Selective Decoating-Induced Activation of Supramolecularly Coated Toxic Nanoparticles for Multiple Applications.

In spite of the rapid emergence of numerous nanoparticles (NPs) for biomedical applications, it is often challenging to precisely control, or effectively tame, the bioactivity/toxicity of NPs, thereby exhibiting limited applications in biomedical areas. Herein, we report the construction of hyaluronic acid (HA)-laminated, otherwise toxic methylviologen (MV), NPs via ternary host-guest complexation among cucurbit[8]uril, trans-azobenzene-conjugated HA, and MV-functionalized polylactic acid NPs (MV-NPs). The high, nonspecific toxicity of MV-NPs was effectively shielded (turned off) by HA lamination, as demonstrated in cells, zebrafish, and mouse models. The supramolecular host-guest interaction-mediated HA coating offered several HA-MV-NP modalities, including hyaluronidase locally and photoirradiation remotely, to precisely remove HA lamination on demand, thereby endowing materials with the capability of selective decoating-induced activation (DIA) for applications as a user-friendly herbicide, a selective antibacterial agent, or an anticancer nanomedicine. This work offers facile supramolecular coating and DIA strategies to effectively tame and precisely control the bioactivity and toxicity of functional nanomaterials for diverse applications.

Susceptibility of larval zebrafish to the seizurogenic activity of GABA type A receptor antagonists.

Previous studies demonstrated that pentylenetetrazole (PTZ), a GABA type A receptor (GABAAR) antagonist, elicits seizure-like phenotypes in larval zebrafish (Danio rerio). Here, we determined whether the GABAAR antagonists, tetramethylenedisulfotetramine (TETS) and picrotoxin (PTX), both listed as credible chemical threat agents, similarly trigger seizures in zebrafish larvae. Larvae of three, routinely used laboratory zebrafish lines, Tropical 5D, NHGRI and Tupfel long fin, were exposed to varying concentrations of PTZ (used as a positive control), PTX or TETS for 20 min at 5 days post fertilization (dpf). Acute exposure to PTZ, PTX or TETS triggered seizure behavior in the absence of morbidity or mortality. While the concentration-effect relationship for seizure behavior was similar across zebrafish lines for each GABAAR antagonist, significantly less TETS was required to trigger seizures relative to PTX or PTZ. Recordings of extracellular field potentials in the optic tectum of 5 dpf Tropical 5D zebrafish confirmed that all three GABAAR antagonists elicited extracellular spiking patterns consistent with seizure activity, although the pattern varied between chemicals. Post-exposure treatment with the GABAAR positive allosteric modulators (PAMs), diazepam, midazolam or allopregnanolone, attenuated seizure behavior and activity but did not completely normalize electrical field recordings in the optic tectum. These data are consistent with observations of seizure responses in mammalian models exposed to these same GABAAR antagonists and PAMs, further validating larval zebrafish as a higher throughput-screening platform for antiseizure therapeutics, and demonstrating its appropriateness for identifying improved countermeasures for TETS and other convulsant chemical threat agents that trigger seizures via GABAAR antagonism.

Activity of the sesquiterpene lactone goyazensolide against Trypanosoma cruzi in vitro and in vivo.

BACKGROUND: The current drugs for Chagas disease treatment present several limitations. METHODS: The sesquiterpene lactone goyazensolide (GZL) was evaluated regarding to cytotoxicity and trypanocidal activity against amastigotes, selectivity index (SI) in vitro, acute toxicity and anti-Trypanosoma cruzi activity in vivo. RESULTS: The in vitro cytotoxicity in H9c2 cells was observed at doses >250 ng mL-1 of GZL and the SI were of 52.82 and 4.85 (24 h) and of 915.00 and 41.00 (48 h) for GZL and BZ, respectively. Nephrotoxicity and hepatotoxicity were not verified. Treatment with GZL of mice infected with CL strain led to a significant decrease of parasitaemia and total survival at doses of 1 and 3 mg kg-1 day-1 by oral and IV, respectively. This last group cured 12.5% of the animals (negativation of HC, PCR, qPCR and ELISA). Animals infected with Y strain showed significant decrease of parasitaemia and higher negativation in all parasitological tests in comparison to BZ and control groups, but were ELISA reactive, as well as the BZ group, but mice treated with 5.0 mg kg-1 day-1 by oral were negative in parasitological tests and survived. CONCLUSION: GZL was more active against T. cruzi than benznidazole in vitro and presented important therapeutic activity in vivo in both T. cruzi strains.

Uleine Disrupts Key Enzymatic and Non-Enzymatic Biomarkers that Leads to Alzheimer's Disease.

BACKGROUND: Alzheimer´s disease, a progressive and degenerative disorder of the brain, is the most common cause of dementia among the elderly. To face its multifactorial nature, the use of single compounds that can simultaneously modulate different targets involved in the neurodegenerative cascade has emerged as an interesting therapeutic approach. OBJECTIVE: This work investigated the ability of uleine, the major indole alkaloid purified from stem barks of the Brazilian medicinal plant Himatanthus lancifolius, to interact with crucial Alzheimer´s disease disruptive targets associated with two of its major neurodegenerative pathways: acetylcholinesterase and butyrylcholinesterase (cholinergic pathway) and ß-secretase and ß-amyloid peptide (amyloidogenic pathway). METHODS: Uleine's capacity to inhibit human acetylcholinesterase and butyrylcholinesterase enzymes was determined measuring the difference between reaction rates with and without uleine monitored at 412 nm using 5,5'- dithiobis-(2- nitrobenzoic acid) as colorimetric agent. FRET based assay was used to evaluate ß-secretase inhibition using DABCYL- Ser-Glu-Val-Asn-Leu-Asp-Ala-Glu-Phe-EDANS as substrate and ß-amyloid peptide spontaneous aggregation assay was performed using the thioflavin T spectroscopy assay. Cell viability and toxicity experiments with PC12 and SH-SY5Y cell lines were performed using the MTT colorimetric assay. RESULTS: Uleine demonstrated strong inhibitory activities for both cholinesterases (IC50 279.0±4.5 and 24.0±1.5 µM, respectively) and ß-secretase (IC50 180±22 nM). Above all, uleine significantly inhibited the self-aggregation of amyloid- ß peptide and was not toxic for PC12 or SH-SY5Y neuronal cells. CONCLUSION: These data show for the first time that the natural compound uleine has a novel, multieffective ability to decelerate or even inhibit the development of Alzheimer´s disease.

Comparison of Pharmacological Potency and Safety of Glutamate Blocker IEM-1913 and Memantine.

Adamantane-containing glutamate blocker IEM-1913 (1-amino-4-(1-adamantane-amino)-butane dihydrochloride) equals to memantine in antiparkinsonian potency, but surpasses it in anticonvulsive, antidepressant, and analgesic activities. Moreover, its use is less toxic and safer. IEM-1913 produces significant pharmacological effects at a wide concentration diapason (0.03-1.00 mg/kg), while memantine is effective within a narrow range only (15-20 mg/kg). High pharmacological efficacy and low toxicity of IEM-1913 can be explained by the fact that in contrast to monocationic selective NMDA antagonist memantine, the dicationic glutamate blocker IEM-1913 produces a combined block of cerebral NMDA and AMPA receptors.

[Primary safety evaluation of sulfated paeoniae radix alba].

The paper is to report the development of a method of quantitative analysis of multi-components by high performance liquid chromatography (HPLC) for simultaneously determining paeoniflorin sulfonate (PS), paeoniflorin (PF) and albiflorin (AF) in sulfated Paeoniae Radix Alba. Moreover, the cytotoxicity of paeoniflorin sulfonate by MTT-assay and the acute toxicity of mice by administration of paeoniflorin sulfonate were evaluated. Chromatographic separation of paeoniflorin sulfonate, PF and AF were performed on a SHISEIDO CAPCELL PAK C18 column (250 mm x 4.6 mm, 5 microm) for HPLC and a mixture of acetonitrile and 0.02% phosphoric acid solution (15 : 85) as the mobile phase. As detector a spectrophotometer set at 230 nm; column temperature 30 degrees C; flow rate 1.0 mL x min(-1). The toxicity of paeoniflorin sulfonate was evaluated by in vitro cytotoxicity carried out on mouse and human primary hepatocytes, and by acute oral toxicity test carried out on mice. The calibration curve of paeoniflorin sulfonate, PF and AF revealed linearity in the range of 0.041 8 - 1.045 0, 0.023 5 - 0.587 5, and 0.039 8 - 0.995 0 mg x mL(-1), respectively (r > 0.999 8). The average recovery was ranged from 99.11% to 101.71%, RSD < 2%. Paeoniflorin sulfonate does not have any cytotoxicity to cells at all the tested concentrations (< or = 300 micromol x L(-1)) in the in vitro cytotoxicity assay. The maximum tolerance dose of paeoniflorin sulfonate solution and extraction of Paeoniae Radix Alba to mouse is 5 g x kg(-1) and 80 g x kg(-1) respectively. The contents of these three components in the samples were determined with the developed method. It is a rapid, convenient and accurate method to determine multi-components. The content of PF in sulfated Paeoniae Radix Alba is significantly lower, and there is negative correlationship between the content of paeoniflorin sulfonate and PF. The in vitro cytotoxicity assay and in vivo mouse acute toxicity test showed that there is no obvious toxicity of paeoniflorin sulfonate and water-soluble extract of sulfated Paeoniae Radix Alba.

Toxicity of cucurbit[7]uril and cucurbit[8]uril: an exploratory in vitro and in vivo study.

Cucurbit[n]urils (CB[n]) are potential stabilizing, solubilizing, activating, and delivering agents for drugs. The toxicity of the macrocyclic host molecules cucurbit[7]uril (CB[7]), the most water-soluble homologue, as well as cucurbit[8]uril (CB[8]) has been evaluated. In vitro studies on cell cultures revealed an IC(50) value of 0.53 +/- 0.02 mM for CB[7], corresponding to around 620 mg of CB[7] per kg of cell material. Live-cell imaging studies performed on cells treated with subtoxic amounts of CB[7] showed no detrimental effects on the cellular integrity as assessed by mitochondrial activity. For CB[8], no significant cytotoxicity was observed within its solubility range. The bioadaptability of the compounds was further examined through in vivo studies on mice, where intravenous administration of CB[7] showed a maximum tolerated dosage of 250 mg kg(-1), while oral administration of a CB[7]/CB[8] mixture showed a tolerance of up to 600 mg kg(-1). The combined results indicate a sufficiently low toxicity to encourage further exploration of CB[n] as additives for medicinal and pharmaceutical use.

Tetramethylenedisulfotetramine: old agent and new terror.

Tetramethylenedisulfotetramine has accounted for numerous intentional and unintentional poisonings in China. In May 2002, the first known case of human illness in the United States caused by tetramethylenedisulfotetramine, a banned neurotoxic rodenticide from China, occurred in New York City. The clinical presentation after tetramethylenedisulfotetramine exposure is dose dependent, and the most recognized complication is status epilepticus. Poisonings may be fatal within hours. No known antidote exists, and treatment is mainly supportive. Anecdotal reports, case reports, and 2 animal studies suggest possible success with certain pharmacologic interventions, including pyridoxine and chelation therapy. Pesticide and rodenticide poisonings, whether intentional or unintentional, pose a serious threat to populations, and the availability of a banned rodenticide such as tetramethylenedisulfotetramine, with its associated morbidity and lethality, is a serious public health concern. Given the recent case report that confirms the presence of tetramethylenedisulfotetramine in the United States, the toxicity of the compound, its unique physical properties, the absence of an antidote, and the history of its use as an agent of intentional mass poisoning, public health entities have undertaken educational efforts to inform the public, health care providers, and emergency personnel of this potentially lethal rodenticide.

Drug evaluation: Bay-59-8862.

Bayer Corp, under license from Indena SpA, is developing BAY-59-8862, a taxane synthesized from 14beta-hydroxy-10-deacetylbaccatin III, for the potential treatment of cancer.

Taxane-based reversal agents modulate drug resistance mediated by P-glycoprotein, multidrug resistance protein, and breast cancer resistance protein.

Overexpression of ATP-binding cassette transport proteins, including P-glycoprotein (Pgp), multidrug resistance (MDR) protein (MRP-1), and breast cancer resistance protein (BCRP), is a well-characterized mechanism of MDR in tumor cells. Although the cytotoxic taxanes paclitaxel and docetaxel are substrates for Pgp-mediated efflux, the semisynthetic taxane analogue ortataxel inhibits drug efflux mediated by Pgp as well as, as we recently demonstrated, MRP-1 and BCRP. Nevertheless, ortataxel is not optimal for development as a clinical MDR modulator because of its cytotoxicity [corrected]. We sought to identify noncytotoxic taxane-based broad-spectrum modulators from a library of noncytotoxic taxane-based reversal agents (tRAs) designed by eliminating the C-13 side chain of the taxane molecule, which inhibits microtubule depolymerization. Twenty tRAs, selected based on modulation of paclitaxel cytotoxicity in Pgp-overexpressing MDA435/LCC6(mdr1) cells, were studied for modulation of retention and cytotoxicity of substrates of MRP-1 and BCRP as well as Pgp in established cell lines overexpressing each of these transporters. Four tRAs modulated MRP-1 and 17 modulated BCRP in addition to Pgp. The four broad-spectrum tRAs strongly modulated daunorubicin and mitoxantrone efflux and enhanced their cytotoxicity in cell lines overexpressing the three MDRs, decreasing IC(50) values by as much as 97% [corrected]. These tRAs, especially tRA 98006, have promise for development as clinical broad-spectrum MDR modulators and warrant more preclinical analysis to determine pharmacokinetic interactions and efficacy.

An evaluation of toxicity of Taxus baccata Linn. (Talispatra) in experimental animals.

A toxicological study was performed in albino mice and rat with methanolic extract and isolated alkaloid of Taxus baccata Linn. (family: Taxaceae). LD(50) study showed the higher toxic activity in stem (TXA-1,2,3) as compared with leaf (TXB-1,2,3) extract. As the extract were further fractionated into crude alkaloids and purified by chromatography the toxicity of these fractions were found to be in increasing order as follows: methanolic extract (1) < crude alkaloidal fraction (2) < purified alkaloidal fraction (3). The effects of leaf and stem extract of T. baccata were studied on certain biochemical and haematological parameters of mice and rat after 10, 20 and 30 days of exposure. Among the parameters examined, the exposed animal exhibited significant decrease in total leukocyte count (TLC), lymphocytes and cholesterol level (mg/dl), whereas increase was observed in serum transminases (SGOT, SGPT) and alkaline phosphatase (AP) of TXA-1 and TXB-1 treated groups indicating toxic conditions associated due to liver involvement.

The preclinical pharmacological profile of WAY-132983, a potent M1 preferring agonist.

Muscarinic M1 preferring agonists may improve cognitive deficits associated with Alzheimer's disease. Side effect assessment of the M1 preferring agonist WAY-132983 showed significant salivation (10 mg/kg i.p. or p.o.) and produced dose-dependent hypothermia after i. p. or p.o. administration. WAY-132983 significantly reduced scopolamine (0.3 mg/kg i.p.)-induced hyperswimming in mice. Cognitive assessment in rats used pretrained animals in a forced choice, 1-h delayed nonmatch-to-sample radial arm maze task. WAY-132983 (0.3 mg/kg i.p) significantly reduced scopolamine (0.3 mg/kg s.c.)-induced errors. Oral WAY-132983 attenuated scopolamine-induced errors; that is, errors produced after combining scopolamine and WAY-132983 (to 3 mg/kg p.o.) were not significantly increased compared with those of vehicle-treated control animals, whereas errors after scopolamine were significantly higher than those of control animals. With the use of miniosmotic pumps, 0.03 mg/kg/day (s.c.) WAY-132983 significantly reduced AF64A (3 nmol/3 microliter/lateral ventricle)-induced errors. Verification of AF64A cholinotoxicity showed significantly lower choline acetyltransferase activity in the hippocampi of AF64A-treated animals, with no significant changes in the striatal or frontal cortex. Cognitive assessment in primates involved the use of pretrained aged animals in a visual delayed match-to-sample procedure. Oral WAY-132983 significantly increased the number of correct responses during short and long delay interval testing. These effects were also apparent 24 h after administration. WAY-132983 exhibited cognitive benefit at doses lower than those producing undesirable effects; therefore, WAY-132983 is a potential candidate for improving the cognitive status of patients with Alzheimer's disease.