alpha-Amylase inhibitory activity of some Malaysian plants used to treat diabetes; with particular reference to Phyllanthus amarus

Anti-inflammatory activity of the functional groups present in Hippophae rhamnoides (Seabuckthorn) leaf extract

ETHNO PHARMACOLOGICAL RELEVANCE

The study explores the anti-inflammatory activity of components present in fractions obtained from leaves of Hippophae rhamnoides in mouse peritoneal macrophages.

AIM OF THE STUDY

Immunomodulators salvage the immune response by enhancing or reducing its capacity to the required level. Plant extracts are extensively used as immunomodulators because of their easy availability, simple methods of preparation and minimum side effects with maximum efficacy.

MATERIALS AND METHODS

The present study was conducted to assess the immunomodulatory activities of phyto constituents present in Seabuckthorn leaves. The aqueous-alcoholic leaf extract was subjected to successive and parallel extraction in the presence of polar and non-polar solvents for fractionation of compounds. Based on the yield, three fractions were selected viz. parallel methanol (PM), successive chloroform (SC) and successive methanol (SM) and screened for in vitro immunomodulatory activities. Peritoneal macrophages were isolated from Balb/c mice and cultured with or without LPS to evaluate the immunomodulatory effect of the three fractions on cell viability, hemolytic activity, nitric oxide (NO) production, cytokine levels, iNOS and COX-2 expressions.

RESULTS

The results revealed that none of the three fractions induced hemolysis. Cells treated with PM fraction significantly suppressed LPS-induced NO production and pro-inflammatory cytokines such as TNF-α, IL-6 and IFN-γ as compared to SC and SM treatment. The iNOS and COX-2 expressions were also significantly reduced after treatment with PM fraction.

CONCLUSIONS

The decrease in LPS-induced NO production, pro-inflammatory cytokine secretion, iNOS and COX-2 expression signifies anti-inflammatory properties of PM fraction containing tannins, proteins and carbohydrate groups. Hence, this plant-derived immunomodulator can be used as a therapeutic agent in inflammatory diseases.

Phenolic Elderberry Extracts, Anthocyanins, Procyanidins, and Metabolites Influence Glucose and Fatty Acid Uptake in Human Skeletal Muscle Cells

Uptake of glucose and fatty acids in skeletal muscle is of interest for type 2 diabetes treatment. The aim was to study glucose and fatty acid uptake in skeletal muscle cells, antioxidant effects, and inhibition of carbohydrate-hydrolyzing enzymes by elderberries. Enhanced glucose and oleic acid uptake in human skeletal muscle cells were observed after treatment with phenolic elderberry extracts, anthocyanins, procyanidins, and their metabolites. The 96% EtOH and the acidified MeOH extracts were highly active. Of the isolated substances, cyanidin-3-glucoside and cyanidin-3-sambubioside showed highest stimulation of uptake. Phloroglucinol aldehyde was most active among the metabolites. Isolated anthocyanins and procyanidins are strong radical scavengers and are good inhibitors of 15-lipoxygenase and moderate inhibitors of xanthine oxidase. As α-amylase and α-glucosidase inhibitors, they are considerably better than the positive control acarbose. The antidiabetic property of elderberry phenolics increases the nutritional value of this plant and indicates potential as functional food against diabetes.

The effects of 6-Gingerol on reproductive improvement, liver functioning and Cyclooxygenase-2 gene expression in estradiol valerate - Induced polycystic ovary syndrome in Wistar rats

6-Gingerol is the major pungent ingredient of ginger with anti-inflammatory and antioxidant properties. In this study, we evaluate the effects of 6-gingerol on the biochemical parameters and ovarian histological improvements in estradiol valerate (EV) induced PCOS rats. Thirty six female Wistar rats were divided into 4 groups: control, received normal diet, PCOS control, received 4 mg/kg EV injection for 28 days and two experimental groups, received an EV injection for 28 days and followed by 6-gingerol (200 μg/_kg and 400 μg/_kg) for 14 days. The administration of EV led to increase body and ovarian weights, abnormality in serum sex steroid profile, decrease in antioxidant activity and increase in COX-2 gene expression. 6-gingerol treatments, particularly the 400 μg/_kg dose, markedly attenuated these alterations. 6-gingerol showed beneficial effects in the EV induced PCOS rats via decreased expression of COX-2, restored biochemical parameters to normal and decreased of cysts in the ovaries.

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.

Effect of Phenolic Compounds from Elderflowers on Glucose- and Fatty Acid Uptake in Human Myotubes and HepG2-Cells

Type 2 diabetes (T2D) is manifested by progressive metabolic impairments in tissues such as skeletal muscle and liver, and these tissues become less responsive to insulin, leading to hyperglycemia. In the present study, stimulation of glucose and oleic acid uptake by elderflower extracts, constituents and metabolites were tested in vitro using the HepG2 hepatocellular liver carcinoma cell line and human skeletal muscle cells. Among the crude extracts, the 96% EtOH extract showed the highest increase in glucose and oleic acid uptake in human skeletal muscle cells and HepG2-cells. The flavonoids and phenolic acids contained therein were potent stimulators of glucose and fatty acid uptake in a dose-dependent manner. Most of the phenolic constituents and several of the metabolites showed high antioxidant activity and showed considerably higher α-amylase and α-glucosidase inhibition than acarbose. Elderflower might therefore be valuable as a functional food against diabetes.

Ocimum basilicum extract exhibits antidiabetic effects via inhibition of hepatic glucose mobilization and carbohydrate metabolizing enzymes

Aim:

Ocimum basilicum L (Lamiaceae) is used as a traditional remedy for different ailments, including diabetes mellitus. This study investigated the antidiabetic effects of an extract of aerial parts of O. basilicum.

Methods:

Antihyperglycemic effect of the extract was determined by its effects on α-amylase and α-glucosidase in vitro, while antidiabetic properties were studied in alloxan induced diabetic rats treated for 28 days with extract and compared to those treated with oral metformin (150 mg/kg). The study and analysis was conducted between 2014 and 2015.

Results:

The treatment with 100 and 200 mg/kg extract significantly (P < 0.05) reduced fasting blood glucose concentration and slightly increased mean body weight in treated groups. Oral glucose tolerance was also significantly (P < 0.05, 0.001) improved in 100 and 400 mg/kg extract-treated groups. The extract caused a dose-dependent increase in liver glycogen content, while it decreased alanine transferase (18.9-30.56%) and aspartate transferase (6.48-34.3%) levels in a non-dose-dependent manner. A dose of 100 mg/kg also reduced serum cholesterol and triglycerides by 19.3 and 39.54%, compared to a 2.6% reduction of cholesterol seen in the metformin-treated group. The extract was observed to produce significant (P < 0.001) concentration-dependent inhibition of α-glucosidase (35.71-100%) and also α-amylase (23.55-81.52%), with estimated inhibitory concentration values of 1.62 and 3.86 mg/mL, respectively.

Conclusions:

The antidiabetic properties of the extract may be due to its ability to suppress endogenous glucose release, inhibit glycogenolysis and/or stimulate glycogenesis.

Proposed mechanisms of Terminalia catappa in hyperglycaemia and associated diabetic complications

Objectives

Terminalia catappa has shown potent antidiabetic activity in the past; however, the exact molecular mechanisms by which it acts have not been elucidated. This review aims at exploring several hypotheses which have been proposed to explain its mechanism of action, including reduction in oxidative stress, inflammation, angiogenesis, lipid profile correction and direct hypoglycaemic actions.

Methods

A thorough review of all the articles, research as well as reviews, available regarding the concerned topic was performed. MEDLINE databases were searched using keywords (and their combinations), such as T. catappa, renin oxidative stress, inflammation, angiogenesis, diabetic retinopathy, α-glucosidase and α-amylase, among several others. English-language articles were preferably selected.

Key findings

Apart from metabolic dysfunctions, several hyperglycaemia-induced pathological conditions come into scene as the after-effects of diabetes. These mainly include inflammation, oxidative stress, angiogenesis and lipid profile alteration, which ultimately result in vascular endothelial dysfunction, hepatic steatosis, lipid peroxidation and apoptosis of endothelial, hepatic and neuronal cells. Terminalia catappa effectively attenuates the progression of diabetic retinopathy and shows significant hypoglycaemic actions. The mechanisms behind these effects were explained.

Conclusion

Terminalia catappa may provide an effective natural product to treat hyperglycaemia and prevent subsequent diabetic complications.

The inhibitory activity of herbal medicines on the keys enzymes and steps related to carbohydrate and lipid digestion

BACKGROUND

Obesity and overweight are consistently associated with metabolic disorders including hyperglycemia and hyperlipidemia. Herbal medicines have been currently suggested as an alternative source of potentially useful antihyperglycemic, antihyperlipidemic, antioxidant activities. The objective of this study was to assess the in vitro inhibitory effects of eleven herbal medicines on carbohydrate and lipid digestive enzymes and the key steps of lipid digestion including the inhibition of micelle formation and the ability to bind bile acid. In addition, antioxidant activity of herbal medicines was also investigated.

METHODS

α-Glucosidase, pancreatic α-amylase, pancreatic lipase, and pancreatic cholesterol esterase inhibitory activities of aqueous extract of herbal medicines were measured using the enzymatic colorimetric assay. The formation of cholesterol micelles was determined using the cholesterol assay kit. The bile acid binding was measured using the colorimetric assay. Antioxidant activities were assessed by using four methods including Trolox equivalent antioxidant capacity (TEAC), oxygen radical absorbance capacity ORAC), superoxide radical scavenging activity (SRSA), and hydroxyl radical scavenging activity (HRSA).

RESULTS

The extracts (1 mg/mL) markedly inhibited intestinal maltase (5.16 - 44.33 %), sucrase (1.25-45.86 %), pancreatic α-amylase (1.75-12.53 %), pancreatic lipase (21.42-85.93 %), and pancreatic cholesterol esterase (2.92-53.35 %). The results showed that all extracts exhibited the inhibitory activity against pancreatic lipase with the IC₅₀ values ranging from 0.015 to 4.259 mg/mL. In addition, the incorporation of cholesterol into micelles was inhibited by the extracts (6.64-33.74 %). The extracts also bound glycodeoxycholic acid (9.9-15.08 %), taurodeoxycholic acid (12.55-18.18 %), and taurocholic acid (11.91 - 18.4 %). Furthermore, the extracts possessed various antioxidant activities including the TEAC values (0.50 - 4.70 μmol trolox/mg dried extract), the ORAC values (9.14-44.41 μmol trolox/mg dried extract), the SRSA (0.31 - 18.82 mg trolox/mg dried extract), and the HRSA (0.05-2.29 mg trolox/mg dried extract). The findings indicated that Syzygium aromaticum, Phyllanthus amarus, Thunbergia laurifolia were the effective promising antihyperglycemic and antihyperlipidemic agents. Statistical analysis demonstrated strong positive significant correlations between the contents of phenolic compounds and % inhibition of pancreatic lipase (r = 0.885, p < 0.001), % inhibition of pancreatic cholesterol esterase (r = 0.761, p < 0.001), and the TEAC value (r = 0.840, p < 0.001). Furthermore, there was a strongly positive correlation between the TEAC value and % inhibition of pancreatic cholesterol esterase (r = 0.851, p < 0.001) and % inhibition of pancreatic lipase (r = 0.755, p < 0.001).

CONCLUSIONS

Three herbal medicines including Syzygium aromaticum, Thunbergia laurifolia, and Phyllanthus amarus markedly inhibited the intestinal α-glucosidase, pancreatic α-amylase, pancreatic lipase, and pancreatic cholesterol esterase. They also reduced formation of cholesterol micelle and bound bile acid. The findings indicate that these herbal medicines might be a promising agent for antihyperglycemic, antihyperlipidemic, and antioxidant activities.

Effect of boiling on the antidiabetic property of enzyme treated sheep milk casein

Aim:

Sheep milk-born bioactive peptides have been found to exhibit various physiological activities. The present work was designed with the aim to evaluate the effect of boiling on antidiabetic property of peptides derived from sheep milk caseinate on hydrolysis with three different proteases.

Materials and Methods:

In this investigation, casein prepared from raw and boiled sheep milk was hydrolyzed by three commercially available proteases (trypsin, pepsin, and chymotrypsin). These hydrolysates collected at different hydrolysis times (60, 120, 160, and 240 min) were assayed for their antidiabetic activity.

Results:

Among the three different enzyme hydrolysates, casein treated with chymotrypsin shows the highest antidiabetic activity among other enzymes. While the antidiabetic effect of raw milk-derived casein hydrolysates always exceeds than effect shown by boiled milk casein hydrolysates.

Conclusion:

The result obtained hence shows that the effect of boiling on the properties of bioactive peptides released during different enzyme digestion depends largely on the enzymatic formulation used and treatment conditions. Chymotrypsin treatment of raw casein yields peptides with maximum antidiabetic activity as compared to pepsin and trypsin. Moreover, the peptides produced after enzymatic treatment of boiled casein show reduced antidiabetic properties. Therefore, enzymatically treated raw milk casein hydrolysates may be used as effective nutritional supplements for diabetic patients, as it causes a significant inhibition of α-amylase activity.

Natural Triterpenoids for the Treatment of Diabetes Mellitus: A Review

Triterpenoids, an important group of secondary metabolites, are widely distributed in nature. Many triterpenoids have been found with potential therapeutic effect against diabetes mellitus. However, the use of triterpenoids for the treatment of diabetes has not been systematically discussed previously. This review summarized the anti-diabetic activity of natural triterpenoids reported since the late 1980s with the emphasis on the molecular mechanisms.

In vitro and in vivo α-amylase and α-glucosidase inhibiting activities of the protein extracts from two varieties of bitter gourd (Momordica charantia L.)

Background

α-amylase and α-glucosidase digest the carbohydrates and increase the postprandial glucose level in diabetic patients. Inhibiting the activity of these two enzymes can control postprandial hyperglycemia, and reduce the risk of developing diabetes. Bitter gourd or balsam pear is one of the important medicinal plants used for controlling postprandial hyperglycemia in diabetes patients. However, there is limited information available on the presence of α-amylase and α-glucosidase inhibiting compounds. In the current study, the protein extracts from the fruits of M. charantia var. charantia (MCC) and M. charantia var. muricata (MCM) were tested for α-amylase and α-glucosidase inhibiting activities in vitro, and glucose lowering activity after oral administration in vivo.

Results

The protein extract from both MCC and MCM inhibited the activity of α-amylase and α-glucosidase through competitive inhibition, which was on par with Acarbose as indicated by in vitro percentage of inhibition (66 to 69 %) and IC50 (0.26 to 0.29 mg/ml). Both the protein extracts significantly reduced peak blood glucose and area under the curve in Streptozotocin-induced diabetic rats, which were orally challenged with starch and sucrose.

Conclusions

Protein extracts from the fruits of the two varieties of bitter gourd inhibited α-amylase and α-glucosidase in vitro and lowered the blood glucose level in vivo on par with Acarbose when orally administrated to Streptozotocin-induced diabetic rats. Further studies on mechanism of action and methods of safe and biologically active delivery will help to develop an anti-diabetic oral protein drug from these plants.

Screening for potential α-glucosidase and α-amylase inhibitory constituents from selected Vietnamese plants used to treat type 2 diabetes

ETHNOPHARMACOLOGICAL RELEVANCE

The 18 plant species investigated in this study have been used as herbal antidiabetic remedies in Vietnamese traditional medicines. This study aimed to evaluate their ability to inhibit α-glucosidase and α-amylase, two key enzymes involved in serum glucose regulation.

MATERIALS AND METHODS

Chloroform, ethanol and water extracts of 18 plants were screened for α-glucosidase and α-amylase inhibitory activity. Analytical-scale HPLC was subsequently used to investigate the most active extracts, where samples with low level of tannins were identified and fractionated into 96-well microplates, followed by α-glucosidase and α-amylase assessment of each well. High-resolution α-glucosidase and α-amylase inhibition profiles constructed from these assays allowed identification of HPLC peaks correlated with α-glucosidase and α-amylase inhibitory activity. The active constituents were subsequently isolated using preparative-scale HPLC and their structure was elucidated by HR-ESIMS and NMR.

RESULTS

Ethanol extracts of Nepenthes mirabilis, Phyllanthus urinaria, and Kandelia candel significantly inhibited α-glucosidase with IC50 values of 32.7±6.3, 39.7±9.7, and 35.4±13.9μg/mL, respectively. Water extracts of N. mirabilis, Phyllanthus amarus, P. urinaria, Lagerstroemia speciosa, Syzygium cumini, Rhizophora mucronata, and K. candel showed IC50 values of 3.3±0.8, 34.9±1.5, 14.6±4.6, 5.4±0.5, 20.9±1.8, 3.3±0.6, and 4.0±0.8μg/mL, respectively. In the α-amylase inhibition assay, ethanol extracts of K. candel and Ficus racemosa showed IC50 of 7.6±0.9 and 46.7±23.6μg/mL, respectively. Showing low tannin constituents as seen from HPLC profiles, P. amarus and P. urinaria water extracts and F. racemosa ethanol extract were subjected to microfractionation. Only high-resolution α-glucosidase inhibition profiles of P. amarus and P. urinaria water extracts showed several active compounds, which were isolated and identified as corilagin (1), repandusinic acid A (2), and mallotinin (3). IC50 of these compounds were 1.70±0.03, 6.10±0.10, and 3.76±0.15μM, respectively. Kinetics analysis revealed that 1 displayed a mixed type mode of inhibition with Ki and Ki' values of 2.37±0.90 and 2.61±0.61μM, respectively, whereas 2 and 3 competitively inhibited α-glucosidase with Ki values of 4.01±0.47 and 0.65±0.11μM, respectively.

CONCLUSION

Corilagin (1), repandusinic acid A (2), and mallotinin (3) were potent α-glucosidase inhibitors contributing significantly to the inhibitory effect observed for the water extracts of P. amarus and P. urinaria.

Hepatoprotective and antidiabetic effects of Pistacia lentiscus leaf and fruit extracts

Pistacia lentiscus (Anacardiaceae) is commonly used in folk medicine to treat various diseases. The aim of the present study was to evaluate the hepatoprotective and antioxidant activities of extracts of P. lentiscus leaves (PL) and fruits (PF) against experimentally induced liver damage. Furthermore, characterization of extracts was attempted by a spectroscopic methodology (Fourier transform infrared spectroscopy) and high-performance liquid chromatography with diode array detection analysis. A hepatoprotective potential against paracetamol [165 mg/kg body weight (b.w.)] toxicity was noticed in mice pretreated with the same dose of PL or PF extract (125 mg/kg b.w.) or a combination of both (PL/PF 63/63 mg/kg b.w.), as revealed by an analysis of biochemical parameters (alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase activities and total bilirubin). These results were confirmed by histological examination of the liver, which revealed significant protection against paracetamol-induced hepatic necrosis. Furthermore, PF extract exhibited a promising antidiabetic activity in streptozotocin-induced diabetic rats, similar to the reference drug glibenclamide (0.91 g/L), a result confirmed by in vitro inhibition of α-amylase. We demonstrated that the leaf crude extract showed the best effect in all tested methods, compared to its fruit counterpart, probably due to the presence of higher amounts of phenolic compounds, as determined by phytochemical and Fourier transform infrared spectroscopy analyses. Moreover, high-performance liquid chromatography with diode array detection led to the identification of six compounds for each part of the plant. Gallic acid, a characteristic compound of Pistacia species, was most abundant in leaves and fruits, while luteolin was detected for the first time in fruits. Obtained activities of P. lentiscus extracts may well be due, at least in part, to the presence of the above compounds.

Oleanolic, Ursolic, and Betulinic Acids as Food Supplements or Pharmaceutical Agents for Type 2 Diabetes: Promise or Illusion?

Oleanolic (OA), ursolic (UA), and betulinic (BA) acids are three triterpenic acids (TAs) with potential effects for treatment of type 2 diabetes (T2DM). Mechanistic studies showed that these TAs act as hypoglycemic and antiobesity agents mainly through (i) reducing the absorption of glucose; (ii) decreasing endogenous glucose production; (iii) increasing insulin sensitivity; (iv) improving lipid homeostasis; and (v) promoting body weight regulation. Besides these promising beneficial effects, it is believed that OA, UA, and BA protect against diabetes-related comorbidities due to their antiatherogenic, anti-inflammatory, and antioxidant properties. We also highlight the protective effect of OA, UA, and BA against oxidative damage, which may be very relevant for the treatment and/or prevention of T2DM. In the present review, we provide an integrative description of the antidiabetic properties of OA, UA, and BA, evaluating the potential use of these TAs as food supplements or pharmaceutical agents to prevent and/or treat T2DM.

Novel nutraceutic therapies for the treatment of metabolic syndrome

Nutraceutic therapies such as berberine, bitter melon, Gymnema sylvestre, Irvingia gabonensis, resveratrol and ursolic acid have been shown to help control metabolic syndrome (MetS). The effect of berberine on glucose and lipid metabolism, hypertension, obesity and MetS has been evaluated in animal models and humans. Most clinical trials involving bitter melon have been conducted to evaluate its effect on glucose metabolism; nevertheless, some studies have reported favorable effects on lipids and blood pressure although there is little information about its effect on body weight. Gymnema sylvestre helps to decrease body weight and blood sugar levels; however, there is limited information on dyslipidemia and hypertension. Clinical trials of Irvingia gabonensis have shown important effects decreasing glucose and cholesterol concentrations as well decreasing body weight. Resveratrol acts through different mechanisms to decrease blood pressure, lipids, glucose and weight, showing its effects on the population with MetS. Finally, there is evidence of positive effects with ursolic acid in in vitro and in vivo studies on glucose and lipid metabolism and on body weight and visceral fat. Therefore, a review of the beneficial effects and limitations of the above-mentioned nutraceutic therapies is presented.

Antidiabetic activity of the ethyl acetate fraction of Ficus lutea (Moraceae) leaf extract: comparison of an in vitro assay with an in vivo obese mouse model

Background

Ficus lutea crude acetone leaf extracts were previously shown to stimulate glucose uptake and insulin secretion of established cells and, inhibit α-amylase and α-glucosidase activities.

Methods

For this study, F. lutea acetone extracts were subjected to solvent-solvent fractionation to yield fractions with differing polarities (hexane, chloroform, dichloromethane, ethyl acetate, n-butanol and water) in an attempt to obtain a more potent fraction with in vitro and probably in vivo activity.

Results

Among these fractions, the ethyl acetate fraction had the highest total polyphenol content (100.5 ± 1.6 mg GAE/g dried extract) and α-glucosidase inhibitory activity (126.8 ± 30.6 μg/ml). It also stimulated the highest glucose uptake of C2C12 muscle cells and decreased extracellular glucose concentration of H-4-II-E liver cells with low cytotoxic activity. The ethyl acetate fraction (10.88 ± 0.55 μg/L at 250 μg/ml) enhanced insulin secretion in RIN-m5F pancreatic β-cells to the same degree as the positive control glibenclamide (11.09 ± 0.07 μg/L at 1μM). While fractionation increased α-glucosidase inhibition and glucose uptake of cells, in the ethyl acetate fraction, the α-amylase inhibition and insulin secretion decreased. The weight reducing and glucose control potential of the ethyl acetate fraction in an obese mouse model, important factors in the amelioration of type II diabetes was determined. The extract had no statistical significant weight reducing activity.

Conclusion

A major finding was the decrease in the area under the curve of the glucose concentration over time in animals that were treated with both a change in diet and with the plant extract. This is linked to increased glucose uptake within the cells, the most likely mechanism is either an increased insulin response or increased insulin secretion.

Selective binding modes and allosteric inhibitory effects of lupane triterpenes on protein tyrosine phosphatase 1B

Protein Tyrosine Phosphatase 1B (PTP1B) has been recognized as a promising therapeutic target for treating obesity, diabetes, and certain cancers for over a decade. Previous drug design has focused on inhibitors targeting the active site of PTP1B. However, this has not been successful because the active site is positively charged and conserved among the protein tyrosine phosphatases. Therefore, it is important to develop PTP1B inhibitors with alternative inhibitory strategies. Using computational studies including molecular docking, molecular dynamics simulations, and binding free energy calculations, we found that lupane triterpenes selectively inhibited PTP1B by targeting its more hydrophobic and less conserved allosteric site. These findings were verified using two enzymatic assays. Furthermore, the cell culture studies showed that lupeol and betulinic acid inhibited the PTP1B activity stimulated by TNFα in neurons. Our study indicates that lupane triterpenes are selective PTP1B allosteric inhibitors with significant potential for treating those diseases with elevated PTP1B activity.

Sequencing, De novo Assembly, Functional Annotation and Analysis of Phyllanthus amarus Leaf Transcriptome Using the Illumina Platform

Phyllanthus amarus Schum. and Thonn., a widely distributed annual medicinal herb has a long history of use in the traditional system of medicine for over 2000 years. However, the lack of genomic data for P. amarus, a non-model organism hinders research at the molecular level. In the present study, high-throughput sequencing technology has been employed to enhance better understanding of this herb and provide comprehensive genomic information for future work. Here P. amarus leaf transcriptome was sequenced using the Illumina Miseq platform. We assembled 85,927 non-redundant (nr) "unitranscript" sequences with an average length of 1548 bp, from 18,060,997 raw reads. Sequence similarity analyses and annotation of these unitranscripts were performed against databases like green plants nr protein database, Gene Ontology (GO), Clusters of Orthologous Groups (COG), PlnTFDB, KEGG databases. As a result, 69,394 GO terms, 583 enzyme codes (EC), 134 KEGG maps, and 59 Transcription Factor (TF) families were generated. Functional and comparative analyses of assembled unitranscripts were also performed with the most closely related species like Populus trichocarpa and Ricinus communis using TRAPID. KEGG analysis showed that a number of assembled unitranscripts were involved in secondary metabolites, mainly phenylpropanoid, flavonoid, terpenoids, alkaloids, and lignan biosynthetic pathways that have significant medicinal attributes. Further, Fragments Per Kilobase of transcript per Million mapped reads (FPKM) values of the identified secondary metabolite pathway genes were determined and Reverse Transcription PCR (RT-PCR) of a few of these genes were performed to validate the de novo assembled leaf transcriptome dataset. In addition 65,273 simple sequence repeats (SSRs) were also identified. To the best of our knowledge, this is the first transcriptomic dataset of P. amarus till date. Our study provides the largest genetic resource that will lead to drug development and pave the way in deciphering various secondary metabolite biosynthetic pathways in P. amarus, especially those conferring the medicinal attributes of this potent herb.

Averrhoa bilimbi Linn.: A review of its ethnomedicinal uses, phytochemistry, and pharmacology

Averrhoa bilimbi Linn. is principally cultivated for medicinal purposes in many tropical and subtropical countries of the world. Literature survey about this plant shows that A. bilimbi is mainly used as a folk medicine in the treatment of diabetes mellitus, hypertension, and as an antimicrobial agent. The prime objective of this review is to accumulate and organize literature based on traditional claims and correlate those with current findings on the use of A. bilimbi in the management of different ailments. Through interpreting already published scientific manuscripts (1995 through 2015) retrieved from the different scientific search engines, namely Medline, PubMed, EMBASE, and Science Direct databases, published articles and reports covering traditional and scientific literature related to A. bilimbi's potential role against various ailments have been thoroughly evaluated, interpreted, and discussed. Several pharmacological studies have demonstrated the ability of this plant to act as antidiabetic, antihypertensive, thrombolytic, antimicrobial, antioxidant, hepatoprotective, and hypolipidemic agent. A. bilimbi holds great value in the complementary and alternative medicine as evidenced by the substantial amount of research on it. Therefore, we aimed to compile an up-to-date and comprehensive review of A. bilimbi that covers its traditional and folk medicine uses, phytochemistry, and pharmacology. Hence, this paper presents an up-to-date and comprehensive review of the ethnomedicinal uses, different chemical constituents, and pharmacological activities of A. bilimbi. So far, the biologically active agents have not been isolated from this plant and this can be a good scientific study for the future antidiabetic, antihypertensive, and antimicrobial implications. Hence, this review targets at emphasizing the diverse traditional claims and pharmacological activities of A. bilimbi with respect to carrying out more scientific studies to isolate active principles through advanced technology.

Influence of Sodium Alginate on Hypoglycemic Activity of Metformin Hydrochloride in the Microspheres Obtained by the Spray Drying

Alginate microspheres with metformin hydrochloride were prepared by the spray drying method in order to improve residence time of drug in the stomach. Nine formulations (F1–F9) with various drug : polymer ratio (1 : 2, 1 : 1, and 2 : 1) and different sodium alginate concentration (1%, 2%, and 3%) were evaluated for size, morphology, drug loading, Zeta potential, and swelling degree.In vitrodrug release, mathematical release profile, and physical state of microspheres were also evaluated. Optimal formulation characterized by the highest drug loading was formulation F6 (drug : polymer ratio 2 : 1 and 2% alginate solution). Based on glucose uptake inSaccharomyces cerevisiaecells andα-amylase inhibition tests, it could be concluded that alginate microspheres enhance hypoglycemic activity of metformin hydrochloride evaluatedin vitro. Designed microspheres are promising as alternative, multicompartment dosage form for metformin hydrochloride delivery.

Bioactive compounds from Carissa opaca roots and xanthine oxidase and alpha-amylase inhibitory activities of their methanolic extract and its fractions in different solvents

Background:

Carissa opaca is known for its many ethnomedicinal uses. There was a need to study its bioactivities and identify its phytochemicals.

Objective:

The objective was to isolate and identify phytochemicals from roots of C. opaca and to evaluate xanthine oxidase (XO) and alpha-amylase inhibitory activities of their methanolic extract and its fractions.

Materials and Methods:

Methanolic extract of finely divided powder of roots of C. opaca was obtained by cold maceration, followed by its fractionation to obtain hexane, chloroform, ethyl acetate, n-butanolic, and aqueous fractions. Phytochemicals screening was done by standard protocols. XO and alpha-amylase inhibitory activities of the methanolic extract and its fractions were studied. The most active ethyl acetate fraction was subjected to the column and thin layer chromatography to isolate its compounds, which were identified by gas chromatography-mass spectrometry and high-performance liquid chromatography comparison.

Results:

Methanolic extract displayed significant activity against both the enzymes with IC₅₀ of 156.0 mg/mL and 5.6 mg/mL for XO and alpha-amylase, respectively. Ethyl acetate fraction showed highest activity against both the enzymes with IC₅₀ of 129 mg/mL and 4.9 mg/mL for XO and alpha-amylase, respectively. Chloroform fraction had IC₅₀ of 154.2 mg/mL and 5.5 mg/mL for XO and alpha-amylase, respectively. Aqueous fraction exhibited significant efficacy against alpha-amylase (IC₅₀ 5.0 mg/mL). Hexane fraction showed good activity against alpha-amylase in a dose-dependent manner but exhibited opposite trend against XO. The compounds isolated from ethyl acetate fraction included limonene, vanillin, lupeol, rutin, quercetin, b-sitosterol, Vitamin E, 2-hydroxyacetophenone, naphthalenone, 2,3,3-trimethyl-2-(3-methylbuta-1,3-dienyl)-6-methylenecyclohexanone, and 2-benzenedicarboxylic acid, mono(2-ethylhexyl) ester.

Conclusions:

Moderately polar phytochemicals of C. opaca roots possess exploitable inhibitory activity against both the enzymes.

Medicinal Plants Traditionally Used for Treatment of Obesity and Diabetes Mellitus - Screening for Pancreatic Lipase and α-Amylase Inhibition

In order to find new pancreatic lipase (PL) and α-amylase inhibitors from natural sources for the treatment of obesity and related diseases as diabetes mellitus II, 23 medicinal plants with weight-reducing, serum glucose-reducing or related potential were investigated. Methanolic and water extracts of the plants were evaluated by using two in vitro test systems. Our findings have shown that the methanolic extract of Hibiscus sabdariffa L. (Malvaceae) showed high inhibitory activities to PL (IC50 : 35.8 ± 0.8 µg/mL) and α-amylase (IC50 : 29.3 ± 0.5 µg/mL). Furthermore, the methanolic extract of Tamarindus indica L. (Leguminosae) showed a high anti-lipase (IC50 : 152.0 ± 7.0 µg/mL) and the aqueous extract a high anti-amylase (IC50 : 139.4 ± 9.0 µg/mL) activity. This work provides a priority list of interesting plants for further study with respect to the treatment of obesity and associated diseases.

Synthesis and Evaluation of Novel Triterpene Analogues of Ursolic Acid as Potential Antidiabetic Agent

Ursolic acid (UA) is a naturally bioactive compound that possesses potential anti-diabetic activity. The relatively safe and effective molecule intrigued us to further explore and to improve its anti-diabetic activity. In the present study, a series of novel UA analogues was synthesized and their structures were characterized. Their bioactivities against the α-glucosidase from baker's yeast were determined in vitro. The results suggested that most of the analogues exhibited significant inhibitory activity, especially analogues 8b and 9b with the IC50 values of 1.27 ± 0.27 μM (8b) and 1.28 ± 0.27 μM (9b), which were lower than the other analogues and the positive control. The molecular docking and 2D-QSAR studies were carried out to prove that the C-3 hydroxyl could interact with the hydrophobic region of the active pocket and form hydrogen bonds to increase the binding affinity of ligand and the homology modelling protein. Thus, these results will be helpful for understanding the relationship between binding mode and bioactivity and for designing better inhibitors from UA analogues.