Kolaviron, a Garcinia kola biflavonoid complex, protects against ischemia/reperfusion injury: pertinent mechanistic insights from biochemical and physical evaluations in rat brain

Morphological evidence for the potential protective effects of curcumin and Garcinia kola against diabetes in the rat hippocampus

This research investigated the effects of sciatic nerve transection and diabetes on the hippocampus, and the protective effects of Garcinia kola and curcumin. Thirty-five adults male Wistar albino rats were divided into five groups: a control group (Cont), a transected group (Sham group), a transected + diabetes mellitus group (DM), a transected + diabetes mellitus + Garcinia kola group (DM + GK), and a transected + DM + curcumin group (DM + Cur), each containing seven animals. The experimental diabetes model was created with the intraperitoneal injection of a single dose of streptozotocin. No procedure was applied to the Cont group, while sciatic nerve transection was performed on the other groups. Garcinia kola was administered to the rats in DM + GK, and curcumin to those in DM + Cur. Cardiac perfusion was performed at the end of the experimental period. Brain tissues were dissected for stereological, histopathological, and immunohistochemical evaluations. The volume ratios of hippocampal layers to the entire hippocampus volume were compared between the groups. Anti-S100, anti-caspase 3, and anti-SOX 2 antibodies were used for immunohistochemical analysis. No statistically significant difference was observed in the volume ratios of the four hippocampal layers. However, the volume ratio of the stratum lucidum was higher in the Sham, DM, and DM + Cur groups compared to the Cont group. While curcumin exhibited a protective effect on hippocampal tissue following diabetes induction, Garcinia kola had only a weak protective effect. Increased cell density and nuclear deterioration due to diabetes and nerve transection can be partially ameliorated by treatment with Garcinia kola and curcumin.

Unraveling Grewia bilamellata Gagnep. Role in cerebral ischemia: Comprehensive in vivo and in silico studies

The present study investigated the neuroprotective properties of whole plants of Grewia bilamellata Gagnep. extract (GBEE) against cerebral ischemia by harnessing both In vivo studies in a rat model and In silico studies focusing on nitric oxide synthase (NOS) inhibition. High-resolution liquid chromatography‒mass spectrometry (HR LC‒MS) analysis identified 32 phytochemicals in the GBEE, 15 of which adhered to Lipinski's rule of five. These compounds exhibited diverse physicochemical properties and high binding affinity to NOS, with cleomiscosin D showing the greatest potential. In vivo, GBEE had significant neuroprotective effects on bilateral common carotid artery occlusion/reperfusion (BCCAO/R) in rats, especially at doses of 200 mg/kg and 400 mg/kg body weight. GBEE treatment improved brain function, as evidenced by EEG normalization, substantial reductions in cerebral infarction size, mitigated neuronal loss, and the restoration of regular histological arrangement in the CA1 hippocampal area of the brain. Furthermore, GBEE enhanced antioxidant defenses by augmenting the activity of catalase (CAT) and superoxide dismutase (SOD), reducing malondialdehyde (MDA) levels, and restoring reduced glutathione (GSH) levels. These effects were accompanied by a decrease in nitric oxide (NO) levels, indicative of attenuated oxidative and nitrosative stress. Collectively, our findings suggest that GBEE is a promising natural therapeutic agent that may prevent or alleviate ischemic brain injury through a multifaceted mechanism involving NOS inhibition and attenuation of the oxidative stress response. This study highlights the therapeutic potential of GBEE and warrants further research into its mechanism of action and possible clinical applications.

Kolaviron neuroprotective effect against okadaic acid-provoked cognitive impairment

Alzheimer's disease (AD) is acknowledged as the main causative factor of dementia that affects millions of people around the world and is increasing at increasing pace. Okadaic acid (OA) is a toxic compound with ability to inhibit protein phosphatases and to induce tau protein hyperphosphorylation and Alzheimer's-like phenotype. Kolaviron (KV) is a bioflavonoid derived from Garcinia kola seeds with anti-antioxidative and anti-inflammation properties. The main goal of this study was to assess whether kolaviron can exert neuroprotective effect against okadaic acid-induced cognitive deficit. Rats had an intracerebroventricular (ICV) injection of OA and pretreated with KV at 50 or 100 mg/kg and examined for cognition besides histological and biochemical factors. OA group treated with KV at 100 mg/kg had less memory deficit in passive avoidance and novel object discrimination (NOD) tasks besides lower hippocampal levels of caspases 1 and 3, tumor necrosis factor α (TNFα) and interleukin 6 (IL-6) as inflammatory factors, reactive oxygen species (ROS), protein carbonyl, malondialdehyde (MDA), and phosphorylated tau (p-tau) and higher level of acetylcholinesterase (AChE) activity, mitochondrial integrity index, superoxide dismutase (SOD), and glutathione (GSH). Moreover, KV pretreatment at 100 mg/kg attenuated hippocampal CA1 neuronal loss and glial fibrillary acidic protein (GFAP) reactivity as a factor of astrogliosis. In summary, KV was able to attenuate cognitive fall subsequent to ICV OA which is partly mediated through its neuroprotective potential linked to mitigation of tau hyperphosphorylation, apoptosis, pyroptosis, neuroinflammation, and oxidative stress and also improvement of mitochondrial health.

Neuroprotective Effects of Quercetin on Ischemic Stroke: A Literature Review

Ischemic stroke (IS) is characterized by high recurrence and disability; however, its therapies are very limited. As one of the effective methods of treating acute attacks of IS, intravenous thrombolysis has a clear time window. Quercetin, a flavonoid widely found in vegetables and fruits, inhibits immune cells from secreting inflammatory cytokines, thereby reducing platelet aggregation and limiting inflammatory thrombosis. In pre-clinical studies, it has been shown to exhibit neuroprotective effects in patients with ischemic brain injury. However, its specific mechanism of action remains unknown. Therefore, this review aims to use published data to elucidate the potential value of quercetin in patients with ischemic brain injury. This article also reviews the plant sources, pharmacological effects, and metabolic processes of quercetin in vivo, thus focusing on its mechanism in inhibiting immune cell activation and inflammatory thrombosis as well as promoting neuroprotection against ischemic brain injury.

An Eluate of the Medicinal Plant Garcinia kola Displays Strong Antidiabetic and Neuroprotective Properties in Streptozotocin-Induced Diabetic Mice

Materials and Methods

G. kola methanolic extract was fractionated using increasingly polar solvents. Fractions were administered to streptozotocin (STZ)-induced diabetic mice until marked motor signs developed in diabetic controls. Fine motor skills indicators were measured in the horizontal grid test (HGT) to confirm the prevention of motor disorders in treated animals. Column chromatography was used to separate the most active fraction, and subfractions were tested in turn in the HGT. Gas chromatography-mass spectrometry (GC-MS) technique was used to assess the components of the most active subfraction.

Results

Treatment with ethyl acetate fraction and its fifth eluate (F5) preserved fine motor skills and improved the body weight and blood glucose level. At dose 1.71 mg/kg, F5 kept most parameters comparable to the nondiabetic vehicle group values. GC-MS chromatographic analysis of F5 revealed 36 compounds, the most abundantly expressed (41.8%) being the β-lactam molecules N-ethyl-2-carbethoxyazetidine (17.8%), N,N-dimethylethanolamine (15%), and isoniacinamide (9%).

Conclusions

Our results suggest that subfraction F5 of G. kola extract prevented the development of motor signs and improved disease profile in an STZ-induced mouse model of diabetic encephalopathy. Antidiabetic activity of β-lactam molecules accounted at least partly for these effects.

Kolaviron ameliorates chronic unpredictable mild stress-induced anxiety and depression: involvement of the HPA axis, antioxidant defense system, cholinergic, and BDNF signaling

OBJECTIVES

This study sought to investigate the beneficial effect of kolaviron (KV) (a biflavonoid) isolated from Garcinia kola seed on chronic unpredictable mild stress (CUMS)-induced anxiety- and depressive-like behavior.

METHODS

Male albino mice were randomly divided into six groups (n=8) as follows; Group I: vehicle-control unstressed; Group II: CUMS-control; Group III-V: CUMS + KV 1, 5 or 50 mg/kg, respectively, Group VI: KV (50 mg/kg, p.o.) unstressed mice. Animals were subjected to CUMS for 14 days, followed by estimation of depressive- and anxiety-like behavior from days 14-16. This was followed by biochemical assays for oxidative stress, hypothalamo-pituitary axis, cholinergic, and BDNF signaling.

RESULTS

CUMS caused significant reduction in time spent in open arms of elevated plus maze test (EPM) and increase in immobility time in tail suspension test (TST) and forced swim test (FST) ameliorated by KV treatments. KV administration also attenuated CUMS-induced malondialdehyde/nitrite generation and decrease in antioxidant enzymes activities in the prefrontal cortex and hippocampus. CUMS increased serum corticosterone, acetylcholinesterase activity, and reduced BDNF level in the PFC and hippocampus were attenuated by KV administration.

CONCLUSIONS

KV prevented CUMS induced anxiety- and depression-like behavior in mice through enhancement of antioxidant defense mechanisms, neurotrophic factors, and cholinergic systems.

Protective properties of Spondias mombin Linn leaves on redox status, cholinergic dysfunction and electrolyte disturbance in cyanide-intoxicated rats

Cyanide is an environmental neurotoxin which has been reported to arrest the normal functioning of the brain. This study investigated the protective properties of methanol and flavonoid-rich extracts of the leaves of Spondias mombin on redox status, cholinergic dysfunction and electrolyte disturbance in cyanide-induced neurotoxicity in rats. Male Wistar rats were orally pre-treated with Spondias mombin methanol leaf extract (SMC) (50, 100 and 150 mg/kg), flavonoid-rich extract (SMF) (25, 50 and 75 mg/kg) or quercetin (20 mg/kg), followed by intraperitoneal administration of 2 mg/kg potassium cyanide. Cyanide intoxication caused brain damage in rats as echoed in the deleterious alterations to activities/levels of endogenous antioxidants and biomarkers/enzymes linked with electrolyte imbalance and neurotoxicity. Pre-treatment with SMC and SMF significantly attenuated these KCN-induced imbalances (p < 0.05). The results suggested that the protection conferred by SMC and SMF probably involves attenuation of oxidative stress and regulation of ionic homeostasis. SMF displayed a better apparent ameliorative activity than SMC and 75 mg/kg SMF offered the best protection suggesting that flavonoids probably contributed to the protective effect of Spondias mombin leaf.

Abatement of neurobehavioral and neurochemical dysfunctions in cerebral ischemia/reperfusion injury by Tetrapleura tetraptera fruit extract

ETHNOPHARMACOLOGICAL RELEVANCE

Tetrapleura tetraptera Taub. (family Fabaceae), is generally found in the lowland forest of tropical Africa. Its leaves and fruits are traditionally used in West Africa for the management of brain disorders.

AIM OF THE STUDY

This study evaluated the effect of Tetrapleura tetraptera methanol fruit extract (TT) on bilateral common carotid artery occlusion-induced cerebral ischemia/reperfusion (I/R) injury in male Wistar rats.

MATERIALS AND METHODS

Rats pretreated with TT for 7 days before a 30 min bilateral common carotid artery occlusion and reperfusion for 24 h were assessed for neurobehavioural deficits. Cortical, striatal and hippocampal oxidative stress, pro-inflammatory events, electrolyte imbalance and neurochemical dysfunctions, as well as hippocampal histopathological alterations, were also evaluated. HPLC-DAD analysis was performed to identify likely compounds contributing to the bioactivity of the extract.

RESULTS

TT reduced I/R-induced behavioral deficits and ameliorated I/R-induced oxidative stress by restoring reduced glutathione level, increasing catalase and superoxide dismutase activities, and also reducing both lipid peroxidation and xanthine oxidase activity in the brain. TT attenuated I/R-increased myeloperoxidase and lactate dehydrogenase activities as well as disturbances in Na⁺ and K⁺ levels. Alterations elicited by I/R in the activities of Na⁺/K⁺ ATPase, complex I, glutamine synthetase, acetylcholinesterase, and dopamine metabolism were abated by TT pretreatment. TT prevented I/R-induced histological changes in the hippocampus. HPLC-DAD analysis revealed the presence of aridanin, a marker compound for Tetrapleura tetraptera, and other phytochemicals.

CONCLUSIONS

These findings indicate that Tetrapleura tetraptera fruit has a protective potential against stroke through modulation of redox and electrolyte imbalances, and attenuation of neurotransmitter dysregulation and other neurochemical dysfunctions. Tetrapleura tetraptera fruit could be a promising source for the discovery of bioactives for stroke therapy.

Kolaviron suppresses dysfunctional reproductive axis associated with multi-walled carbon nanotubes exposure in male rats

Reproductive toxicity associated with excessive exposure to multi-walled carbon nanotubes (MWCNTs), which are commonly used in medicine as valuable drug delivery systems, is well documented. Kolaviron, a bioflavonoid isolated from Garcinia kola seeds, elicits numerous health beneficial effects related to its anti-inflammatory, anti-genotoxic activities, anti-apoptotic, and antioxidant properties. However, information on the role of kolaviron in MWCNTs-induced reproductive toxicity is not available in the literature. Herein, we assessed the protective effects of kolaviron on MWCNTs-induced dysfunctional reproductive axis in rats following exposure to MWCNTs (1 mg/kg) and concurrent treatment with kolaviron (50 or 100 mg/kg body weight) for 15 successive days. Results showed that MWCNTs-induced dysfunctional reproductive axis as evidenced by deficits in pituitary and testicular hormones, marker enzymes of testicular function, and sperm functional characteristics were abrogated in rats co-administered with kolaviron. Moreover, co-administration of kolaviron-abated MWCNTs-induced inhibition of antioxidant enzyme activities increases in oxidative stress and inflammatory indices. This is evidenced by diminished levels of tumor necrosis factor-alpha, nitric oxide, lipid peroxidation, reactive oxygen, and nitrogen species as well as reduced activity of myeloperoxidase in testes, epididymis, and hypothalamus of the rats. Biochemical data on the chemoprotection of MWCNTs-induced reproductive toxicity were corroborated by histological findings. Taken together, kolaviron suppressed dysfunctional reproductive axis associated with MWCNTs exposure via abrogation of oxidative stress and inflammation in male rats.

Evaluation of metabolic, antioxidant and anti-inflammatory effects of Garcinia kola on diabetic rats

Garcinia kola (G. kola), is a plant characterized by its hypoglycemic properties. We recently reported our findings on the extracts of G. kola, in which we found that it prevented the loss of inflammation-sensible neuronal populations in streptozotocin (STZ)-induced rat models of type 1 diabetes mellitus (T1DM).

In the present study we assessed the effect of G. kola bioactive compounds extracted successively with water, hexane, methylene chloride, ethyl acetate, and butanol. through analyzing biochemical markers of oxidative stress, inflammation, and metabolic function in STZ-induced diabetic animals.

Animals made diabetic by a single injection with STZ (60 mg/kg, i.p.), were treated daily with either vehicle solution, insulin, or G. kola extracts and its fractions from the first to the 6th-week post-injection. Biochemical markers; glucose, insulin, C-peptide, neuron-specific enolase (NSE), creatinine kinase, glutathione peroxidase, malondialdehyde (MDA), resistin, soluble E-selectin (SE-Selectin), and C-reactive proteins (CRP) levels in the sera were determined in the study groups. A marked increase in blood glucose (209.26% of baseline value), and a decrease in body weight (−12.37%) were observed in diabetic control animals but not in animals treated with either insulin or G. kola extracts and its fractions. The sub-fraction F5, G. kola ethyl acetate had the highest bioactive activities, with a maintenance of blood sugar, malondialdehyde, C-peptide, E-selectin, C-reactive protein (CRP) and neuron-specific enolase (NSE) to levels and responses comparable to healthy non-diabetic vehicle group and the positive control diabetic insulin-treated group.

Our findings suggest that G. kola may have a strong therapeutic potential against T1DM and its microvascular complications.

Prophylaxis with a multicomponent nutraceutical abates transient cerebral ischemia/reperfusion injury

The effect of a multicomponent nutraceutical on cerebral ischemia/reperfusion injury in male Wistar rats was investigated. Animals were administered with the nutraceutical, Trévo™, for 7 days before 30 min of bilateral common carotid artery occlusion-induced cerebral ischemia and 24 hr of reperfusion. Behavioral assessment, biochemical estimations in the brain cortex, striatum, and hippocampus, and hippocampal histopathological evaluation were carried out after treatments. Results showed that ischemia/reperfusion-induced motor and cognitive deficits were abated in rats pretreated with Trévo™. Additionally, prophylaxis with Trévo™ blunted ischemia/reperfusion-induced redox stress, proinflammatory events, disturbances in neurotransmitter metabolism, mitochondrial dysfunction, and histoarchitectural aberrations in the discreet brain regions. In summary, supplementation with Trévo™ provided neuroprotection to rats against transient cerebral ischemia/reperfusion injury and could be explored as a promising approach in stroke prevention. PRACTICAL APPLICATIONS: There is a worldwide increase in the incidence of cerebral ischemia or stroke. Although an advanced health care system and effective control of risk factors have led to the declining incidence in developed nations, a definitive cure for stroke remains elusive and the situation is growing worse in developing nations. The results of the present study revealed that supplementation with Trévo™ ameliorated neurobehavioral, neurochemical, and histopathological consequences of brain ischemia/reperfusion injury and could, therefore, be beneficial in stroke prevention and management.

Impact of Natural Compounds on Neurodegenerative Disorders: From Preclinical to Pharmacotherapeutics

Among the major neurodegenerative disorders (NDDs), Alzheimer’s disease (AD) and Parkinson’s disease (PD), are a huge socioeconomic burden. Over many centuries, people have sought a cure for NDDs from the natural herbals. Many medicinal plants and their secondary metabolites are reported with the ability to alleviate the symptoms of NDDs. The major mechanisms identified, through which phytochemicals exert their neuroprotective effects and potential maintenance of neurological health in ageing, include antioxidant, anti-inflammatory, antithrombotic, antiapoptotic, acetylcholinesterase and monoamine oxidase inhibition and neurotrophic activities. This article reviews the mechanisms of action of some of the major herbal products with potential in the treatment of NDDs according to their molecular targets, as well as their regional sources (Asia, America and Africa). A number of studies demonstrated the beneficial properties of plant extracts or their bioactive compounds against NDDs. Herbal products may potentially offer new treatment options for patients with NDDs, which is a cheaper and culturally suitable alternative to conventional therapies for millions of people in the world with age-related NDDs.

Kolaviron via anti-inflammatory and redox regulatory mechanisms abates multi-walled carbon nanotubes-induced neurobehavioral deficits in rats

Exposure to multi-walled carbon nanotubes (MWCNTs) reportedly elicits neurotoxic effects. Kolaviron is a phytochemical with several pharmacological effects namely anti-oxidant, anti-inflammatory, and anti-genotoxic activities. The present study evaluated the neuroprotective mechanism of kolaviron in rats intraperitoneally injected with MWCNTs alone at 1 mg/kg body weight or orally co-administered with kolaviron at 50 and 100 mg/kg body weight for 15 consecutive days. Following exposure, neurobehavioral analysis using video-tracking software during trial in a novel environment indicated that co-administration of both doses of kolaviron significantly (p < 0.05) enhanced the locomotor, motor, and exploratory activities namely total distance traveled, maximum speed, total time mobile, mobile episode, path efficiency, body rotation, absolute turn angle, and negative geotaxis when compared with rats exposed to MWCNTs alone. Further, kolaviron markedly abated the decrease in the acetylcholinesterase activity and antioxidant defense system as well as the increase in oxidative stress and inflammatory biomarkers induced by MWCNT exposure in the cerebrum, cerebellum, and mid-brain of rats. The amelioration of MWCNT-induced neuronal degeneration in the brain structures by kolaviron was verified by histological and morphometrical analyses. Taken together, kolaviron abated MWCNT-induced neurotoxicity via anti-inflammatory and redox regulatory mechanisms.

Medicinal Potential, Utilization and Domestication Status of Bitter Kola (Garcinia kola Heckel) in West and Central Africa

Garcinia kola Heckel (Clusiaceae), known as bitter kola, is a multipurpose tree indigenous to West and Central Africa. This highly preferred species is called “wonder plant” because all of its parts can be used as medicine. Its seeds, the most valued product of the tree, are commonly eaten to prevent/cure gastric disorders and for their typical astringent taste. There is a vast evidence that bioactive components of the seeds can serve as alternative medicine to treat/prevent severe illnesses such as malaria, hepatitis and immune-destructive diseases. Despite the species’ pharmaceutical potential and its high preference by West and Central African communities, G. kola is still at the beginning of its domestication process. Even though, there are numerous scientific articles published on species‘ biological activities, it is a difficult task to find basic information on its diversity, distribution, genetics, silvicultural management or botany. Therefore, in this very first review published on G. kola, we summarize all relevant information known about the species, target some of the challenges connected with its cultivation and propose a leading direction for future research and domestication process.

Kolaviron attenuated arsenic acid induced-cardiorenal dysfunction via regulation of ROS, C-reactive proteins (CRP), cardiac troponin I (CTnI) and BCL2

Arsenic acid is one of the abundant environmental pollutants present in soil, water and the air. Undoubtedly, it has found its way to the food chain in which humans and animals are the final targets thereby causing arrays of disease conditions including cardiovascular and renal dysfunction. Hence, the use of phytochemicals present in medicinal plants has gained global acceptance as chemotherapeutic agents that can prevent, ameliorate, reverse or treat diseases. From our study, arsenic acid intoxication led to significant increase in heart rate (HR), QRS, together with prolonged QT and QTc interval. However, Kolaviron (KV) at the dosage of 100 and 200 mg/kg body weight reversed the aforementioned electrocardiographic (ECG) changes. KV pre-treatment also ameliorated cardiorenal dysfunction via significant reduction in cardiac and renal markers of oxidative stress such as malondialdehyde, hydrogen peroxide generation, myeloperoxidase activity and nitric oxide contents. Immunohistochemistry revealed expressions of renal C-reactive proteins (CRP) and expressions of anti-apoptotic protein BCL2 in KV treated rats. Furthermore, cardiac troponin I (CTnI) expressions were lower in KV treated rats. Taken together, KV mitigated arsenic-acid induced cardiovascular dysfunction via up-regulation of antioxidant defense system and down-regulation of inflammatory and apoptotic signaling pathways.

Improvement of 2-Vessel Occlusion Cerebral Ischaemia/Reperfusion-Induced Corticostriatal Electrolyte and Redox Imbalance, Lactic Acidosis and Modified Acetylcholinesterase Activity by Kolaviron Correlates with Reduction in Neurobehavioural Deficits

Background

Disruption of electrolyte, redox and neurochemical homeostasis alongside cellular energy crisis is a hallmark of cerebral ischaemia and reperfusion injury.

Purpose

This study investigated the effect of kolaviron (KV) on cortical and striatal cation imbalance, oxidative stress and neurochemical disturbances as well as neurobehavioural deficits in animals subjected to bilateral common carotid artery occlusion (BCCAO)-induced ischaemia/reperfusion injury.

Methods

KV was administered at a dose of 100 or 200 mg/kg to male Wistar rats 1 h before a 30 min BCCAO/4 h reperfusion (I/R). This was followed by neurobehavioral assessment and biochemical evaluations of cation levels, oxidative stress indicators, lactate dehydrogenase activity and acetylcholinesterase (AChE) activity in the brain of animals.

Conclusion

KV significantly restored altered cortical and striatal Ca²⁺, Na⁺, K⁺ and Mg²⁺ levels, ameliorated redox imbalance, lactic acidosis and modified AChE activity caused by I/R injury. The favourable neurobehavioural effects of KV correlated with biochemical outcomes. The pharmacological potential of KV in the treatment and management of ischemic stroke and allied pathological conditions via multiple targets (neurotransmitter metabolism, bioenergetic failure and ionic homeostasis) is highlighted by the study.

Ethyl-acetate fraction of Trichilia catigua restores long-term retrograde memory and reduces oxidative stress and inflammation after global cerebral ischemia in rats

We originally reported that an ethyl-acetate fraction (EAF) of Trichilia catigua prevented the impairment of water maze learning and hippocampal neurodegeneration after transient global cerebral (TGCI) in mice. We extended that previous study by evaluating whether T. catigua (i) prevents the loss of long-term retrograde memory assessed in the aversive radial maze (AvRM), (ii) confers hippocampal and cortical neuroprotection, and (iii) mitigates oxidative stress and neuroinflammation in rats that are subjected to the four vessel occlusion (4-VO) model of TGCI. In the first experiment, naive rats were trained in the AvRM and then subjected to TGCI. The EAF was administered orally 30min before and 1h after TGCI, and administration continued once per day for 7days post-ischemia. In the second experiment, the EAF was administered 30min before and 1h after TGCI, and protein carbonylation and myeloperoxidase (MPO) activity were assayed 24h and 5days later, respectively. Retrograde memory performance was assessed 8, 15, and 21days post-ischemia. Ischemia caused persistent retrograde amnesia, and this effect was prevented by T. catigua. This memory protection (or preservation) persisted even after the treatment was discontinued, despite the absence of histological neuroprotection. Protein carbonyl group content and MPO activity increased around 43% and 100%, respectively, after TGCI, which were abolished by the EAF of T. catigua. The administration of EAF did not coincide with the days of memory testing. The data indicate that antioxidant and/or antiinflammatory actions in the early phase of ischemia/reperfusion contribute to the long-term antiamnesic effect of T. catigua.

Garcinia kola seeds may prevent cognitive and motor dysfunctions in a type 1 diabetes mellitus rat model partly by mitigating neuroinflammation

Background We reported recently that extracts of seeds of Garcinia kola, a plant with established hypoglycemic properties, prevented the loss of inflammation-sensible neuronal populations like Purkinje cells in a rat model of type 1 diabetes mellitus (T1DM). Here, we assessed G. kola extract ability to prevent the early cognitive and motor dysfunctions observed in this model. Methods Rats made diabetic by single injection of streptozotocin were treated daily with either vehicle solution (diabetic control group), insulin, or G. kola extract from the first to the 6th week post-injection. Then, cognitive and motor functions were assessed using holeboard and vertical pole behavioral tests, and animals were sacrificed. Brains were dissected out, cut, and processed for Nissl staining and immunohistochemistry. Results Hyperglycemia (209.26 %), body weight loss (-12.37 %), and T1DM-like cognitive and motor dysfunctions revealed behavioral tests in diabetic control animals were not observed in insulin and extract-treated animals. Similar, expressions of inflammation markers tumor necrosis factor (TNF), iba1 (CD68), and Glial fibrillary acidic protein (GFAP), as well as decreases of neuronal density in regions involved in cognitive and motor functions (-49.56 % motor cortex, -33.24 % medial septal nucleus, -41.8 % /-37.34 % cerebellar Purkinje /granular cell layers) were observed in diabetic controls but not in animals treated with insulin or G. kola. Conclusions Our results indicate that T1DM-like functional alterations are mediated, at least partly, by neuroinflammation and neuronal loss in this model. The prevention of the development of such alterations by early treatment with G. kola confirms the neuroprotective properties of the plant and warrant further mechanistic studies, considering the potential for human disease.

Ameliorative effect of kolaviron, a biflavonoid complex from Garcinia kola seeds against scopolamine-induced memory impairment in rats: role of antioxidant defense system

In Alzheimer's disease (AD) basal forebrain cholinergic neurons appear to be targeted primarily in early stages of the disease. Scopolamine (muscarinic receptor antagonist) has been used for decades to induce working and reference memory impairment in rodents. In this study, we evaluated the protective effect of kolaviron, a biflavonoid complex isolated from Garcinia kola seeds extract against scopolamine-induced memory impairment/oxidative stress. Rats were pretreated with kolaviron (25, 50 or 100 mg/kg p.o.) for 3 consecutive days, scopolamine (3 mg/kg, i.p.) was administered 1 h post-treatment on day 3. Five minutes post-scopolamine injection, memory function was assessed using the Y-maze or Morris water maze tests (MWM) in rats. The rats were sacrificed and brains isolated on the 8th day after the MWM test for estimation of acetylcholinesterase activity and nitrosative/oxidative stress status. Scopolamine injection induced deficit (P < 0.05) in percentage alternation behaviour in the Y-maze test indicating memory impairment which was ameliorated by kolaviron in a dose-dependent manner. Also, pre-training treatment with kolaviron significantly improved spatial learning evidenced in the session-dependent and more efficient localization of the hidden platform in the MWM test. Moreover, scopolamine injection induced significant increase in lipid peroxidation (prefrontal cortex), nitrite generation (striatum and hippocampus) and a decrease in glutathione (prefrontal cortex, striatum and hippocampus) and superoxide dismutase (striatum and hippocampus) level which was attenuated by kolaviron pre-treatment. These findings showed that kolaviron possesses cognition enhancing effect through enhancement of antioxidant defense and cholinergic systems.

MORIN MITIGATES OXIDATIVE STRESS, APOPTOSIS AND INFLAMMATION IN CEREBRAL ISCHEMIC RATS

Background:

Morin is a flavanoid which exhibits potent antioxidant activity in various oxidative stress related diseases. The current study was attempted to scrutinize the preclinical bio-efficacy of morin on focal ischemia.

Methods:

The animal model of focal cerebral ischemic injury was done by midbrain carotid artery occlusion (MCAO) method, followed by Morin (30mg/kg) administration for seven days.

Results:

The outcome of the study showed that treatment with morin displayed positive effects in reducing the focal cerebral ischemia. This effect was evident with the improvements in neurological deficits, reduction in MDA content and elevation of antioxidant levels (SOD, GSH and Gpx). Furthermore, protein expression of Bax and caspase-3 were effectively down-regulated, whilst the expression of Bcl-2 was significantly elevated. On the other hand, the mRNA expression of proinflammatory cytokines was significantly reduced in focal cerebral ischemic rats upon morin intervention.

Conclusion:

Thus, the beneficial effects of morin on cerebral ischemia assault may result from the reduction of oxidative stress, inhibition of apoptosis and inflammation. The neuroprotective effects of morin supplement may serve as potent adjuvant in the amelioration of ischemic stroke.

Garcinia kola aqueous suspension prevents cerebellar neurodegeneration in long-term diabetic rat - a type 1 diabetes mellitus model

ETHNOPHARMACOLOGICAL RELEVANCE

The development of compounds able to improve metabolic syndrome and mitigate complications caused by inappropriate glycemic control in type 1 diabetes mellitus is challenging. The medicinal plant with established hypoglycemic properties Garcinia kola Heckel might have the potential to mitigate diabetes mellitus metabolic syndrome and complications.

AIM OF THE STUDY

We have investigated the neuroprotective properties of a suspension of G. kola seeds in long-term type 1 diabetes mellitus rat model.

MATERIALS AND METHODS

Wistar rats, made diabetic by single injection of streptozotocin were monitored for 8 months. Then, they were administered with distilled water or G. kola oral aqueous suspension daily for 30 days. Body weight and glycemia were determined before and after treatment. After sacrifice, cerebella were dissected out and processed for stereological quantification of Purkinje cells. Histopathological and immunohistochemical analyses of markers of neuroinflammation and neurodegeneration were performed.

RESULTS

Purkinje cell counts were significantly increased, and histopathological signs of apoptosis and neuroinflammation decreased, in diabetic animals treated with G. kola compared to diabetic rats given distilled water. Glycemia was also markedly improved and body weight restored to non-diabetic control values, following G. kola treatment.

CONCLUSIONS

These results suggest that G. kola treatment improved the general condition of long-term diabetic rats and protected Purkinje cells partly by improving the systemic glycemia and mitigating neuroinflammation.

Kolaviron, a biflavonoid of Garcinia kola seed mitigates ischemic/reperfusion injury by modulation of pro-survival and apoptotic signaling pathways

Objective:

The study was designed to investigate the ameliorative effect of Kolaviron (KV) on ischemic/reperfusion injury in experimental animal models.

Materials and Methods:

Male Wistar rats were randomly divided into two groups: Group 1 received corn oil as a vehicle and rats in Group 2 were administered KV at 200 mg/kg for 4 weeks. The rats were fed with rat standard chow pellet and water administered ad libitum. After 4 weeks of KV administration, hearts were excised and mounted on the working heart perfusion system. Western blot analysis for protein expression was carried out on frozen heart samples.

Results:

There was significant (P < 0.05) reduction in the activity of catalase, superoxide dismutase, and glutathione peroxidase with concomitant reduction in oxygen radical absorbance capacity in ischemic rat heart of control compared to group pre-treated with KV, respectively. Similarly, intracellular reactive oxygen species and malondialdehyde were significantly elevated in control compared to KV pre-treated rats. KV significantly increased total Akt/protein kinase B (PKB), phosphorylated Akt/PKB at serine 473 and also caused a significant reduction in p38 mitogen-activated protein kinase, Caspase 3, and cleaved poly adenosine diphosphate ribose polymerase.

Conclusion:

Taken together, KV offered significant cardioprotection via free radical scavenging activity and upregulation of pro-survival pathway.

Phytochemicals in Ischemic Stroke

Stroke is the second foremost cause of mortality worldwide and a major cause of long-term disability. Due to changes in lifestyle and an aging population, the incidence of stroke continues to increase and stroke mortality predicted to exceed 12 % by the year 2030. However, the development of pharmacological treatments for stroke has failed to progress much in over 20 years since the introduction of the thrombolytic drug, recombinant tissue plasminogen activator. These alarming circumstances caused many research groups to search for alternative treatments in the form of neuroprotectants. Here, we consider the potential use of phytochemicals in the treatment of stroke. Their historical use in traditional medicine and their excellent safety profile make phytochemicals attractive for the development of therapeutics in human diseases. Emerging findings suggest that some phytochemicals have the ability to target multiple pathophysiological processes involved in stroke including oxidative stress, inflammation and apoptotic cell death. Furthermore, epidemiological studies suggest that the consumption of plant sources rich in phytochemicals may reduce stroke risk, and so reinforce the possibility of developing preventative or neuroprotectant therapies for stroke. In this review, we describe results of preclinical studies that demonstrate beneficial effects of phytochemicals in experimental models relevant to stroke pathogenesis, and we consider their possible mechanisms of action.

Glutamine Synthetase: Role in Neurological Disorders

Glutamine synthetase (GS) is an ATP-dependent enzyme found in most species that synthesizes glutamine from glutamate and ammonia. In brain, GS is exclusively located in astrocytes where it serves to maintain the glutamate-glutamine cycle, as well as nitrogen metabolism. Changes in the activity of GS, as well as its gene expression, along with excitotoxicity, have been identified in a number of neurological conditions. The literature describing alterations in the activation and gene expression of GS, as well as its involvement in different neurological disorders, however, is incomplete. This review summarizes changes in GS gene expression/activity and its potential contribution to the pathogenesis of several neurological disorders, including hepatic encephalopathy, ischemia, epilepsy, Alzheimer's disease, amyotrophic lateral sclerosis, traumatic brain injury, Parkinson's disease, and astroglial neoplasms. This review also explores the possibility of targeting GS in the therapy of these conditions.