Roles of Marine Macroalgae or Seaweeds and Their Bioactive Compounds in Combating Overweight, Obesity and Diabetes: A Comprehensive Review

Obesity and diabetes are matters of serious concern in the health sector due to their rapid increase in prevalence over the last three decades. Obesity is a severe metabolic problem that results in energy imbalance that is persistent over a long period of time, and it is characterized by insulin resistance, suggesting a strong association with type 2 diabetes (T2D). The available therapies for these diseases have side effects and some still need to be approved by the Food and Drug Administration (FDA), and they are expensive for underdeveloped countries. Hence, the need for natural anti-obesity and anti-diabetic drugs has increased in recent years due to their lower costs and having virtually no or negligible side effects. This review thoroughly examined the anti-obesity and anti-diabetic effects of various marine macroalgae or seaweeds and their bioactive compounds in different experimental settings. According to the findings of this review, seaweeds and their bioactive compounds have been shown to have strong potential to alleviate obesity and diabetes in both in vitro and in vivo or animal-model studies. However, the number of clinical trials in this regard is limited. Hence, further studies investigating the effects of marine algal extracts and their bioactive compounds in clinical settings are required for developing anti-obesity and anti-diabetic medicines with better efficacy but lower or no side effects.

Senna petersiana (Bolle) leaf extract modulates glycemic homeostasis and improves dysregulated enzyme activities in fructose-fed streptozotocin-induced diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Senna petersiana (Bolle) is a native South African medicinal shrub combined locally with other plant products to manage diabetes or used as a single therapy for several other ailing conditions.

AIM OF THE STUDY

This study evaluated the antidiabetic and antilipidemic effects of S. petersiana leaf ethanol extract and its modulatory effects on dysregulated enzyme activities in fructose-fed streptozotocin-induced diabetic rats.

MATERIALS AND METHODS

Six groups of 6-weeks old male Sprague Dawley rats were used in this study. Diabetes was induced in four of the groups by injecting (i.p.) 40 mg/kg of streptozotocin after a two-weeks feeding of 10% fructose via drinking water, while animals in the two normal groups were given similar volume of vehicle buffer and normal drinking water, respectively. After the confirmation of diabetes, treatment with 150 and 300 mg/kg body weight of the ethanolic leaf extract of S. petersiana proceeded for a period of 6 weeks.

RESULTS

Oral administration of S. petersiana leaf extract significantly lowered blood glucose, food and liquid intake, glycosylhaemoglobin in blood, liver and cardiac biomarkers, and lipid profile in serum and atherogenic index (AIP) in both the low and high-dose treated animal groups. This was accompanied by a simultaneous increase in Homeostatic Model Assessment-beta (HOMA-β) score, serum high-density lipoproteins cholesterol (HDL-c), and insulin levels. It also improved pancreatic and serum-reduced glutathione (GSH) levels, catalase, and superoxide dismutase (SOD) enzymes activities with a simultaneous reduction in malondialdehyde (MDA) and nitric oxide (NO) concentrations. Moreover, the extract modulated dysregulated α-amylase, lipase, cholinesterase, and 5' nucleotidase enzyme activities in pancreatic tissue as well as glycogen metabolism in the liver. Analysis of the phytochemicals in the S. petersiana extract showed the presence of phytol, 4a,7,7,10a-tetramethyldodecahydrobenzo[f]-chromen-3-ol, phytol acetate, solasodine glucoside, cassine, veratramine and solasodine acetate. Amongst these compounds, solasodine glucoside had the best binding energy (ΔG) with the selected diabetes-linked enzymes via molecular docking simulation.

CONCLUSION

Data from this study demonstrate the antidiabetic effects of S. petersiana leaf extract via the modulation of the dysregulated indices involved in type 2 diabetes and its associated complications. Although it has been shown safe in animals, further toxicological studies are required to ensure its safety for diabetes management in humans.

Bridelia ferruginea Benth. (Euphorbiaceae) mitigates oxidative imbalance and lipotoxicity, with concomitant modulation of insulin signaling pathways via GLUT4 upregulation in hepatic tissues of diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Bridelia ferruginea Benth. (Euphorbiaceae) is among the medicinal plants commonly used for the management of type 2 diabetes (T2D) and its complications.

AIM OF THE STUDY

The hepato-therapeutic effect of the butanol fraction of Bridelia ferruginea leaves was investigated in diabetic rats.

METHODS

The butanol fraction of B. ferruginea was given to type 2 diabetic rats at both low and high doses (150 and 300 mg/kg bodyweight, respectively), while metformin and glibenclamide served as the standard anti-diabetic drugs. A normal toxicological group was administered a high dose of the fraction. At the end of the experimental period, the rats were sacrificed, and their livers and psoas muscle collected. The liver was assayed for oxidative stress markers, liver glycogen content, lipid metabolite profile (using GC-MS) and their metabolic pathways were analyzed using the MetaboAnalyst 5.0 online server. The expression of GLUT4 was also assayed in the liver and muscle as well as the identification of signaling pathways associated with GLUT4 expression using the Enrichr online server. In silico molecular docking was used to investigate the molecular interactions of some postulated compound found in B. ferruginea with GLUT4. The ability of the fraction to stimulate muscle glucose uptake was determined in isolated rat psoas muscle ex vivo.

RESULTS

Treatment with the high dose of fraction caused an inhibition of lipid peroxidation as well as the elevation of catalase, SOD, glutathione reductase and glutathione peroxidase activities in the rat liver. There was an increased expression of GLUT4 in livers and muscles of diabetic rats following treatment with B. ferruginea. Treatment with the fraction also caused inactivation of diabetes-activated pathways and changes in the distribution of the hepatic lipid metabolites. Molecular docking analysis revealed strong molecular interactions of pyrogallol and sitosterol with GLUT4.

CONCLUSIONS

These data illustrate the hepato-protective effect of B. ferruginea in diabetic rats which compare favorably with the tested anti-diabetic drugs (metformin and glibenclamide).

Meeting report of the chief editorial board meeting for World Journal of Diabetes 2021

The 2021 online editorial board meeting of the World Journal of Diabetes (WJD) was held on November 9, 2021. Jin-Lei Wang, General Manager on behalf of the Baishideng Publishing Group, and Professor Islam, one of the Editors-in-Chiefs (EiCs) of the WJD, organized the meeting. Three EiCs and 18 Baishideng Publishing Group staff attended the meeting. The meeting goal was to brief the EiCs on the journal’s performance, discuss the issues of concern of the EiCs, and gather ideas for the journal’s development in 2022. As of November 8, the WJD had received 287 manuscripts since the year’s start, among which 122 met the criteria for publication. These numbers represent an increase of 117.4% for submissions and 110.3% for publications compared to those in 2020. However, how to effectively control the academic quality of manuscripts and attract high-quality original article submissions remain a challenge. The EiCs provided feedback and suggestions centered on three topics: (1) Who should and how to control the academic quality of the manuscripts; (2) How the EiCs perform their responsibilities; and (3) The distinctive and shared responsibilities of the publisher and the EiCs.

GC-MS metabolomics reveals dysregulated lipid metabolic pathways and metabolites in diabetic testicular toxicity: Therapeutic potentials of raffia palm (Raphia hookeri G. Mann & H. Wendl) wine

ETHNOPHARMACOLOGICAL RELEVANCE

Raffia palm (Raphia hookeri G. Mann & H. Wendl) wine (RPW) is a natural beverage obtained from the R. hookeri consumed for refreshment and medicinal purposes. For medicinal purposes, it is used singly or as macerating agent for other medicinal plants for the treatment of several diseases.

AIM

This study investigates the effect of Raffia palm wine on dysregulated lipid metabolic pathways in testicular tissues of type 2 diabetic (T2D) rats.

METHODS

Raffia palm wine (150 and 300 mg/kg bodyweight) was administered to two T2D groups respectively, another T2D group was not administered treatment and served as negative control, while metformin served as the standard drug. After 6 weeks of treatment, the rats were sacrificed, and the testes collected. After weighing, the organs were homogenized in 20% methanol/ethanol and centrifuged at 20,000 g to extract the lipid metabolites.

RESULTS

GC-MS analysis of the supernatants revealed an alteration of the metabolites on induction of T2D, with concomitant generation of 10 metabolites. Raffia palm wine inhibited the T2D-generated metabolites while replenishing cholesterol and squalene levels, with concomitant generation of 7 and 8 metabolites for low and high dose treatment respectively. Pathway enrichment analysis of the metabolites revealed a decreased level of steroid biosynthesis and increased level of fatty acid biosynthesis. Raffia palm wine inactivated glycerolipid, fatty acid, and arachidonic acid metabolisms, fatty acid biosynthesis and fatty acid elongation in mitochondria pathways, and activated pathways for plasmalogen synthesis, mitochondrial beta-oxidation of long chain saturated fatty acids.

CONCLUSION

The replenishment and generation of these metabolites and additional ones as well as activation of pathways involved in energy generation, phospholipids, antioxidant activity, steroidogenesis and spermatogenesis suggest a therapeutic effect of Raffia palm wine against hyperglycemic-induced testicular dysfunction.

Vanillin modulates activities linked to dysmetabolism in psoas muscle of diabetic rats

Skeletal muscles are important in glucose metabolism and are affected in type 2 diabetes (T2D) and its complications. This study investigated the effect of vanillin on redox imbalance, cholinergic and purinergic dysfunction, and glucose-lipid dysmetabolism in muscles of rats with T2D. Male albino rats (Sprague-Dawley strain) were fed 10% fructose ad libitum for 2 weeks before intraperitoneally injecting them with 40 mg/kg streptozotocin to induce T2D. Low (150 mg/kg bodyweight (BW)) and high (300 mg/kg BW) doses of vanillin were orally administered to diabetic rats. Untreated diabetic rats and normal rats made up the diabetic control (DC) and normal control (NC) groups, respectively. The standard antidiabetic drug was metformin. The rats were humanely put to sleep after 5 weeks of treatment and their psoas muscles were harvested. There was suppression in the levels of glutathione, activities of SOD, catalase, ENTPDase, 5'Nucleotidase and glycogen levels on T2D induction. This was accompanied by concomitantly elevated levels of malondialdehyde, serum creatine kinase-MB, nitric oxide, acetylcholinesterase, ATPase, amylase, lipase, glucose-6-phosphatase (G6Pase), fructose-1,6-biphophastase (FBPase) and glycogen phosphorylase activities. T2D induction further resulted in the inactivation of fatty acid biosynthesis, glycerolipid metabolism, fatty acid elongation in mitochondria and fatty acid metabolism pathways. There were close to normal and significant reversals in these activities and levels, with concomitant reactivation of the deactivated pathways following treatment with vanillin, which compared favorably with the standard drug (metformin). Vanillin also significantly increased muscle glucose uptake ex vivo. The results suggest the therapeutic effect of vanillin against muscle dysmetabolism in T2D as portrayed by its ability to mitigate redox imbalance, inflammation, cholinergic and purinergic dysfunctions, while modulating glucose-lipid metabolic switch and maintaining muscle histology.

Caffeic Acid Protects against Iron-Induced Cardiotoxicity by Suppressing Angiotensin-Converting Enzyme Activity and Modulating Lipid Spectrum, Gluconeogenesis and Nucleotide Hydrolyzing Enzyme Activities

The protective effects of caffeic acid on angiotensin-converting enzyme (ACE) and purinergic enzyme activities, as well as gluconeogenesis was investigated in iron-induced cardiotoxicity. Cardiotoxicity was induced in heart tissues harvested from healthy male SD rats by 0.1 mM FeSO₄. Treatment was carried out by co-incubating hearts tissues with caffeic acid and 0.1 mM FeSO₄. Cardiotoxicity induction significantly (p < 0.05) depleted GSH level, SOD, catalase, and ENTPDase activities, with concomitant elevation of the levels of malondialdehyde (MDA), nitric oxide, ACE, ATPase, glycogen phosphorylase, glucose 6-phosphatase, fructose 6-biphsophatase, and lipase activities. There was significant (p < 0.05) reversion in these levels and activities on treatment with caffeic acid. Caffeic acid also caused depletion in cardiac levels of cholesterol, triglyceride, LDL-c, while elevating HDL-c level. Our results suggest the protective effect of caffeic acid against iron-mediated cardiotoxicity as indicated by its ability to suppress oxidative imbalance and ACE activity, while concomitantly modulating nucleotide hydrolysis and metabolic switch.

Quinoline Functionalized Schiff Base Silver (I) Complexes: Interactions with Biomolecules and In Vitro Cytotoxicity, Antioxidant and Antimicrobial Activities

A series of fifteen silver (I) quinoline complexes Q1-Q15 have been synthesized and studied for their biological activities. Q1-Q15 were synthesized from the reactions of quinolinyl Schiff base derivatives L1-L5 (obtained by condensing 2-quinolinecarboxaldehyde with various aniline derivatives) with AgNO₃, AgClO₄ and AgCF₃SO₃. Q1-Q15 were characterized by various spectroscopic techniques and the structures of [Ag(L1)₂]NO₃Q1, [Ag(L1)₂]ClO₄Q6, [Ag(L2)₂]ClO₄Q7, [Ag(L2)₂]CF₃SO₃Q12 and [Ag(L4)₂]CF₃SO₃Q14 were unequivocally determined by single crystal X-ray diffraction analysis. In vitro antimicrobial tests against Gram-positive and Gram-negative bacteria revealed the influence of structure and anion on the complexes' moderate to excellent antibacterial activity. In vitro antioxidant activities of the complexes showed their good radical scavenging activity in ferric reducing antioxidant power (FRAP). Complexes with the fluorine substituent or the thiophene or benzothiazole moieties are more potent with IC₅₀ between 0.95 and 2.22 mg/mL than the standard used, ascorbic acid (2.68 mg/mL). The compounds showed a strong binding affinity with calf thymus-DNA via an intercalation mode and protein through a static quenching mechanism. Cytotoxicity activity was examined against three carcinoma cell lines (HELA, MDA-MB231, and SHSY5Y). [Ag(L2)₂]ClO₄Q7 with a benzothiazole moiety and [Ag(L4)₂]ClO₄Q9 with a methyl substituent had excellent cytotoxicity against HELA cells.

Hyperglycemia alters lipid metabolism and ultrastructural morphology of cerebellum in brains of diabetic rats: Therapeutic potential of raffia palm (Raphia hookeri G. Mann & H. Wendl) wine

The present study investigated the effect of raffia palm (Raphia hookeri) wine (RPW) on hyperglycemia-mediated lipid metabolites and pathways, functional chemistry and ultrastructural morphology of cerebellums in type 2 diabetes (T2D). T2D was induced in male Sprague-Dawley rats by feeding with 10% fructose ad libitum for 2 weeks before injecting intraperitoneally with 40 mg/kg bodyweight (bw) streptozotocin. Following confirmation of hyperglycemia at blood glucose >200 mg/dL, diabetic rats were treated with RPW at 150 and 300 mg/kg bw respectively. Metformin served as the standard drug. Negative and normal controls consisted of untreated diabetic and non-diabetic rats, respectively. After 5 weeks of treatment, the rats were humanely sacrificed, and their cerebellum excised from the harvested brains. GC-MS analysis revealed significant alterations in cerebellar lipid metabolites depicted by changes in unsaturated and saturated fatty acids, fatty - esters, alcohols, and amides, glycols and steroids on induction of T2D. Pathway enrichment analysis of the lipid metabolites revealed inactivation of arachidonic metabolic pathway following T2D induction. Treatment with both doses of RPW restored most of the metabolites, while reactivating arachidonic acid metabolism (high dose only). Low dose of RPW led to the activation of retinol metabolism. Both doses of RPW maintained cerebellar functional chemistry as revealed by FTIR analysis. TEM analysis revealed swollen mitochondria, depleted numbers of synaptic vesicles, and shrunk synaptic clefts following induction of T2D. These ultrastructural morphologies were improved in RPW-treated rats. These results portray the therapeutic potential of raffia palm wine in the management of neurodegenerative complications in T2D.

Ferric-Induced Pancreatic Injury Involves Exacerbation of Cholinergic and Proteolytic Activities, and Dysregulation of Metabolic Pathways: Protective Effect of Caffeic Acid

The protective effect of caffeic acid on ferric-induced pancreatic injury was investigated using ex vivo and in silico models. Incubation of pancreatic tissues with Fe²⁺ led to significant depleted levels of glutathione (GSH) and SOD and catalase activities, with concomitant elevated levels of malondialdehyde (MDA) and nitric oxide (NO) and acetylcholinesterase and α-chymotrypsin activities. Treatment with caffeic acid led to significant reversion of these levels and activities. Molecular docking revealed a higher binding affinity of caffeic acid with acetylcholinesterase via hydrogen bonding, Pi-Pi stacking, and Van der Waals interactions. FTIR spectroscopy of pancreatic metabolite revealed little or no effect by caffeic acid on functional groups in ferric-induced injured pancreas. The LC-MS analysis of the metabolites revealed Fe²⁺ caused a 20% depletion of the normal metabolites, with concomitant generation of glyceraldehyde and 3,4-dihydroxymandelaldehyde. Treatment with caffeic acid led to the restoration of TG(22:4(7Z,10Z,13Z,16Z)/24:0/22:5(7Z,10Z,13Z,16Z,19Z)) and dTDP-D-glucose, while depleting glyceraldehyde as well as activating gluconeogenesis. These results indicate the ability of caffeic acid to protect against ferric toxicity by exacerbating antioxidative activities, with concomitant inhibition of MDA and NO levels while deactivating metabolic pathways linked to oxidative stress.

Kolaviron stimulates glucose uptake with concomitant modulation of metabolic activities implicated in neurodegeneration in isolated rat brain, without perturbation of tissue ultrastructural morphology

Reduced glucose uptake usually occurs in type 2 diabetes due to down-regulation of brain glucose transporters. The potential of kolaviron, a biflavonoid from Garcinia kola to stimulate glucose uptake and suppress glucose-induced oxidative toxicity were investigated in rat brain. Its molecular interactions with the target proteins were investigated in silico. Kolaviron was incubated with excised rat brain in the presence of glucose for 2 h, with metformin serving as a positive control. Kolaviron caused a significant (p < 0.05) increase in glucose uptake, glutathione level, superoxide dismutase, catalase, ATPase, ENTPDase and 5'-nucleotidase activities, while concomitantly depleting malondialdehyde level, acetylcholinesterase and butyrylcholinesterase activities compared to brains incubated with glucose only. Electron microscopy (SEM and TEM) analysis revealed kolaviron had little or no effect on the ultrastructural morphology of brain tissues as evidenced by the intact dendritic and neuronal network, blood vessels, mitochondria, synaptic vesicles, and pre-synaptic membrane. SEM-EDX analysis revealed a restorative effect of glucose-induced alteration in brain elemental concentrations, with total depletion of aluminum and zinc. MTT analysis revealed kolaviron had no cytotoxic effect on HT-22 cells. Molecular docking revealed a potent interaction between kolaviron and catalase at the SER114 and MET350 residues, with a binding energy of 12 kcal/mol. Taken together, these results portray the potential of kolaviron to stimulate glucose uptake while concomitantly coffering a neuroprotective effect.

Dacryodes edulis (G. Don) H.J. Lam modulates glucose metabolism, cholinergic activities and Nrf2 expression, while suppressing oxidative stress and dyslipidemia in diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Dacryodes edulis L. is an evergreen tree indigenous to western and eastern Africa which is utilized for nutritional and medicinal purposes. Folklorically, different parts of the tree are used in treating and managing diabetes and its complications.

AIMS

The antidiabetic effect of the butanol fraction of D. edulis ethanol extract (BFDE) was studied in fructose-streptozotocin induced type 2 diabetic rats.

METHODS

The ethanol extract was fractionated to yield the hexane, dichloromethane, ethyl acetate, butanol and aqueous fractions. The in vitro antidiabetic activities of the fractions were determined by their ability to inhibit α-glucosidase activity. BDFE was the most active and showed no cytotoxic effect while stimulating glucose uptake in 3T3-L1 adipocytes. Thus, selected for in vivo study. Diabetic rats were grouped into 4. The negative control group was administered water only, another group was treated with metformin (200 mg/kg bodyweight), while the other groups were administered BDFE at 150 and 300 mg/kg bodyweight respectively. Two other groups consisting of normal rats were given water and BFDE (300 mg/kg bodyweight) respectively, with the former serving as normal control. After 6 weeks of intervention, the rats were humanely sacrificed using appropriate anaesthesia.

RESULTS

Treatment with the fraction significantly (p < 0.05) reduced the blood glucose level of the diabetic rats, with concomitant increase in serum insulin secretion. It also caused significant (p < 0.05) elevation of reduced glutathione level, superoxide dismutase, catalase, α-amylase, and ATPase activities, with concomitant depletion in myeloperoxidase activity, NO and MDA levels of the serum and pancreas. The pancreatic morphology and β-cell function were significantly improved in BFDE-treated rats, with restoration of the pancreatic capillary networks. Treatment with BFDE significantly (p < 0.05) inhibited the activities of glycogen phosphorylase, fructose 1,6 biphosphatase, glucose 6 phosphatase, and acetylcholinesterase, while suppressing the expression of Nrf2. HPLC analysis revealed the presence of gallic acid, vanillic acid, vanillin, and (-)-epicatechin in the fraction.

CONCLUSION

These results portray the antidiabetic and antioxidative properties of BFDE, which may be a synergistic consequence of the identified phenolics.

Vanillin and vanillic acid modulate antioxidant defense system via amelioration of metabolic complications linked to Fe2+-induced brain tissues damage

The therapeutic effect of phenolics on neurodegenerative diseases has been attributed to their potent antioxidant properties. In the present study, the neuroprotective activities of vanillin and vanillic acid were investigated in Fe²⁺- induced oxidative toxicity in brain tissues by investigating their therapeutic effects on oxidative imbalance, cholinergic and nucleotide-hydrolyzing enzymes activities, dysregulated metabolic pathways. Their cytotoxicity was investigated in hippocampal neuronal cell lines (HT22). The reduced glutathione level, SOD and catalase activities were ameliorated in tissues treated with the phenolics, with concomitant depletion of malondialdehyde and nitric oxide levels. They inhibited acetylcholinesterase and butyrylcholinesterase activities, while concomitantly elevated ATPase activity. Treatment with vanillin led to restoration of oxidative-depleted metabolites and reactivation of the pentose phosphate and purine metabolism pathways, with concomitant activation of pathways for histidine and selenoamino metabolisms. While vanillic acid restored and reactivated oxidative-depleted metabolites and pathways but did not activate any additional pathway. Both phenolics portrayed good binding affinity for catalase, with vanillic acid having the higher binding energy of -7.0 kcal/mol. Both phenolics were not cytotoxic on HT22 cells, and their toxicity class were predicted to be 4. Only vanillin was predicted to be permeable across the blood brain barrier (BBB). These results insinuate that vanillin and vanillic acid confer a neuroprotective effect on oxidative brain damage, when vanillin being the most potent.

The antidiabetic properties of the hot water extract of kola nut (Cola nitida (Vent.) Schott & Endl.) in type 2 diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Cola nitida is amongst the evergreen plants native to West Africa used in the treatment of various ailments including diabetes.

AIM OF THE STUDY

This study aims to investigate the antidiabetic effects of the hot water extract of C. nitida seeds in type 2 diabetic rats.

METHODS

Type 2 diabetic rats were orally administered with low (150 mg/kg bw) and high (300 mg/kg bw) doses of the hot water extract for 6 wk and thereafter, blood glucose, insulin level, lipid profile, pancreatic β-cell function, perfusion and morphology, redox imbalance, glycolytic and cholinergic enzymes, as well as of caspase-3 and Nrf2 expressions were measured.

RESULTS

Treatment with the extract led to significant depletion of blood glucose, serum triglycerides, LDL-cholesterol, fructosamine, ALT, and uric acids, while elevating serum insulin and HDL-cholesterol levels. The infusion also significantly (p < 0.05) elevated GSH level, SOD, catalase, α-amylase, and ATPase activities, with concomitant depletion of myeloperoxidase enzyme activity, and NO and MDA levels in the serum and pancreas. Significantly (p < 0.05) improved pancreatic β-cell function and morphology were observed in rats treated with C. nitida, with restored pancreatic capillary networks. C. nitida inhibited the activities of glycogen phosphorylase, fructose 1,6 biphosphatase, glucose 6 phosphatase, and acetylcholinesterase while downregulated the Nrf2 expression. NMR analysis of the extract revealed the presence of caffeine and theobromine. The molecular docking studies indicated that identified compounds displayed strong molecular interactions with caspase-3 and Nrf2.

CONCLUSION

These results insinuate the antidiabetic activities of C. nitida hot water extract and may be attributed to the NMR-identified compounds.

Type 2 diabetes induced oxidative brain injury involves altered cerebellar neuronal integrity and elemental distribution, and exacerbated Nrf2 expression: therapeutic potential of raffia palm (Raphia hookeri) wine

Neurodegenerative diseases, such as Alzheimer's disease have been recognized as one of the microvascular complications of type 2 diabetes (T2D). In this study, the effect of T2D on neuronal integrity and elemental distribution in the cerebellar cortex, as well as the therapeutic effect of Raffia Palm (Raphia hookeri) wine (RPW) were investigated in male albino rats. T2D was induced in 4 groups of rats using fructose and streptozotocin. One group served as negative control which was administered water, the second and third group were administered 150 and 300 mg/kg bodyweight of RPW, while the fourth was administered metformin (200 mg/kg bodyweight). Two other groups of normal rats were administered distilled water (control) and of RPW (300 mg/kg bodyweight). The rats were sacrificed after 5 weeks of treatment, and brains were collected. The cerebellum was removed, and several parts analyzed by immunochemistry, histology and scanning electron microscopy (SEM). Remaining brain tissues were used to analyze for the oxidative stress biomarkers and acetylcholinesterase activity. These analyses revealed oxidative damage with concomitantly increased acetylcholinesterase activity and upregulation of Nrf2 expression in the diabetic brain cerebellar cortexes. Histological and microscopic analysis also revealed altered distribution of neurons and axonal nodes with concomitant elevated levels of several heavy metals. Treatment with RPW significantly elevated glutathione (GSH) level, superoxide dismutase (SOD) and catalase activities, as well as depleted acetylcholinesterase and malondialdehyde (MDA) level and concomitantly inhibited Nrf2 expression. It also improved neuronal integrity and reduced the levels of heavy metals in brain. Taken together, the results of this study suggest that the RPW may afford a novel neuroprotective potential against diabetic neurodegeneration.

Raffia palm (Raphia hookeri G. Mann & H. Wendl) wine modulates glucose homeostasis by enhancing insulin secretion and inhibiting redox imbalance in a rat model of diabetes induced by high fructose diet and streptozotocin

ETHNOPHARMACOLOGICAL RELEVANCE

Raffia palm (Raphia hookeri) wine (RPW) is amongst the natural products from plants, utilized singly or in combination with other medicinal plants for the treatment of several ailments including Diabetes Mellitus (DM). However, there is a scientific dearth on its antidiabetic activity.

AIM

The antidiabetic effect of RPW and its possible mechanism of actions were investigated in diabetic rats.

METHODS

Four groups of male SD rats were first supplied with 10% fructose solution ad libitum for 2 weeks instead of drinking water followed by an intraperitonial injection of streptozotocin (40 mg/kg) to induce diabetes. Two diabetic groups were administered RPW at 150 and 300 mg/kg bodyweight (BW) respectively; a group was administered with metformin, while the other one was served as a negative control. Two groups of normal rats were administered with water and RPW (300 mg/kg BW) and served as normal control and normal toxicology group, respectively.

RESULTS

Five weeks treatment of RPW led to significant (p < 0.05) increase in serum insulin and HDL-c levels with concomitant reduction in blood glucose, fructosamine, ALT, uric acid, triglycerides and LDL-c levels in diabetic rats. Rats treated with RPW had elevated levels of GSH, SOD, catalase, ATPase and α-amylase activities, while reduced NO level and myeloperoxidase activity was observed in their serum and pancreatic tissues. RPW also improved pancreatic β-cell function and restored β- and acinar cells morphology, and capillary networks. The activities of glycogen phosphorylase, fructose 1,6 biphosphatase, glucose-6-phosphatase, and acetylcholinesterase were also inhibited in RPW-treated diabetic rats, with concomitant down regulation of Nrf2 gene expression.

CONCLUSION

The data of this study suggest that RPW modulates glucose homeostasis by enhancing insulin secretion as well as inhibiting redox imbalance in diabetic rats, which may be attributed to the synergetic effects of its phytochemical constituents as identified by GC-MS analysis.

Vernonia Amygdalina Del. stimulated glucose uptake in brain tissues enhances antioxidative activities; and modulates functional chemistry and dysregulated metabolic pathways

Brain glucose uptake is usually reduced in type 2 diabetes owing to downregulation of brain glucose transporters. The ability of Vernonia amygdalina to stimulate glucose uptake as well as ameliorate glucose-induced oxidative stress and proinflammation were investigated in rat brain. Hot infusion of V. amygdalina leaves was incubated with rat brain tissues for 2 h in the presence of glucose. Another incubation with glucose only, served as negative control while metformin served as positive control. Incubation of brain tissues with V. amygdalina led to significant (p < 0.05) increase in glucose uptake, reduced glutathione, nitric oxide and non-thiol proteins levels, superoxide dismutase, catalase and ATPase activities, while concomitantly decrease in myeloperoxidase activity and malondialdehyde level compared to the negative control. Incubation with glucose only, led to the development of nitrate, amide II and amide I functional groups which were removed on incubation with the infusion. LC-MS analysis revealed depletion of oxidative stress-induced 2-keto-glutaramic acid and cysteinyl-tyrosine metabolites in brain tissues, with concomitant generation of S-formylglutathione and adenosine tetraphosphate by the infusion. Pathway analysis of the metabolites revealed an activation of pyruvate metabolism pathway in the negative control, with the infusion reducing the intensity fold. LC-MS analysis of the infusion revealed the presence of l-serine, l-cysteine, l-proline, nicotinic acid, cumidine, salicylic acid, isoquinoline, 3-methyl-, and γ-octalactone. Except for l-serine, l-cysteine and l-proline, the other compounds were predicted to be permeable across the blood brain barrier. These results indicate the brain glucose uptake stimulatory and neuroprotective effect of V. amygdalina.

Hyperglycemia-induced oxidative brain injury: Therapeutic effects of Cola nitida infusion against redox imbalance, cerebellar neuronal insults, and upregulated Nrf2 expression in type 2 diabetic rats

The therapeutic effect of the hot water infusion of Cola nitida against hyperglycemia-induced neurotoxicity, cerebellar neurodegeneration and elemental deregulations was investigated in fructose-streptozotocin induced rat model of type 2 diabetes (T2D). A diabetic group was administered drinking water, two other diabetic groups were treated with C. nitida at 150 and 300 mg/kg bodyweight respectively, while another group was administered metformin (200 mg/kg bodyweight). Two other groups consisting of normal rats, were administered drinking water and C. nitida (300 mg/kg bodyweight). After 6 weeks of treatment, their brains were collected. Treatment with C. nitida led to suppression of oxidative stress, significantly elevating reduced glutathione (GSH) levels, superoxide dismutase and catalase activities, concomitant with depletion of malondialdehyde (MDA) levels. Acetylcholinesterase and ATPase activities were significantly inhibited in C. nitida-treated diabetic rats. Histological and microscopic analysis also revealed a restorative effect of C. nitida on T2D-altered distribution of elements, neurons and axonal nodes. Treatment with C. nitida also led to significant inhibition of Nrf2 expression in the cerebellar cortex. These results suggest the therapeutic effects of C. nitida in maintenance of the neuronal integrity and antioxidant status of the brain in T2D. These neuroprotective activities can be attributed to the identified alkaloid, caffeine in the infusion.

Commercially available non-nutritive sweeteners modulate the antioxidant status of type 2 diabetic rats

Non-nutritive sweeteners (NNS) are increasingly being used by diabetics, but little is known about their effects on antioxidant status. We investigated the effects of ad libitum consumption of commercially available NNS (aspartame, saccharin, sucralose, and cyclamate-based sweeteners) on antioxidative markers in a rat model of type 2 diabetes (T2D). NNS consumption reduced (p < 0.05) T2D-induced lipid peroxidation and boosted serum, hepatic, renal, cardiac, and pancreatic glutathione (GSH) levels. Catalase, glutathione reductase, superoxide dismutase, and glutathione peroxidase activity was increased in the serum and most organs upon diabetes induction, perhaps due to adaptative antioxidant response to the diabetes-induced lipid peroxidation. NNS showed varying effects on serum and tissue antioxidant enzymes of animals. An antioxidant capacity scores sheet of NNS, suggest that aspartame-based NNS may not exert antioxidant effects in diabetics, while saccharin-based NNS may be a potent antioxidative sweetener as seen in the animal model of T2D. PRACTICAL APPLICATIONS: The use of NNS is becoming more popular, especially for diabetic individuals. While there are several commercial NNS available in the market, little is known about how they affect the antioxidant status of consumers. We therefore investigated how some commercially available NNS affect the antioxidant status of diabetic rats. Observed data revealed varying effects of NNS on serum and different organs, which suggest that some NNS may be better than others for diabetic oxidative stress and thus may be recommended for consumers. However, this finding is subject to additional corroborative clinical studies.

Raffia palm (Raphia hookeri) wine extenuates redox imbalance and modulates activities of glycolytic and cholinergic enzymes in hyperglycemia-induced testicular injury in type 2 diabetic rats

This study investigated the effects of Raffia palm wine (RPW) on redox imbalance, glycolytic and cholinergic enzymes, and ATPase activities in hyperglycemia-induced oxidative testicular injury. Type 2 diabetes (T2D) was induced in male albino rats (Sprague-Dawley) by first administering 10% fructose solution for 14 days, before injecting with an intraperitoneal injection (40 mg/kg body weight) of streptozotocin. Raffia palm wine was administered to two diabetic groups at 150 and 300 mg/kg body weight (bw), when untreated diabetic group was used as a negative control, and metformin-fed group was served as a positive control. The rats were sacrificed after 5 weeks of treatment, and testes were harvested. Treatment with RPW led to lower levels of nitric oxide, malondialdehyde and myeloperoxidase activity, with concomitant elevation of reduced glutathione level, superoxide dismutase, catalase and ATPase activities. Raffia palm wine also inhibited glycogen phosphorylase, glucose-6-phosphatase, fructose-1,6-bisphosphatase, and acetylcholinesterase, while restoring the altered testicular morphology to near-normal. The results of this study suggest the therapeutic potentials of RPW against the effects of T2D on testicular functions and morphology. PRACTICAL APPLICATIONS: Diabetes mellitus is one of the fastest growing global epidemy, with most developing countries being at the receiving end owing to the cost of treatment. Testicular damage has been recognized as one of the complications of diabetes, and if left untreated will lead to erectile dysfunction followed by infertility. Raffia palm wine is among the common natural beverage in West Africa, which is utilized for both social and medicinal purposes. In this study, for the first time we showed its ability to protect diabetes-induced testicular injury in type 2 diabetic rats. This may be of great benefit in managing diabetes associated erectly dysfunction and male infertility, as Raffia palm wine is readily available in all seasons. This study will also improve the medicinal use of this wine, which may also indirectly improve its commercial benefit.