HPLC-DAD phenolics analysis, α-glucosidase, α-amylase inhibitory, molecular docking and nutritional profiles of Persicaria hydropiper L.

BACKGROUND: Natural phenolic compounds and Phenolics-rich medicinal plants are also of great interest in the management of diabetes. The current study was aimed to analyze phenolics in P. hydropiepr L extracts via HPLC-DAD analysis and assess their anti-diabetic potentials using in-vitro and in-silico approaches. METHODS: Plant crude methanolic extract (Ph.Cme) was evaluated for the presence of phenolic compounds using HPLC-DAD analysis. Subsequently, samples including crude (Ph.Cr), hexane (Ph.Hex), chloroform (Ph.Chf), ethyl acetate (Ph.EtAc), butanol (Ph.Bt), aqueous (Ph.Aq) and saponins (Ph.Sp) were tested for α-glucsidase and α-amylase inhibitory potentials and identified compounds were docked against these target enzymes using Molecular Operating Environment (MOE) software. Fractions were also analyzed for the nutritional contents and acute toxicity was performed in animals. RESULTS: In HPLC-DAD analysis of Ph.Cme, 24 compounds were indentfied and quantified. Among these, Kaemferol-3-(p-coumaroyl-diglucoside)-7-glucoside (275.4 mg g- 1), p-Coumaroylhexose-4-hexoside (96.5 mg g- 1), Quercetin-3-glucoronide (76.0 mg g- 1), 4-Caffeoylquinic acid (58.1 mg g- 1), Quercetin (57.9 mg g- 1), 5,7,3'-Trihydroxy-3,6,4',5'-tetramethoxyflavone (55.5 mg g- 1), 5-Feruloylquinic acid (45.8 mg g- 1), Cyanidin-3-glucoside (26.8 mg g- 1), Delphinidin-3-glucoside (24 mg g- 1), Quercetin-3-hexoside (20.7 mg g- 1) were highly abundant compounds. In α-glucosidase inhibition assay, Ph.Sp were most effective with IC50 value of 100 µg mL-1. Likewise in α-amylase inhibition assay, Ph.Chf, Ph.Sp and Ph.Cme were most potent fractions displayed IC50 values of 90, 100 and 200 µg mL-1 respectively. Docking with the α-glucosidase enzyme revealed top ranked conformations for majority of the compounds with Kaemferol-3-(p-coumaroyl-diglucoside)-7-glucoside as the most active compound with docking score of - 19.80899, forming 14 hydrogen bonds, two pi-H and two pi-pi linkages with the Tyr 71, Phe 158, Phe 177, Gln 181, Arg 212, Asp 214, Glu 276, Phe 300, Val 303, Tyr 344, Asp 349, Gln 350, Arg 439, and Asp 408 residues of the enzyme. Likewise, docking with α-amylase revealed that most of the compounds are well accommodated in the active site residues (Trp 59, Tyr 62, Thr 163, Leu 165, Arg 195, Asp 197, Glu 240, Asp 300, His 305, Asp 356) of the enzyme and Cyanidin-3-rutinoside displayed most active compound with docking score of - 15.03757. CONCLUSIONS: Phytochemical studies revealed the presence of highly valuable phenolic compounds, which might be responsible for the anti-diabetic potentials of the plant samples.

Mangosteen xanthone γ-mangostin exerts lowering blood glucose effect with potentiating insulin sensitivity through the mediation of AMPK/PPARγ.

Diabetes mellitus (DM) is concomitant with significant morbidity and mortality and its prevalence is accumulative in worldwide. The conventional antidiabetic agents are known to mitigate the symptoms of diabetes; however, they may also cause side and adverse effects. There is an imperative necessity to conduct preclinical and clinical trials for the discovery of alternative therapeutic agents that can overcome the drawbacks of current synthetic antidiabetic drugs. This study aimed to investigate the efficacy of lowering blood glucose and underlined mechanism of γ-mangostin, mangosteen (Garcinia mangostana) xanthones. The results showed γ-Mangostin had a antihyperglycemic ability in short (2 h)- and long-term (28 days) administrations to diet-induced diabetic mice. The long-term administration of γ-mangostin attenuated fasting blood glucose of diabetic mice and exhibited no hepatotoxicity and nephrotoxicity. Moreover, AMPK, PPARγ, α-amylase, and α-glucosidase were found to be the potential targets for simulating binds with γ-mangostin after molecular docking. To validate the docking results, the inhibitory potency of γ-mangostin againstα-amylase/α-glucosidase was higher than Acarbose via enzymatic assay. Interestingly, an allosteric relationship between γ-mangostin and insulin was also found in the glucose uptake of VSMC, FL83B, C2C12, and 3T3-L1 cells. Taken together, the results showed that γ-mangostin exerts anti-hyperglycemic activity through promoting glucose uptake and reducing saccharide digestion by inhibition of α-amylase/α-glucosidase with insulin sensitization, suggesting that γ-mangostin could be a new clue for drug discovery and development to treat diabetes.

Negative regulation of AMPK signaling by high glucose via E3 ubiquitin ligase MG53.

As a master regulator of metabolism, AMP-activated protein kinase (AMPK) is activated upon energy and glucose shortage but suppressed upon overnutrition. Exaggerated negative regulation of AMPK signaling by nutrient overload plays a crucial role in metabolic diseases. However, the mechanism underlying the negative regulation is poorly understood. Here, we demonstrate that high glucose represses AMPK signaling via MG53 (also called TRIM72) E3-ubiquitin-ligase-mediated AMPKα degradation and deactivation. Specifically, high-glucose-stimulated reactive oxygen species (ROS) signals AKT to phosphorylate AMPKα at S485/491, which facilitates the recruitment of MG53 and the subsequent ubiquitination and degradation of AMPKα. In addition, high glucose deactivates AMPK by ROS-dependent suppression of phosphorylation of AMPKα at T172. These findings not only delineate the mechanism underlying the impairment of AMPK signaling in overnutrition-related diseases but also highlight the significance of keeping the yin-yang balance of AMPK signaling in the maintenance of metabolic homeostasis.

In Search for Multi-Target Ligands as Potential Agents for Diabetes Mellitus and Its Complications-A Structure-Activity Relationship Study on Inhibitors of Aldose Reductase and Protein Tyrosine Phosphatase 1B.

Diabetes mellitus (DM) is a complex disease which currently affects more than 460 million people and is one of the leading cause of death worldwide. Its development implies numerous metabolic dysfunctions and the onset of hyperglycaemia-induced chronic complications. Multiple ligands can be rationally designed for the treatment of multifactorial diseases, such as DM, with the precise aim of simultaneously controlling multiple pathogenic mechanisms related to the disease and providing a more effective and safer therapeutic treatment compared to combinations of selective drugs. Starting from our previous findings that highlighted the possibility to target both aldose reductase (AR) and protein tyrosine phosphatase 1B (PTP1B), two enzymes strictly implicated in the development of DM and its complications, we synthesised 3-(5-arylidene-4-oxothiazolidin-3-yl)propanoic acids and analogous 2-butenoic acid derivatives, with the aim of balancing the effectiveness of dual AR/PTP1B inhibitors which we had identified as designed multiple ligands (DMLs). Out of the tested compounds, 4f exhibited well-balanced AR/PTP1B inhibitory effects at low micromolar concentrations, along with interesting insulin-sensitizing activity in murine C2C12 cell cultures. The SARs here highlighted along with their rationalization by in silico docking experiments into both target enzymes provide further insights into this class of inhibitors for their development as potential DML antidiabetic candidates.

Inhibitory Potential of Acroptilon repens against Key Enzymes involved in Alzheimer and Diabetes, Phytochemical Profile, Radical Scavenging, and Antibacterial Activity.

Background: This study was devoted to assessing the inhibitory potential of acetone, methanol, and ethanol extracts of Acroptilon repens against disease-associated enzymes, as well as their antioxidant/antibacterial activity and phytochemical composition. Methods: Comparative assessment using various antioxidant evaluation methods, including ferric reducing antioxidant power, scavenging ability on 2,2-diphenyl-1-picrylhydrazyl radical and hydrogen peroxide, and reducing power, indicated that the acetone extract presented the highest antioxidant activity, due to its highest total antioxidant content. Results: The total phenolic content and total flavonoids content of these extracts were 3.44 ± 0.32 mg GAE/g DW and 2.09 ± 0.2 mg QE/g DW, respectively. The hydrodistillation essential oil from A. repens was analyzed by gas chromatography-mass spectroscopy, and 17 compounds were identified. All extracts showed good inhibitory activities against disease-related enzyme acetylcholinesterase and α-amylase, with the lowest IC50 for acetonic extract. Extracts of A. repens exhibited inhibiting activities against the Gram-positive bacteria, with the most effect of acetone extract. Conclusion: Our findings suggest A. repens as a promising source of natural antioxidant, antimicrobial, anti-cholinesterase and anti-amylase agents for the management of oxidative damage, and pharmaceutical, food, and cosmeceutical purposes.

Glucokinase activation as antidiabetic therapy: effect of nutraceuticals and phytochemicals on glucokinase gene expression and enzymatic activity.

Diabetes represents an important public health problem. Recently, new molecular targets have been identified and exploited to treat this disease. Due to its pivotal role in glucose homeostasis, glucokinase (GCK) is a promising target for the development of novel antidiabetic drugs; however, pharmacological agents that modulate GCK activity have been linked to undesirable side-effects, limiting its use. Interestingly, plants might be a valuable source of new therapeutic compounds with GCK-activating properties and presumably no adverse effects. In this review, we describe biochemical characteristics related to the physiological and pathological importance of GCK, as well as the mechanisms involved in its regulation at different molecular levels. Posteriorly, we present a compendium of findings supporting the potential use of nutraceuticals and phytochemicals in the management of diabetes through modulation of GCK expression and activity. Finally, we propose critical aspects to keep in mind when designing experiments to evaluate GCK modulation properly.

Garcinia linii extracts exert the mediation of anti-diabetic molecular targets on anti-hyperglycemia.

Different portions (stem GIS and leaf GIL) of Garcinia linii were extracted by ethanol/water and crude extracts were employed to investigate the contents of total phenol and flavonoids, antioxidation activities, and inhibitory activities of α-amylase and α-glucosidase via enzymatic assay and OGTT and OSTT for lowering glucose levels. The data revealed that GlS and GlL contained different levels of flavonoids and total phenol. Furthermore, the results showed the extracts exhibited remarkable antioxidation activities and inhibitory activities of α-amylase and α-glucosidase. In silico docking studies were done using Gold software and the probable molecules retrieved from PubChem were docked with several anti-diabetic relate targets, the results showed several components of G. linii could potentially inhibit diabetic molecules when compared with clinic drugs. The cell glucose uptake data also confirmed that GlL and GlS could retain the active component in the regulation of insulin, AMPK, PPARγ, and DPP4. In vivo, the evidence showed G. linii extracts including syringaldehyde suppressed effect of hyperglycemia on OSTT and OGTT assays. These results suggest that G. linii extract has a potential therapeutic value for the treatment of diabetes in humans.

In vitro enzyme inhibitory and cytotoxic studies with Evolvulus alsinoides (Linn.) Linn. Leaf extract: a plant from Ayurveda recognized as Dasapushpam for the management of Alzheimer's disease and diabetes mellitus.

BACKGROUND: Evolvulus alsinoides (Linn.) Linn. (Convolvulaceae) is a therapeutic herb alleviating brain patterns associated with three categories of regulatory principles of the body, mind, and behaviour. In the current research, enzyme inhibition and cytotoxic potentials of E. alsinoides (L.) L. leaf extract has been studied validating its potential application. METHODS: The plant phenolics in the leaf extracts obtained via cold-maceration with solvents viz.: n-hexane, chloroform, ethyl acetate, methanol, and water were quantitatively analyzed. The antioxidant potency was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and Ferric Reducing Ability of Plasma (FRAP) assays at five concentrations (100-500 µg). The enzyme inhibition potential was performed with α-amylase, α-glucosidase, and acetylcholinesterase at seven concentrations (25-500 µg). The experiments were done in triplicates and statistically validated using Minitab-17 and SPSS 22. RESULTS: Water extract contain 45.08 ± 0.02 mg GAE/g, 49.30 ± 0.07 mg GAE/g, 211.21 ± 0.02 mg QE/g tannins, phenolics, flavonoids respectively. Its antioxidant activity was supported by IC50 52.43 ± 0.2 µg/mL (DPPH assay) and 41.58 ± 0.03 (FRAP assay). Methanolic extract inhibits α-amylase with IC50 1.33 ± 0.05 µg/mL. Water extract inhibits α-glucosidase and acetylcholinesterase with IC50 3.58 ± 0.02 µg/mL and 4.46 ± 0.03 µg/mL. Cytotoxicity studies with SH-SY5Y cell-line substantiate the inhibition potential of water extract with IC50 103.0035 µg/mL. DISCUSSION AND CONCLUSIONS: The extracts with potent antioxidant and enzyme-inhibiting activity were determined. The findings of the research are the first report about the inhibition effects of Evolvulus alsinoides (Linn.) Linn extracts against α-amylase, α-glucosidase and acetylcholinesterase. The extracts shall be examined in future studies to evaluate its pharmaceutical potential.

Vascular adenosine monophosphate-activated protein kinase: Enhancer, brake or both?

Adenosine monophosphate-activated protein kinase (AMPK), expressed/present ubiquitously in the body, contributes to metabolic regulation. In the vasculature, activation of AMPK is associated with several beneficial biological effects including enhancement of vasodilatation, reduction of oxidative stress and inhibition of inflammatory reactions. The vascular protective effects of certain anti-diabetic (metformin and sitagliptin) or lipid-lowering (simvastatin and fenofibrate) therapeutic agents, of active components of Chinese medicinal herbs (resveratrol and berberine) and of pharmacological agents (AICAR, A769662 and PT1) have been attributed to the activation of AMPK (in endothelial cells, vascular smooth muscle cells and/or perivascular adipocytes), independently of changes in the metabolic profile (eg glucose tolerance and/or plasma lipoprotein levels), leading to improved endothelium-derived nitric oxide-mediated vasodilatation and attenuated endothelium-derived cyclooxygenase-dependent vasoconstriction. By contrast, endothelial AMPK activation with pharmacological agents or by genetic modification is associated with reduced endothelium-dependent relaxations in small blood vessels and elevated systolic blood pressure. Indeed, AMPK activators inhibit endothelium-dependent hyperpolarization (EDH)-type relaxations in superior mesenteric arteries, partly by inhibiting endothelial calcium-activated potassium channel signalling. Therefore, AMPK activation is not necessarily beneficial in terms of endothelial function. The contribution of endothelial AMPK in the regulation of vascular tone, in particular in the microvasculature where EDH plays a more important role, remains to be characterized.

Protein Tyrosine Phosphatase (PTP1B): A promising Drug Target Against Life-threatening Ailments.

BACKGROUND: Protein tyrosine phosphatases are enzymes which help in the signal transduction in diabetes, obesity, cancer, liver diseases and neurodegenerative diseases. PTP1B is the main member of this enzyme from the protein extract of human placenta. In phosphate inhibitors development, significant progress has been made over the last 10 years. In early-stage clinical trials, few compounds have reached whereas in the later stage trials or registration, yet none have progressed. Many researchers investigate different ways to improve the pharmacological properties of PTP1B inhibitors. OBJECTIVE: In the present review, authors have summarized various aspects related to the involvement of PTP1B in various types of signal transduction mechanisms and its prominent role in various diseases like cancer, liver diseases and diabetes mellitus. CONCLUSION: There are still certain challenges for the selection of PTP1B as a drug target. Therefore, continuous future efforts are required to explore this target for the development of PTP inhibitors to treat the prevailing diseases associated with it.

Evaluation of the Anti-Diabetic Activity of Some Common Herbs and Spices: Providing New Insights with Inverse Virtual Screening.

Culinary herbs and spices are widely used as a traditional medicine in the treatment of diabetes and its complications, and there are several scientific studies in the literature supporting the use of these medicinal plants. However, there is often a lack of knowledge on the bioactive compounds of these herbs and spices and their mechanisms of action. The aim of this study was to use inverse virtual screening to provide insights into the bioactive compounds of common herbs and spices, and their potential molecular mechanisms of action in the treatment of diabetes. In this study, a library of over 2300 compounds derived from 30 common herbs and spices were screened in silico with the DIA-DB web server against 18 known diabetes drug targets. Over 900 compounds from the herbs and spices library were observed to have potential anti-diabetic activity and liquorice, hops, fennel, rosemary, and fenugreek were observed to be particularly enriched with potential anti-diabetic compounds. A large percentage of the compounds were observed to be potential polypharmacological agents regulating three or more anti-diabetic drug targets and included compounds such as achillin B from yarrow, asparasaponin I from fenugreek, bisdemethoxycurcumin from turmeric, carlinoside from lemongrass, cinnamtannin B1 from cinnamon, crocin from saffron and glabridin from liquorice. The major targets identified for the herbs and spices compounds were dipeptidyl peptidase-4 (DPP4), intestinal maltase-glucoamylase (MGAM), liver receptor homolog-1 (NR5A2), pancreatic alpha-amylase (AM2A), peroxisome proliferator-activated receptor alpha (PPARA), protein tyrosine phosphatase non-receptor type 9 (PTPN9), and retinol binding protein-4 (RBP4) with over 250 compounds observed to be potential inhibitors of these particular protein targets. Only bay leaves, liquorice and thyme were found to contain compounds that could potentially regulate all 18 protein targets followed by black pepper, cumin, dill, hops and marjoram with 17 protein targets. In most cases more than one compound within a given plant could potentially regulate a particular protein target. It was observed that through this multi-compound-multi target regulation of these specific protein targets that the major anti-diabetic effects of reduced hyperglycemia and hyperlipidemia of the herbs and spices could be explained. The results of this study, taken together with the known scientific literature, indicated that the anti-diabetic potential of common culinary herbs and spices was the result of the collective action of more than one bioactive compound regulating and restoring several dysregulated and interconnected diabetic biological processes.

Vitellaria paradoxa nutshells from seven sub-Saharan countries as potential herbal medicines for treating diabetes based on chemical compositions, HPLC fingerprints and bioactivity evaluation.

The aim of the study was to determine the feasibility of the Vitellaria paradoxa nutshell as a new medicinal resource for treating diabetes. A total of forty-one compounds were identified by HPLC-DAD-Q-TOF-MS and phytochemical methods in V. paradoxa nutshell methanol extract. Based on HPLC fingerprints, four characteristic constituents were quantified and the origin of twenty-eight V. paradoxa nutshells from seven sub-Saharan countries was compared, which were classified into three groups with chemometric method. Twenty-eight samples contained high total phenolic content, and exhibited moderate-higher antioxidant activity and strong α-glucosidase inhibitory activity. Furthermore, all fractions and isolated compounds were evaluated for their antioxidant and α-glucosidase inhibitory activities, and α-glucosidase inhibitory action mechanism of four characteristic constituents including protocatechuic acid, 3, 5, 7-trihydroxycoumarin, (2R, 3R)-(+)-taxifolin and quercetin was investigated via molecular docking method, which were all stabilized by hydrogen bonds with α-glucosidase. The study provided an effective approach to waste utilization of V. paradoxa nutshell, which would help to resolve waste environmental pollution and provide a basis for developing potential herbal resource for treating diabetes.

ANTIOXIDANT ACTIVITY AND A-AMYLASE INHIBITORY POTENTIAL OF ROSA CANINA L.

BACKGROUND: Diabetes mellitus is one of the most common endocrinal disorders and medicinal plants continue to play an important role in the management of this disease. In this study, Rosa canina was investigated for the antioxidant and α-amylase inhibition activities. MATERIALS AND METHODS: Methanolic extract of Rosa canina was investigated for its potential antioxidant activity. The extracts' total phenolic and flavonoid contents and scavenging capacity for free radicals were evaluated. The α-amylase inhibition assay was also carried. RESULTS: Rosa canina extract exhibits a total Phenolic and flavonoid levels respectively (21.918 mg GAE/g and 2.647mg ER/g). The free radical scavenging activity was found to be prominent against DPPH with an IC50 of 0.668 mg/ml and against ABTS with an IC50 of 0.467 mg/ml. Extract showed a significant ferric ion reducing activities with an IC50 of4.962 mg/ml. CONCLUSION: Rosa canina exerted a higher inhibitory activity against α-amylase. The obtained results support the antidiabetic use of rosa canina.

Protective effects of Cynara scolymus leaves extract on metabolic disorders and oxidative stress in alloxan-diabetic rats.

BACKGROUND: Diabetes mellitus (DM) is associated with hyperglycemia, inflammatory disorders and abnormal lipid profiles, currently the extracts from leaves of cynara scolymus has been discovered to treat metabolic disorders and has been stated by multitudinous scientists according to a good source of polyphenols compounds. The present study aimed to evaluate the protective effect of the ethanol leaves extract of C. scolymus in alloxan induced stress oxidant, hepatic-kidney dysfunction and histological changes in liver, kidney and pancreas of different experimental groups of rats. METHODS: We determinate the antioxidant activity by ABTS .+ and antioxidant total capacity (TAC) of all extracts of C. scolymus leaves, the inhibition of α-amylase activity in vitro was also investigated. Forty male Wistar rats were induced to diabetes with a single dose intraperitoneal injection (i.p.) of alloxan (150 mg/kg body weight (b.w.)). Diabetic rats were orally and daily administrated of ethanol extract from C. scolymus at two doses (200-400 mg/kg, b.w) or (12 mg/kg, b.w) with anti-diabetic reference drug, Acarbose for one month. Ethanol extract of C. scolymus effect was confirmed by biochemical analysis, antioxidant activity and histological study. RESULTS: The results indicated that the ethanol extract from leaves of C. scolymus showed the highest antioxidant activity by ABTS .+ (499.43g± 39.72 Trolox/g dry extract) and (128.75 ± 8.45 mg VC /g dry extract) for TAC and endowed the powerful inhibition in vitro of α-amylase activity with IC50=72,22 ug/uL. In vivo, the results showed that ethanol extract from the leaves of C. scolymus (200-400 mg/kg) decreased significantly (p < 0.001) the α-amylase levels in serum of diabetic rats, respectively associated with significant reduction (p < 0.001) in blood glucose rate of 42,84% and 37,91% compared to diabetic groups after 28 days of treatment, a significant lowered of plasma total cholesterol (T-Ch) by 18,11% and triglyceride (TG) by 60,47%, significantly and low-density lipoproteins (LDL-C) by 37,77%, compared to diabetic rats, moreover, the administration of ethanol extract appears to exert anti-oxidative activity demonstrated by the increase of CAT, SOD and GSH activities in liver, kidney and pancreas of diabetic rats. This positive effect of the ethanol extract from C. scolymus was confirmed by histological study. CONCLUSION: These observed strongly suggest that ethanol extract from the leaves of C. scolymus has anti-hyperglycemic properties, at least partly mediated by antioxidant and hypolipidemic effects.

Modulatory effects of Caralluma fimbriata extract against high-fat diet induced abnormalities in carbohydrate metabolism in Wistar rats.

The present study was aimed to evaluate the modulatory effects of hydroalcoholic extract of Caralluma fimbriata (CFE) by assaying the activities of key enzymes of carbohydrate metabolism and changes in glycogen content (liver and muscle) in high-fat (HF) diet-induced diabetic rats. In vitro glucose uptake studies were carried out in both psoas muscle and adipose tissue. The inhibitory effect of the extract on α-amylase was determined in in vitro studies. Male Wistar rats of body weight around 180g were divided into five groups (n=8), two of these groups were fed with standard pellet diet and the other three groups were fed with HF- (60%) diet. CFE (200mg/kg body weight/day) was administered through oral route to each group of standard pellet diet rats and HF-fed rats and Metformin (Met) (20mg/kg body weight/day) was administered through oral route to HFD+Met group for 90 days. At the end of the experimental period, biochemical parameters related to glycogen content in liver and muscle, and intestinal disaccharidases like maltase, sucrase and lactase were assayed. Alterations in the activities of enzymes of glucose metabolism (hexokinase, phosphorfructoki nase, pyruvate kinase, glucose-6-phosphatase, fructose-1,6-bisphosphatase, and glucose-6-phosphate dehydrogenase), intestinal disaccharidases and glycogen content as observed in the high fat diet-fed rats were prevented with CFE/Met administration. From this study, we observed that CFE/Met could significantly restore the levels of glycogen in liver and muscle and key enzymes of carbohydrate metabolism to near normal in groups-HFD+CFE and HFD+Met. The skeletal muscle of HF-diet fed rats showed degenerative changes of muscle myofibers with fat deposition. These changes were attenuated in the HFD group treated with CFE/Met and retained their normal structure appearance. It can be concluded from these results that CFE might be of value in reducing the alterations related to carbohydrate metabolism under high calorie diet consumption.

An assessment of the nutraceutical potential of Juglans regia L. leaf powder in diabetic rats.

In this study, we evaluated the nutraceutical potential of Juglans regia L. (a dietary supplement and food-additive) by evaluating the in-vitro anti-diabetic potential and by assessing the in-vivo anti-hyperglycaemic, anti-hyperlipidaemic, and organ-protective effects of freshly-dried and powdered leaves of J. regia L. in diabetic rats. In the in-vivo experiments, dry powder of J. regia L. leaf (25, 50 and 100 mg/kg) was administered orally, twice daily (9.00 a.m. and 5 p.m.) to streptozocin-induced diabetic rats over a period of 28 days, during which body weight and blood glucose were monitored weekly. At the end of the experimental period, animals were sacrificed, blood was taken for assessment of lipid profile, antioxidant activity and liver/kidney biochemistry; while samples of the pancreas, liver and kidneys were fixed, processed, sectioned, and stained for general histology. Phytochemical evaluations of three extracts were carried out using HPLC-PDA validated procedures, while enzyme-inhibitory potentials were tested against α-amylase and α-glucosidase. In-vivo assays showed that twice-daily administration of J. regia L. leaf resulted in weight gain, glycaemic control, reversal of dyslipidaemia and biochemical evidences of liver/kidney injury, and protection against pancreas, liver and kidney tissue injury.

Effects of Aphloia theiformis on key enzymes related to diabetes mellitus.

CONTEXT: Aphloia theiformis (Vahl.) Benn. (Flacourtiaceae) (AT) is traditionally used for the management of diabetes mellitus (DM), but there is no scientific data regarding activity against enzymes linked to this condition. OBJECTIVE: To evaluate the kinetics of AT on key enzymes inhibition related to DM, and establish the antioxidant profile of AT. MATERIALS AND METHODS: Dried powdered AT leaves were used to prepare crude methanol extract (70% v/v) (CME). Kinetics of CME (5000 to 156.25 µg/mL) on α-amylase, α-glucosidase, and lipase inhibition were studied. CME was partitioned using solvents of increasing polarity and kinetics of enzyme inhibition of each fraction (1000-31.25 µg/mL) was evaluated. Potent fractions were combined to assess any synergistic effect. Total phenol, flavonoid, tannin, anthocyanin contents, and antioxidant capacity of AT was evaluated using standard spectrophotometric methods. RESULTS: CME, ethyl acetate, and n-butanol fractions showed potent inhibitory activities against the enzymes with IC50 ranging from 22.94-939.97 µg/mL. Significant (p < 0.05) reduction in IC50 (15.72 and 157.03 µg/mL against α-amylase and lipase, respectively) was observed when ethyl acetate and n-butanol fractions were combined; showing synergism. The extracts showed noncompetitive inhibition against α-amylase and α-glucosidase. Ethyl acetate, n-butanol fractions, and CME showed highest antioxidant capacities (0.44-1.41 µg GAE/mg sample), and phenol content (211.74-675.53 µg GAE/mg sample). CONCLUSION: This study supports the use of AT in the management of DM and provides the rationale for bioactivity guided isolation and characterization of compounds from the ethyl acetate and n-butanol fractions.

Antidiabetic Potential of Purple and Red Rice (Oryza sativa L.) Bran Extracts.

Pigmented rice contains anthocyanins and proanthocyanidins that are concentrated in the bran layer. In this study, we determined the phenolic, flavonoid, anthocyanin, and proanthocyanidin content of five rice bran (1 brown, 2 red, and 2 purple) extracts. Each bran extract was evaluated for inhibitory effects on α-amylase and α-glucosidase activity, two key glucosidases required for starch digestion in humans. All purple and red bran extracts inhibited α-glucosidase activity, however only the red rice bran extracts inhibited α-amylase activity. Additionally, each bran extract was examined for their ability to stimulate glucose uptake in 3T3-L1 adipocytes, a key function in glucose homeostasis. Basal glucose uptake was increased between 2.3- and 2.7-fold by exposure to the red bran extracts, and between 1.9- and 3.1-fold by exposure to the purple bran extracts. In red rice bran, the highest enzyme inhibition and glucose uptake was observed with a proanthocyanidin-enriched fraction. Both IITA red bran and IAC purple bran increased expression of GLUT1 and GLUT4 mRNA, and genes encoding insulin-signaling pathway proteins.

Potent Antidiabetic Activity and Metabolite Profiling of Melicope Lunu-ankenda Leaves.

Diabetes mellitus is normally characterized by chronic hyperglycemia associated with disturbances in the fat, carbohydrate, and protein metabolism. There is an increasing trend of using natural products instead of synthetic agents as alternative therapy for disorders due to their fewer side effects. In this study, antidiabetic and antioxidant activities of different Melicope lunu-ankenda (ML) ethanolic extracts were evaluated using inhibition of α-glucosidase and 2,2-diphenyl-l-picrylhydrazyl (DPPH) radicals scavenging activity, respectively; whereas, proton nuclear magnetic resonance ((1) H NMR) and ultra-high performance liquid chromatography-tandem mass spectrometric (UHPLC-MS/MS) techniques were used for metabolite profiling of ML leaf extracts at different concentrations of ethanol and water. Sixty percent of ethanolic ML extract showed highest inhibitory effect against α-glucosidase enzyme (IC50 of 37 µg/mL) and DPPH scavenging activity (IC50 of 48 µg/mL). Antidiabetic effect of ML extracts was also evaluated in vivo and it was found that the high doses (400 mg/Kg BW) of ML extract exhibited high suppression in fasting blood glucose level by 62.75%. The metabolites responsible for variation among ML samples with variable ethanolic levels have been evaluated successfully using (1) H-NMR-based metabolomics. The principal component analysis (PCA) and partial least squares(PLS) analysis scores depicted clear and distinct separations into 4 clusters representing the 4 ethanolic concentrations by PC1 and PC2, with an eigenvalue of 69.9%. Various (1) H-NMR chemical shifts related to the metabolites responsible for sample difference were also ascribed. The main bioactive compounds identified attributing toward the separation included: isorhamnetin, skimmianine, scopoletin, and melicarpinone. Hence, ML may be used as promising medicinal plant for the development of new functional foods, new generation antidiabetic drugs, as a single entity phytomedicine or in combinational therapy.

Impact of physiological, pathological and environmental factors on the expression and activity of human cytochrome P450 2D6 and implications in precision medicine.

With only 1.3-4.3% in total hepatic CYP content, human CYP2D6 can metabolize more than 160 drugs. It is a highly polymorphic enzyme and subject to marked inhibition by a number of drugs, causing a large interindividual variability in drug clearance and drug response and drug-drug interactions. The expression and activity of CYP2D6 are regulated by a number of physiological, pathological and environmental factors at transcriptional, post-transcriptional, translational and epigenetic levels. DNA hypermethylation and histone modifications can repress the expression of CYP2D6. Hepatocyte nuclear factor-4α binds to a directly repeated element in the promoter of CYP2D6 and thus regulates the expression of CYP2D6. Small heterodimer partner represses hepatocyte nuclear factor-4α-mediated transactivation of CYP2D6. GW4064, a farnesoid X receptor agonist, decreases hepatic CYP2D6 expression and activity while increasing small heterodimer partner expression and its recruitment to the CYP2D6 promoter. The genotypes are key determinants of interindividual variability in CYP2D6 expression and activity. Recent genome-wide association studies have identified a large number of genes that can regulate CYP2D6. Pregnancy induces CYP2D6 via unknown mechanisms. Renal or liver diseases, smoking and alcohol use have minor to moderate effects only on CYP2D6 activity. Unlike CYP1 and 3 and other CYP2 members, CYP2D6 is resistant to typical inducers such as rifampin, phenobarbital and dexamethasone. Post-translational modifications such as phosphorylation of CYP2D6 Ser135 have been observed, but the functional impact is unknown. Further functional and validation studies are needed to clarify the role of nuclear receptors, epigenetic factors and other factors in the regulation of CYP2D6.