Neuroprotective effect of Cubebin: A dibenzylbutyrolactone lignan on scopolamine-induced amnesia in mice.

BACKGROUND & OBJECTIVES: Acetylcholinesterase (AChE) inhibitors represent a major class of drugs which provide symptomatic relief and improvement in cognitive function in Alzheimer's disease (AD). In this study, cubebin, a dibenzylbutyrolactone lignan, was isolated from Piper cubeba and investigated for its AChE inhibitory activity in an attempt to explore its potential for memory-enhancing activities in mice. METHODS: Molecular docking of cubebin was carried out followed by in vitro AChE activity. Mice were treated with cubebin (25 & 50 mg/kg; i.p.), for three days and memory impairment was induced by scopolamine (3 mg/kg; i.p.). Memory function was evaluated by Morris water maze (MWM) test. Biochemical parameters of oxidative stress and cholinergic function were estimated in brain. RESULTS: Molecular docking study revealed that cubebin was well bound within the binding site of the AChE enzyme showing interactions such as π-π stacking and hydrogen bonding with residues present therein. Cubebin inhibited AChE enzyme in an in vitro assay with IC50value of 992 µM. Scopolamine administration caused a significant impairment of learning and memory in mice, as indicated by a marked decrease in MWM performance. Scopolamine administration also produced a significant enhancement of brain AChE activity and oxidative stress in mice brain. Pre-treatment of cubebin (25 and 50 mg/kg; i.p.) significantly prevented scopolamine-induced learning and memory deficits along with attenuation of scopolamine-induced rise in brain AChE activity and oxidative stress level. INTERPRETATION & CONCLUSIONS: Cubebin showed promising protective activity in scopolamine-induced spatial memory impairment in mice. This could be attributed to its brain AChE inhibition and antioxidant activity.

The modulatory role of phloretin in Aß25-35 induced sporadic Alzheimer's disease in rat model.

Alzheimer's disease (AD) is the leading neurodegenerative disorder with extracellular senile plaques and neurofibrillary tangles as the major hallmarks. The objective was to evaluate the effect of phloretin in a chronic model of sporadic AD by injecting aggregated form of Aß25-35 peptide sequence intracerebroventricularly (icv) in Wistar rats. To achieve this, male Wistar rats were injected with aggregated Aß25-35 peptide icv, followed by 21 days phloretin (2.5 mg/kg, 5 mg/kg) administration after recovery period. Barnes maze and elevated plus maze along with the biochemical estimation of antioxidant enzymes activities were conducted. The hippocampus region of the rat brains were stained with Congo red and Nissl stain. TNF-α was estimated in the brain homogenates using the ELISA assay. In this study, phloretin improved the spatial memory formation and retention in Barnes maze test. Additionally, phloretin alleviated the antioxidant defense biomarkers and thereby reduced oxidative stress, decreased TNF-α-mediated neuroinflammation. Furthermore, phloretin treatment showed decreased amyloid beta accumulation in the CA1 region and less number of pyknotic nuclei in the dentate gyrus of the Aß25-35-injected rat brains. The above experimental findings evinced the promising role of phloretin in Aß25-35-injected rats and which further envisage its potential to be explored in the treatment of AD.

The effect of phloretin on synaptic proteins and adult hippocampal neurogenesis in Aß (1-42)-injected male Wistar rats.

OBJECTIVES: Considering the deleterious effect of Aß1-42, a study was designed to evaluate the effect of phloretin on altered synaptic proteins and adult hippocampal neurogenesis in Aß1-42-injected Wistar rats. METHODS: The rats were pretreated with 5 mg/kg p.o dose of phloretin and donepezil (positive control) for 28 days, followed by intrahippocampal injections of aggregated Aß1-42. After termination, perfused brains were isolated and subjected to Western blot and immunohistochemistry (IHC) analysis. KEY FINDINGS: The Western blot revealed that Aß1-42-injected rats had significantly low levels of synaptophysin as compared to sham control. Phloretin pretreatment significantly protected the presynaptic protein synaptophysin against the effects of Aß1-42. There were no significant changes in the levels of PSD95 between different groups. The IHC findings showed that Aß1-42 significantly reduced the Ki67 and DCX in the dentate gyrus as compared to sham control. However, phloretin significantly improved the number of Ki67- and DCX-positive neurons in the dentate gyrus region as compared to Aß1-42 group. CONCLUSIONS: This study demonstrated the protective effect of phloretin on synaptophysin and adult neuronal proliferating cells in Aß1-42-injected rats. The encouraging findings highlight the potential of phloretin as a dietary supplement targeting key therapeutic mechanisms in neurodegenerative disorders such as AD.

Antiepileptogenic effects of borneol in pentylenetetrazole-induced kindling in mice.

Borneol, a bicyclic monoterpene, can easily cross the blood brain barrier and was found to possess gamma amino butyric acid (GABA) modulatory effect. The present study was aimed at investigating the antiepileptogenic effect of borneol in the pentylenetetrazole (PTZ)-induced kindling besides its ability to suppress oxidative stress and neuroinflammatory marker, glial fibrillary acidic protein (GFAP). Repeated administration of a subconvulsive dose of PTZ (35 mg/kg, i.p.) on every alternate day for 4 weeks produced kindling in mice. Borneol (5, 10, and 25 mg/kg, i.p.) and diazepam (1 mg/kg, i.p.) were given as a pretreatment prior to each PTZ injection during the progression of kindling. Oxidative stress parameters such as superoxide dismutase (SOD), reduced glutathione (GSH), catalase (CAT), and lipid peroxidation (LPO) were assessed at the end of the study. Neuronal damage was assessed by hematoxylin and eosin staining technique. GFAP was also evaluated in the hippocampus region of the brain by using immunohistochemistry. Borneol significantly suppressed the process of epileptogenesis in PTZ-kindled mice. The biochemical alterations induced by PTZ kindling were ameliorated in borneol-treated animals which was indicated by decreased LPO and increased SOD, GSH, CAT levels. The distinct neuronal damage observed in the kindled group was counteracted by borneol. Furthermore, it decreased the levels of GFAP which was manifested by reduced immunostaining. The above results are suggestive of the antiepileptogenic potential of borneol in the PTZ-induced kindling model of epilepsy, and thus, it could be a prospective molecule in the treatment of epilepsy.

Nootropic, neuroprotective and neurotrophic effects of phloretin in scopolamine induced amnesia in mice.

Phloretin (PHL), a dihydrochalcone flavonoid usually present in the roots and leaves of apple tree. In vitro study on GT1-7 immortalized hypothalamic neurons exposed to amyloid beta (25-35), demonstrated that PHL significantly influenced membrane fluidity and potential. PHL also significantly decreased excitotoxicity by restoring the calcium homeostasis in the same. Thus, PHL proves to be a promising therapeutic moiety which should be further screened in the treatment of Alzheimer's disease. The objective of the present study was to evaluate the nootropic, neuroprotective and neurotrophic roles of PHL in the subacute scopolamine induced amnesia in mice. In this study, mice were pretreated with PHL 2.5mg/kg, 5mg/kg, 10mg/kg and Donepezil (DON) 1mg/kg intraperitoneally (i.p) for 14days. The last 7days of treatment regimen included daily injection of SCP 1.5mg/kg to induce cognitive deficits. Mice were subjected to behavioral analysis. Biochemical estimation of the brain homogenates for acetylcholinesterase and oxidative stress biomarkers were conducted. Furthermore, immunohistochemical analysis for the brain derived neurotrophic factor (BDNF) was carried out particularly in the hippocampus. PHL was found to significantly improve the performance of mice in Morris water maze test (P<0.001) and significantly decreased the acetylcholinesterase activity (P<0.001) at all doses compared to SCP treated mice. Also, PHL significantly elevated the activity of antioxidant enzymes viz. superoxide dismutase, catalase, reduced glutathione levels (P<0.001) and decreased malonaldehyde levels (P<0.001) in comparison with the SCP group. Immunohistochemistry revealed that PHL treatment dose dependently improved BDNF levels in the hippocampus which were found to be significantly depleted (P<0.001) in the SCP group. Additionally, PHL (10mg/kg) significantly enhanced the spatial memory formation (P<0.05) and neurotrophicity (P<0.001) compared to DON (1mg/kg). The aforementioned research findings suggested that PHL has nootropic, neuroprotective and neurotrophic activities in SCP induced memory impaired mice and hence, is a promising therapeutic moiety in the treatment of AD.

RETRACTED: Neuroprotective and neurotrophic effects of Apigenin and Luteolin in MPTP induced parkinsonism in mice.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief. It has been highlighted that there is image manipulation. Fig. 6 b), e) ad f) are the same images from Fig 5 a), b), c) from Patil, S.P., Jain, P.D., Ghumatkar, P.J., Tambe, R., Sathaye, S., 2014. Neuroprotective effect of metformin in MPTP-induced Parkinson's disease in mice. Neuroscience 277, 747­754 and used to describe different drug doses and treatments in the paper. Fig. 8 d), e) and f) are the same image manipulated to be results for different drug treatments. Fig. 10a), b) and h) are the same images as Fig. 7 B) in the paper Patil, S.P., Jain, P.D., Ghumatkar, P.J., Tambe, R., Sathaye, S., 2014. Neuroprotective effect of metformin in MPTP-induced Parkinson's disease in mice. Neuroscience 277, 747­754 and used to describe different drug treatments. The authors acknowledge there are serious errors and agree with the retraction of this paper.

Evaluation of Cardioprotective Effect of 3,5,3'-Tri-iodo-L-thyronine in Isoproterenol-Induced Cardiotoxicity.

T(3) (3,5,3'-triiodothyronine) has drawn relatively little attention in relation to cardiovascular (CVS) diseases. The present study was designed to evaluate the cardioprotective action of T(3) in isoproterenol-(ISO-) induced cardiac toxicity. Female Wistar rats were exposed with ISO (100 mg/kg, body weight, subcutaneously) for 2 days at the interval of 24 h followed by T(3) (3 µg/kg, body weight, orally) treatment for 3 days. Positive control rats received only ISO (100 mg/kg, body weight, subcutaneously) for 2 days at the interval of 24 hrs. Control group animals received normal saline as a vehicle. As expected, ISO-induced significant changes were observed in low-density lipoprotein, total cholesterol, ALT, CK-MB to TCK ratio, and prolongation of QT interval in electrocardiogram, which is toward normalization after T(3) treatment. Lower heart weight, upregulation of cardiac myosin heavy chain alpha (MHC-α), and reduced inflammatory cell infiltration, myonecrosis, vacuolar changes, and a trend toward normal cardiac muscle fiber architecture in microscopic examination of cardiac tissue further support the cardioprotective effect of T(3).