Effects of kolaviron on hepatic oxidative stress in streptozotocin induced diabetes

Garcinia kola: a critical review on chemistry and pharmacology of an important West African medicinal plant

Garcinia kola Heckel (Clusiaceae) is a tree indigenous to West and Central Africa. All plant parts, but especially the seeds, are of value in local folklore medicine. Garcinia kola is used in treatment of numerous diseases, including gastric disorders, bronchial diseases, fever, malaria and is used to induce a stimulating and aphrodisiac effect. The plant is now attracting considerable interest as a possible source of pharmaceutically important drugs. Several different classes of compounds such as biflavonoids, benzophenones, benzofurans, benzopyran, vitamin E derivatives, xanthones, and phytosterols, have been isolated from G. kola, of which many appears to be found only in this species, such as garcinianin (found in seeds and roots), kolanone (fruit pulp, seeds, roots), gakolanone (stem bark), garcinoic acid, garcinal (both in seeds), garcifuran A and B, and garcipyran (all in roots). They showed a wide range of pharmacological activities (e.g. analgesic, anticancer, antidiabetic, anti-inflammatory, antimalarial, antimicrobial, hepatoprotective and neuroprotective effects), though this has only been confirmed in animal models. Kolaviron is the most studied compound and is perceived by many studies as the active principle of G. kola. However, its research is associated with significant flaws (e.g. too high doses tested, inappropriate positive control). Garcinol has been tested under better conditions and is perhaps showing more promising results and should attract deeper research interest (especially in the area of anticancer, antimicrobial, and neuroprotective activity). Human clinical trials and mechanism-of-action studies must be carried out to verify whether any of the compounds present in G. kola may be used as a lead in the drug development.

Ninety-day oral toxicological profiling of Kolaviron (an extract of Garcinia kola) in male and female rats

There remains an insufficiency of data on the long-term toxicological profile of Garcinia kola Heckel and its extract, Kolaviron (KV), despite several studies on its pharmacological effects. This research was designed to investigate the long-term histopathological, hematological, biochemical, hormonal, reproductive, and oxidative effects of 90 days administration of KV to male and female rats, as well as additional 30 days reversibility study to assess the potential for reversal of induced effects. Fifty-six male and female Wistar rats divided into four groups were treated orally with distilled water/propylene glycol, 20 mg/kg KV, 100 mg/kg KV, and 500 mg/kg KV for 90 days. At the end of 90 days and 30 additional days of reversibility study, 5 ml blood was collected from animals for relevant analyses. Vital organs were harvested for histopathological assessments. In this study, KV did not elicit any adverse effect on histopathological presentations of vital organs which were generally non-abnormal. There was significant increase (p < 0.05) in LEU, MON, EOS%, BAS%, HCT (male animals) and LYM%, EOS%, BAS%, RBC, hemoglobin and MCH (female animals). There was significant diminution (p < 0.05) in cholesterol, triglycerides, LDL, and VLDL levels, with significant increase (p < 0.05) in HDL level in both male and female animals. KV elicited a non-significant increase in sperm count accompanied by a significant increase (p < 0.05) in levels of Follicle stimulating hormone (FSH) and testosterone in male rats. Furthermore, KV elicited significant (p < 0.001-0.05) elevation in the levels of GSH, SOD and CAT, and diminution in the level of MDA. The findings in this study suggest that long-term administration of KV is considerably safe with some variations in response between male and female animals. The possible sustenance of observed effects after cessation of KV administration, lipid lowering, erythropoiesis inducing, and immune system boosting activities of KV were confirmed in this study.

Therapeutic role of kaempferol and myricetin in streptozotocin-induced diabetes synergistically via modulation in pancreatic amylase, glycogen storage and insulin secretion

Kaempferol and Myricetin alone have promising benefits on diabetes and related complications, yet the effectiveness of cotreating the two compounds on diabetes have not been studied. The existing investigation was to study the combined anti-diabetic effect of kaempferol and myricetin in Streptozotocin (STZ)-activated diabetes in rats. To evaluate the anti-diabetic activity, 36 Wistar rats were segregated into six groups; Normal, 50 mg/kg STZ-induced diabetes, and four (50 mg/kg kaempferol, 50 mg/kg myricetin, 25 mg/kg kaempferol + myricetin, and 5 mg/kg glibenclamide) compound-treated diabetic groups. The effects of co-treatment on parameters, glucose, insulin, lipid profile, liver enzymes, antioxidant biomarkers, and inflammatory cytokines were measured. The study revealed that combined treatment restored the assessed parameters including glucose levels, inflammatory cytokines, oxidative markers, and lipid and liver enzymes in diabetic rats. The results indicate that cotreatment of kaempferol and myricetin has a beneficial role against diabetes suggesting that cotreatment of these compounds can be used therapeutically in treating diabetes.

Therapeutic Efficacy of Natural Product 'C-Phycocyanin' in Alleviating Streptozotocin-Induced Diabetes via the Inhibition of Glycation Reaction in Rats

Diabetes is a long-term metabolic disorder characterized by persistently elevated blood sugar levels. Chronic hyperglycemia enhances glucose-protein interactions, leading to the formation of advanced glycation end products (AGEs), which form irreversible cross-links with a wide variety of macromolecules, and accumulate rapidly in the body tissues. Thus, the objective of this study was to assess the therapeutic properties of C-phycocyanin (C-PC) obtained from Plectonema species against oxidative stress, glycation, and type 2 diabetes mellitus (T2DM) in a streptozotocin (STZ)-induced diabetic Wistar rat. Forty-five days of C-PC administration decreased levels of triglycerides (TGs), blood glucose, glycosylated hemoglobin, (HbA1c), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), liver and kidney function indices, and raised body weight in diabetic rats. C-PC suppressed biochemical glycation markers, as well as serum carboxymethyllysine (CML) and fluorescent AGEs. Additionally, C-PC maintained the redox state by lowering lipid peroxidation and protein-bound carbonyl content (CC), enhancing the activity of high-density lipoprotein cholesterol (HDL-C) and renal antioxidant enzymes, and preserving retinal and renal histopathological characteristics. Thus, we infer that C-PC possesses antidiabetic and antiglycation effects in diabetic rats. C-PC may also act as an antidiabetic and antiglycation agent in vivo that may reduce the risk of secondary diabetic complications.

Antioxidant Potential of Non-Extractable Fractions of Dried Persimmon (Diospyros kaki Thunb.) in Streptozotocin-Induced Diabetic Rats

Oxidative stress causes the progression of diabetes and its complications; thus, maintaining the balance between reactive oxygen species produced by hyperglycemia and the antioxidant defense system is important. We herein examined the antioxidant potential of non-extractable fractions of dried persimmon (NEP) against oxidative stress in diabetic rats. Rats with streptozotocin-induced type 1 diabetes (50 mg/kg body weight) were administered NEP for 9 weeks. Antioxidant enzyme activities and concentration of antioxidants in liver tissues were analyzed with a microplate reader. Extensor digitorum longus (EDL) and soleus muscle fibers were stained with succinate dehydrogenase and muscle fiber sizes were measured. The administration of NEP increased the body weight of diabetes rats. Regarding antioxidant activities, the oxygen radical absorbance capacity and superoxide dismutase activity in liver tissues significantly increased. In addition, increases in glutathione peroxidase activity in liver tissues and reductions in the cross-sectional area of EDL muscle fibers were significantly suppressed. In these results, NEP improved the antioxidant defense system in the liver tissues of diabetic rats, in addition to attenuating of muscle fibers atrophy against oxidative damage induced by hyperglycemia.

Antioxidative, Anti-Inflammatory, Anti-Obesogenic, and Antidiabetic Properties of Tea Polyphenols-The Positive Impact of Regular Tea Consumption as an Element of Prophylaxis and Pharmacotherapy Support in Endometrial Cancer

Endometrial cancer (EC) is second only to cervical carcinoma among the most commonly diagnosed malignant tumours of the female reproductive system. The available literature provides evidence for the involvement of 32 genes in the hereditary incidence of EC. The physiological markers of EC and coexisting diet-dependent maladies include antioxidative system disorders but also progressing inflammation; hence, the main forms of prophylaxis and pharmacotherapy ought to include a diet rich in substances aiding the organism’s response to this type of disorder, with a particular focus on ones suitable for lifelong consumption. Tea polyphenols satisfy those requirements due to their proven antioxidative, anti-inflammatory, anti-obesogenic, and antidiabetic properties. Practitioners ought to consider promoting tea consumption among individuals genetically predisposed for EC, particularly given its low cost, accessibility, confirmed health benefits, and above all, suitability for long-term consumption regardless of the patient’s age. The aim of this paper is to analyse the potential usability of tea as an element of prophylaxis and pharmacotherapy support in EC patients. The analysis is based on information available from worldwide literature published in the last 15 years.

Type-2 diabetic rat heart: The effect of kolaviron on mTOR-1, P70S60K, PKC-α, NF-kB, SOD-2, NRF-2, eNOS, AKT-1, ACE, and P38 MAPK gene expression profile

It has been established that genetic factors partially contribute to type-2 diabetes and vascular disease development. This study determined the effect of kolaviron on the expression profile of genes associated with the insulin signaling pathway and involved in regulating glucose and lipid metabolism, oxidative stress, inflammation, vascular functions, pro-survival and the apoptosis pathway in the heart of type-2 diabetic rats. After induction and confirmation of type-2 diabetes seven days after, the rats were treated with kolaviron for twenty-eight days before being euthanized. Organs were harvested and stored at - 80 °C in a biofreezer. Total RNA was extracted from the ventricle, reverse transcribed to cDNA followed by a real-time quantitative polymerase chain reaction (RT-qPCR) analysis of the expression of mTOR-1, P70S60K, PKC-α, NF-kB, SOD-2, NRF-2, eNOS, AKT-1, ACE, p38 MAPK and the reference gene (GAPDH), after which they were normalized/standardized. The results show an increase in the relative mRNA expression of mTOR/P70S60K/PKCα /P38MAPK/NF-KB/ACE and a decrease in the relative mRNA expression of NRF2/SOD/AKT/eNOS in the heart of the diabetic rats. Nevertheless, kolaviron modulated the expression profile of these genes, which suggest a therapeutic effect and target for vascular dysfunction and complications in type-2 diabetes through the activation of the NRF-2/AKT-1/eNOS signaling pathway and suppression of the NF-kB/PKC signaling pathway.

Effect of kolaviron on islet dynamics in diabetic rats

Kolaviron, a biflavonoid isolated from the edible seeds of Garcinia kola, lowers blood glucose in experimental models of diabetes; however, the underlying mechanisms are not yet fully elucidated. The objective of the current study was to assess the effects of kolaviron on islet dynamics in streptozotocin-induced diabetic rats. Using double immunolabeling of glucagon and insulin, we identified insulin-producing β- and glucagon-producing α-cells in the islets of diabetic and control rats and determined the fractional β-cell area, α-cell area and islet number. STZ challenged rats presented with islet hypoplasia and reduced β-cell area concomitant with an increase in α-cell area. Kolaviron restored some islet architecture in diabetic rats through the increased β-cell area. Overall, kolaviron-treated diabetic rats presented a significant (p < 0.05) increase in the number of large and very large islets compared to diabetic control but no difference in islet number and α-cell area. The β-cell replenishment potential of kolaviron and its overall positive effects on glycemic control suggest that it may be a viable target for diabetes treatment.

Kolaviron: A Biflavonoid with Numerous Health Benefits

BACKGROUND

The increasing interests on the healing properties of medicinal plants have led to a paradigm shift from the use of synthetic drug to the search of natural medicines for the treatment and management of several diseases. Like other phenolics flavonoids have been continuously explored for their medicinal benefits, with their potent antioxidant activity being a major interest. Kolaviron (KVN) is a biflavonoid isolated from Garcinia kola Heckel, which has been reported for its potent antioxidant and anti-inflammatory properties. These properties have been explored in several disease models including reproductive toxicity, cardiotoxicity, diabetes mellitus, gastrotoxicity and hepatotoxicity.

OBJECTIVES

The present study was aimed to review the reported medicinal properties of KVN in order to provide some guidelines and direction to researchers on KVN research.

METHODS

A literature search was conducted with the aim of identifying peer-reviewed published data on KVN and their biological activities. Different academic and/or scientific search engines were utilized including but not limited to Google Scholar, PubMed, ScienceDirect and so on.

RESULTS

Among all the studied disease models obtained from the literatures, the effect of KVN on reproductive toxicity was the most studied as it represented 25% of all the studies, followed by neuroprotective, cardioprotective and hepatoprotective activities of Kolaviron. From our identified studies, KVN has been shown to have antidiabetic, cardioprotective, neuroprotective, hematoprotective, nephroprotective, gastroprotective, hepatoprotective activities. KVN also has effects on malaria and reproductive health, which can be explored for novel drug and nutraceutical developments for related ailments. Unfortunately, while toxicity data are lacking, most studies are limited to in vitro and/or in vivo models, which may impede translation in this area of research.

CONCLUSION

Based on data gathered from the literature search, it is evident that KVN possesses numerous health benefits, which can be attributed to its potent antioxidant and anti-inflammatory activities. However, more studies are required in this area of research to validate the medicinal value of kolaviron, which may positively influence the economic value of plant, Garcinia kola.

Dietary effects of Garcinia kola seed meal on growth performance, hematology and serum biochemical parameters of weaned rabbits

Background and Aim:

Garcinia kola seed (GKS) is used to prevent and cure a number of gastric-related ailments. GKS contain a copious amount of polyphenols and can be utilized as a natural growth promoter in the nutrition of weaned rabbits. This study aimed to determine the dietary effects of GKS meal (GKSM) on the growth performance, hematology and serum biochemical parameters of weaned rabbits.

Materials and Methods:

GKS were dried and ground into powder. Thirty-two 8-week-old crossbred rabbits with an average weight of 614 g were randomly divided into four dietary groups. The diets were designated as follows: Control (corn-soybean based diet with 0% GKSM) and the GKSM-supplemented diets with 1.5% GKSM, 3% GKSM, and 4.5% GKSM. On the 56^th day of the feeding trial, blood was collected from the marginal ear vein of all rabbits and transferred into two separate labeled tubes. The first set of blood was used to determine the hematological indices. The second set of blood was transferred into plain bottles and allowed to coagulate. The coagulated blood was subjected to standard methods of serum separation, and the sera were harvested and used to evaluate serum biochemical parameters.

Results:

Although the average final body weight was highest in rabbits fed with 1.5% GKSM; this value was similar to rabbits fed with 0% and 4.5% GKSM. The average daily weight gain was highest in rabbits fed with 1.5% GKSM, while the feed conversion ratio was improved in the 0% and 1.5% GKSM groups. The dietary treatments also had a significant effect on the red blood cell count (RBC) and hemoglobin (Hb) concentration, while other blood parameters did not differ significantly (p > 0.05). Higher inclusion levels (3% and 4.5%) of GKSM led to a significant increase in RBC and Hb values (p < 0.05). The total protein increased at all levels of GKSM inclusion (p < 0.05). Bilirubin, sodium, and potassium levels significantly decreased at 4.5% GKSM inclusion (p < 0.05). Urea levels were lowered at 1.5% and 4.5% GKSM inclusion, while cholesterol levels were decreased at 3% and 4.5% dietary levels.

Conclusion:

From the results of the present study, the supplementation of up to 4.5% GKSM revealed no harmful effect on the hematological and serum biochemical parameters of weaned rabbits, while their growth performance improved at a 1.5% inclusion level of GKSM.

Kolaviron Ameliorates 7, 12-Dimethylbenzanthracene - Induced Mammary Damage in Female Wistar Rats

BACKGROUND

Kolaviron (KV) is a flavonoid rich portion obtained from Garcinia kola seeds with a number of reported pharmacological effects. However, its ameliorative effects on 7,12-Dimethylbenzanthracene (DMBA)-induced mammary damage has not been fully investigated, despite the reported use of the seeds in the treatment of inflammatory related disorders.

OBJECTIVE

To evaluate the ameliorative effects of KV on DMBA-induced mammary damage in female Wistar rats.

METHODS

Forty-nine (49) female Wistar rats were randomly assigned into seven groups of seven rats each. DMBA was administered orally to rats in five of the groups as a single dose of 80 mg/kg body wt while the remaining two groups received the vehicle. The rats were palpated weekly for 3 months to monitor tumor formation. After 3 months of DMBA administration, 1 ml of blood was collected to assay for estrogen receptor- α (ER-α) level. Thereafter, the vehicle (dimethyl sulfoxide) was daily administered to the negative control and positive control groups for the 14 days duration of the experiment while three groups were each given a daily oral dose of 50, 100 and 200 mg/kg body wt of KV for the duration of the experiment. The last DMBA-induced group received 10 mg/kg body wt of the standard drug tamoxifen twice in a week and the remaining DMBA-free group received 200 mg/kg body wt KV. Subsequently, the animals were humanly sacrificed and ER-α, sialic acids, sialidase, sialyltransferase levels were assay for in blood and mammary tissues followed by histopathological examinations.

RESULTS

Significantly higher levels of estrogen receptor-α (ER-α), formation of lobular neoplastic cells, epithelial hyperplasia, lymphocyte infiltration and increased sialylation were detected in DMBA-induced rats. Treatment with KV at 50, 100 and 200 mg/kg body weight resulted in a significant (p<0.05) decrease in ER-α level, significantly (p<0.05) lower free serum sialic acid (21.1%), total sialic acid level of the mammary tissue (21.57%), sialyltransferase activity (30.83%) as well as mRNA level of the sialyltransferase gene (ST3Gal1) were observed after KV interventions.

CONCLUSION

The findings suggest that KV could be further explored in targeting DMBA-induced mammary damage implicated in mammary carcinogenesis.

Functional relevance of Gedunin as a bona fide ligand of NADPH oxidase 5 and ROS scavenger: An in silico and in vitro assessment in a hyperglycemic RBC model

Clinical evidence suggests that type 2 diabetes therapy can greatly benefit from the suppression of reactive oxygen species generation and the activation or restoration of cellular antioxidant mechanisms. In human, NADPH oxidase (NOX) is the main producer of reactive oxygen species (ROS) that supress the activity of endogenous antioxidant enzymes. In the present study, the antioxidant potential of Gedunin was studied. In silico findings reveal its strong binding affinity with NOX5 C terminal HSP90 binding site that disrupts NOX5 stability and its ability to generate ROS, leading to restoration antioxidant enzymes activities. It was found that Gedunin suppressed hyperglycaemia induced oxidative stress in an in vitro RBC model and markedly reversed glucose induced changes including haemoglobin glycosylation and lipid peroxidation. A significant restoration of activities of cellular antioxidant enzymes; superoxide dismutase, catalase and glutathione peroxidase in the presence of Gedunin revealed its ability to reduce oxidative stress. These results substantiated Gedunin as a bona fide inhibitor of human NOX5 and a ROS scavenging antioxidant with promising therapeutic attributes including its natural origin and inhibition of multiple diabetic targets.

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In silico study reveals Gedunin as a bonafied ligand of human NOX5.

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Gedunin binds at NADPH oxidase C terminal HSP90 binding site and inhibits ROS formation.

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Gedunin reverses hemoglobin glycosylation, lipid peroxidation and restores activity of cellular antioxidant enzymes.

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Gedunin exhibits antioxidant property with dual mode of action: as an ROS scavenger and NOX5 inhibitor.

Safety assessment of oral administration of ethanol extract of Justicia carnea leaf in healthy wistar rats: hematology, antioxidative and histology studies

Background

Consumption of medicinal plants has diverse therapeutic benefits and could also have toxic effect. Justicia carnea is a medicinal plant that is used conventionally as blood tonic from time immemorial in Nigeria. The aim of this study is to evaluate the safety of ethanol extract of J. carnea leaf assessing the hematology indices, organ antioxidant system and histology in healthy male wistar rats.

Methods

Powdered sample was extracted using absolute ethanol and concentrated to obtain a slurry paste of J. carnea ethanol extracts. Acute toxicity was determined in two phases using Lorke method. In subacute study, rats were randomized into six groups of five rats per group: Group 1 (control) received distilled water, group 2, 3, 4, 5, 6 received 50, 100, 500, 800 and 1200 mg/kg body weight of J. carnea ethanol extract once daily using oral gavage. At the end of 14th day of administration, rats were allowed to fast overnight, sacrificed to collect samples for biochemical analysis and histopathological examination.

Results

The LD50 of extract was greater than 5000 mg/kg body weight. Higher doses (> 500 mg/kg) of extract significantly (p < 0.05) increased RBC, hemoglobin and platelet compared to the control. Liver superoxide dismutase (SOD) activity was significantly (p < 0.05) increased at 1200 mg/kg while other tested doses caused no detrimental effect on glutathione, catalase, SOD and malondialdehyde level in liver and kidney. Histopathological examination of liver and kidney showed mild to severe pathological lesion in a dose dependent manner.

Conclusions

The results of this study suggests that ethanol extract of J. carnea leaf is relatively safe, could be beneficial in alleviating hematology related abnormalities without causing adverse effects on endogenous antioxidant system. However, caution should be taken as higher dose at 1200 mg/kg could cause noticeable tissue injury.

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.

Quercetin Loaded Monolaurate Sugar Esters-Based Niosomes: Sustained Release and Mutual Antioxidant-Hepatoprotective Interplay

Flavonoids possess different interesting biological properties, including antibacterial, antiviral, anti-inflammatory and antioxidant activities. However, unfortunately, these molecules present different bottlenecks, such as low aqueous solubility, photo and oxidative degradability, high first-pass effect, poor intestinal absorption and, hence, low systemic bioavailability. A variety of delivery systems have been developed to circumvent these drawbacks, and among them, in this work niosomes have been selected to encapsulate the hepatoprotective natural flavonoid quercetin. The aim of this study was to prepare nanosized quercetin-loaded niosomes, formulated with different monolaurate sugar esters (i.e., sorbitan C12; glucose C12; trehalose C12; sucrose C12) that act as non-ionic surfactants and with cholesterol as stabilizer (1:1 and 2:1 ratio). Niosomes were characterized under the physicochemical, thermal and morphological points of view. Moreover, after the analyses of the in vitro biocompatibility and the drug-release profile, the hepatoprotective activity of the selected niosomes was evaluated in vivo, using the carbon tetrachloride (CCl₄)-induced hepatotoxicity in rats. Furthermore, the levels of glutathione and glutathione peroxidase (GSH and GPX) were measured. Based on results, the best formulation selected was glucose laurate/cholesterol at molar ratio of 1:1, presenting spherical shape and a particle size (PS) of 161 ± 4.6 nm, with a drug encapsulation efficiency (EE%) as high as 83.6 ± 3.7% and sustained quercetin release. These niosomes showed higher hepatoprotective effect compared to free quercetin in vivo, measuring serum biomarker enzymes (i.e., alanine and aspartate transaminases (ALT and AST)) and serum biochemical parameters (i.e., alkaline phosphatase (ALP) and total proteins), while following the histopathological investigation. This study confirms the ability of quercetin loaded niosomes to reverse CCl₄ intoxication and to carry out an antioxidant effect.

A New Possible Mechanism by Which Punicalagin Protects against Liver Injury Induced by Type 2 Diabetes Mellitus: Upregulation of Autophagy via the Akt/FoxO3a Signaling Pathway

The aim of this study was to investigate the protective effect of punicalagin (PU), which is a main component of pomegranate polyphenols, against liver injury induced by Type 2 diabetes mellitus (T2DM) and to explore the molecular mechanism based on autophagy in vivo and in vitro. In T2DM mice, we found that PU significantly improved liver histology, reversed serum biochemical abnormalities, and increased the autophagosome number in the liver. In HepG2 cells cultured in a high-glucose environment, PU upregulated the glucose uptake level. Both in vivo and in vitro, PU upregulated the expression of autophagy-related proteins, such as LC3b and p62, and reduced the phosphorylated Akt/total Akt and phosphorylated FoxO3a/total FoxO3a protein ratios, and these effects were enhanced by LY294002 (a PI3K/Akt inhibitor). In summary, our current findings suggest that PU protects against liver injury induced by T2DM by restoring autophagy through the Akt/FoxO3a signaling pathway.

Mid-dose losartan mitigates diabetes-induced hepatic damage by regulating iNOS, eNOS, VEGF, and NF-κB expressions

Background/aim

Losartan, an antihypertensive drug, is highly preferred in patients with diabetes mellitus (DM) and hypertension because of its retarding effect on diabetic nephropathy. In this study, we investigated the potential therapeutic effect of different doses of losartan on hepatic damage in a streptozotocin (STZ, 50 mg/kg)-induced DM model in rats.

Materials and methods

In this study, five different groups were formed: control, DM, low-dose losartan (5 mg/kg), mid-dose losartan (20 mg/kg), and high-dose losartan (80 mg/kg). Liver tissues of experimental groups were evaluated immunohistochemically for TUNEL, iNOS, eNOS, VEGF, and NF-κB pathways. In addition to immunohistochemical analysis, analyses of SOD and MDA, which are oxidative stress markers, were also performed and the results were evaluated together.

Results

When biochemical and immunohistochemical findings were evaluated together, it was found that the results obtained from the mid-dose losartan group were closer to those of the control than the other groups.

Conclusion

This study indicated that mid-dose losartan administration may have a therapeutic effect by inhibiting apoptosis and regulating iNOS, eNOS, VEGF, and NF-κB protein expressions in DM-induced hepatic damage.

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.

Effects of Quercetin on Lipid and Protein Damage in the Liver of Streptozotocin-Induced Experimental Diabetic Rats

Quercetin (QR) is part of a subclass of flavonoids called flavonols. We aimed to investigate the effect of QR on malondialdehyde (MDA), advanced oxidation protein products (AOPPs), and glutathione peroxidase (GSH-Px) activity in the liver of diabetic rats. We compared four groups of male adult Wistar albino rats: a control group, an untreated diabetic group, diabetic groups treated with QR, and QR group. Diabetes was induced by a single injection of streptozotocin (STZ) (50 mg/kg). Animals were kept in standard condition. On the 31st day of the study, the liver tissue was removed for biochemical parameters and histopathological evaluations. In an untreated diabetic group, liver MDA and AOPP levels were significantly higher than all groups. QR treatment significantly decreased the increased MDA, AOPP levels, and increased the decreased GSH-Px enzyme activity in liver tissues. The QR-treated rats in the diabetic group showed an improved histological appearance. Lesser vesicular vacuolization and fibrotic areas were observed in the QR-treated diabetic group than in the diabetic group. The STZ-induced liver injury is associated with oxidative stress, and coadministration of QR may reduce this damage effectively in a rat model. Our results are also supported by morphological improvement in liver tissue. Therefore, we think QR may be effective in treating hyperglycemia and oxidative damage in diabetes.

Malaysian propolis, metformin and their combination, exert hepatoprotective effect in streptozotocin-induced diabetic rats

AIMS

Hepatic oxidative stress and weak antioxidant defence system resulting in hepatic lesion, has been reported in diabetic rats. The present study investigated the possible hepatoprotective effects of Malaysian propolis (MP) in diabetic rats, on the background that MP has been reported to have anti-hyperglycemic, antioxidant and anti-inflammatory effects.

MATERIALS AND METHODS

Sprague-Dawley rats were randomly divided into 5 groups, namely: normal control (NC), diabetic control (DC), diabetic on 300 mg/kg b.w. MP, diabetic on 300 mg/kg b.w. metformin, and diabetic on MP and metformin combined therapy. Treatment was done orally for 4 weeks, and NC and DC groups received distilled water as vehicle.

KEY FINDINGS

Results showed increased fasting blood glucose and serum markers of hepatic lesion (aspartate aminotransferase, alkaline phosphatase, alanine aminotransferase and gamma-glutamyl transferase), increased hepatic lactate dehydrogenase activity, decreased hepatic superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase and glutathione reductase activities, increased immunoexpressions of nuclear factor kappa B, tumor necrosis factor-α, interleukin(IL)-1β and caspase-3, and decreased immunoexpressions of IL-10 and proliferating cell nuclear antigen in the liver of DC group. Histopathology of the liver revealed numerous hepatocytes with pyknotic nuclei and inflammatory infiltration, while periodic acid-schiff staining decreased in the liver of DC group. Treatment with MP attenuated these negative effects and was comparable to metformin. Furthermore, these effects were better attenuated in the combined therapy-treated diabetic rats.

SIGNIFICANCE

Malaysian propolis attenuates hepatic lesion in DM and exerts a synergistic protective effect with the anti-hyperglycemic medication, metformin.

Medicinal plants with anti-inflammatory activities from selected countries and regions of Africa

Various nonsteroidal anti-inflammatory drugs have been shown to reduce pain and inflammation by blocking the metabolism of arachidonic acid by isoform of cyclooxygenase enzyme, thereby reducing the production of prostaglandin. Sadly, there are many side effects associated with the administration of nonsteroidal anti-inflammatory drugs. However, there are medicinal plants with anti-inflammatory therapeutic effects with low or no side effects. The Afri-can continent is richly endowed with diverse medicinal plants with anti-inflammatory activities that have been shown to be effective in the treatment of inflammatory conditions in traditional medicine. Interestingly, scientists have examined some of these African medicinal plants and documented their biological and therapeutic activities. Unfortunately, medicinal plants from different countries in Africa with anti-inflammatory properties have not been documented in a single review paper. It is important to document the ethnobotanical knowledge and applications of anti-inflammatory medicinal plants from selected countries representing different regions of the African continent. This paper therefore documents anti-inflammatory activities of various medicinal plants from different geographical regions of Africa with the aim of presenting the diversity of medicinal plants that are of traditional or therapeutic use in Africa.

Silymarin prevents lipid accumulation in the liver of rats with type 2 diabetes via sirtuin1 and SREBP-1c

BACKGROUND

In this study, we have investigated whether silymarin intake influences lipid and glycogen content in conjunction with sirtuin1 (SIRT1) and sterol regulatory element-binding protein 1c (SREBP-1c) expressions in liver of type 2 diabetic rat.

METHODS

Thirty-six male Wistar rats were randomly divided into six groups: control groups (C) and diabetic groups (D); the control groups received 60 or 120 mg/kg silymarin (C+S60 or C+S120), and the diabetic groups received 60 or 120 mg/kg silymarin (D+S60 or D+S120) daily for 8 weeks. Serum biochemical parameters, as well as glycogen, lipid and oxidative stress biomarkers, in the liver tissue were measured by spectrophotometric methods. Additionally, SIRT1 and SREBP-1c messenger RNA (mRNA) expressions were evaluated by quantitative polymerase chain reaction.

RESULTS

Diabetes caused a significantly increased fasting blood sugar, homeostasis model assessment for insulin resistance, liver total cholesterol and triglyceride (TG) content, which were attenuated after the administration of silymarin. Dietary silymarin caused the improvement of lipid content in the liver of diabetic rats. Moreover, silymarin administration promoted SIRT1, suppressed SREBP-1c mRNA expression, reduced liver nitric oxide and protein carbonyl content, and increased liver glycogen, catalase and glutathione peroxidase activity. Furthermore, histopathological changes were improved in the treated groups.

CONCLUSIONS

Silymarin administration considerably restored hepatic changes induced by streptozotocin and nicotinamide. The upregulation of SIRT1 mRNA expression by silymarin may be associated with decreased lipid, increased glycogen content and downregulation of the SREBP-1c gene in the liver.

The role of pollutants in type 2 diabetes mellitus (T2DM) and their prospective impact on phytomedicinal treatment strategies

Type 2 diabetes mellitus (T2DM) is the most common form of diabetes and it is characterized by high blood sugar and abnormal sera lipid levels. Although the specific reasons for the development of these abnormalities are still not well understood, traditionally, genetic and lifestyle behavior have been reported as the leading causes of this disease. In the last three decades, the number of diabetic patients has drastically increased worldwide, with current statistics suggesting the number is to double in the next two decades. To combat this incurable ailment, orthodox medicines, to which economically disadvantaged patients have minimal access to, have been used. Thus, a considerable amalgamation of medicinal plants has recently been proven to possess therapeutic capabilities to manage T2DM, and this has prompted studies primarily focusing on the healing aspect of these plants, and ultimately, their commercialization. Hence, this review aims to highlight the potential threat of pollutants, i.e., polyfluoroalkyl compounds (PFCs), endocrine disrupting chemicals (EDCs) and heavy metals, to medicinal plants, and their prospective impact on the phytomedicinal therapy strategies for T2DM. It is further suggested that auxiliary research be undertaken to better comprehend the factors that influence the uptake of these compounds by these plants. This should include a comprehensive risk assessment of phytomedicinal products destined for the treatment of T2DM. Regulations that control the use of PFC-precursors in certain developing countries are also long overdue.

Pulmonary oxidative stress in diabetic rats exposed to hyperoxia

Purpose:

To evaluate the pulmonary oxidative stress in diabetic rats exposed to hyperoxia for 90 minutes.

Methods:

Forty male Wistar rats were divided into four groups, each one containing 10 animals, according to the oxygen concentration to which they were exposed: 21%, 50%, 75% and 100% (hyperoxia). In each group five animals were randomly induced to diabetes by means of at a dose of 55 mg/kg of streptozotocin (STZ).

Results:

Seventy two hours after diabetes induction, a significant difference was seen in blood glucose in the experimental groups in comparison with the control. In the experimental groups a significant difference was observed in the concentration of malondialdehyde (MDA) in lung tissue and blood plasma (p<0.05), except the 50% group. In the control group, significant differences in the MDA concentration in plasma and lung tissue were also observed (p<0.05), except the 75% group. The MDA concentration in lung tissue in comparison with the diabetic and non-diabetic groups showed a significant difference in the 21% group; however, no difference was seen in the 75 and 100% groups.

Conclusion:

In diabetic animals high oxygen concentrations (75 and 100%) do not appear to exert deleterious effects on lipid peroxidation in lung tissue.

Multidirectional inhibition of cortico-hippocampal neurodegeneration by kolaviron treatment in rats

Earliest signs of neurodegenerative cascades in the course of Alzheimer's disease (AD) are seen within the prefrontal cortex (PFC) and hippocampus, with pathological evidences in both cortical structures correlating with manifestation of behavioural and cognitive deficits. Despite the enormous problems associated with AD's clinical manifestations in sufferers, therapeutic advances for the disorder are still very limited. Therefore, this study examined cortico-hippocampal microstructures in models of AD, and evaluated the possible beneficial roles of kolaviron (Kv)-a biflavonoid complex in rats. Nine groups of rats were orally exposed to sodium azide (NaN₃) or aluminium chloride (AlCl₃) solely or in different combinations with Kv. Sequel to sacrifice and transcardial perfusion (using buffered saline then 4% paraformaldehyde), PFC and hippocampal tissues were harvested and processed for: spectrophotometric assays of oxidative stress and neuronal bioenergetics parameters, histological demonstration of cytoarchitecture and immunohistochemical evaluation of astrocytes and neuronal cytoskeleton. Results showed alterations in mitochondrial functions, which led to compromised neuronal antioxidant system, dysfunctional neural bioenergetics, hypertrophic astrogliosis, cytoskeletal dysregulation and neuronal death within the PFC and hippocampus. These degenerative events were associated with NaN₃ and AlCl₃ toxicity in rats. Furthermore, Kv inhibited cortico-hippocampal degeneration through multiple mechanisms that primarily involved halting of biochemical cascades that activate proteases which destroy molecules expedient for cell survival, and others that mediate a program of cell suicide in neuronal apoptosis. In conclusion, Kv showed important neuroprotective roles within cortico-hippocampal cells through multiple mechanisms, and particularly has prominent prophylactic activity than regenerative potentials.

Garcinol and Its Role in Chronic Diseases

The various bioactive compounds isolated from leaves and fruits of Garcinia sps plants, have been characterized and experimentally demonstrated to be anti-oxidant, anti-inflammatory and anti-cancer in nature. Garcinol, a polyisoprenylated benzophenone, obtained from plant Garcinia indica has been found to be an effective inhibitor of several key regulatory pathways (e.g., NF-kB, STAT3 etc.) in cancer cells, thereby being able to control malignant growth of solid tumours in vivo. Despite its high potential as an anti-neoplastic modulator of several cancer types such as head and neck cancer, breast cancer, hepatocellular carcinoma, prostate cancer, colon cancer etc., it is still in preclinical stage due to lack of systematic and conclusive evaluation of pharmacological parameters. While it is promising anti-cancer effects are being positively ascertained for therapeutic development, studies on its effectiveness in ameliorating other chronic diseases such as cardiovascular diseases, diabetes, allergy, neurodegenerative diseases etc., though seem favourable, are very recent and require in depth scientific investigation.

Antidiabetic effects of Brucea javanica seeds in type 2 diabetic rats

Background

Brucea javanica (B. javanica) seeds, also known as “Melada pahit” in Indo-Malay region are traditionally used to treat diabetes. The objective of this study was to determine antidiabetic, antioxidant and anti-inflammatory effects of B. javanica seeds on nicotinamide (NA)-streptozotocin (STZ) induced type 2 diabetic (T2D) rats and to analyze its chemical composition that correlate with their pharmacological activities.

Methods

A hydroethanolic extract of B. javanica seeds was fractionated with n-hexane, chloroform and ethyl acetate. An active fraction was selected after screening for its ability to inhibit α-glucosidase and glycogen phosphorylase α (GP-α). Isolation and characterization were carried out by using column chromatography, NMR and LCMS/MS. All isolates were assayed for inhibition of GP-α and α-glucosidase. Antidiabetic effect of active fraction was further evaluated in T2D rat model. Blood glucose and body weight were measured weekly. Serum insulin, lipid profile, renal function, liver glycogen and biomarkers of oxidative stress and inflammation were analyzed after 4-week treatment and compared with standard drug glibenclamide.

Results

Ethyl acetate fraction (EAF) exerted good inhibitory potential for α-glucosidase and GP-α compared with other fractions. Chromatographic isolation of the EAF led to the identification of seven compounds: vanillic acid (1), bruceine D (2), bruceine E (3), parahydroxybenzoic acid (4), luteolin (5), protocatechuic acid (6), and gallic acid (7). Among them, Compound (5) was identified as the most potent inhibitor of GP-α and α-glucosidase and its GP-α inhibitory activity (IC₅₀ = 45.08 μM) was 10-fold higher than that of caffeine (IC₅₀ = 457.34 μM), and α-glucosidase inhibitory activity (IC₅₀ = 26.41 μM) was 5.5-fold higher than that of acarbose (IC₅₀ = 145.83 μM), respectively. Compounds (4), (6), and (7) inhibited GP-α activity in a concentration-dependent manner with IC₅₀ values of 357.88, 297.37, and 214.38 μM, and their inhibitory effect was higher than that of caffeine. These compounds exhibited weak potency on α-glucosidase compared with acarbose. Compounds (1), (2), and (3) showed no inhibition on both GP-α and α-glucosidase. In vivo study showed that EAF treatment significantly reduced blood glucose level, increased insulin and glycogen contents, decreased markers of oxidative stress and inflammation, and lipid levels in T2D rats compared with untreated group.

Conclusions

The EAF has potential therapeutic value for the treatment of T2D via acting as GP-α and α-glucosidase inhibitors by improving hepatic glucose and carbohydrate metabolism, suppressing oxidative stress, and preventing inflammation in T2D rats. According to the results, the efficacy of EAF could be due to the presence of luteolin along with synergistic effect of multiple compounds such as parahydroxybenzoic acid, protocatechuic acid, and gallic acid in B. javanica seeds.