to suggest that the antiophidic activity may be due an inhibitory action upon snake venom metalloproteinases (SVMPs) and/or serine proteinases (SVSPs), including fibrinogenolytic enzymes, clotting factors activators and thrombin like enzymes (SVTLEs), as well upon catalytically inactive phospholipases A2 (Lys49 PLA2). Anti-inflammatory activity, at least partially, could also be related to the inhibition of local effects. Additionally, protein precipitating and antioxidant activities may also be important features contributing to the activity presented. In conclusion, the results demonstrate the potential antiophidic activity of J. gossypiifolia extract, including its significant action upon local effects, suggesting that it may be used as a new source of bioactive molecules against bothropic venom.

Use of OpdA, an organophosphorus (OP) hydrolase, prevents lethality in an African green monkey model of acute OP poisoning.

Organophosphorus (OP) pesticides are a diverse class of acetylcholinesterase (AChE) inhibitors that are responsible for tremendous morbidity and mortality worldwide, killing approximately 300,000 people annually. Enzymatic hydrolysis of OPs is a potential therapy for acute poisoning. OpdA, an OP hydrolase isolated from Agrobacterium radiobacter, has been shown to decrease lethality in rodent models of OP poisoning. This study investigated the effects of OpdA on AChE activity, plasma concentrations of OP, and signs of toxicity after administration of dichlorvos to nonhuman primates. A dose of 75 mg/kg dichlorvos given orally caused apnea within 10 min with a progressive decrease in heart rate. Blood AChE activity decreased to zero within 10 min. Respirations and AChE activity did not recover. The mean dichlorvos concentration rose to a peak of 0.66 µg/ml. Treated monkeys received 1.2mg/kg OpdA iv immediately after poisoning with dichlorvos. In Opda-treated animals, heart and respiratory rates were unchanged from baseline over a 240-minute observation period. AChE activity slowly declined, but remained above 25% of baseline for the entire duration. Dichlorvos concentrations reached a mean peak of 0.19 µg/ml at 40 min after poisoning and decreased to a mean of 0.05 µg/ml at 240 min. These results show that OpdA hydrolyzes dichlorvos in an African green monkey model of lethal poisoning, delays AChE inhibition, and prevents lethality.

Prophylactic and therapeutic effects of garlic extract on Nerium oleander-induced arrhythmia: a new approach to antiarrhythmic therapy in an ovine model.

CONTEXT: Oleander is a potent cardiotoxic plant and is a common cause of poisoning in human and animals. There is no affordable and cost-effective treatment for oleander poisoning. Objective. To evaluate the prophylactic and therapeutic effects of garlic extract (Allium sativum) on Nerium oleander (a potent cardiotoxic plant) intoxication in sheep. MATERIALS AND METHODS: Eight sheep were intravenously infused with an unsterilized hydro-ethanol extract of garlic (50 mg/kg) before or after receiving a lethal dose of dried leaves (as a powder) of oleander (100 mg/kg, orally). The cardiac rhythm was continuously monitored using biopotential wireless transmitters and telemetry system. For evaluation of therapeutic effects, six sheep received the lethal dose of oleander and were administered with garlic extract after development of cardiac arrhythmias. Subsequently, the survived animals from the therapeutic study (four sheep) were administered with oleander without receiving any medication. Some blood constituents, including total antioxidant capacity, malondialdehyde, and troponin I, were compared between treated and untreated animals. RESULTS: Pretreatment with garlic extract reversed the arrhythmia caused by oleander to its previous normal rhythm in seven sheep, but, one sheep died of ventricular fibrillation. On therapeutic treatment, four sheep survived while two died of ventricular fibrillation. Dosing with oleander without receiving garlic extract resulted in death of all sheep due to ventricular fibrillation. Blood constituents did not show any significant changes between treated and untreated sheep, and before and after intoxication. CONCLUSIONS: Garlic extract reduced the case fatality from 100% to 12.5% and 33.3% as a prophylactic or therapeutic agent, respectively. Additionally, garlic extract delayed the time of onset of arrhythmias and prolonged the interval between intoxication and death of the animals. Garlic extract could be considered to be a potential and affordable antidote in oleander poisoning. However additional studies with a larger sample size and in other species need to be performed to confirm the results in this study.

Antioxidant, hepatoprotective and hypolipidemic effects of methanolic root extract of Cassia singueana in rats following acute and chronic carbon tetrachloride intoxication.

OBJECTIVE: To evaluate in vivo antioxidant and hepatoprotective activities of the methanolic extract of the root of Cassia singueana in rats following acute and chronic carbon tetrachloride intoxication. METHODS: Malondialdehyde (MDA), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and bilirubin as indices of liver damage and lipid peroxidation were detected in rats after intraperitoneal administration of extract (5 mg/kg). RESULTS: The liver, kidney and heart showed significant reduction (P<0.05) in the levels of MDA from (0.18±0.04), (0.23±0.07) and (0.26±0.10) nmol/mg respectively in the CCl4 control to (0.15±0.03), (0.17±0.04) and (0.17±0.07) nmol/mg protein in groups pre-treated with the extract for three days at 5 mg/kg). Similarly, compared to the CCl4 control, significant reduction (P<0.05) in serum AST, ALT and bilirubin as well as in level of total cholesterol and MDA with concomitant increase in HDL cholesterol, superoxide dismutase and catalase levels when CCl4-intoxicated rats were treated with Cassia singueana root extract for two weeks. CONCLUSIONS: These results suggest that methanolic extract of Cassia singueana contain potent antioxidant compounds that can offer significant protection against hepatic and oxidative injuries.

A specific antidote for dabigatran: functional and structural characterization.

Dabigatran etexilate is a direct thrombin inhibitor and used widely as an anticoagulant for the prevention of stroke in patients with atrial fibrillation. However, anticoagulation therapy can be associated with an increased risk of bleeding. Here, we present data on the identification, humanization, and in vitro pharmacology of an antidote for dabigatran (aDabi-Fab). The X-ray crystal structure of dabigatran in complex with the antidote reveals many structural similarities of dabigatran recognition compared with thrombin. By a tighter network of interactions, the antidote achieves an affinity for dabigatran that is ~350 times stronger than its affinity for thrombin. Despite the structural similarities in the mode of dabigatran binding, the antidote does not bind known thrombin substrates and has no activity in coagulation tests or platelet aggregation. In addition we demonstrate that the antidote rapidly reversed the anticoagulant activity of dabigatran in vivo in a rat model of anticoagulation. This is the first report of a specific antidote for a next-generation anticoagulant that may become a valuable tool in patients who require emergency procedures.

Antidotes, antibody-mediated immunity and the future of pharmaceutical product development.

If new scientific knowledge is to be more efficiently generated and applied toward the advancement of health, human safety must be more effectively addressed in the conduct of research. Given the present difficulties of accurately predicting biological outcomes of novel interventions in vivo, the imperative of human safety suggests the development of novel pharmaceutical products in tandem with their prospective antidotes in anticipation of possible adverse events, to render the risks of initial clinical trials more acceptable from a regulatory standpoint. Antibody-mediated immunity provides a generally applicable mechanistic basis for developing antidotes to both biologicals and small-molecule drugs (such that antibodies may serve as antidotes to pharmaceutical agents as a class including other antibodies) and also for the control and prevention of both infectious and noninfectious diseases via passive or active immunization. Accordingly, the development of prophylactic or therapeutic passive-immunization strategies using antipeptide antibodies is a plausible prelude to the development of corresponding active-immunization strategies using peptide-based vaccines. In line with this scheme, global proliferation of antibody- and vaccine-production technologies, especially those that obviate dependence on the cold chain for storage and transport of finished products, could provide geographically distributed breakout capability against emerging and future health challenges.

Identification and characterization of novel catalytic bioscavengers of organophosphorus nerve agents.

In an effort to discover novel catalytic bioscavengers of organophosphorus (OP) nerve agents, cell lysates from a diverse set of bacterial strains were screened for their capacity to hydrolyze the OP nerve agents VX, VR, and soman (GD). The library of bacterial strains was identified using both random and rational approaches. Specifically, two representative strains from eight categories of extremophiles were chosen at random. For the rational approach, the protein sequence of organophosphorus hydrolase (OPH) from Brevundimonas diminuta was searched against a non-redundant protein database using the Basic Local Alignment Search Tool to find regions of local similarity between sequences. Over 15 protein sequences with significant sequence similarity to OPH were identified from a variety of bacterial strains. Some of these matches were based on predicted protein structures derived from bacterial genome sequences rather than from bona fide proteins isolated from bacteria. Of the 25 strains selected for nerve agent testing, three bacterial strains had measurable levels of OP hydrolase activity. These strains are Ammoniphilus oxalaticus, Haloarcula sp., and Micromonospora aurantiaca. Lysates from A. oxalaticus had detectable hydrolysis of VR; Haloarcula sp. had appreciable hydrolysis of VX and VR, whereas lysates from M. aurantiaca had detectable hydrolysis of VR and GD.

Strategies for the selection of catalytic antibodies against organophosphorus nerve agents.

Among the strategies aimed at biocompatible means for organophosphorus nerve agents neutralization, immunoglobulins have attracted attention in the 1990's and 2000's both for their ability to immobilize the toxicants, but also for their ability to be turned into enzymatically active antibodies known as catalytic antibodies or abzymes (antibodies--enzymes). We will present here a critical review of the successive strategies used for the selection of these nerve agent-hydrolyzing abzymes, based on hapten design, namely antibodies raised against a wide variety of transition state analogs, and eventually the strategies based on anti-idiotypic antibodies and reactibodies.

Effects of Tamarind (Tamarindus indicus Linn) seed extract on Russell's viper (Daboia russelli siamensis) venom.

Snake bite has been regarded as an important health problem in Myanmar since early 1960's. In the recent years, there has been growing interest in alternative therapies and therapeutic use of natural products, especially those derive from plants. In Myanmar and Indian traditional medicine, various plants have used as a remedy for treating snake bite. The present study was carried out to evaluate the effects of alcohol extract of Tamarind (Tamarindus indica Linn.) seed on some biologic properties of Russell's viper (Daboia russelli siamensis) venom (RVV). The Phospholipase A2 (PLA2) enzyme, coagulase enzyme and caseinolytic enzyme activities of Russell's viper venom (RVV) were reduced when mixed and incubated with the extract. When the RVV and the different amount of extracts were preincubated and injected intramuscularly into mice, all of them survived, but all the mice in the control group died. On the other hand, when RVV were injected first followed by the extract into mice, all of them died. If the extract was injected near the site where Russell's viper venom was injected, all the mice survived for more than 24 hours and the survival time prolonged but they all died within 96 hours. In conclusion, according to the results obtained, the extract neutralizes some biologic properties of the Russell's viper venom and prolonged the survival time if the extract was injected near the site where the Russell's viper venom was injected.