A new rat model of acute seizures induced by tutin

The toxic natural product tutin causes epileptic seizures in mice by activating calcineurin

Tutin, an established toxic natural product that causes epilepsy in rodents, is often used as a tool to develop animal model of acute epileptic seizures. However, the molecular target and toxic mechanism of tutin were unclear. In this study, for the first time, we conducted experiments to clarify the targets in tutin-induced epilepsy using thermal proteome profiling. Our studies showed that calcineurin (CN) was a target of tutin, and that tutin activated CN, leading to seizures. Binding site studies further established that tutin bound within the active site of CN catalytic subunit. CN inhibitor and calcineurin A (CNA) knockdown experiments in vivo proved that tutin induced epilepsy by activating CN, and produced obvious nerve damage. Together, these findings revealed that tutin caused epileptic seizures by activating CN. Moreover, further mechanism studies found that N-methyl-D-aspartate (NMDA) receptors, gamma-aminobutyric acid (GABA) receptors and voltage- and Ca²⁺- activated K⁺ (BK) channels might be involved in related signaling pathways. Our study fully explains the convulsive mechanism of tutin, which provides new ideas for epilepsy treatment and drug development.

Insight into Drug Resistance in Status Epilepticus: Evidence from Animal Models

Status epilepticus (SE), a condition with abnormally prolonged seizures, is a severe type of epilepsy. At present, SE is not well controlled by clinical treatments. Antiepileptic drugs (AEDs) are the main therapeutic approaches, but they are effective for SE only with a narrow intervening window, and they easily induce resistance. Thus, in this review, we provide an updated summary for an insight into drug-resistant SE, hoping to add to the understanding of the mechanism of refractory SE and the development of active compounds. Firstly, we briefly outline the limitations of current drug treatments for SE by summarizing the extensive experimental literature and clinical data through a search of the PubMed database, and then summarize the common animal models of refractory SE with their advantages and disadvantages. Notably, we also briefly review some of the hypotheses about drug resistance in SE that are well accepted in the field, and furthermore, put forward future perspectives for follow-up research on SE.

Picrotoxane sesquiterpenoids: chemistry, chemo- and bio-syntheses and biological activities

Covering: up to December 2021Picrotoxane sesquiterpenoids are a special category of natural products known to have a picrotoxane skeleton and are characterised by a highly oxidised cis-hydrindene core, lactone rings, and epoxide functionalities. Ever since the first picrotoxane was isolated from Menispermum cocculus in the early 19^th century, these compounds have long attracted the attention of natural product chemists, synthetic chemists, and pharmacologists for their particular structures and powerful biological activities. This review extensively summarizes a total of 132 naturally occurring picrotoxane sesquiterpenoids, taking into account their distributions, structural classifications, chemical and bio-synthetic researches, and bioactivities. It provides a comprehensive and in-depth perspective for further investigation on picrotoxane sesquiterpenoids.

Biocidal efficacy of tutin and its influence on immune cells and expression of growth-blocking and neuroglian peptides in Mythimna separata (Lepidoptera: Noctuidae)

Mythimna separata Walker (Lepidoptera: Noctuidae) is one of the major pests that can cause severe damage to grain crops. The development of low-toxicity and high-performance botanical insecticides is becoming the focus of new pesticide research to control M. separata. Tutin, a sesquiterpene lactone compound obtained from Coriaria sinica Maxim, a native Chinese poisonous plant, has antifeedant, absorption, and stomach poisoning against a variety of pests. To understand the toxic effect of tutin on M. separata larvae, we set out to determine their antifeedant, mortality, paralysis, weight change, and to examine the spreading of M. separata hemocytes under different concentrations of tutin treatment. Tissue distribution of the immune-associated gene growth-blocking peptide (GBP) and neuroglian peptide (Nrg) was detected by reverse transcription polymerase chain reaction (PCR). Furthermore, real-time quantitative PCR was carried out to determine the expression profiles of GBP and Nrg after different concentrations of tutin stimulation. Our results revealed that tutin exhibited significant antifeedant and insecticidal activities, paralysis, weight loss to M. separata. Besides, tutin significantly influenced on the morphology of hemocytes and enhanced the expression of GBP and Nrg in M. separata.

Formation of quaternary centres by copper catalysed asymmetric conjugate addition to β-substituted cyclopentenones with the aid of a quantitative structure-selectivity relationship

A new asymmetric conjugate addition method was developed for β-substituted cyclopentenones to form quaternary centres using alkylzirconocene nucleophiles giving up to 97% yield and 92% ee.

A new asymmetric conjugate addition method was developed for β-substituted cyclopentenones to form quaternary centres using alkylzirconocene nucleophiles giving up to 97% yield and 92% ee. Key to the reaction's success was the design of suitable phosphoramidite ligands which was aided by a linear quantitative structure–selectivity relationship (QSSR). QSSR models were created from the ligand screening data (a total of 36 ligands) which revealed important electronic and steric requirements and led to the synthesis of more enantioselective ligands. DFT calculations of competing transition structures enable the interpretation of the electronic and steric terms present in the QSSR models.

Phytochemistry and Biology of Loranthus parasiticus Merr, a Commonly Used Herbal Medicine

Loranthus parasiticus Merr (L. parasiticus) is a member of Loranthaceae family and is an important medicinal plant with a long history of Chinese traditional use. L. parasiticus, also known as Sang Ji Sheng (in Chinese), benalu teh (in Malay) and baso-kisei (in Japanese), is a semiparasitic plant, which is mostly distributed in the southern and southwestern regions of China. This review aims to provide a comprehensive overview of the ethnomedicinal use, phytochemistry and pharmacological activity of L. parasiticus and to highlight the needs for further investigation and greater global development of the plant's medicinal properties. To date, pharmacological studies have demonstrated significant biological activities, which support the traditional use of the plant as a neuroprotective, tranquilizing, anticancer, immunomodulatory, antiviral, diuretic and hypotensive agent. In addition, studies have identified antioxidative, antimutagenic, antiviral, antihepatotoxic and antinephrotoxic activity. The key bioactive constituents in L. parasiticus include coriaria lactone comprised of sesquiterpene lactones: coriamyrtin, tutin, corianin, and coriatin. In addition, two proanthocyanidins, namely, AC trimer and (+)-catechin, have been recently discovered as novel to L. parasiticus. L. parasiticus usefulness as a medicinal plant with current widespread traditional use warrants further research, clinical trials and product development to fully exploit its medicinal value.

EEG characterization of audiogenic seizures in the hamster strain GASH:Sal

The study was performed to characterize GASH:SAL audiogenic seizures as true epileptic activity based on electroencephalographic markers acquired with a wireless implanted radiotelemetry system. We analyzed cortical EEG patterns synchronized with video recordings of convulsive behavior of the GASH:Sal hamster following an acoustic stimulus. All GASH:Sal presented archetypal motor symptoms comparable to current animal models of generalized tonic-clonic epilepsy. Seizures consisted of an initial bout of wild running, followed by opisthotonus, tonic-clonic convulsions, tonic limb extension, and terminated in postictal depression. EEG patterns correlated with behavior and displayed phase appropriate spike-wave complexes, low-amplitude desynchronized activity, and high frequency large-amplitude peaks. Our results confirm that electroencephalographic profiles of the audiogenic seizures of the hamster GASH:Sal are parallel to EEG patterns of other animal models of generalized tonic-clonic seizures. Therefore, this animal may serve as an appropriate model for epilepsy research.

Investigation of the possible biological activities of a poisonous South African plant; Hyaenanche globosa (Euphorbiaceae)

The present study was undertaken to explore the possible biochemical activities of Hyaenanche globosa Lamb. and its compounds. Two different extracts (ethanol and dichloromethane) of four different parts (leaves, root, stem, and fruits) of H. globosa were evaluated for their possible antibacterial, antityrosinase, and anticancer (cytotoxicity) properties. Two pure compounds were isolated using column chromatographic techniques. Active extracts and pure compounds were investigated for their antioxidant effect on cultured 'Hela cells'. Antioxidant/oxidative properties of the ethanolic extract of the fruits of H. globosa and purified compounds were investigated using reactive oxygen species (ROS), ferric-reducing antioxidant power (FRAP), and lipid peroxidation thiobarbituric acid reactive substance (TBARS) assays. The ethanolic extract of the leaves and fruits of H. globosa showed the best activity, exhibiting a minimum inhibitory concentration (MIC) of 3.1 mg/ ml and a minimum bactericidal concentration (MBC) of 1.56 and 6.2 mg/ml, respectively, against M. smegmatis. The ethanolic extract of the fruits of H. globosa (F.E) showed the highest percentage of inhibitory activity of monophenolase (90.4% at 200 mug/ml). In addition, F.E exhibited 50% inhibitory concentration (IC(50)) of 37.7 mug/ml on the viability of 'HeLa cells' using cytotoxicity MTT assay. Subsequently, F.E was fractionated using phase-partitioning with n-hexane, ethyl acetate, and n-butanol. The cytotoxicity of these fractions were determined in vitro using different cancer cell lines. The n-hexane fraction exhibited the highest activity of toxicity. Therefore, this fraction was subjected to further separation by chromatographic methods. Two pure compounds known as: 'Tutin' and 'hyenanchin' were isolated and their structures were determined by NMR spectroscopic methods. Unpredictably, none of them showed significant (P < 0.01) inhibition on cell viability/proliferation at the concentrations that were used. F.E showed significant anti-tyrosinase, antibacterial, and cytotoxicity effects, therefore it can be considered as an effective inhibitor alone or in combination with other plant extracts.

RNAi inhibits Coriaria lactone-induced MDR1b overexpression in rat brain microvascular endothelial cells

P-glyprotein (multidrug resistance gene 1, MDR1) was the first isolated and most extensively investigated refractory epilepsy-related drug-resistant protein. Coriaria lactone (CL) can induce P-glyprotein expression of brain capillary and astrocytes in vivo. We established the primary rat brain microvascular endothelial cell (BMECs) models overexpressing P-glycoprotein induced by CL successfully and infected them with adenovirus vector, which carry small interfering RNA (siRNA) designed to target MDR1b. MDR1b mRNA levels and P-glyprotein expression in experimental group decreased significantly 72 h after infection, and the fluorescence intensity of rhodamine within the cells of experimental group increased significantly. So, CL can induce P-glyprotein overexpression in BMECs in vitro, and siRNA can effectively inhibit expression of P-glyprotein and decrease its "pumping out" function. This may offer a new method and rationale for studying the mechanism of refractory epilepsy and relevant gene therapy.