The role of lipid and carbohydrate digestive enzyme inhibitors in the management of obesity: a review of current and emerging therapeutic agents

Acyl pyrazole sulfonamides as new antidiabetic agents: synthesis, glucosidase inhibition studies, and molecular docking analysis

Diabetes mellitus is a multi-systematic chronic metabolic disorder and life-threatening disease resulting from impaired glucose homeostasis. The inhibition of glucosidase, particularly α-glucosidase, could serve as an effective methodology in treating diabetes. Attributed to the catalytic function of glucosidase, the present research focuses on the synthesis of sulfonamide-based acyl pyrazoles (5a-k) followed by their in vitro and in silico screening against α-glucosidase. The envisaged structures of prepared compounds were confirmed through NMR and FTIR spectroscopy and mass spectrometry. All compounds were found to be more potent against α-glucosidase than the standard drug, acarbose (IC50 = 35.1 ± 0.14 µM), with IC50 values ranging from 1.13 to 28.27 µM. However, compound 5a displayed the highest anti-diabetic activity (IC50 = 1.13 ± 0.06 µM). Furthermore, in silico studies revealed the intermolecular interactions of most potent compounds (5a and 5b), with active site residues reflecting the importance of pyrazole and sulfonamide moieties. This interaction pattern clearly manifests various structure-activity relationships, while the docking results correspond to the IC50 values of tested compounds. Hence, recent investigation reveals the medicinal significance of sulfonamide-clubbed pyrazole derivatives as prospective therapeutic candidates for treating type 2 diabetes mellitus (T2DM).

Effect of tea polyphenols supplement on growth performance, antioxidation, and gut microbiota in squabs

Early life nutritional supplementation can significantly improve pigeon health. Both the nutritional crops of parental pigeons and the intestinal development of squabs play key roles in the growth rate of squabs. Tea polyphenols (TPs), as natural plant extracts, exhibit potential biological activities. However, the impact of TPs on the intestinal function of squabs is not known. This study evaluated the effects of TPs on growth performance, immunity, antioxidation, and intestinal function in squabs. A total of 432 young pigeons (1 day old) were divided into four groups: a control group (fed a basic diet) and three treatment groups (low, medium, and high dose groups; 100, 200, and 400 mg/kg TPs, respectively). On the 28th day, samples of serum, mucosal tissue, and digests from the ileum of squabs were collected for analysis. The results revealed that TP supplementation significantly reduced the feed-to-meat ratio and improved the feed utilization rate and serum biochemical indices in squabs. Additionally, it enhanced the intestinal barrier function of birds by promoting intestinal development and integrity of tight junctions and regulating digestive enzyme activities and intestinal flora. Mechanistically, TPs activated the Nrf2-ARE signaling pathway, which may be associated with improved antioxidant and immune responses, correlating with an increased abundance of Candida arthritis and Corynebacterium in the ileum.

Influence of traditional processing and genotypes on the antioxidant and antihyperglycaemic activities of yellow-fleshed cassava

Yellow-fleshed cassava root (YFCR) is processed into traditional products that may influence its bioactivities. In this study, the antioxidant and anti-hyperglycaemic activities of three traditional products (lafun, fufu and gari) from five genotypes (IITA-TMS-IBA070337, 182961, 182962, 182986, 183044) of YFCR were evaluated. The YFCR genotypes were grown at the International Institute of Tropical Agriculture (IITA) research field, Ibadan. The bioactive constituents (total carotenoids, total phenolics, tannins and total flavonoids), antioxidant [2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) radical cation (ABTS^•+) and 1,1-diphenyl-2- picrylhydrazyl radical (DPPH^•) scavenging capacities, and reducing power], and starch-digesting enzymes (α-amylase and α-glucosidase) inhibitory activities of the products were determined using standard laboratory methods. The glucose response of the products was assessed in human subjects. The concentrations of the bioactive constituents of the products from different genotypes varied significantly (p < 0.05). The ABTS^•+ and DPPH^• scavenging capacities and the reducing power of the products also differed significantly (p < 0.05), such that the lafun from IITA-TMS-IBA182962, IITA-TMS-IBA070337 and IITA-TMS-IBA070337 had the strongest ABTS^•+ and DPPH^• scavenging capacities, and reducing power, respectively. The α-amylase and α-glucosidase inhibitory activities of the three products differed significantly (p < 0.05), with the lafun from IITA-TMS-IBA070337 and IITA-TMS-IBA07033 having the strongest α-amylase and α-glucosidase inhibitory activity, respectively. Also, the lafun from IITA-TMS-182986 had the least glucose response, while the fufu from IITA-TMS-IBA070337 had the highest glucose response. Overall, the lafun from different genotypes of YFCR had the most potent antioxidant and starch-digesting enzymes inhibitory activities and the least glucose responses. Hence, lafun may be a promising dietary intervention targeting oxidative stress, hyperglycaemia, and their resultant type 2 diabetes.

Biogenic Phytochemicals Modulating Obesity: From Molecular Mechanism to Preventive and Therapeutic Approaches

The incidence of obesity and over bodyweight is emerging as a major health concern. Obesity is a complex metabolic disease with multiple pathophysiological clinical conditions as comorbidities are associated with obesity such as diabetes, hypertension, cardiovascular disorders, sleep apnea, osteoarthritis, some cancers, and inflammation-based clinical conditions. In obese individuals, adipocyte cells increased the expression of leptin, angiotensin, adipocytokines, plasminogen activators, and C-reactive protein. Currently, options for treatment and lifestyle behaviors interventions are limited, and keeping a healthy lifestyle is challenging. Various types of phytochemicals have been investigated for antiobesity potential. Here, we discuss pathophysiology and signaling pathways in obesity, epigenetic regulations, regulatory mechanism, functional ingredients in natural antiobesity products, and therapeutic application of phytochemicals in obesity.

Antioxidant and Starch-Hydrolyzing Enzymes Inhibitory Properties of Striga-Resistant Yellow-Orange Maize Hybrids

Most of the health benefits derived from cereals are attributed to their bioactive compounds. This study evaluated the levels of the bioactive compounds, and the antioxidant and starch-hydrolyzing enzymes inhibitory properties of six pipeline Striga-resistant yellow-orange maize hybrids (coded AS1828-1, 4, 6, 8, 9, 11) in vitro. The maize hybrids were grown at the International Institute of Tropical Agriculture (IITA), Nigeria. The bioactive compounds (total phenolics, tannins, flavonoids, and phytate) levels, antioxidant (DPPH^• and ABTS^•+ scavenging capacity and reducing power) and starch-hydrolyzing enzymes (α-amylase and α-glucosidase) inhibitory activities of the maize hybrids were determined by spectrophotometry. At the same time, carotenoids were quantified using a reverse-phase HPLC system. The ranges of the bioactive compounds were: 11.25-14.14 mg GAE/g (total phenolics), 3.62-4.67 mg QE/g (total flavonoids), 3.63-6.29 mg/g (tannins), 3.66-4.31% (phytate), 8.92-12.11 µg/g (total xanthophylls), 2.42-2.89 µg/g (total β-carotene), and 3.17-3.77 µg/g (total provitamin A carotenoids). Extracts of the maize hybrids scavenged DPPH^• (SC₅₀: 9.07-26.35 mg/mL) and ABTS^•+ (2.65-7.68 TEAC mmol/g), reduced Fe³⁺ to Fe²⁺ (0.25 ± 0.64-0.43 ± 0.01 mg GAE/g), and inhibited α-amylase and α-glucosidase, with IC₅₀ ranges of 26.28-52.55 mg/mL and 47.72-63.98 mg/mL, respectively. Among the six clones of the maize hybrids, AS1828-9 had the highest (p < 0.05) levels of tannins and phytate and the strongest antioxidant and starch-hydrolyzing enzymes inhibitory activities. Significant correlations were observed between total phenolics and the following: ABTS^•+ (p < 0.01, r = 0.757), DPPH^• SC₅₀ (p < 0.01, r = -0.867), reducing power (p < 0.05, r = 0.633), α-amylase IC₅₀ (p < 0.01, r = -0.836) and α-glucosidase IC₅₀ (p < 0.05, r = -0.582). Hence, the Striga-resistant yellow-orange maize hybrids (especially AS1828-9) may be beneficial for alleviating oxidative stress and postprandial hyperglycemia.

Polyacetylene Glycosides: Isolation, Biological Activities and Synthesis

Polyacetylene glycosides (PAGs) constitute a relatively small class of secondary metabolites characterized by the presence of a sugar unit anomerically connected to a polyacetylene. These compounds are found in fungi, seaweed, and more often in plants. PAGs exhibit a wide range of biological and pharmacological activities and, as a result, the literature of these compounds has grown exponentially in recent years.

Phytochemical screening, antiobesity, antidiabetic and antimicrobial assessments of Orobanche aegyptiaca from Palestine

Background

Microbial resistance, diabetes mellitus, and obesity are global health care problems that have posed a serious threat to both human and environmental ecosystems. The goals of the present investigations are to investigate the phytoconstituents, antilipase, anti-α-amylase, and antimicrobial activity of Orobanche aegyptiaca Pers. (OA) from Palestine.

Methods

Identification of the phytoconstituents of OA plant petroleum ether, methylene chloride, chloroform, acetone, and methanol extracts were conducted using pharmacopeia’s methods, while porcine pancreatic lipase and α–amylase inhibitory activities were examined using p-nitrophenyl butyrate and 3,5-dinitro salicylic acid methods, respectively. Moreover, the antimicrobial activity was evaluated utilizing broth microdilution assay against eight bacterial and fungal strains.

Results

The phytochemical screening results showed that the methanol extract of the OA plant is rich in phytochemical components, also this extract has powerful antilipase potential with an IC₅₀ value of 19.49 ± 0.16 μg/ml comparing with the positive control (Orlistat) which has antilipase activity with IC₅₀ value of 12.3 ± 0.35 μg/ml. Moreover, the methanol and chloroform extracts have powerful α-amylase inhibitory activity with IC₅₀ values of 28.18 ± 0.22 and 28.18 ± 1.22 μg/ml, respectively comparing with Acarbose which has α-amylase inhibitory activity with IC₅₀ dose of 26.3.18 ± 0.28 μg/ml. The antibacterial results showed that the methylene chloride extract exhibited the highest antibacterial activity among the other OA plant extracts with a MIC value of 0.78 mg/ml against S. aureus, while, the methylene chloride, petroleum ether, and chloroform extracts of the OA plant showed potential antifungal activity against C. albicans strains with MIC value of 0.78 mg/ml.

Conclusion

The OA methanol and chloroform extracts could be excellent candidates as antilipase and anti-α-amylase bioactive materials. In addition, methylene chloride, petroleum ether, and chloroform extracts could be potential natural antimicrobial products.

Red Wine High-Molecular-Weight Polyphenolic Complex: An Emerging Modulator of Human Metabolic Disease Risk and Gut Microbiota

Moderate red wine consumption has been linked to reduced chronic disease risk. Thus far, little has been known about the physicochemical properties and potential biological effects of high-molecular-weight polyphenolic complexes (HPPCs), a major fraction of red wine polyphenols. In this work, the stability and biochemical properties of HPPCs under simulated gastrointestinal conditions in vitro were studied. The results showed that HPPCs were resistant to simulated gastric digestion (SGD) and simulated intestinal digestion (SID). They exhibited significant inhibitory activity against key metabolic syndrome-associated digestive enzymes, achieving 17.1-90.9% inhibition of pancreatic α-amylase, lipase, and cholesterol esterase at 0.02-0.45 mg/mL. HPPCs were metabolized by gut microbiota (GM), leading to significantly enhanced antioxidant capacity when compared with the original, SGD, and SID samples. Furthermore, they favorably modulated GM profiles, which was accompanied by significantly increased short-chain fatty acid generation during the early colonic fermentation phase. These findings suggest that HPPCs are a promising modulator of human metabolic disease risk.

Alpha-amylase as molecular target for treatment of diabetes mellitus: A comprehensive review

The alpha (α)-amylase is a calcium metalloenzyme that aids digestion by breaking down polysaccharide molecules into smaller ones such as glucose and maltose. In addition, the enzyme causes postprandial hyperglycaemia and blood glucose levels to rise. α-Amylase is a well-known therapeutic target for the treatment and maintenance of postprandial blood glucose elevations. Various enzymatic inhibitors, such as acarbose, miglitol and voglibose, have been found to be effective in targeting this enzyme, prompting researchers to express an interest in developing potent alpha-amylase inhibitor molecules. The review mainly focused on designing different derivatives of drug molecules such as benzofuran hydrazone, indole hydrazone, spiroindolone, benzotriazoles, 1,3-diaryl-3-(arylamino) propan-1-one, oxadiazole and flavonoids along with their target-receptor interactions, IC₅₀ values and other biological activities.

Structural elucidation, molecular docking, α-amylase and α-glucosidase inhibition studies of 5-amino-nicotinic acid derivatives

In this study, 5-amino-nicotinic acid derivatives (1-13) have been designed and synthesized to evaluate their inhibitory potential against α-amylase and α-glucosidase enzymes. The synthesized compounds (1-13) exhibited promising α-amylase and α-glucosidase activities. IC50 values for α-amylase activity ranged between 12.17 ± 0.14 to 37.33 ± 0.02 µg/mL ± SEM while for α-glucosidase activity the IC50 values were ranged between 12.01 ± 0.09 to 38.01 ± 0.12 µg/mL ± SEM. In particular, compounds 2 and 4-8 demonstrated significant inhibitory activities against α-amylase and α-glucosidase and the inhibitory potential of these compounds was comparable to the standard acarbose (10.98 ± 0.03 and 10.79 ± 0.17 µg/mL ± SEM, respectively). In addition, the impact of substituent on the inhibitory potential of these compounds was assessed to establish structure activity relationships. Studies in molecular simulations were conducted to better comprehend the binding properties of the compounds. All the synthesized compounds were extensively characterized with modern spectroscopic methods including 1H-NMR, 13C-NMR, FTIR, HR-MS and elemental analysis.

Anthocyanin-rich fraction from Thai berries interferes with the key steps of lipid digestion and cholesterol absorption

Several studies have documented the hypolipidemic effect of anthocyanin-rich plants in vitro and in vivo. The objective of this study was to elucidate the inhibitory activity of anthocyanin-rich fraction from Thai berries against fat digestive enzymes. The ability of Thai berries to bind bile acid, disrupt cholesterol micellization and the cholesterol uptake into Caco-2 cells was also determined. The content of total phenolics, flavonoid and anthocyanin in Prunus domestica L. (TPE), Antidesma bunius (L.) Spreng, Syzygium cumini (L.) Skeels, and Syzygium nervosum A. Cunn. Ex DC was 222.7–283.5 mg gallic acid equivalents, 91.2–184.3 mg catechin equivalents, and 37.9–49.5 mg cyanidin-3-glucoside equivalents/g extract, respectively. The anthocyanin-rich fraction of all extracts inhibited pancreatic lipase and cholesterol esterase with the IC₅₀ values of 90.6–181.7 μg/mL and 288.7–455.0 μg/mL, respectively. Additionally, all extracts could bind primary and secondary bile acids (16.4–36.6%) and reduce the solubility of cholesterol in artificial micelles (53.0–67.6%). Interestingly, TPE was the most potent extract on interfering the key steps of lipid digestion among the tested extracts. In addition, TPE (0.10–0.50 mg/mL) significantly reduced the cholesterol uptake into Caco-2 cells in a concentration-dependent manner. These results demonstrate a new insight into the role of anthocyanin-rich Thai berry extract on interfering the key steps of lipid digestion and absorption.

Lipase inhibitory activity assay for fermented milk

The lipase inhibitory activity method described here was developed to identify potential anti-obesity properties in milk fermented with different strains of lactic acid bacteria via inhibition of pancreatic lipase and a subsequent decrease in fat digestion and absorption in the gut. The method is based on the hydrolysis of 4-nitrophenyl octanoate by pancreatic lipase and the subsequent release of p-nitrophenol, a coloured product whose absorbance can be measured at 412 nm. Inhibition of lipase leads to a decrease in the amount of p-nitrophenol released and a subsequent reduction in the absorbance with respect to a 100% activity control. The assay was developed by adapting various methods previously described in published literature and includes modifications that are key to adapt the existing protocols to fermented milk samples, in particular the pH issues encountered when analysing acidic samples:•A two buffer system is introduced to allow optimal pH control after addition of fermented milk samples with pH values between 3.5 and 6.5.•A post-clarification filtration step is added for samples where turbidity remains after addition of the clarifying reagent for dairy products.•An absorbance correction factor is calculated and applied to the samples to account for the reduction in the absorbance of p-nitrophenol caused by milk.

Inhibitory Activities of Polyphenolic Extracts of Bangladeshi Vegetables against α-Amylase, α-Glucosidase, Pancreatic Lipase, Renin, and Angiotensin-Converting Enzyme

The aim of the study was to determine the in vitro enzyme inhibition activities of aqueous polyphenolic extracts of nine popular Bangladeshi vegetables, namely ash gourd, bitter gourd, brinjal, Indian spinach, kangkong, okra, ridge gourd, snake gourd, and stem amaranth. Polyphenolic glycosides were the major compounds present in the extracts. Inhibition of α-amylase (up to 100% at 1 mg/mL) was stronger than α-glucosidase inhibition (up to 70.78% at 10 mg/mL). The Indian spinach extract was the strongest inhibitor of pancreatic lipase activity (IC₅₀ = 276.77 µg/mL), which was significantly better than that of orlistat (381.16 µg/mL), a drug. Ash gourd (76.51%), brinjal (72.48%), and snake gourd (66.82%) extracts were the most effective inhibitors of angiotensin-converting enzyme (ACE), an enzyme whose excessive activities have been associated with hypertension. Brinjal also had a significantly higher renin-inhibitory activity than the other vegetable extracts. We conclude that the vegetable extracts may have the ability to reduce enzyme activities that have been associated with hyperglycemia, hyperlipidemia, and hypertension.

Inhibitory effect of a weight-loss Chinese herbal formula RCM-107 on pancreatic α-amylase activity: Enzymatic and in silico approaches

Reducing carbohydrates digestion by having a low glycaemic index (GI) foods has been linked to weight loss. Inhibiting related enzymes is an alternative way to decrease carbohydrate digestion. RCM-107 (Slimming Plus), an eight-herb formula that is modified from RCM-104, indicated significant weight-loss action in clinical trials. However, no published research has studied its mechanism of action on reducing carbohydrate absorption via suppressing the activities of porcine pancreatic alpha-amylase (PPA). In this paper, we used fluorescence PPA inhibition assay to investigate the inhibitory effects of RCM-107 and the individual herbs present in this herbal mixture on amylase activity. Subsequently, molecular docking predicted the key active compounds that may be responsible for the enzyme inhibition. According to our results, both the RCM-107 formula and several individual herbs displayed α-amylase inhibitory effects. Also, marginal synergistic effects of RCM-107 were detected. In addition, alisol B, (-)-epigallocatechin-3-gallate (EGCG) and plantagoside have been predicted as the key active compounds that may be responsible for the α-amylase inhibition effect of RCM-107 according to inter-residue contact analysis. Finally, Glu233, Gln63, His305, Asp300 and Tyr151 are predicted to be markers of important areas with which potential amylase inhibitors would interact. Therefore, our data has provided new knowledge on the mechanisms of action of the RCM-107 formula and its individual herbal ingredients for weight loss, in terms of decreasing carbohydrate digestion via the inhibition of pancreatic alpha-amylase.

Isorhapontigenin Improves Diabetes in Mice via Regulating the Activity and Stability of PPARγ in Adipocytes

Isorhapontigenin is a natural bioactive stilbene isolated from various plants and fruits. It has been reported to exhibit several physiological activities including anticancer and anti-inflammation activity in vitro and in experimental animal models. This study aimed to investigate whether isorhapontigenin exerts antidiabetic effects in vivo. To this end, diabetic db/db mice were treated with either 25 mg kg^-1 of isorhapontigenin or vehicle intraperitoneally for a period of 5 weeks. The results show that isorhapontigenin treatment significantly reduced postprandial levels of glucose, insulin, as well as free fatty acid, three markers of diabetes. Further studies show that isorhapontigenin treatment markedly improves insulin sensitivity and glucose tolerance of db/db mice as shown by ITT and GTT. Together, these physiological results show that isorhapontigenin possesses antidiabetic properties in vivo. Mechanistically, the isorhapontigenin-mediated antidiabetic effect is caused by favorable changes in adipose tissue, including reductions in adipocyte diameter and improved adipose insulin sensitivity. Further studies with 3T3-L1 cells show that isorhapontigenin treatment promotes preadipocyte differentiation by upregulation of the activity of the master adipogenic regulator PPARγ and deceleration of its proteasomal degradation. Together, our results establish for the first time an important role of isorhapontigenin as a potential nutraceutical agent for diabetes treatment.

Macroalgae of Izmir Gulf: Cystoseira barbata, Cystoseira compressa and Cystoseira crinita species have high α-glucosidase and Moderate Pancreatic Lipase Inhibition Activities

Hyperglycemia and hyperlipidemia have been symptoms of many serious diseases such as diabetes and atherosclerosis overall the world. Thus, drug researchers have focused on new, natural and healthy drug alternatives. Marine macroalgae is a great source of hypoglycemic, hypolipidemic or hypocholesterolemic agents. In this study, we investigated that hypoglycemic, hypolipidemic and cytotoxic potentials of 22 marine macroalgae from the Gulf of Izmir. According to our results, the cold methanol extract of Polysiphonia denudata exhibited the highest antioxidant activity (93.6%) compared to BHA (95.3%). Three Cystoseira species, Cystoseria crinita (91.9%), Cystoseria barbata (90.7%), Cystoseria compressa (89.8%) showed higher α-glucosidase inhibition rates than oral antidiabetic acarbose (79.5%). It has also been observed that same species are potent inhibitors of pancreatic lipase. Cytotoxicity test revealed that these extracts did not cause viability inhibition on MCF-7. The results of maltose- glucose assay indirectly displayed that Cystoseira cold methanolic extracts inhibited maltose consumption better than acarbose on HT29. The results of this screening study show that these Cystoseira species may provide non- toxic bioactive agents to control non-communicable diseases (NCDs) such as cardiovascular disease and diabetes mellitus.

Dietary Polyphenols and Gene Expression in Molecular Pathways Associated with Type 2 Diabetes Mellitus: A Review

Type 2 diabetes mellitus (T2DM) is a complex metabolic disorder with various contributing factors including genetics, epigenetics, environment and lifestyle such as diet. The hallmarks of T2DM are insulin deficiency (also referred to as β-cell dysfunction) and insulin resistance. Robust evidence suggests that the major mechanism driving impaired β-cell function and insulin signalling is through the action of intracellular reactive oxygen species (ROS)-induced stress. Chronic high blood glucose (hyperglycaemia) and hyperlipidaemia appear to be the primary activators of these pathways. Reactive oxygen species can disrupt intracellular signalling pathways, thereby dysregulating the expression of genes associated with insulin secretion and signalling. Plant-based diets, containing phenolic compounds, have been shown to exhibit remedial benefits by ameliorating insulin secretion and insulin resistance. The literature also provides evidence that polyphenol-rich diets can modulate the expression of genes involved in insulin secretion, insulin signalling, and liver gluconeogenesis pathways. However, whether various polyphenols and phenolic compounds can target specific cellular signalling pathways involved in the pathogenesis of T2DM has not been elucidated. This review aims to evaluate the modulating effects of various polyphenols and phenolic compounds on genes involved in cellular signalling pathways (both in vitro and in vivo from human, animal and cell models) leading to the pathogenesis of T2DM.

Untargeted Metabolomic Profiling, Multivariate Analysis and Biological Evaluation of the True Mangrove (Rhizophora mucronata Lam.)

Currently, there is a renewed interest towards the development of plant-based pharmacophores. In this work, 16 extracts prepared from the leaves, twigs, roots and fruits of a hydro-halophyte, Rhizophora mucronata Lam. (Family: Rhizophoraceae), were studied for possible antioxidant activity and the phenolic profiles established. Thereafter, enzymatic inhibitory activities (α-amylase, α-glucosidase, tyrosinase, acetyl- (AChE), butyrylcholinesterase (BChE), lipase, and elastase) were assessed. The total phenolic, flavonoid, phenolic acid, tannin, flavanol and triterpenoid content were estimated using standard assays. An untargeted metabolomics-based approach, based on ultra-high-pressure liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry (UHPLC-QTOF-MS) followed by multivariate statistics, was then used to comprehensively profile and describe the phenolics present. UHPLC-QTOF-MS allowed for putatively annotating 104 phenolic acids, 103 flavonols, 94 flavones, 71 anthocyanins, 66 tyrosols, 29 lignans, 15 alkylphenols and 10 stilbenes in the extracts. Nine strains (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Methicillin-resistant Staphylococcus aureus (MRSA), Salmonella enteritidis, Sarcina lutea, Proteus mirabilis, Bacillus cereus and Candida albicans) were then used to investigate the antimicrobial properties. The methanolic twig extract exhibited significant reducing potential towards Cu (II)/Cu (I) and Fe (III)/Fe (II) (1336.88 ± 15.70 and 710.18 ± 21.04 mg TE/g, respectively) and was the most potent DPPH radical scavenger (807.07 ± 6.83 mg TE/g). Additionally, the methanolic twig extract showed significant inhibition against most targeted enzymes. Anti-microbial results showed that all extracts were active against MRSA. Multivariate analysis demonstrated that the phenolic profile of ethyl acetate extracts and leaves were the two most discriminative parameters in terms of solvents and organs, respectively. The present findings indicated that R. mucronata may be further explored for the management/prevention of oxidative stress, neurodegenerative complications and hyperpigmentation.

Effect of Myristica fragrans extract on total body composition in cafeteria diet induced obese rats

It is of interest to evaluate the effect of Myristica fragrans on body composition of cafeteria diet induced obese rats. Thirty rats (150-160g) grouped into 5 and each group contains 6 rats. Group-1 was normal control and 2-5 groups were fed with cafeteria diet for 15 weeks to induce obesity. From 16th week to 25th week test drugs were given as mentioned in the experimental protocol. Body weight, BMI, changes in body composition was measured by TOBEC, adipose tissue weights, organ weights, abdominal circumference were measured according to standard methods. After 70days of treatment with MFE 200mg/kg, 400mg/kg Body weight reduced by 9.29%, 12.87% respectively. BMI was also decreased. Abdominal circumference, total fat percentage, organ weights, was substantially reduced. At 400mg/kg of MFE has shown maximum potentiality when compared with 200mg/kg. Orlistat 50mg was used as standard drug. Tetrahydrofuran, flavonoids, saponins, present in Myristica fragrans has shown anti obesity activity. Our findings explain the potentiality of phytochemicals as a potent anti obesity agent, provide scientific evidence for its traditional use and suggest the possible mechanism of action.

Formulation of a Mixture of Plant Extracts for Attenuating Postprandial Glycemia and Diet-Induced Disorders in Rats

The aim of this study was to design a mixture consisting of plant-derived preparations containing inhibitors of carbohydrate digestion and/or glucose absorption that could lower postprandial glycemia and attenuate dietary-induced disorders. The following standardized preparations were tested: white mulberry leaf extract, green coffee bean extract, white kidney bean extract, pomelo fruit extract, bitter melon fruit extract, and purified l-arabinose. The study design was composed of oral sucrose and starch tolerance tests in Wistar rats preceded by a single ingestion of the preparations or their mixtures. Then, a 20 week-long experiment was conducted on rats that were fed a high-fat diet and supplemented with the most effective mixture. Based on the results of the oral sucrose and starch tolerance tests, the mulberry leaf extract, l-arabinose, kidney bean extract, and coffee bean extract were selected for composing three mixtures. The most effective inhibition of postprandial glycemia in the oral tolerance tests was observed after the ingestion of a mixture of mulberry leaf, kidney bean, and coffee bean extract. The glucose-lowering effect of the mixture and its effective dosage was confirmed in the feeding experiment.

Cyanidin-3-rutinoside acts as a natural inhibitor of intestinal lipid digestion and absorption

BACKGROUND

Cyanidin-3-rutinoside (C3R), a naturally occurring anthocyanin, possesses anti-oxidant, anti-hyperglycemic, anti-glycation and cardioprotective properties. However, its mechanisms responsible for anti-hyperlipidemic activity have not been fully identified. The aim of the study was to investigate the lipid-lowering mechanisms of C3R through inhibition of lipid digestion and absorption in vitro.

METHODS

The inhibitory activity of C3R against pancreatic lipase and cholesterol esterase was evaluated using enzymatic fluorometric and enzymatic colorimetric assays, respectively. An enzyme kinetic study using Michaelis-Menten and the derived Lineweaver-Burk plot was performed to understand the possible types of inhibition. The formation of cholesterol micelles was determined using the cholesterol assay kit. The bile acid binding was measured using the colorimetric assay. The NBD cholesterol uptake in Caco-2 cells was determined using fluorometric assay. The mRNA expression of cholesterol transporter (Niemann-Pick C1-like 1) was determined by RT-PCR.

RESULTS

The results showed that C3R was a mixed-type competitive inhibitor of pancreatic lipase with the IC₅₀ value of 59.4 ± 1.41 μM. Furthermore, C3R (0.125-1 mM) inhibited pancreatic cholesterol esterase about 5-18%. In addition, C3R inhibited the formation of cholesterol micelles and bound to primary and secondary bile acid. In Caco-2 cells, C3R (12.5-100 μM) exhibited a significant reduction in cholesterol uptake in both free cholesterol (17-41%) and mixed micelles (20-30%). Finally, C3R (100 μM) was able to suppress mRNA expression of NPC1L1 in Caco-2 cells after 24 h incubation.

CONCLUSIONS

The present findings suggest that C3R acts as a lipid-lowering agent through inhibition of lipid digestion and absorption.

Phenolic compounds and bioactivity evaluation of aqueous and methanol extracts of Allium mongolicum Regel

Allium mongolicum Regel (AM), widely distributed in western China, is a traditional Mongolian medicine herb. Two different solvents as water and methanol were used to extract AM, and their antioxidant capacity and inhibitory effects against key enzymes related to metabolic syndrome were assessed. The antioxidant capacity was evaluated through the assay of radical scavenging ability on DPPH and ABTS and reducing power assays. In addition, the total phenolic content and total flavonoids content were quantificated and analyzed. Aqueous extract, having higher phenolic content (10.20 mg GAE/g DW) and flavonoid content (4.02 mg QE/g DW), showed better antioxidant and inhibitory effects against lipase and angiotensin-converting enzyme (ACE); as for α-glucosidase, the extract made by methanol showed better ability. In general, the aqueous extract of A. mongolicum Regel has the potential to be used as a functional food or nutraceutical in prevention and treatment of obesity and hypertension due to the high antioxidant and sound inhibitory potential against vital enzymes relevant to obesity and hypertension.

A novel protocol for the preparation of active recombinant human pancreatic lipase from Escherichia coli

An active recombinant human pancreatic lipase (recHPL) was successfully prepared for the first time from the Escherichia coli expression system using short Strep-tag II (ST II). The recHPL-ST II was solubilized using 8 M urea from E.coli lysate and purified on a Strep-Tactin-Sepharose column. After refolding by stepwise dialyses in the presence of glycerol and Ca2+ for 2 days followed by gel filtration, 1.8-6 mg of active recHPL-ST II was obtained from 1 L of culture. The recHPL was non-glycosylated, but showed almost equal specific activity, pH-dependency and time-dependent stability compared to those of native porcine pancreatic lipase (PPL) at 37°C. However, the recHPL lost its lipolytic activity above 50°C, showing a lower heat-stability than that of native PPL, which retained half its activity at this temperature.

The Postprandial Anti-Hyperglycemic Effect of Pyridoxine and Its Derivatives Using In Vitro and In Vivo Animal Models

In the current study, we investigated the inhibitory activity of pyridoxine, pyridoxal, and pyridoxamine, against various digestive enzymes such as α-glucosidases, sucrase, maltase, and glucoamylase. Inhibition of these enzymes involved in the absorption of disaccharide can improve post-prandial hyperglycemia due to a carbohydrate-based diet. Pyridoxal (4.14 mg/mL of IC₅₀) had the highest rat intestinal α-glucosidase inhibitory activity, followed by pyridoxamine and pyridoxine (4.85 and 5.02 mg/mL of IC₅₀, respectively). Pyridoxal demonstrated superior inhibition against maltase (0.38 mg/mL IC₅₀) and glucoamylase (0.27 mg/mLIC₅₀). In addition, pyridoxal showed significant higher α-amylase inhibitory activity (10.87 mg/mL of IC₅₀) than that of pyridoxine (23.18 mg/mL of IC₅₀). This indicates that pyridoxal can also inhibit starch hydrolyzing by pancreatic α-amylase in small intestine. Based on these in vitro results, the deeper evaluation of the anti-hyperglycemic potential of pyridoxine and its derivatives using Sprague-Dawley (SD) rat models, was initiated. The post-prandial blood glucose levels were tested two hours after sucrose/starch administration, with and without pyridoxine and its derivatives. In the animal trial, pyridoxal (p < 0.05) had a significantly reduction to the postprandial glucose levels, when compared to the control. The maximum blood glucose levels (Cmax) of pyridoxal administration group were decreased by about 18% (from 199.52 ± 22.93 to 164.10 ± 10.27, p < 0.05) and 19% (from 216.92 ± 12.46 to 175.36 ± 10.84, p < 0.05) in sucrose and starch loading tests, respectively, when compared to the control in pharmacodynamics study. The pyridoxal administration significantly decreased the minimum, maximum, and mean level of post-prandial blood glucose at 0.5 h after meals. These results indicate that water-soluble vitamin pyridoxine and its derivatives can decrease blood glucose level via the inhibition of carbohydrate-hydrolyzing and absorption-linked enzymes. Therefore, pyridoxal may have the potential to be used as a food ingredient for the prevention of prediabetes progression to type 2 diabetes.

Starch Digestion-Related Amylase Genetic Variant Affects 2-Year Changes in Adiposity in Response to Weight-Loss Diets: The POUNDS Lost Trial

Salivary and pancreatic amylases (encoded by AMY1 and AMY2 genes, respectively) are responsible for digesting starchy foods. AMY1 and AMY2 show copy number variations that affect differences in amylase amount and activity, and AMY1 copies have been associated with adiposity. We investigated whether genetic variants determining amylase gene copies are associated with 2-year changes in adiposity among 692 overweight and obese individuals who were randomly assigned to diets varying in macronutrient content. We found that changes in body weight (BW) and waist circumference (WC) were significantly different according to the AMY1-AMY2 rs11185098 genotype. Individuals carrying the A allele (indicating higher amylase amount and activity) showed a greater reduction in BW and WC at 6, 12, 18, and 24 months than those without the A allele (P < 0.05 for all). The association was stronger for long-term changes compared with short-term changes of these outcomes. The genetic effects on these outcomes did not significantly differ across diet groups. In conclusion, the genetic variant determining starch metabolism influences the response to weight-loss dietary intervention. Overweight and obese individuals carrying the AMY1-AMY2 rs11185098 genotype associated with higher amylase activity may have greater loss of adiposity during low-calorie diet interventions.

Ayurvedic anti-diabetic formulation Lodhrasavam inhibits alpha-amylase, alpha-glucosidase and suppresses adipogenic activity in vitro

BACKGROUND

The patho-physiological cross-talk between diabetes and obesity is well established. However, the choices of drugs suitable for combined treatment of diabetes and obesity are limited. Integration of complementary and alternative medicines (CAMs), like Ayurveda, with modern medicine would be a promising strategy to fill this gap. The diagnostic principles of Ayurveda define obesity as one of the predisposing factors of Madhumeha (correlated as diabetes) and recommends specific formulations for managing obese-diabetes. Lodhrasavam is one such poly-herbal formulation prescribed for obese-diabetic patients.

OBJECTIVES

The present study is an attempt to demonstrate the possible modes of action of Lodhrasavam, built on the hypothesis that the formulation can exert both anti-diabetic and anti-obesity actions.

MATERIALS AND METHODS

Lodhrasavam, following simulated gastro-intestinal digestion, was monitored for inhibition of α-amylase, α-glucosidase (key digestive enzyme targets of anti-diabetic drugs) and adipogenesis using standard in vitro model systems.

RESULTS

Lodhrasavam digest inhibited α-amylase (90%) and α-glucosidase (78%) activity as well as reduced the differentiation of 3T3-L1 fibroblasts to adipocytes. Upon fractionation, the enzyme inhibitory activity and anti-adipogenic activity of the digest were found distributed in different solvent fractions. This partly indicates a potential pharmacological networking of chemically and functionally diverse bioactive molecules in Lodhrasavam.

CONCLUSION

The study provides a possible mode of action and an experimental support for the Ayurvedic use of Lodhrasavam for managing obese-diabetes. Generating scientific evidences and understanding the modes of action, in contemporary scientific language, would essentially help in expanding global acceptance of potentials of CAMs in the management of life style disorders.

Potential of rooibos, its major C-glucosyl flavonoids, and Z-2-(β-D-glucopyranosyloxy)-3-phenylpropenoic acid in prevention of metabolic syndrome

Risk factors of type 2 diabetes mellitus (T2D) and cardiovascular disease (CVD) cluster together and are termed the metabolic syndrome. Key factors driving the metabolic syndrome are inflammation, oxidative stress, insulin resistance (IR), and obesity. IR is defined as the impairment of insulin to achieve its physiological effects, resulting in glucose and lipid metabolic dysfunction in tissues such as muscle, fat, kidney, liver, and pancreatic β-cells. The potential of rooibos extract and its major C-glucosyl flavonoids, in particular aspalathin, a C-glucoside dihydrochalcone, as well as the phenolic precursor, Z-2-(β-D-glucopyranosyloxy)-3-phenylpropenoic acid, to prevent the metabolic syndrome, will be highlighted. The mechanisms whereby these phenolic compounds elicit positive effects on inflammation, cellular oxidative stress and transcription factors that regulate the expression of genes involved in glucose and lipid metabolism will be discussed in terms of their potential in ameliorating features of the metabolic syndrome and the development of serious metabolic disease. An overview of the phenolic composition of rooibos and the changes during processing will provide relevant background on this herbal tea, while a discussion of the bioavailability of the major rooibos C-glucosyl flavonoids will give insight into a key aspect of the bioefficacy of rooibos.

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.

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.

Low serum amylase and obesity, diabetes and metabolic syndrome: A novel interpretation

For the last decade, low serum amylase (hypoamylasemia) has been reported in certain common cardiometabolic conditions such as obesity, diabetes (regardless of type), and metabolic syndrome, all of which appear to have a common etiology of insufficient insulin action due to insulin resistance and/or diminished insulin secretion. Some clinical studies have shown that salivary amylase may be preferentially decreased in obese individuals, whereas others have revealed that pancreatic amylase may be preferentially decreased in diabetic subjects with insulin dependence. Despite this accumulated evidence, the clinical relevance of serum, salivary, and pancreatic amylase and the underlying mechanisms have not been fully elucidated. In recent years, copy number variations (CNVs) in the salivary amylase gene (AMY1), which range more broadly than the pancreatic amylase gene (AMY2A and AMY2B), have been shown to be well correlated with salivary and serum amylase levels. In addition, low CNV of AMY1, indicating low salivary amylase, was associated with insulin resistance, obesity, low taste perception/satiety, and postprandial hyperglycemia through impaired insulin secretion at early cephalic phase. In most populations, insulin-dependent diabetes is less prevalent (minor contribution) compared with insulin-independent diabetes, and obesity is highly prevalent compared with low body weight. Therefore, obesity as a condition that elicits cardiometabolic diseases relating to insulin resistance (major contribution) may be a common determinant for low serum amylase in a general population. In this review, the novel interpretation of low serum, salivary, and pancreas amylase is discussed in terms of major contributions of obesity, diabetes, and metabolic syndrome.

Postprandial effects of a polyphenolic grape extract (PGE) supplement on appetite and food intake: a randomised dose-comparison trial

Background

There is recent evidence that glucose delivered to the distal small intestine (SI) may stimulate the ileal brake and inhibit appetite. High polyphenolic grape extract (PGE) has been shown to inhibit α-amylase and α-glucosidase activity, two key enzymes required for starch digestion, in vitro. It is hypothesised to slow digestion and absorption of starch in the proximal SI such that glucose may be delivered distally into the ileum and suppress appetite. This study investigated the safety and efficacy of a PGE supplement, delivered within a capsule and consumed with a high-starch breakfast, on appetite ratings and ad libitum energy intake (EI) at a subsequent lunch meal.

Methods

Twenty healthy, non-obese (BMI 18–28 kg/m²) male volunteers participated in a randomised, double blind, placebo controlled, three arm, cross-over study. Participants were administered (i) low dose PGE₅₀₀ (500 mg), (ii) high dose PGE₁₅₀₀ (1500 mg), and (iii) matched placebo with a 2MJ high-starch breakfast (white bread); followed 3 h later by a single item buffet-style lunch meal (pasta and meat sauce). Outcome variables were feelings of hunger, fullness, prospective thoughts of food (TOF) and satisfaction assessed using visual analogue scales (VAS); and ad lib energy and macronutrient intake at the lunch meal.

Results

There was no detectable effect of PGE₅₀₀ or PGE₁₅₀₀ compared with placebo (all, time*supplement interaction, P > 0.05) on VAS-assessed hunger, fullness, TOF or satisfaction. There was also no evidence that PGE significantly altered ad lib energy or macronutrient intake at the lunch meal relative to placebo (P > 0.05). EI following PGE₅₀₀ was +164 kJ higher than placebo (+5.3 %, P > 0.05); and EI following PGE₁₅₀₀was −51 kJ lower than placebo (−1.7 %, P > 0.05).

Conclusions

Whilst well tolerated, there was no evidence that encapsulated low dose PGE₅₀₀ or high dose PGE₁₅₀₀ consumed with a high starch breakfast meal altered postprandial hunger, fullness, TOF or satisfaction relative to a matched placebo. Nor was there evidence that either dose altered ad lib energy or macronutrient intake at an outcome meal.

Trial registration

ACTRN12614000041651

Structure-Based Optimization and Biological Evaluation of Pancreatic Lipase Inhibitors as Novel Potential Antiobesity Agents

The unusual fused β-lactone vibralactone was isolated from cultures of the basidiomycete Boreostereum vibrans and has been shown to significantly inhibit pancreatic lipase. In this study, a structure-based lead optimization of vibralactone resulted in three series of 104 analogs, among which compound C1 exhibited the most potent inhibition of pancreatic lipase, with an IC50 value of 14 nM. This activity is more than 3000-fold higher than that of vibralactone. The effect of compound C1 on obesity was investigated using high-fat diet (HFD)-induced C57BL/6 J obese mice. Treatment with compound C1 at a dose of 100 mg/kg significantly decreased HFD-induced obesity, primarily through the improvement of metabolic parameters, such as triglyceride levels.

Lactobacillus gasseri SBT2055 suppresses fatty acid release through enlargement of fat emulsion size in vitro and promotes fecal fat excretion in healthy Japanese subjects

Background

Lactobacillus gasseri SBT2055 (LG2055) has been shown to prevent abdominal adiposity, and suppression of lipid absorption is considered a possible mechanism, detail of which, however, are poorly understood. In the present study, we evaluated the effects of LG2055 on fat hydrolysis by determining pancreatic lipase activity and fat emulsion properties in vitro. We also examined whether LG2055 influences fecal fat excretion in humans.

Methods

Pancreatic lipase activity was investigated in vitro using an artificially prepared fat emulsion and 4-methylumbelliferyl oleate (4-MUO) as substrates. The concentrations of free fatty acids and 4-methylumbelliferone were quantified. Fat emulsion droplet size was measured using a particle size analyzer. The clinical study was performed as a double-blind, randomized, placebo-controlled trial. Subjects consumed 100 g of fermented milk (FM)/d, either with or without LG2055 supplementation, for seven days. Fecal samples were collected during three-day pre-observational and FM intake periods and fecal fat levels were determined.

Results

LG2055 dose-dependently suppressed lipase activity in the fat emulsion assay but not in the 4-MUO assay. LG2055 dose-dependently increased fat emulsion droplet size. The effects of LG2055 on lipase activity and fat emulsion properties were increased compared with four other tested strains (Lactobacillus gasseri SBT0317, Lactobacillus gasseri JCM1131^T, Lactobacillus. delbrueckii subsp. bulgaricus JCM1002^T and Streptococcus thermophilus ATCC19258^T). In our clinical study, fecal fat level after FM intake was significantly increased compared with that observed before FM intake in the LG2055-containing active FM group but not the control FM group lacking LG2055.

Conclusions

LG2055 increased fat emulsion droplet size, resulting in the suppression of lipase-mediated fat hydrolysis. The influence of LG2055 on the physicochemical properties of fat emulsion provides a mechanism for the probiotic-mediated suppression of lipid absorption and promotion of fecal fat excretion in humans.

Trial registration

UMIN000015772

Chalcones and their therapeutic targets for the management of diabetes: structural and pharmacological perspectives

Diabetes Mellitus (DM) is the fastest growing metabolic disorder affecting about 387 million people across the globe and is estimated to affect 592 million people by year 2030. The search for newer anti-diabetic agents is the foremost need to control the accelerating diabetic population. Several natural and (semi) synthetic chalcones deserve the credit of being potential candidates that act by modulating the therapeutic targets PPAR-γ, DPP-4, α-glucosidase, PTP1B, aldose reductase, and stimulate insulin secretion and tissue sensitivity. In this review, a comprehensive study (from January 1977 to October 2014) of anti-diabetic chalcones, their molecular targets, structure activity relationships (SARs), mechanism of actions (MOAs) and patents have been described. The compounds which showed promising activity and have a well-defined MOAs, SARs must be considered as prototype for the design and development of potential anti-diabetic agents. They should be evaluated critically at all clinical stages to ensure their therapeutic and toxicological profile to meet the demand of diabetics.

Recent approaches of lipid-based delivery system for lymphatic targeting via oral route

Lymphatic system is a key target in research field due to its distinctive makeup and huge contributing functions within the body. Intestinal lymphatic drug transport (chylomicron pathway) is intensely described in research field till date because it is considered to be the best for improving oral drug delivery by avoiding first pass metabolism. The lymphatic imaging techniques and potential therapeutic candidates are engaged for evaluating disease states and overcoming these conditions. The novel drug delivery systems such as self-microemulsifying drug delivery system, nanoparticles, liposomes, nano-lipid carriers, solid lipid carriers are employed for delivering drugs through lymphatic system via various routes such as subcutaneous route, intraperitoneal route, pulmonary route, gastric sub-mucosal injection, intrapleural and intradermal. Among these colloidal particles, lipid-based delivery system is considered to be the best for lymphatic delivery. From the last few decades, mesenteric lymph duct cannulation and thoracic lymph duct cannulation are followed to assess lymphatic uptake of drugs. Due to their limitations, chylomicrons inhibitors and in-vitro models are employed, i.e. lipolysis model and permeability model. Currently, research on this topic still continues and drainage system used to deliver the drugs against lymphatic disease as well as targeting other organs by modulating the chylomicron pathway.

Effects of Passiflora nitida Kunth leaf extract on digestive enzymes and high caloric diet in rats

The present study investigated inhibition of pancreatic lipase and metabolic effects of high caloric diet in rats. The Passiflora nitida hydroethanol leaf extract (PNE) was used in in vitro assays or administered to rats to study dyslipidemia. Inhibition of lipase in vitro was studied by a spectrophotometric assay using orlistat as the positive control. The effects of PNE on reduction of postprandial triglyceride were studied by oral fat-overloading in rats. Metabolic alterations were induced using the cafeteria diet and 4 weeks post-treatment with PNE or orlistat and blood samples were collected and biochemical analyses were performed. Liver and retroperitoneal fat tissues were obtained to analyze weight and steatosis. IC50 (lg/mL) values for pancreatic lipase inhibition were 21.2 ± 0.8 and 0.1 ± 0.01 for PNE and orlistat, respectively. Oral administration of lipid emulsion resulted in postprandial hypertriglyceridemia at 3 h postadministration and when rats were then administered PNE and orlistat there was decreased of triglyceride levels by 15 % compared to control. Although the energy consumption by the cafeteria diet had been higher, there was no significant weight gain observed in the study groups. The cafeteria diet resulted in a significant increase of weight in the retroperitoneal fat and hypertriglyceridemia levels that could be significantly reduced by PNE and orlistat treatment. We hypothesized that PNE administration prevented the hypertriglyceridemia in rats with a high caloric diet, possibly owing to reduction of lipid absorption and pancreatic lipase inhibition.

Rapid screening and identification of α-amylase inhibitors from Garcinia xanthochymus using enzyme-immobilized magnetic nanoparticles coupled with HPLC and MS

α-Amylase inhibitors play an important role in management of diabetes and obesity. In order to rapidly discover potent α-amylase inhibitors from medicinal plants, a ligands-screening method based on enzyme-immobilized magnetic nanoparticles integrated with HPLC was developed. Amine-terminated magnetic nanoparticles were prepared for the immobilization of α-amylase. Based on the affinity theory, the α-amylase-coated magnetic nanoparticles were employed to fish out the ligands from the extracts of Garcinia xanthochymus, and the elutes were examined by HPLC. As a result, three ligands were screened out. Isolation and identification were carried out subsequently. By analyzing the UV, MS and NMR spectra, they were identified as three biflavonoids including GB2a glucoside (2), GB2a (3) and fukugetin (4). The IC50 values of the three compounds were also determined. The results suggest the proposed approach is efficient and accurate, and has great potential in rapid discovery of drug candidates from medical plants.

Lipase inhibitory and LDL anti-oxidative triterpenes from Abies sibirica

A methanol extract of Abies sibirica Ladeb, a Mongolian medicinal plant, had an inhibitory effect on both lipase activity in mouse plasma and LDL anti-oxidative activity, which are preventative factors for arteriosclerosis. The extract was fractionated by silica gel column chromatography and its active constituents were sought. From lipid soluble fractions, 20 terpenoids including seven hitherto unknown triterpenes were isolated. The latter triterpenes had either a γ-lactone ring with a lactol or a derivative thereof. Their chemical structures were determined by spectroscopic methods. The lipase inhibitory activity and LDL anti-oxidative activity of these compounds were evaluated. Some constituents (either lipase inhibitory or LDL anti-oxidative activities) had moderate inhibitory activities.

Coconut-derived D-xylose affects postprandial glucose and insulin responses in healthy individuals

Metabolic alterations including postprandial hyperglycemia have been implicated in the development of obesity-related diseases. Xylose is a sucrase inhibitor suggested to suppress the postprandial glucose surge. The objectives of this study were to assess the inhibitory effects of two different concentrations of xylose on postprandial glucose and insulin responses and to evaluate its efficacy in the presence of other macronutrients. Randomized double-blind cross-over studies were conducted to examine the effect of D-xylose on postprandial glucose and insulin response following the oral glucose tolerance test (OGTT). In study 1, the overnight-fasted study subjects (n = 49) consumed a test sucrose solution (50 g sucrose in 130 ml water) containing 0, 5, or 7.5 g D-xylose powder. In study 2, the overnight-fasted study subjects (n = 50) consumed a test meal (50 g sucrose in a 60 g muffin and 200 ml sucrose-containing solution). The control meal provided 64.5 g of carbohydrates, 4.5 g of fat, and 10 g of protein. The xylose meal was identical to the control meal except 5 g of xylose was added to the muffin mix. In study 1, the 5 g xylose-containing solutions exhibited significantly lower area under the glucose curve (AUCg) and area under the insulin curve (AUCi) values for 0-15 min (P < 0.0001, P < 0.0001), 0-30 min (P < 0.0001, P < 0.0001), 0-45 min (P < 0.0001, P < 0.0001), 0-60 min (P < 0.0001, P < 0.0001), 0-90 min (P < 0.0001, P < 0.0001) and 0-120 min (P = 0.0071, P = 0.0016). In study 2, the test meal exhibited significantly lower AUCg and AUCi values for 0-15 min (P < 0.0001, P < 0.0001), 0-30 min (P < 0.0001, P < 0.0001), 0-45 min (P < 0.0001, P = 0.0005), 0-60 min (P = 0.0002, P = 0.0025), and 0-90 min (P = 0.0396, P = 0.0246). In conclusion, xylose showed an acute suppressive effect on the postprandial glucose and insulin surges.