Antidiabetic Activity of Gnidia glauca and Dioscorea bulbifera: Potent Amylase and Glucosidase Inhibitors

Fenugreek derived diosgenin as an emerging source for diabetic therapy

Diabetes is a chronic metabolic disease that endangers the entire body's tissues and organs. Diabetes impairs glucose and insulin regulation in the human body by causing pancreatic cell damage. Diabetes modifies pathways such as serine/threonine protein kinase (Akt) and Protein kinase C (PKC)/- glucose transporter 4 (GLUT4), peroxisome proliferator-activated receptor (PPAR) glucose absorption, and inhibits α-amylase and α-glucosidase, Sodium/glucose cotransporter 1 (SGLT-1), and Na+-K+-ATPase activity. Diabetes may also be caused by a decrease in the expression of sterol regulatory element binding protein 1 (SREBP-1) and its target genes, fatty acid synthase (FAS), stearoyl-CoA desaturase-1 (SCD-1), and acetyl-CoA carboxylase α (ACC), as well as a decrease in the levels of C/EBP homologous protein (CHOP), Caspase12, and Caspase3 proteins. Diabetes has long been linked to diseases of the cardiovascular, nervous, skeletal, reproductive, hepatic, ocular, and renal systems. Diosgenin, a steroidal compound derived from fenugreek, aids in the prevention of diabetes by altering cellular pathways in favor of healthy bodily functions. Diosgenin is a new nutraceutical on the market that claims to cure diabetes in particular. This article focuses on diosgenin extraction and purification, fenugreek bioactive compounds, pharmacological properties of diosgenin, mode of action of diosgenin to cure diabetes, and dosages.

Detoxification technology and mechanism of processing with Angelicae sinensis radix in reducing the hepatotoxicity induced by rhizoma Dioscoreae bulbiferae in vivo

Rhizoma Dioscoreae Bulbiferae (RDB) was effective on relieving cough and expectorant but accompanied by severe toxicity, especially in hepatotoxicity. A previous study found that processing with Angelicae Sinensis Radix (ASR) reduced RDB-induced hepatotoxicity. However, up to now, the optimized processing process of ASR-processed RDB has not been explored or optimized, and the detoxification mechanism is still unknown. This study evaluated the detoxification technology and possible mechanism of processing with ASR on RDB-induced hepatotoxicity. The optimized processing process of ASR-processed RDB was optimized by the content of diosbulbin B (DB), the levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and histopathological analysis. The processing detoxification mechanism was evaluated by detecting the antioxidant levels of nuclear factor E2 related factor 2 (Nrf2) and its downstream heme oxygenase 1 (HO-1), quinone oxidoreductase 1 (NQO1), glutamylcysteine ligase catalytic subunit (GCLM), and the levels of downstream antioxidant factors of Nrf2. Besides, the antitussive and expectorant efficacy of RDB was also investigated. This work found that processing with ASR attenuated RDB-induced hepatotoxicity, which can be verified by reducing the levels of ALT, AST, and ALP, and reversing the pathological changes of liver histomorphology. And the optimized processing process of ASR-processed RDB is “processing at a mass ratio of 100:20 (RDB:ASR) and a temperature of 140°C for 10 min.” Further results corroborated that the intervention of processed products of ASR-processed RDB remarkably upregulated the Nrf2/HO-1/NQO1/GCLM protein expression levels in liver, and conserved antitussive and expectorant efficacy of RDB. The above findings comprehensively indicated that the optimized processing process of ASR-processed RDB was “processing at a mass ratio of 100:20 (RDB:ASR) and a temperature of 140°C for 10 min,” and the processing detoxification mechanism involved enhancing the level of Nrf2-mediated antioxidant defense in liver as a key target organ.

Could consumption of yam (Dioscorea) or its extract be beneficial in controlling glycaemia: a systematic review

Yam (Dioscorea spp.) and its associated extracts have been shown to possess a variety of biological activities and identified as beneficial in the control of glycaemia in patients with type II diabetes mellitus (T2DM). The objective was to conduct a systematic search of the literature to investigate whether yam and its extract can improve glycaemia and whether the consumption of yam could be beneficial for managing T2DM. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and the Population, Invention, Comparison and Outcome framework, three databases (PubMed, Scopus and Web of Science) were searched using a key term strategy. Strict inclusion criteria were employed to identify all relevant and available studies. The quality of these studies was assessed using SYRCLE's Risk of Bias tool. Ten studies were included, and all studies consisted of findings from rodent models of diabetes, including animals consuming high fat diets or genetic models of diabetes. All ten studies showed that the consumption of yam and/or its extracts (containing dioscin, dioscorin, diosgenin, DA-9801/02 or Chinese yam polysaccharides) improved glycaemia. These included improvements in fasting blood glucose and reductions in glucose and increase in insulin levels following a glucose tolerance test. Furthermore, significant changes in body weight and adiposity were observed in nine studies, these included improvements in lipid biomarkers in four and reductions in inflammatory markers in one. The current work indicates that the consumption of yam or its extracts can be beneficial for improving blood glucose; however, the molecular mechanism for these effects remains largely unknown. Future trials on human subjects are warranted.

Tumor-suppressing effect of bartogenic acid in ovarian (SKOV-3) xenograft mouse model

Bartogenic acid (BA), a natural pentacyclic triterpenoid, proved to have chemomodulatory, anticancer, antidiabetic, anti-arthritic, and anti-inflammatory activity. Based on structure-activity relationship (SAR) approaches, BA has close structural resemblance to oleanolic acid and ursolic acid. These two pentacyclic triterpenoids are well accepted with respect to their therapeutic value in various ailments including anti-cancer activity. The aim of this study is to evaluate the efficacy of BA as a possible antitumor agent, along with its safety in SKOV-3 ovarian cancer. In vitro cytotoxicity of BA and paclitaxel on human ovarian cancer cells (SKOV-3) was assessed using MTT assay. Antitumor potential of BA alone, standard anticancer drug (paclitaxel) alone, and BA in combination with paclitaxel were evaluated in SKOV-3 xenografted SCID mice. Immunohistochemical analysis of NF-κB was performed and analyzed in SKOV-3 tumors. BA alone and BA in combination with paclitaxel significantly inhibited the tumor growth. IC₅₀ of BA was found to be 15.72 μM. Similarly, paclitaxel showed significant antitumor effect with IC₅₀ of 3.234 μM. Treatments of paclitaxel, BA, and combination of BA with paclitaxel were well tolerated during treatment period. Immunohistochemical analysis of NF-κB in SKOV-3 tumors treated with BA in combination with paclitaxel revealed antitumor effect in terms of inhibition of NF-κB. Our results suggested that BA exhibits promising antitumor effect in the restriction of SKOV-3 cells and tumors with considerable safety.

In Vitro and In Silico Evaluation for the Inhibitory Action of O. basilicum Methanol Extract on α-Glucosidase and α-Amylase

Diabetes mellitus is a metabolic disease that predominates, nowadays. It causes hyperglycemia and consequently major health complications. Type II diabetes is the most common form and is a result of insulin resistance in the target tissues. To treat this disease, several mechanisms have been proposed. The most direct route is via inhibiting the intestinal enzymes, e.g., α-glucosidase and α-amylase, responsible for intestinal polysaccharide digestion that therefore would reduce the absorption of monosugars through the intestinal walls. In this study, we shed the light on this route by testing the inhibitory effect of Ocimum basilicum extract on the enzymes α-glucosidase and α-amylase in vitro and in silico. Experimental procedures were performed to test the effect of the O. basilicum methanol extract from aerial parts followed by the in silico docking. 500 μg/mL of the extract led to 70.2% ± 8.6 and 25.4% ± 3.3 inhibition on α-glucosidase and α-amylase activity, respectively. Similarly, the effect of caffeic acid, a major extract ingredient, was also tested, and it caused 42.7% ± 3.0 and 47.1% ± 4.0 inhibition for α-amylase and α-glucosidase, respectively. Docking experiments were performed to predict the phytochemicals responsible for this robust inhibitory activity in the O. basilicum extracts. Several compounds have shown variable levels of inhibition, e.g., caffeic acid, pyroglutamic acid, and uvasol. The results indicated that O. basilicum can be a potent antidiabetic drug.

Antimalarial properties and molecular docking analysis of compounds from Dioscorea bulbifera L. as new antimalarial agent candidates

Background

At present, the emergence and spread of antimalarial drug resistance has become a significant problem worldwide. There has been a challenge in searching for natural products for the development of novel antimalarial drugs. Therefore, this study aims to evaluate compounds from Dioscorea bulbifera responsible for antimalarial properties and investigate potential interactions of the compounds with Plasmodium falciparum lactate dehydrogenase (PfLDH), an essential glycolytic enzyme in the parasite’s life cycle.

Methods

An in vitro study of antimalarial activity against chloroquine (CQ)-resistant Plasmodium falciparum (K1 strain) and CQ-sensitive P. falciparum (3D7 strain) was performed using the ³H-hypoxanthine uptake inhibition method. The cytotoxic effects of the pure compounds were tested against Vero cells using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The interactions of the compounds with the PfLDH active site were additionally investigated using a molecular docking method.

Results

Quercetin (6) exhibited the highest antimalarial activity against the P. falciparum K1 and 3D7 strains, with IC₅₀ values of 28.47 and 50.99 μM, respectively. 2,4,3′,5′-Tetrahydroxybibenzyl (9), 3,5-dimethoxyquercetin (4) and quercetin-3-O-β-D-galactopyranoside (14) also possessed antimalarial effects against these two strains of P. falciparum. Most pure compounds were nontoxic against Vero cells at a concentration of 80 μg/ml, except for compound 9, which had a cytotoxic effect with a CC₅₀ value of 16.71 μM. The molecular docking results indicated that 9 exhibited the best binding affinity to the PfLDH enzyme in terms of low binding energy (− 8.91 kcal/mol) and formed strong hydrogen bond interactions with GLY29, GLY32, THR97, GLY99, PHE100, THR101 and ASN140, amino acids as active sites. In addition, 6 also possessed remarkable binding affinity (− 8.53 kcal/mol) to PfLDH by interacting with GLY29, ILE31, ASP53, ILE54, THR97 and THR101.

Conclusion

Quercetin is a major active compound responsible for the antimalarial activity of D. bulbifera and is an inhibitor of PfLDH. These findings provide more evidence to support the traditional use of D. bulbifera for malaria treatment. Structural models of its interactions at the PfLDH active site are plausibly useful for the future design of antimalarial agents.

Anti-inflammatory, wound healing and antioxidant potential of compounds from Dioscorea bulbifera L. bulbils

BACKGROUND

Dioscorea bulbifera L. (Dioscoreaceae) has been traditionally used in Thai folk medicine as a diuretic and anthelmintic, for longevity preparations, and for wound and inflammation treatment. This plant is also commonly used in traditional Indian and Chinese medicines in the treatment of sore throat, gastric cancer, rectal carcinoma and goiters. However, the wound healing effects of the active compounds in this plant have not been investigated.

OBJECTIVE

This study aimed to identify compounds responsible for the wound healing activity of D. bulbifera and determine their potential anti-inflammatory and antioxidant activities.

METHODS

Crude extracts of D. bulbifera bulbils, their derived fractions and eleven purified compounds were tested for anti-inflammatory activity against LPS-induced NO production in RAW264.7 macrophages. The wound healing effects were evaluated via cell proliferation and migration assays using human dermal fibroblasts (HDFs), and the antioxidant effects were determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical (•OH) scavenging activity assays.

RESULTS

15,16-Epoxy-6α-O-acetyl-8β-hydroxy-19-nor-clero-13(16),14-diene-17,12;18,2-diolide (2), (+)-catechin (5), quercetin (6) and myricetin (11) exhibited significantly potent wound healing effects and promoted marked cell proliferation, resulting in % viabilities of 107.4-137.6, 121.1-151.9, 98.0-131.9, 90.9-115.9, respectively. Among them, (+)-catechin produced the highest % cell migration, resulting in 100.0% wound closure sooner (at day 2) than the other compounds. In addition, 1 μg/ml (+)-catechin significantly increased fibroblast migration by 2.4-fold compared to that in the control after 24 h. Regarding anti-inflammatory properties, kaempferol (7) and quercetin (6) decreased (p < 0.005) NO production, with IC50 values of 46.6 and 56.2 μM, respectively. In addition, the crude extracts, solvent fractions and flavonoid compounds were also found to possess marked antioxidant activity in both DPPH and •OH radical scavenging assays.

CONCLUSIONS

These findings provide more evidence to support the traditional use of D. bulbifera for the treatment of wounds and inflammation.

Encapsulation Preserves Antioxidant and Antidiabetic Activities of Cactus Acid Fruit Bioactive Compounds under Simulated Digestion Conditions

Cactus acid fruit (Xoconostle) has been studied due its content of bioactive compounds. Traditional Mexican medicine attributes hypoglycemic, hypocholesterolemic, anti-inflammatory, antiulcerogenic and immunostimulant properties among others. The bioactive compounds contained in xoconostle have shown their ability to inhibit digestive enzymes such as α-amylase and α-glucosidase. Unfortunately, polyphenols and antioxidants in general are molecules susceptible to degradation due to storage conditions, (temperature, oxygen and light) or the gastrointestinal tract, which limits its activity and compromises its potential beneficial effect on health. The objectives of this work were to evaluate the stability, antioxidant and antidiabetic activity of encapsulated extract of xoconostle within double emulsions (water-in-oil-in-water) during storage conditions and simulated digestion. Total phenols, flavonoids, betalains, antioxidant activity, α-amylase and α-glucosidase inhibition were measured before and after the preparation of double emulsions and during the simulation of digestion. The ED40% (treatment with 40% of xoconostle extract) treatment showed the highest percentage of inhibition of α-glucosidase in all phases of digestion. The inhibitory activity of α-amylase and α-glucosidase related to antidiabetic activity was higher in microencapsulated extracts than the non-encapsulated extracts. These results confirm the viability of encapsulation systems based on double emulsions to encapsulate and protect natural antidiabetic compounds.

Thermoase-hydrolysed pigeon pea protein and its membrane fractions possess in vitro bioactive properties (antioxidative, antihypertensive, and antidiabetic)

Enzymatic hydrolysis can liberate bioactive peptides from protein materials, thus, pigeon pea was hydrolysed using thermoase. Crude hydrolysate (PPHT) was subjected to ultrafiltration using different molecular weight cutoffs to collect <1, 1-3, 3-5, 5-10, and >10 kDa peptide fractions. Fractions were analysed for in vitro antioxidative, antihypertensive, and antidiabetic properties. The peptide fractions had stronger DPPH^• scavenging and renin inhibition when compared to PPHT. In contrast, ACE inhibition was stronger for the PPHT and <1 kDa peptide fraction while activity decreased as peptide size increased. The <1 kDa peptide also showed significantly stronger ferric reducing antioxidant power, OH^• scavenging and inhibition of linoleic acid oxidation when compared to PPHT. α-amylase and α-glucosidase were inhibited by all the peptide fractions, though the 3-5 and >10 kDa had higher values. We conclude that the PPHT and peptide fractions could serve as potential ingredients to formulate antihypertensive and antidiabetic functional foods and nutraceuticals. PRACTICAL APPLICATIONS: Oxidative stress promotes the generation of free radicals, which have a significant impact in the pathogenesis of human chronic diseases such as cardiovascular impairment, cancer, and diabetes. Peptides generated from enzymatic hydrolysis of proteins have been identified to impart beneficial health effects. In this work, we showed that a thermoase digest of pigeon pea protein as well as the fractionated peptides had strong antioxidant properties in addition to exhibiting inhibitory activities against renin and angiotensin converting enzyme, the main therapeutic targets for antihypertensive agents. The peptide products also inhibited α-amylase and α-glucosidase activities, providing potential ingredients that can be used to formulate antidiabetic functional foods.

In silico and in vitro analysis reveal multi-target anti-hyperglycaemic properties of gedunin, a limonoid from neem (Azadirachta indica)

Background

Insulin secretion and insulin related pathways have been the prime targets in the treatment of diabetes for a long time. However, recently a lot of attention is being directed towards addressing hyperglycaemia as the main perpetrator of the symptoms in this metabolic disorder. This new treatment approach also involves greater inclination to plant derived therapeutic agents for their safety and probable minimal side effects. The objective of the present study was to scientifically elucidate the potential of gedunin (a limonoid from Neem tree) as an anti-hyperglycaemic agent.

Methods

The effect of gedunin on pancreatic and salivary amylase activity and glucose transport across yeast cell membrane was tested at three different concentrations (5 μM, 10 μM and 20 μM) using known inhibitor acarbose as the standard. Multiple Ligand Simultaneous Docking was used to study the interaction of gedunin with salivary and pancreatic amylase and determine binding affinity and specificity of this interaction.

Results

The in vitro results documented a steady, linear pancreatic alpha amylase (ovine) inhibition in a concentration dependent manner with gedunin showing lower IC50 value of 20.25 μM against acarbose (IC50 = 31.12 μM) a known enzyme inhibitor used as standard in the present study. The inhibition of salivary amylase by gedunin was also distinct. Yeast cell glucose uptake studies revealed remarkable inhibition of glucose absorption at 10 μM and 20 μM concentration of gedunin (5.45% and 13.87% respectively with respect to control). Corroborating the in vitro findings even in the docking studies gedunin exhibited higher docking score (− 8.12 Kcal/mol) and higher enzyme inhibition potency (Ki = 1.12 μM) with human pancreatic amylase-substrate complex as compared to acarbose (docking score-5.24 Kcal/mol, Ki = 110.8 μM). The studies further suggested a non-competitive, mixed kind of inhibition by gedunin. As evident from this current in vitro study, gedunin had shown significant inhibition of alpha amylases and glucose uptake at much lower concentration (5, 10 and 20 μM) than previous studies where the concentrations used were (20.7–124.3 μM).

Conclusion

This study lays strong evidence to the rationale of gedunin being an important lead compound to developing a promising hyperglycaemic agent, simultaneously targeting glucose absorption in the intestine and enzymatic digestion of polysaccharides.

Structure-Activity-Relationship and Mechanistic Insights for Anti-HIV Natural Products

Acquired Immunodeficiency Syndrome (AIDS), which chiefly originatesfroma retrovirus named Human Immunodeficiency Virus (HIV), has impacted about 70 million people worldwide. Even though several advances have been made in the field of antiretroviral combination therapy, HIV is still responsible for a considerable number of deaths in Africa. The current antiretroviral therapies have achieved success in providing instant HIV suppression but with countless undesirable adverse effects. Presently, the biodiversity of the plant kingdom is being explored by several researchers for the discovery of potent anti-HIV drugs with different mechanisms of action. The primary challenge is to afford a treatment that is free from any sort of risk of drug resistance and serious side effects. Hence, there is a strong demand to evaluate drugs derived from plants as well as their derivatives. Several plants, such as Andrographis paniculata, Dioscorea bulbifera, Aegle marmelos, Wistaria floribunda, Lindera chunii, Xanthoceras sorbifolia and others have displayed significant anti-HIV activity. Here, weattempt to summarize the main results, which focus on the structures of most potent plant-based natural products having anti-HIV activity along with their mechanisms of action and IC50 values, structure-activity-relationships and important key findings.

Green synthesis of zinc oxide nanoparticles from the leaf, stem and in vitro grown callus of Mussaenda frondosa L.: characterization and their applications

Biosynthesis of zinc oxide nanoparticles (ZnO-NPs) was achieved by utilizing the reducing and capping potential of leaf, stem and callus aqueous extracts of Mussaenda frondosa.The bioreduced ZnO-NPs were characterized using powder X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis spectroscopy), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), fourier transform infrared spectroscopy (FTIR) and dynamic light scattering (DLS) techniques. UV–visible spectra of ZnO-NPs showed a strong absorption peak at 370, 376 and 373 nm corresponding to the band gap energy of 3.33, 3.27 and 3.30 eV for ZnO-NPs obtained from leaf (L-ZnO-NP), stem (S-ZnO-NP) and callus (C-ZnO-NP) aqueous extracts, respectively. XRD analysis confirmed the formation of hexagonal wurtzite structures having an average grain size between 5 and 20 nm in diameter. FTIR spectra revealed the presence of stretching vibrations of –O–H, C–H, C–N, C = O groups involved in reduction and stabilization of nanoparticles. SEM images recognize the presence of spongy, spherical, porous agglomerated nanoparticles. DLS analysis and zeta potential values validated the stability of ZnO-NPs. The present investigation puts light on the photocatalytic activity and biological (antioxidant, anti-inflammatory, antidiabetic, antimicrobial, anticancerous) applications of ZnO-NPs. The current study is an attempt to describe an effective, simple and eco-friendly method of ZnO-NP synthesis and to evaluate its potential for various industrial and medical applications.

Effect of silver doping on antidiabetic and antioxidant potential of ZnO nanorods

BACKGROUND

Increasing resistance to available drugs and their associated side-effects have drawn wide attention towards designing alternative therapeutic strategies for control of hyperglycemia and oxidative stress. The roles of the sizes and shapes of the nanomaterials used in the treatment and management of Type 2 Diabetes Mellitus (T2DM) in preventing chronic hyperglycaemia and oxidative stress are investigated. We report specifically on the effects of doping silver (Ag) into the ZnO nanorods (ZnO:Ag NR's) as a rational drug designing strategy.

METHODS

Inhibition of porcine pancreatic α-amylase, murine pancreatic amylase, α-glucosidase, murine intestinal glucosidase and amyloglucosidase are checked for evaluation of antidiabetic potential. In addition, the radical scavenging activities of ZnO:Ag NR's against nitric oxide, DDPH and superoxide radicals are evaluated.

RESULTS

Quantitative radical scavenging and metabolic enzyme inhibition activities of ZnO:Ag NR's at a concentration of 100 μg/mL were found to depend on the amount of Ag doped in up to a threshold level (3-4 %). Circular dichroism analysis revealed that the interaction of the NR's with the enzymes altered their secondary conformation. This alteration is the underlying mechanism for the potent enzyme inhibition.

CONCLUSIONS

Enhanced inhibition of enzymes and scavenging of free radicals primarily responsible for reactive oxygen species (ROS) mediated damage, provide a strong scientific rationale for considering ZnO:Ag NR's as a candidate nanomedicine for controlling postprandial hyperglycaemia and the associated oxidative stress.

Anti-obesity effects of dichloromethane leaf extract of Gnidia glauca in high fat diet-induced obese rats

BACKGROUND

Obesity is a chronic metabolic disorder characterized by increased adipose tissue mass due to positive energy balance. Prescription of anti-obesity drugs can be useful adjuncts to diet and exercise for obese patients who have failed to achieve weight loss. However, these drugs are ineffective and are associated with adverse effects. In recent times, medicinal plants have drawn a sharp focus owing to their biocompatibility and effectiveness. Attempts to determine the therapeutic effects and identification of bio-active principles from herbal prescriptions have become the prime focus in the validation of their folkloric usage and in drug discovery programs. Therefore, the present study aimed to determine the anti-obesity effects of Dichloromethane leaf extract of Gnidia glauca in high-fat-diet-induced obese rats.

METHODS

Obesity was induced experimentally in white albino Wistar rats by feeding them with prepared high-fat-diet and water ad libitum for a period of 12 weeks. The in-vivo anti-obesity effects were determined by oral administration of Gnidia glauca at dosage levels of 200, 250 and 300 mg/kg body weight from the 6th to 12th week of study. Phytochemical analysis of Gnidia glauca was conducted using gas chromatography linked to mass spectrophotometer.

RESULTS

The results indicated that Gnidia glauca exhibited potent anti-obesity effects. It significantly reduced the body weight, organ weights, organo-somatic indices, anthropometric indices, the total fat content, adiposity index, atherogenic index as well as various lipid profiles. It also decreased the total feed intake. However, it significantly increased levels of high-density lipoproteins and rectal body temperature of rats. Quantitative phytochemical analysis also revealed the presence of various phytocompounds that have shown to be associated with anti-obesity effects.

CONCLUSION

The anti-obesity effects of Gnidia glauca maybe attributed to the phytochemicals present. The present study, therefore, scientifically validates the traditional use of Gnidia glauca as a potential candidate for the synthesis of new effective anti-obesity supplement.

Anil Kumar N, Sharopov F, Ramírez-Alarcón K, Ruiz-Ortega A, Abdulmajid Ayatollahi S, Valere Tsouh Fokou P, Kobarfard F, Amiruddin Zakaria Z, Iriti M, Taheri Y, Martorell M, Sureda A, N. Setzer W, Durazzo A, Lucarini M, Santini A, Capasso R, Adrian Ostrander E, -ur-Rahman A, Iqbal Choudhary M, C. Cho W, Sharifi-Rad J. Antidiabetic Potential of Medicinal Plants and Their Active Components

Diabetes mellitus is one of the major health problems in the world, the incidence and associated mortality are increasing. Inadequate regulation of the blood sugar imposes serious consequences for health. Conventional antidiabetic drugs are effective, however, also with unavoidable side effects. On the other hand, medicinal plants may act as an alternative source of antidiabetic agents. Examples of medicinal plants with antidiabetic potential are described, with focuses on preclinical and clinical studies. The beneficial potential of each plant matrix is given by the combined and concerted action of their profile of biologically active compounds.

Antidiabetic Activity of Cactus Acid Fruit Extracts: Simulated Intestinal Conditions of the Inhibitory Effects on α-amylase and α-glucosidase

Acid cactus fruits “xoconostle” have been used since the pre-Columbian period as a treatment against diverse diseases. In this study, bioactive compounds (phenols and flavonoids) and the in vitro inhibition effect against α-amylase and α-glucosidase were evaluated. Four different extracts of cactus acid fruits were prepared from (1) endocarp, (2) mesocarp, (3) pericarp and (4) whole fruit (WFE). The results showed significant differences (p < 0.05) between extracts. Pericarp extracts had 2.23 ± 0.01 mg of gallic acid equivalents per gram GAE/g of phenol content and 0.84 ± 0.14 mg quercetin equivalents per gram QE/g flavonoid content, while WFE presented 1.52 ± 0.04 mg GAE/g and 0.84 ± 0.14 mg QE/g; however, the inhibition of α-amylase and α-glucosidase were higher with WFE. It was found by using 25 mg/mL of WFE an α-amylase inhibition of 63. ± 1.53% and with 30 mg/mL of WFE an α-glucosidase inhibition of 46.5 ± 1.45% after simulated intestinal conditions. The WFE could be used as a therapeutic strategy in controlled diets of diabetic patients due to its low cost, natural origin, and effect after simulated intestinal conditions.

Chromatographic Method for Determination of the Amino Acid Content in Dioscorea bulbifera L. Tubers by RP-HPLC

Background: The present study was carried out for determination of amino acid content in tubers of Dioscorea bulbifera using reverse-phase high-performance liquid chromatography. Methods: The method involved the vapor phase hydrolysis of the sample, automated derivatisation of the amino acids with the aid of AccQ-Fluor reagent kit, separated on a high performance liquid chromatography equipped with photo diode array (HPLC-PDA) at 254 nm having column temperature of 37 ºC. Results: The proportional molar concentration for each amino acid was calculated based on the concentration of standard amino acids and expressed as μg amino acid/mg sample. Methionine, aspartic acid and leucine were major components while as tyrosine was found minor from the plant on dry weight basis. Conclusion: The method is reliable, simple and economical for determining the amino acid content of Dioscorea bulbifera tubers.

Gnidia glauca- and Plumbago zeylanica-Mediated Synthesis of Novel Copper Nanoparticles as Promising Antidiabetic Agents

Rapid, eco-friendly, and cost-effective one-pot synthesis of copper nanoparticles is reported here using medicinal plants like Gnidia glauca and Plumbago zeylanica. Aqueous extracts of flower, leaf, and stem of G. glauca and leaves of P. zeylanica were prepared which could effectively reduce Cu2+ ions to CuNPs within 5 h at 100°C which were further characterized using UV-visible spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive spectroscopy, dynamic light scattering, X-ray diffraction, and Fourier-transform infrared spectroscopy. Further, the CuNPs were checked for antidiabetic activity using porcine pancreatic α-amylase and α-glucosidase inhibition followed by evaluation of mechanism using circular dichroism spectroscopy. CuNPs were found to be predominantly spherical in nature with a diameter ranging from 1 to 5 nm. The phenolics and flavonoids in the extracts might play a critical role in the synthesis and stabilization process. Significant change in the peak at ∼1095 cm-1 corresponding to C-O-C bond in ether was observed. CuNPs could inhibit porcine pancreatic α-amylase up to 30% to 50%, while they exhibited a more significant inhibition of α-glucosidase from 70% to 88%. The mechanism of enzyme inhibition was attributed due to the conformational change owing to drastic alteration of secondary structure by CuNPs. This is the first study of its kind that provides a strong scientific rationale that phytogenic CuNPs synthesized using G. glauca and P. zeylanica can be considered to develop candidate antidiabetic nanomedicine.

In Vitro Antioxidant Properties of Dichloromethanolic Leaf Extract of Gnidia glauca (Fresen) as a Promising Antiobesity Drug

The acquisition of ethnobotanical information from traditional practitioners remains an empirical aspect of understanding the ethnopharmacology research. However, integration of information on chemical composition of plant extracts and their pharmacological activities forms a key resource for synthesis of new and effective therapeutics. In traditional African medicine, Gnidia glauca has folkloric remedies against obesity and its associated oxidative stress-mediated complications. However, the upsurge in its use has not been accompanied with scientific validations to support these claims. The present study aimed to determine the antioxidant potential of G glauca as a promising antiobesity agent. The antioxidant effects of the extract were assessed against 1,1-diphenyl-2-picrylhydrazyl, hydroxyl, hydrogen peroxide, nitric oxide, and superoxide radicals as well as lipid peroxidation, iron-chelating effect, and ferric-reducing power. Phytochemical analysis was conducted using gas chromatography linked to mass spectrophotometry. The results revealed that G glauca exhibited scavenging activities against all radicals formed. Besides, the extract showed iron chelation and ferric reducing abilities. The extract indicated a lower half maximal inhibitory concentration value than the standards used. For instance, the extract inhibited 50% of the formation of 2,2-diphenyl-1-picrylhydrazine at the concentration of 1.33 ± 0.03 mg/mL relative to 1.39 ± 0.06 mg/mL of the standard, vitamin C at 1% confidence limit. Similarly, the extract scavenged 50% of hydroxyl radical at 204.34 ± 10.64 μg/mL relative to 210.05 ± 8.80 μg/mL of gallic acid. The extract also contained various phytochemicals that have been associated with antiobesity effects. The synergistic effects of these phytocompounds increase their bioavailability and action on multiple molecular targets thereby correcting obesity-induced oxidative stress.

Dietary Flavonoids and Acarbose Synergistically Inhibit α-Glucosidase and Lower Postprandial Blood Glucose

The inhibition of porcine pancreatic α-amylase and mammalian α-glucosidase by 16 individual flavonoids was determined. The IC₅₀ values for baicalein, (+)-catechin, quercetin, and luteolin were 74.1 ± 5.6, 175.1 ± 9.1, 281.2 ± 19.2, and 339.4 ± 16.3 μM, respectively, against α-glucosidase. The IC₅₀ values for apigenin and baicalein were 146.8 ± 7.1 and 446.4 ± 23.9 μM, respectively, against α-amylase. The combination of baicalein, quercetin, or luteolin with acarbose showed synergistic inhibition, and the combination of (+)-catechin with acarbose showed antagonistic inhibition of α-glucosidase. The combination of baicalein or apigenin with acarbose showed additive inhibition of α-amylase at lower concentrations and antagonistic inhibition at a higher concentration. Kinetic studies of α-glucosidase activity revealed that baicalein alone, acarbose alone, and the combination showed noncompetitive, competitive, and mixed-type inhibition, respectively. Molecular modeling revealed that baicalein had higher affinity to the noncompetitive binding site of maltase, glucoamylase, and isomaltase subunits of α-glucosidase, with glide scores of -7.64, -6.98, and -6.88, respectively. (+)-Catechin had higher affinity to the active sites of maltase and glucoamylase and to the noncompetitive site of isomaltase. After sucrose loading, baicalein dose-dependently reduced the postprandial blood glucose (PBG) level in mice. The combination of 80 mg/kg baicalein and 1 mg/kg acarbose synergistically lowered the level of PBG, and the hypoglycemic effect was comparable to 8 mg/kg acarbose. The results indicated that baicalein could be used as a supplemental drug or dietary supplement in dietary therapy for diabetes mellitus.

The Phytocomplex from Fucus vesiculosus and Ascophyllum nodosum Controls Postprandial Plasma Glucose Levels: An In Vitro and In Vivo Study in a Mouse Model of NASH

Edible seaweeds have been consumed by Asian coastal communities since ancient times. Fucus vesiculosus and Ascophyllum nodosum extracts have been traditionally used for the treatment of obesity and several gastrointestinal diseases. We evaluated the ability of extracts obtained from these algae to inhibit the digestive enzymes α-amylase and α-glucosidase in vitro, and control postprandial plasma glucose levels in a mouse model of non-alcoholic steatohepatitis (NASH); a liver disease often preceding the development of Type 2 diabetes (T2DM). This model was obtained by the administration of a high-fat diet. Our results demonstrate that these algae only delayed and reduced the peak of blood glucose (p < 0.05) in mice fed with normal diet, without changing the area under the blood glucose curve (AUC). In the model of NASH, the phytocomplex was able to reduce both the postprandial glycaemic peak, and the AUC. The administration of the extract in a diet particularly rich in fat is associated with a delay in carbohydrate digestion, but also with a decrease in its assimilation. In conclusion, our results indicate that this algal extract may be useful in the control of carbohydrate digestion and absorption. This effect may be therapeutically exploited to prevent the transition of NASH to T2DM.

Rhododendron oldhamii leaf extract improves fatty liver syndrome by increasing lipid oxidation and decreasing the lipogenesis pathway in mice

Some members of Rhododendron genus are traditionally used as medicinal plants for arthritis, acute and chronic bronchitis, asthma, pain, inflammation, rheumatism, hypertension and metabolic diseases. To the best of our knowledge, there is no report on the protective effects of R. oldhamii leaf extract on non-alcoholic fatty liver disease (NAFLD) in vivo and in vitro. In this study, the effects of R. oldhamii leaf extract on inhibiting the free fatty acid (FFA)-induced accumulation of fat in HepG2 cells and on improving fatty liver syndrome in mice with high fat diet (HFD)-induced NAFLD were investigated. For the in vitro assay, HepG2 cells were treated with FFAs (oleate/palmitate = 2:1) with or without treatment with R. oldhamii leaf ethyl acetate (EtOAc) fraction to observe lipid accumulation using Nile red and oil red O stains. For the in vivo assay, C57BL/6 mice were randomly assigned to three groups (n = 5), including the normal diet group, the HFD group and the HFD+EtOAc group. After 11 weeks, body weight, serum biochemical indices and the mRNA expressions of the liver tissue, as well as the outward appearance, weight and histopathological analysis of liver and adipose tissues were evaluated. Among the fractions derived from R. oldhamii leaf, the EtOAc fraction exhibited a strong fat-accumulation inhibitory activity. Following reverse-phase high-performance liquid chromatography (HPLC), four specific phytochemicals, including (2R, 3R)-astilbin (AS), hyposide (HY), guaijaverin (GU) and quercitrin (QU), were isolated and identified from the EtOAc fraction of R. oldhamii leaf extract. Among them, AS and HY showed excellent fat-accumulation inhibitory activity. Thus, the EtOAc fraction of R. oldhamii leaf and its derived phytochemicals have great potential in preventing FFA-induced fat accumulation. In addition, the EtOAc fraction of R. oldhamii leaf significantly improved fatty liver syndrome and reduced total cholesterol (TC) and triglyceride (TG) in HFD-induced NAFLD mice at a dosage of 200 mg/kg BW. These results demonstrated that the methanolic extracts from R. oldhamii leaf have excellent inhibitory activities against fat accumulation and anti-NAFLD activities and thus have great potential as a natural health product.

Anti-HIV-1 integrase compounds from Dioscorea bulbifera and molecular docking study

CONTEXT

Dioscorea bulbifera L. (Dioscoreaceae) has been used in a traditional Thai longevity medicine preparation. Isolation of inhibitors from natural products is a potential source for continuous development of new HIV-1 integrase (IN) inhibitors.

OBJECTIVE

The objective of this study is to isolate the compounds and evaluate their anti-HIV-1 IN activity, as well as to predict the potential interactions of the compounds with an IN.

MATERIALS AND METHODS

The ethyl acetate and water fractions (1-100 μg/mL) of Dioscorea bulbifera bulbils were isolated and tested for their anti-HIV-1 IN activity using the multiplate integration assay (MIA). The interactions of the active compounds with IN were investigated using a molecular docking method.

RESULTS AND DISCUSSIONS

The ethyl acetate and water fractions of Dioscorea bulbifera bulbils afforded seven compounds. Among these, allantoin (1), 2,4,3',5'-tetrahydroxybibenzyl (2), and 5,7,4'-trihydroxy-2-styrylchromone (5) were isolated for the first time from this plant. Myricetin (4) exhibited the most potent activity with an IC50 value of 3.15 μM, followed by 2,4,6,7-tetrahydroxy-9,10-dihydrophenanthrene (3, IC50 value= 14.20 μM), quercetin-3-O-β-D-glucopyranoside (6, IC50 value = 19.39 μM) and quercetin-3-O-β-D-galactopyranoside (7, IC50 value = 21.80 μM). Potential interactions of the active compounds (3, 4, 6, and 7) with the IN active site were additionally investigated. Compound 4 showed the best binding affinity to IN and formed strong interactions with various amino acid residues. These compounds interacted with Asp64, Thr66, His67, Glu92, Asp116, Gln148, Glu152, Asn155, and Lys159, which are involved in both the 3'-processing and strand transfer reactions of IN. In particular, galloyl, catechol, and sugar moieties were successful inhibitors for HIV-1 IN.

Novel platinum-palladium bimetallic nanoparticles synthesized by Dioscorea bulbifera: anticancer and antioxidant activities

Medicinal plants serve as rich sources of diverse bioactive phytochemicals that might even take part in bioreduction and stabilization of phytogenic nanoparticles with immense therapeutic properties. Herein, we report for the first time the rapid efficient synthesis of novel platinum-palladium bimetallic nanoparticles (Pt-PdNPs) along with individual platinum (PtNPs) and palladium (PdNPs) nanoparticles using a medicinal plant, Dioscorea bulbifera tuber extract (DBTE). High-resolution transmission electron microscopy revealed monodispersed PtNPs of size 2-5 nm, while PdNPs and Pt-PdNPs between 10 and 25 nm. Energy dispersive spectroscopy analysis confirmed 30.88% ± 1.73% elemental Pt and 68.96% ± 1.48% elemental Pd in the bimetallic nanoparticles. Fourier transform infrared spectra indicated strong peaks at 3,373 cm(-1), attributed to hydroxyl group of polyphenolic compounds in DBTE that might play a key role in bioreduction in addition to the sharp peaks at 2,937, 1,647, 1,518, and 1,024 cm(-1), associated with C-H stretching, N-H bending in primary amines, N-O stretching in nitro group, and C-C stretch, respectively. Anticancer activity against HeLa cells showed that Pt-PdNPs exhibited more pronounced cell death of 74.25% compared to individual PtNPs (12.6%) or PdNPs (33.15%). Further, Pt-PdNPs showed an enhanced scavenging activity against 2,2-diphenyl-1-picrylhydrazyl, superoxide, nitric oxide, and hydroxyl radicals.

Enrichment and Purification of Polyphenol Extract from Sphallerocarpus gracilis Stems and Leaves and in Vitro Evaluation of DNA Damage-Protective Activity and Inhibitory Effects of α-Amylase and α-Glucosidase

An efficient preparative separation method for Sphallerocarpus gracilis stems and leaves polyphenols (SGslP) was established in this study. An X-5 macroporous adsorption resin was selected for the purification of the SGslP, and the polyphenol content of the purified SGslP (PSGslP) was increased 5.11-fold from 8.29% to 42.38% after one treatment run. The chemical composition of the PSGslP was analyzed by HPLC-MS/MS, and the predominant compounds were found to be luteolin-7-glucoside, acacetin-7-acetyglycoside and its isomers. In addition, the PSGslP was evaluated in vitro to determine the DNA damage-protective activity and inhibitory effects of α-amylase and α-glucosidase. The results indicated that the PSGslP exhibited significant protective activities against both ROO• and •OH radical-induced DNA damage. Moreover, the PSGslP exerted a dose-dependent inhibition effect on α-glucosidase but no inhibitory effect on α-amylase. These findings indicate that the Sphallerocarpus gracilis stems and leaves are good natural sources of antioxidants and are potent inhibitors of α-glucosidase activity and are potential anti-diabetic inhibitor.

Management of cognitive determinants in senile dementia of Alzheimer's type: therapeutic potential of a novel polyherbal drug product

BACKGROUND AND OBJECTIVE

The enigmatic etiology of neurodegenerative diseases poses a challenge for the development of novel and efficient drugs. The objective of the present study was to evaluate the efficacy of a polyherbal (test) formulation on cognitive functions, inflammatory markers and oxidative stress in healthy elderly as well as senile dementia of Alzheimer's type (SDAT) patients.

METHOD

A randomized double-blind placebo- and active-controlled clinical trial was performed in healthy elderly subjects and SDAT patients with an age range of 60-75 years. The polyherbal test formulation along with a placebo was given to healthy elderly subjects while the SDAT patients received either the test formulation containing extracts of Bacopa monnieri (whole plant), Hippophae rhamnoides (leaves and fruits) and Dioscorea bulbifera (bulbils) at a dose of 500 mg or donepezil drug (Aricept) at a dose of 10 mg, twice daily, for a period of 12 months. After every three months, cognitive functions were assessed by determining the mini mental state examination (MMSE) score, digital symbol substitution (DSS; subtest of the Wechsler Adult Intelligence Scale-Revised), immediate and delayed word recall (digital memory apparatus-Medicaid systems, Chandigarh, India), attention span (Attention Span Apparatus-Medicaid systems, Chandigarh, India), functional activity questionnaire (FAQ) and depression (geriatric depression scale) scores. Further inflammatory markers and level of oxidative stress were analyzed using standard biochemical tests.

RESULTS

The trial was performed in 109 healthy subjects and 123 SDAT patients of whom 97 healthy subjects and 104 SDAT patients completed the study. Administration of the test formulation for a period of 12 months was effective in improving cognitive functions in the SDAT patients, when compared to the donepezil-treated group, as determined by the DSS (38.984 ± 3.016 vs 35.852 ± 4.906, P = 0.0001), word recall immediate (3.594 ± 1.003 vs 2.794 ± 0.593, P < 0.0001) and attention span (4.918 ± 1.239 vs 4.396 ± 0.913, P = 0.0208) scores. A significant improvement in the FAQ (11.873 ± 2.751 vs 9.801 ± 1.458, P < 0.0001) and depression (16.387 ± 2.116 vs 21.006 ± 2.778, P < 0.0001) scores was also observed, whereas no significant differences were observed in the MMSE and word recall delayed scores. The level of inflammation and oxidative stress was markedly reduced in the SDAT patients treated with the test formulation when compared to the donepezil-treated group indicating a likely mechanism of action of the test formulation (homocysteine 30.22 ± 3.87 vs 44.73 ± 7.11 nmol/L, P < 0.0001; C-reactive protein [CRP] 4.751 ± 1.149 vs 5.887 ± 1.049 mg/L, P < 0.0001; tumour necrosis factor alpha [TNF-α] 1139.45 ± 198.87 vs 1598.77 ± 298.52 pg/ml, P < 0.0001; superoxide dismutase [SOD] 1145.92 ± 228.75 vs 1296 ± 225.72 U/g Hb, P = 0.0013; glutathione peroxidase [GPx] 20.78 ± 3.14 vs 25.99 ± 4.11 U/g Hb, P < 0.0001; glutathione [GSH] 9.358 ± 2.139 vs 6.831 ± 1.139 U/g Hb, P < 0.0001; thiobarbituric acid reactive substances [TBARS] 131.62 ± 29.68 vs 176.40 ± 68.11 nmol/g Hb, P < 0.0001). Similarly, when healthy elderly subjects treated with the test formulation for 12 months were compared to the placebo group, a significant (P < 0.001) improvement in cognitive measures (MMSE, DSS, word recall delayed but not immediate, attention span, FAQ and depression scores) and a reduction in inflammation (reduction in homocysteine, CRP, IL-6 and TNF-α levels) and oxidative stress levels (reduction in SOD, GPx and TBARS and increase in GSH) was observed. This indicated a protective effect of the test formulation in managing cognitive decline associated with the ageing process.

CONCLUSION

The results of this study demonstrate the therapeutic potential of this novel polyherbal formulation for the management and treatment of SDAT.

Flavonoids from Salvia chloroleuca with α-Amylsae and α-Glucosidase Inhibitory Effect

It is believed that the inhibition of carbohydrate hydrolyzing enzymes including α-amylase and α-glucosidase is one of the therapeutic approaches to decrease the postprandial glucose level after a meal, especially in the people with type 2 diabetes. Medicinal plants and their extracts are one of the main sources to find new inhibitors to the enzymes. In our study four flavonoids, namely luteolin 7-O-glucoside (1), luteolin 7-O-glucuronide (2), diosmetin 7-O-glucuronide (3) and salvigenin (4) were isolated from aerial parts of Salvia chloroleuca. The inhibitory activity of these compounds against α-amylase and α-glucosidase were evaluated. Compounds 1, 2 and 3 showed potent α-glucosidase inhibitory effect with IC50 values of 18.3, 14.7, and 17.1 µM, respectively. Also these compounds exhibited moderate α-amylase activity with IC50 values 81.7, 61.5, and 76.3 µM, respectively.

Indigenous traditional knowledge and usage of folk bio-medicines among Rongmei tribe of Tamenglong district of Manipur, India

BACKGROUND

Rongmei tribe (Kooki), are inhabitant of the Charoi Chagotlong village, Tupul, Tamenglong district of Manipur have the traditional knowledge of folk bio-medicine based on diverse plant species for the prevention and cure of certain chronic diseases. The aim of this study was to document and preserve the indigenous knowledge of the Rongmei tribe on folk medicines.

MATERIAL AND METHODS

The present work was based on methodical field survey conducted between 2010, to 2013. Local people of within 30-70 age groups of both sexes were interviewed and a group discussion (using a structured interview schedule), was held to know about the type of plant parts used in folk bio-medicines, and their mode of use. The interviewers were drawn from a wide array of disciplines (Vendors, Farmers club, NGO's, scientific societies, etc.), to obtain maximum information in relation to folk bio-medicine.

RESULTS

A total of 60 species belonging to 36 different families (ranging from gymnosperm to angiosperm with medicinal benefits), were discussed briefly with significant emphasis on their local name, scientific name, family, parts used; they claimed to cure various ailments from these plants in this mode of folk bio-medicine. The different plant parts used were leaves, fruits, bulbs, bark, roots, seeds, tuber, trunk, flower, shoot, whole plant, rhizome, stem, wood and berries. Based on a life form of the reported plants comprise herbs, shrubs, trees, grasses, bulb, vine, climber, tuber and succulent.

CONCLUSION

Efforts should be made to promote the use of traditional biomedicines within rural communities to preserve the traditional knowledge.

Diosgenin from Dioscorea bulbifera: novel hit for treatment of type II diabetes mellitus with inhibitory activity against α-amylase and α-glucosidase

Diabetes mellitus is a multifactorial metabolic disease characterized by post-prandial hyperglycemia (PPHG). α-amylase and α-glucosidase inhibitors aim to explore novel therapeutic agents. Herein we report the promises of Dioscorea bulbifera and its bioactive principle, diosgenin as novel α-amylase and α-glucosidase inhibitor. Among petroleum ether, ethyl acetate, methanol and 70% ethanol (v/v) extracts of bulbs of D. bulbifera, ethyl acetate extract showed highest inhibition upto 72.06 ± 0.51% and 82.64 ± 2.32% against α-amylase and α-glucosidase respectively. GC-TOF-MS analysis of ethyl acetate extract indicated presence of high diosgenin content. Diosgenin was isolated and identified by FTIR, 1H NMR and 13C NMR and confirmed by HPLC which showed an α-amylase and α-glucosidase inhibition upto 70.94 ± 1.24% and 81.71 ± 3.39%, respectively. Kinetic studies confirmed the uncompetitive mode of binding of diosgenin to α-amylase indicated by lowering of both Km and Vm. Interaction studies revealed the quenching of intrinsic fluorescence of α-amylase in presence of diosgenin. Similarly, circular dichroism spectrometry showed diminished negative humped peaks at 208 nm and 222 nm. Molecular docking indicated hydrogen bonding between carboxyl group of Asp300, while hydrophobic interactions between Tyr62, Trp58, Trp59, Val163, His305 and Gln63 residues of α-amylase. Diosgenin interacted with two catalytic residues (Asp352 and Glu411) from α-glucosidase. This is the first report of its kind that provides an intense scientific rationale for use of diosgenin as novel drug candidate for type II diabetes mellitus.

Pancreatic islet regeneration and some liver biochemical parameters of leaf extracts of Vitex doniana in normal and streptozotocin-induced diabetic albino rats

OBJECTIVE

To test two water soluble extracts (aqueous and ethanolic) obtained from the leaves of Vitex doniana in normal and streptozotocin-induced diabetic rats for their effects on pancreatic endocrine tissues and serum marker enzymes for a period of 21 d.

METHODS

A total of 55 rats divided into 11 groups of 5 rats each were assigned into diabetic and non-diabetic groups and followed by a daily administration of ethanolic and aqueous extracts for 21 d. Group 1 was the normal control while group 7 was treated with standard drug.

RESULTS

The histopathological studies of the diabetic rats indicated increase in the volume density of islets, percent of β-cells and size of islet in the groups that received the plant extracts, which suggested regeneration of β-cells along with β-cells repairs, as compared with the non-treated diabetic control which showed complete degeneration of the islet cells. There was significant reduction (P<0.05) in the serum activities of marker enzymes, alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase in diabetes treated rats, whereas an insignificant increase (P>0.01) in the serum activities of marker enzymes was observed for non-diabetic treated rats. Results of total bilirubin, direct bilirubin and unconjugated bilirubin showed that diabetic control group was significantly higher (P<0.05) in total bilirubin and unconjugated bilirubin compared with treated groups while non-diabetic treated groups showed no significant increase (P>0.01) in total bilirubin and direct bilirubin compared with the normal control.

CONCLUSION

This herbal therapy appears to bring about repair/regeneration of the endocrine pancreas and hepatic cells protection in the diabetic rat.

Phytochemical analysis and free radical scavenging activity of medicinal plants Gnidia glauca and Dioscorea bulbifera

Gnidia glauca and Dioscorea bulbifera are traditional medicinal plants that can be considered as sources of natural antioxidants. Herein we report the phytochemical analysis and free radical scavenging activity of their sequential extracts. Phenolic and flavonoid content were determined. Scavenging activity was checked against pulse radiolysis generated ABTS^•+ and OH radical, in addition to DPPH, superoxide and hydroxyl radicals by biochemical methods followed by principal component analysis. G. glauca leaf extracts were rich in phenolic and flavonoid content. Ethyl acetate extract of D. bulbifera bulbs and methanol extract of G. glauca stem exhibited excellent scavenging of pulse radiolysis generated ABTS^•+ radical with a second order rate constant of 2.33×10⁶ and 1.72×10⁶, respectively. Similarly, methanol extract of G. glauca flower and ethyl acetate extract of D. bulbifera bulb with second order rate constants of 4.48×10⁶ and 4.46×10⁶ were found to be potent scavengers of pulse radiolysis generated OH radical. G. glauca leaf and stem showed excellent reducing activity and free radical scavenging activity. HPTLC fingerprinting, carried out in mobile phase, chloroform: toluene: ethanol (4: 4: 1, v/v) showed presence of florescent compound at 366 nm as well as UV active compound at 254 nm. GC-TOF-MS analysis revealed the predominance of diphenyl sulfone as major compound in G. glauca. Significant levels of n-hexadecanoic acid and octadecanoic acid were also present. Diosgenin (C₂₇H₄₂O₃) and diosgenin (3á,25R) acetate were present as major phytoconstituents in the extracts of D. bulbifera. G. glauca and D. bulbifera contain significant amounts of phytochemicals with antioxidative properties that can be exploited as a potential source for herbal remedy for oxidative stress induced diseases. These results rationalize further investigation in the potential discovery of new natural bioactive principles from these two important medicinal plants.

Enzymes inhibition and antidiabetic effect of isolated constituents from Dillenia indica

Aims. This study was designed to investigate the enzyme inhibitory and antidiabetic activity for the constituents isolated from Dillenia indica. Methods. The leaves of D. indica were extracted with methanol and subjected to fractionation and chromatographic separation, which led to the isolation of seven compounds: betulinic acid (1), n-heptacosan-7-one (2), n-nonatriacontan-18-one (3), quercetin (4), β sitosterol (5), stigmasterol (6), and stigmasteryl palmitate (7). Among these isolates, compounds 1, 4, 5, and 6 were evaluated for in vitro enzyme inhibition and compounds 4, 5 and 6 were evaluated for antidiabetic activity in streptozotocin-nicotinamide induced diabetic mice. Results. Compounds 1, 4, 5, and 6 showed 47.4, 55.2, 48.8, and 44.3% α-amylase inhibition, respectively, and 52.2, 78.2, 52.5, and 34.2% α-glucosidase inhibition, respectively, at the dose of 50 µg/kg. Compounds 4, 5 and 6 also showed significant (∗P < 0.05) antidiabetic activity in streptozotocin-nicotinamide induced diabetic mice at the dose of 10 mg/kg. Conclusion. These results provide evidence that Dillenia indica might be a potential source of antidiabetic agents.

Synthesis and glycosidase inhibitory activity of novel (2-phenyl-4H-benzopyrimedo[2,1-b]-thiazol-4-yliden)acetonitrile derivatives

A series of (2-phenyl-4H-benzopyrimodo[2,1-b][1,3]thiazol-4-yliden-4-yliden)acetonitrile derivatives have been prepared by ring transformation reaction of 4-(methylthio)-2-oxo-6-aryl-2H-pyrane-3-carbonitriles. The yield of ring transformation product is moderate to good. Furthermore the glycosidase inhibitory activities were tested by using α-amylase and α-glucosidase pancreatic, intestinal and liver enzymes, responsible for hyperglycemia in type II diabetes. The results revealed that all compounds exhibit significant glycosidase inhibitory activity.

Gnidia glauca flower extract mediated synthesis of gold nanoparticles and evaluation of its chemocatalytic potential

Background

Novel approaches for synthesis of gold nanoparticles (AuNPs) are of utmost importance owing to its immense applications in diverse fields including catalysis, optics, medical diagnostics and therapeutics. We report on synthesis of AuNPs using Gnidia glauca flower extract (GGFE), its detailed characterization and evaluation of its chemocatalytic potential.

Results

Synthesis of AuNPs using GGFE was monitored by UV-Vis spectroscopy and was found to be rapid that completed within 20 min. The concentration of chloroauric acid and temperature was optimized to be 0.7 mM and 50°C respectively. Bioreduced nanoparticles varied in morphology from nanotriangles to nanohexagons majority being spherical. AuNPs were characterized employing transmission electron microscopy, high resolution transmission electron microscopy. Confirmation of elemental gold was carried out by elemental mapping in scanning transmission electron microscopic mode, energy dispersive spectroscopy and X-ray diffraction studies. Spherical particles of size ~10 nm were found in majority. However, particles of larger dimensions were in range between 50-150 nm. The bioreduced AuNPs exhibited remarkable catalytic properties in a reduction reaction of 4-nitrophenol to 4-aminophenol by NaBH₄ in aqueous phase.

Conclusion

The elaborate experimental evidences support that GGFE can provide an environmentally benign rapid route for synthesis of AuNPs that can be applied for various purposes. Biogenic AuNPs synthesized using GGFE exhibited excellent chemocatalytic potential.

Hypoglycemic and Hypolipidemic Effects of Ethanolic Extract of Mirabilis jalapa L. Root on Normal and Diabetic Mice

The present study investigated the insulin sensitivity, hypoglycemic, and hypolipidemic activities of ethanolic extract of Mirabilis jalapa L. root (EEM) in normal and diabetic mice. After induction of diabetes with streptozotocin, both normal and diabetic mice were singly or repeatedly for 28 days administrated with EEM at doses of 2, 4, 8 g/kg, respectively. Before induction of diabetes, mice were administrated with EEM at doses of 2, 4, 8 g/kg for 14 days and were injected with streptozotocin and continued on EEM administration for another 28 days. Both after and before induction of diabetes, repeated administration with 4, 8 g/kg EEM continually lowered blood glucose level, decreased serum insulin level and improved insulin sensitivity index, and lowered serum total cholesterol, triglyceride levels and triglyceride content in liver and skeletal muscle, and increased glycogen content in these tissues; but repeated administration had no influence on those indexes of normal mice. Single administration with EEM (4, 8 g/kg) showed hypoglycemic effect in oral glucose tolerance test in normal and diabetic mice. Single administration with EEM had no hypoglycemic and hypolipidemic effects on normal and diabetic mice. These results suggest that EEM possesses both potential insulin sensitivity, hypoglycemic, and hypolipidemic effects on diabetes.

Synthesis of silver nanoparticles using Dioscorea bulbifera tuber extract and evaluation of its synergistic potential in combination with antimicrobial agents

BACKGROUND

Development of an environmentally benign process for the synthesis of silver nanomaterials is an important aspect of current nanotechnology research. Among the 600 species of the genus Dioscorea, Dioscorea bulbifera has profound therapeutic applications due to its unique phytochemistry. In this paper, we report on the rapid synthesis of silver nanoparticles by reduction of aqueous Ag(+) ions using D. bulbifera tuber extract.

METHODS AND RESULTS

Phytochemical analysis revealed that D. bulbifera tuber extract is rich in flavonoid, phenolics, reducing sugars, starch, diosgenin, ascorbic acid, and citric acid. The biosynthesis process was quite fast, and silver nanoparticles were formed within 5 hours. Ultraviolet-visible absorption spectroscopy, transmission electron microscopy, high-resolution transmission electron microscopy, energy dispersive spectroscopy, and x-ray diffraction confirmed reduction of the Ag(+) ions. Varied morphology of the bioreduced silver nanoparticles included spheres, triangles, and hexagons. Optimization studies revealed that the maximum rate of synthesis could be achieved with 0.7 mM AgNO(3) solution at 50°C in 5 hours. The resulting silver nanoparticles were found to possess potent antibacterial activity against both Gram-negative and Gram-positive bacteria. Beta-lactam (piperacillin) and macrolide (eryth-romycin) antibiotics showed a 3.6-fold and 3-fold increase, respectively, in combination with silver nanoparticles selectively against multidrug-resistant Acinetobacter baumannii. Notable synergy was seen between silver nanoparticles and chloramphenicol or vancomycin against Pseudomonas aeruginosa, and was supported by a 4.9-fold and 4.2-fold increase in zone diameter, respectively. Similarly, we found a maximum 11.8-fold increase in zone diameter of streptomycin when combined with silver nanoparticles against E. coli, providing strong evidence for the synergistic action of a combination of antibiotics and silver nanoparticles.

CONCLUSION

This is the first report on the synthesis of silver nanoparticles using D. bulbifera tuber extract followed by an estimation of its synergistic potential for enhancement of the antibacterial activity of broad spectrum antimicrobial agents.