Anticonvulsant effect of Sphaeranthus flower extracts in mice

A stimuli-responsive nanocarrier for diagnosis of seizures and inhibition of glutaminase in epilepsy

Epilepsy is marked by unpredictable and recurrent episodes of seizures. It is characterized by glutamate excitotoxicity and changes in stimuli such as pH, temperature and oxidative environment. This study aimed to formulate novel nanoparticulate theranostic nanocarrier for combined effects of diagnosis and treatment of epilepsy by: i) in-situ detection of epileptic conditions through characteristic changes in pH through the synthesis of pH-responsive polymer (CS-g-PD) and ii) 'on-demand' therapeutic alleviation of epileptic seizures through an inhibitor of glutaminase, 6-diazo-5-oxo-norleucine (DON). The formulation of DON-CS-g-PD-SLNs possessed nanodimensions (∼197.56 ± 17.87) nm and zeta potential (4.19 ± 0.29), with entrapment efficiency of (80.29 ± 0.006%). The coating pH-responsive polymer showed good sensitivity for acidic conditions by releasing the drug in pH 6.4 and resisting release in higher pH 7.2. In-vivo studies in Wistar rats showed suppression of epileptic seizures, escalation in the duration latency and reduction in duration of convulsions and recovery period. Furthermore, it was also successful in reducing the levels of glutaminase (p<0.0001) in the brain of PTZ-kindled rats, thereby leading to a decrease in glutamate levels (p<0.01). Hence, the nanocarriers show promising potential as 'on-demand' theranostics in epilepsy by reducing both the incidence and severity of convulsions.

Pharmacognostic profiles, evaluation of analgesic, anti-inflammatory and anticonvulsant activities of Newbouldia laevis (P. Beauv.) Seem. ex Bureau leaf and root extracts in Wistar rats

ETHNOPHARMACOLOGICAL RELEVANCE

Newbouldia laevis is a popular medicinal plant whose leaves and roots are used in Nigeria as ethnomedicinal prescriptions for pain, inflammation, convulsion, and epilepsy. These claims have not been scientifically verified prior to this study.

AIM OF THE STUDY

To determine pharmacognostic profiles of the leaves and roots and evaluate the analgesic, anti-inflammatory, and anticonvulsant activities of methanol leaf and root extracts in Wistar rats.

MATERIAL AND METHODS

The pharmacognostic profiles of the leaves and roots were determined using standard procedures to serve as fingerprints for the plant. The methanol leaf and root extracts of Newbouldia laevis were tested for acute toxicity using the OECD's up and down method at the maximum dose of 2000 mg/kg (orally) in Wistar rats. Analgesic studies were carried out in acetic acid-induced writhing in rats and tail immersion. The anti-inflammatory activity of the extracts was evaluated using carrageenan-induced rat paw-oedema and formalin-induced inflammation in rats' mode. The anticonvulsant activity was determined using strychnine-induced, pentylenetetrazol-induced, and maximal electroshock-induced rat convulsion models. For each of these studies, the extracts doses of 100, 200 and 400 mg/kg were administered to the rats following the oral route.

RESULTS

The pharmacognostic profiles showed that the leaves possessed deep-sunken paracytic stomata (5-8-16 mm²; adaxial, 8-11-24 mm²; abaxial epidermis), vein islets (2-4-10 mm²; adaxial), vein terminations (10-14-18 mm²; adaxial), palisade ratio (8.3-12.5-16.4 mm²; adaxial, 2.5-6.8-12.2 mm²; adaxial), covering unicellular trichome (8-14; adaxial), spheroidal calcium oxalate crystals (3-5 μm), and oval-shaped striated starch grain with no hilum (0.5-4.3 μm). The transverse section of the leaf showed the presence of spongy and palisade parenchyma as well as a closed vascular bundle. The root powder showed the presence of brachy sclereid, fibers without lumen, and lignin. All physicochemical parameters fall within the acceptable limits, phytochemical contents showed mainly glycosides, alkaloids, and steroids while acute oral toxicity (LD₅₀) of the parts for 14 days did not produce any toxicity signs or mortality in the rats. The extracts produced dose-dependent (100-400 mg/kg) analgesic involving opioid receptors, anti-inflammatory, and anticonvulsant activities in the rats which were significant (p ≤ 0.05) when compared to the standard drugs. The leaf extract possessed the most potent analgesic and anti-inflammatory effects in the rats, while the most anticonvulsant effects were observed in rats treated with the leaf extract. Both extracts showed elevated levels of protection against strychnine-induced, pentylenetetrazol-induced, and maximal electroshock-induced seizure in rats.

CONCLUSION

Our study revealed some pharmacognostic profiles of Newbouldia laevis leaves and roots that are vital for its identification from closely related species often used for adulteration in traditional medicine. The study further showed that the leaf and root extracts of the plant possessed dose-dependent analgesics, anti-inflammatory and anti-convulsant activities in rats, thus, justifying its use for the treatment of these diseases in Nigerian traditional medicine. There is a need to further study its mechanisms of action towards drug discovery.

β-Cyclodextrin-crosslinked synthetic neuropeptide Y-based nanosponges in epilepsy by contributing GABAergic signal

Neuropeptide Y (NPY) is a polypeptide sequence useful in regulating physiological functions like homeostasis, feeding, etc., but its usage is restricted due to its short half-life. β-cyclodextrin-crosslinked nanosponges improve the drug release and stability due to its wide cavity, which is helpful to deliver therapeutics. The present work aimed to formulate synthetic NPY-based nanocarriers as sponges by polymer condensation mechanism using design experiment to improve the peptide release and stability. The validated nanosponges exhibited a particle size of 423.42 ± 5.32 nm, 75.82 ± 7.43 % entrapment efficiency and 83.50 ± 6.54 % NPY release for 24 h. The NPY and β-cyclodextrin interaction was confirmed by X-ray diffraction, Fourier transform infrared and nuclear magnetic resonance spectroscopy. The NPY-loaded nanosponges were found stable for 6 months at two conditions (5 ± 2 °C and 25 ± 2 °C). The cross-linked nanocarriers of synthetic peptide-based nanosponges powder at different doses were administered intranasally using a metered-dose inhaler in the animal model to check its antiepileptic activity. The synthetic NPY-loaded nanosponges at higher doses showed significant antiepileptic effects equivalent to the standard drug (administered orally) in maximal electroshock and chemically-induced seizures with an increase of NPY in the brain directly proportional to GABAergic signalling by increase in GABA levels resulting in convulsions attenuation.

Anticonvulsant effects of desvenlafaxine on modulating brain monoamine and oxidative stress in mice

Desvenlafaxine succinate (DVS) inhibits serotonin reuptake selectively and is approved for major depressive disorders. This research investigated influence of DVS on modulating brain monoamine and oxidative stress in mice. The antiepileptic potential of DVS (10, 20, or 30 mg/kg/i.p.) in pentylenetetrazole (PTZ; 85 mg/kg) with i.p. route of administration, strychnine (STR; 75 mg/kg) with i.p. route, pilocarpine (400 mg/kg) with s.c. route and maximal electroshock MES-induced convulsion in mouse models. The activities of oxidative stress, i.e. superoxide dismutase (SOD), glutathione (GSH) and lipid peroxidation (LPO) as well as gamma-aminobutyric acid (GABA) in the brains of PTZ-induced convulsive mice. Treatment with DVS increased the latency to develop siezures and declined mortalities in rodents against PTZ, STR and pilocarpine-induced convulsions. Results of MES-leaded siezures revealed that DVS reduced tonic hind limb extension duration and mortalities significantly. Brain, SOD, GSH and GABA level were significantly (P<0.01) increased and LPO reduced significantly (P<0.01) after DVS treatment. Furthermore, the DVS did not show any motor coordination signs in the rotarod test. We demonstrated that the role of DVS in convulsion genesis in mice under control condition and attenuate the PTZ-induced oxidative damage.