Olusola Olalekan Elekofehinti

Saponins: Anti-diabetic principles from medicinal plants – A review

Diabetes mellitus (DM) represents a global health problem. It is the most common of the endocrine disorders and is characterized by chronic hyperglycemia due to relative or absolute lack of insulin secretion or insulin actions. According to the World Health Organization projections, the diabetes population is likely to increase to 300 million or more by the year 2025. Current synthetic agents and insulin used effectively for the treatment of diabetes are scarce especially in rural areas, expensive and have prominent adverse effects. Complementary and alternative approaches to diabetes management such as isolation of phytochemicals with anti-hyperglycemic activities from medicinal plants is therefore imperative. Saponins are phytochemical with structural diversity and biological activities. This paper reviews saponins and various plants from which they were isolated as well as properties that make them ideal for antidiabetic remedy.

Saponin as regulator of biofuel: implication for ethnobotanical management of diabetes

There has been a sharp rise in the global prevalence of diabetes, obesity, and their comorbid conditions within the last decade prompting significant research into possible causes and cure via therapeutic intervention and lifestyle adjustments. Here, the molecular bases of antidiabetic plants used in the prehistorical treatment of diabetes and obesity are reviewed with particular focus on saponin as the phytotherapeutic principle. Until recently, the phytotherapeutic potentials of saponins have been masked in the heterogeneity of phytochemicals co-extractable during traditional preparations. With improved technique of purification and cutting edge biological assay methods, saponins have emerged as a regulator of primary biofuel availability through direct interaction with energy metabolism, cell signaling, and gene expression. Specific cases of lipoprotein lipase/peroxisome proliferator-activated receptor (PPAR)-gamma/phosphatidylinositide 3-kinase (PI-3-K)/protein kinase B (Akt) activation, adiponectin gene upregulation, fatty acid binding protein 4 repression (FABP4), and glucose transporter type 4 (Glut4) membrane exocytosis have been documented which provide molecular basis for hypocholesterolemic, hypoglycemic, and anti-obesity manifestations observed in experimental animals following saponin treatment. Although intensified research is required to characterize the pharmacophoric features in saponins exhibiting these interactions, however, this preliminary lead is valuable if the world will be free of diabetes, obesity, hypertension, hyperlipidemia, and atherosclerosis in no distant future.

African eggplant (Solanum anguivi Lam.) fruit with bioactive polyphenolic compounds exerts in vitro antioxidant properties and inhibits Ca(2+)-induced mitochondrial swelling.

OBJECTIVEnTo evaluate the antioxidant and radical scavenging activities of Solanum anguivi fruit (SAG) and its possible effect on mitochondrial permeability transition pore as well as mitochondrial membrane potential (ΔΨm) isolated from rat liver.nnnMETHODSnAntioxidant activity of SAG was assayed by using 2,2-diphenyl-1-picrylhydrazyl (DPPH), reducing power, iron chelation and ability to inhibit lipid peroxidation in both liver and brain homogenate of rats. Also, the effect of SAG on mitochondrial membrane potential and mitochondrial swelling were determined. Identification and quantification of bioactive polyphenolics was done by HPLC-DAD.nnnRESULTSnSAG exhibited potent and concentration dependent free radical-scavenging activity (IC50/DPPH=275.03±7.8 μg/mL). Reductive and iron chelation abilities also increase with increase in SAG concentration. SAG also inhibited peroxidation of cerebral and hepatic lipids subjected to iron oxidative assault. SAG protected against Ca(2+) (110 μmol/L)-induced mitochondrial swelling and maintained the ΔΨm. HPLC analysis revealed the presence of gallic acid [(17.54±0.04) mg/g], chlorogenic acid (21.90±0.02 mg/g), caffeic acid (16.64±0.01 mg/g), rutin [(14.71±0.03) mg/g] and quercetin [(7.39±0.05) mg/g].nnnCONCLUSIONSnThese effects could be attributed to the bioactive polyphenolic compounds present in the extract. Our results suggest that SAG extract is a potential source of natural antioxidants that may be used not only in pharmaceutical and food industry but also in the treatment of diseases associated with oxidative stress.

Tithonia diversifolia saponin-blood lipid interaction and its influence on immune system of normal wistar rats

This study investigated the effect of saponins (20-100mg/kg) from Tithonia diversifolia leaf (STD) on the liver, kidney, heart, lipid profile and hematological parameters of normal rats. The results showed that STD (20-100mg/kg) though caused a slight increase in the liver, heart and kidney activity of ALT, AST, ALP and GGT (p<0.05), did not result in corresponding increase in the serum level of these enzymes. A significant reduction in the level of triglycerides, LDL and cholesterol, creatinine, urea, LDH, PCV and hemoglobin were observed with a concomitant increase in HDL, white blood cell and lymphocyte. These study demonstrated the role of STD in enhancing immune response and in reducing cholesterol and triglycerides in normal rats at studied dosages.

Cytotoxic and antioxidative potentials of ethanolic extract of Eugenia uniflora L. (Myrtaceae) leaves on human blood cells

Eugenia uniflora is used in the Brazilian folk medicine to treat intestinal disorders and hypertension. However, scanty information exist on its potential toxicity to human, and little is known on its antioxidant activity in biological system. Hence, we investigated for the first time the potential toxic effects of ethanolic extract (EtOH) of E. uniflora (EEEU) in human leukocytes and erythrocytes, as well as its influence on membrane erythrocytes osmotic fragility. In addition, EEEU was chemically characterized and its antioxidant capacity was evaluated. We found that EEEU (1-480μg/mL) caused neither cytotoxicity nor DNA damage evaluated by Trypan blue and Comet assay, respectively. EEEU (1-480μg/mL) did not have any effect on membrane erythrocytes fragility. In addition, EEEU inhibited Fe2+-induced lipid peroxidation in rat brain and liver homogenates, and scavenged the DPPH radical. EEEU presented some polyphenolic compounds with high content such as quercetin, quercitrin, isoquercitrin, luteolin and ellagic acid, which may be at least in part responsible for its beneficial effects. Our results suggest that consumption of EEEU at relatively higher concentrations may not result in toxicity. However, further in vitro and in vivo studies should be conducted to ascertain its safety.

Saponins as adipokines modulator: A possible therapeutic intervention for type 2 diabetes

Development of type 2 diabetes has been linked to β-cell failure coupled with insulin resistance and obesity. Adipose tissue, known as the fat store, secretes a number of hormones and proteins collectively termed adipokines some of which regulate insulin sensitivity. Dysregulation in the secretion of adipokines has been linked to insulin resistance and type 2 diabetes. In this review, we summarized evidence of the role of adipokines with focus on leptin, adiponectin, adipsin, visfatin and apelin in the pathogenesis of type 2 diabetes and discussed the potential of saponins to modify the ill-regulated adipokines secretions, which could promote the use of this class of phytochemicals as potential antidiabetics agents.

Effects of Tapinanthus globiferus and Zanthoxylum zanthoxyloides extracts on human leukocytes in vitro

Objective: This study aimed at investigating the genotoxicity and cytotoxicity effect of Tapinanthus globiferus and Zanthoxylum zanthoxyloides to human leukocytes. In addition, the reductive potential and the chemical composition of the two plant extracts were also determined. Materials and Methods: Human leukocytes were obtained from healthy volunteer donors. The genotoxicity and cytotoxicity of T. globiferus and Z. zanthoxyloides were assessed using the comet assay and trypan blue exclusion, respectively. The antioxidant activity of the plant extracts was evaluated by the reducing power assay. Furthermore, high-performance liquid chromatography-diode array detector was used to characterize and quantify the constituents of these plants. Results: T. globiferus (10-150 µg/mL) was neither genotoxic nor cytotoxic at the concentrations tested, suggesting that it can be consumed safely at relatively high concentrations. However, Z. zanthoxyloides showed cytoxicity and genotoxicity to human leukocytes at the highest concentration tested (150 µg/mL). In addition, the total reducing power of T. globiferus was found higher than Z. zanthoxyloides in potassium ferricyanide reduction. Both plants extract contained flavonoids (rutin and quercetin) and phenolic acids (chlorogenic and caffeic). Conclusion: The results obtained support the fact that some caution should be paid regarding the dosage and the frequency of use of Z. zanthoxyloides extract.

Comparative research performance of top universities from the northeastern Brazil on three pharmacological disciplines as seen in scopus database

Objectives Postgraduate programmes around the world are periodically subjected to research performance evaluation through bibliometric indicators. In this research, we characterized and compared the research performance of 15 universities from Northeastern Brazil, in which 13 were among the top Universities of the Latin America. Methods Specifically, total documents, citations and the h-index of each university were retrieved from the Elsevier Scopus database and were analysed not only for historical scientific achievement but also across the period of the past 6 years (2010–2015). Using these bibliometric indicators, we also investigated the performance of programmes at these Universities that have their papers indexed in the Scopus database under the category of “Pharmacology, Toxicology and Pharmaceuticals” for the same period. Results We found that the Federal University of Pernambuco (UFPE) and the Federal University of Ceará (UFC) were the most productive institutions, producing 17847 and 15048 documents, respectively. The number of papers published by each of these universities in the past six years represented more than 50% of their entire productivity. With regards to their scientific output in “Pharmacology, Toxicology and Pharmaceutics”, UFC showed the highest number of published documents followed by UFPE and the Federal University of Paraíba (UFPB). UFC received the highest h-index (with and without self-citations) and number of citations and shared their most cited papers with foreign institutions from the USA and Germany. However, papers from UFC were published in journals with lower impact factors (2.322). Conclusions The present study shows where each of these universities stands and can be helpful in identifying potential collaborators in these areas of knowledge.

Potential use of bitter melon (Momordica charantia) derived compounds as antidiabetics: In silico and in vivo studies

Momordica charantia (bitter lemon) belongs to the cucurbitaceae family which has been extensively used in traditional medicines for the cure of various ailments such as cancer and diabetes. The underlying mechanism of M. charantia to maintain glycemic control was investigated. GLP-1 and DPP-4 gene modulation by M. charantia (5-20% inclusion in rats diet) was investigated in vivo by RT-PCR and possible compounds responsible for diabetic action predicted through in silico approach. Phytochemicalss previously characterized from M. charantia were docked into glucacon like peptide-1 receptor (GLP-1r), dipeptidyl peptidase (DPP4) and Takeda-G-protein-receptor-5 (TGR5) predicted using Autodock Vina. The results of the in silico suggests momordicosides D (ligand for TGR5), cucurbitacin (ligand for GLP-1r) and charantin (ligand for DPP-4) as the major antidiabetic compounds in bitter lemon leaf. M. charantia increased the expression of GLP-1 by about 295.7% with concomitant decreased in expression of DPP-4 by 87.2% with 20% inclusion in rats diet. This study suggests that the mechanism underlying the action of these compounds is through activation of TGR5 and GLP-1 receptor with concurrent inhibition of DPP4. This study confirmed the use of this plant in diabetes management and the possible bioactive compounds responsible for its antidiabetic property are charantin, cucurbitacin and momordicoside D and all belong to the class of saponins.

Caffeine-supplemented diet modulates oxidative stress markers and improves locomotor behavior in the lobster cockroach Nauphoeta cinerea

The effects of caffeine supplementation is well documented in conventional animal models, however, in the lobster cockroaches Nauphoeta cinerea, they have not been reported. Thus, the aim of this study was to investigate the locomotor behavior and biochemical endpoints in the head of the nymphs of N. cinerea following 60 days exposure to food supplemented with 0, 0.5, 1.0, 2.5, 5.0 and 10.0u202fmg of caffeine/g of diet. The analysis of the locomotor behavior using the video-tracking software, Any-maze, for 12u202fmin revealed that caffeine supplementation caused significant behavioral improvement. There was increase in distance travelled, velocity, frequency of rotation and turn angle (stereotypical behavior such as circling movements), and this was supported by the representative track plots of the path travelled by cockroaches in the open-field arena. In addition, caffeine supplementation markedly increased total thiol and non-protein thiol glutathione (GSH) levels in the heads of cockroaches, and this was in parallel with significant reduction of lipid peroxidation and free Fe(II) content. Taking together, our results indicate that long-term caffeine supplementation may exert preventive effects against oxidative stress and support the use of N. cinerea as an efficient alternative model to assess the efficacy of food molecules.