Activity-guided isolation of α-amylase, α-glucosidase, and pancreatic lipase inhibitory compounds from Rhus coriaria L

Phytochemical Profiling and Assessment of Antidiabetic Activity of Curcuma Angustifolia Rhizome Methanolic Extract: An In Vitro and In Silico Analysis

Curcuma angustifolia Roxb. is a plant with medicinal potential, traditionally used to treat different diseases. The present study aimed to determine the antidiabetic activity of C. angustifolia rhizome in vitro and in silico. The methanolic extract of C. angustifolia rhizome was analyzed by FTIR and GC-MS to determine the phytochemicals present. The antidiabetic potential of the extract was evaluated by different assays in vitro. The extract inhibited both α-amylase and α-glucosidase enzymes and the glucose diffusion through the dialysis membrane in a concentration-dependent manner with IC50 values of 530.39±0.09, 293.75±0.11, and 551.74±0.3 μg/ml respectively. The methanolic extract also improved yeast cell's ability to take up glucose across plasma membranes and the adsorption of glucose. The findings were supported by molecular docking studies. The results showed that the methanol extract of C. angustifolia rhizome has significant antidiabetic activity and thus can be also studied to isolate the potential compound with antidiabetic activities.

Effect of PENN-DIABEX, a novel polyherbal formulation, in high fat diet streptozotocin-induced diabetic rats

Diabetes, a chronic metabolic disorder affecting millions worldwide, presents a significant health challenge characterized by impaired glucose regulation and potential complications. This study examines the antidiabetic effects of a polyherbal formulation (PENN-DIABEX) prepared from five different medicinal plant extracts. The objective is to ascertain its efficacy in managing streptozotocin (STZ) induced diabetes in rats. To accomplish this, six distinct groups of rats were involved five with induced diabetes and one serving as a normal control. Among the diabetic groups, one received no treatment, functioning as the diabetic control group. The remaining three groups were administered PHF in three different doses while the 6th group was given metformin. On the last day of the experiment, all rats were sacrificed, and blood samples were taken in collecting tubes to analyze blood biochemical parameters. Additionally, tissue samples from the liver, kidney, and pancreas were preserved in formalin solution for subsequent histopathological activity. The results of the study revealed that treatment with PHF in diabetic rats led to a significant (P < 0.01) improvement in fasting blood glucose levels (FBG), glycated hemoglobin (HbA1c), and various biochemical markers including LFTs, RFTs, and lipid profiling. Furthermore, the histology of the liver, kidney, and pancreas indicated that the formulation did not induce any metabolic toxicity. Comparative analysis of the antidiabetic effects of PHF with those of metformin, revealed that the PHF showed better results than the standard drug. This suggests its potential utilization as a safer and alternative approach in the treatment of diabetes.

New Insights into the Latest Advancement in α-Amylase Inhibitors of Plant Origin with Anti-Diabetic Effects

The rising predominance of type 2 diabetes, combined with the poor medical effects seen with commercially available anti-diabetic medications, has motivated the development of innovative treatment approaches for regulating postprandial glucose levels. Natural carbohydrate digestion enzyme inhibitors might be a viable option for blocking dietary carbohydrate absorption with fewer side effects than manufactured medicines. Alpha-amylase is a metalloenzyme that facilitates digestion by breaking down polysaccharides into smaller molecules such as maltose and maltotriose. It also contributes to elevated blood glucose levels and postprandial hyperglycemia. As a result, scientists are being urged to target α-amylase and create inhibitors that can slow down the release of glucose from carbohydrate chains and prolong its absorption, thereby resulting in lower postprandial plasma glucose levels. Natural α-amylase inhibitors derived from plants have gained popularity as safe and cost-effective alternatives. The bioactive components responsible for the inhibitory actions of various plant extracts have been identified through phytochemical research, paving the way for further development and application. The majority of the findings, however, are based on in vitro investigations. Only a few animal experiments and very few human investigations have confirmed these findings. Despite some promising results, additional investigation is needed to develop feasible anti-diabetic drugs based on plant-derived pancreatic α-amylase inhibitors. This review summarizes the most recent findings from research on plant-derived pancreatic α-amylase inhibitors, including plant extracts and plant-derived bioactive compounds. Furthermore, it offers insights into the structural aspects of the crucial therapeutic target, α-amylases, in addition to their interactions with inhibitors.

Methodologies for Assessing Pancreatic Lipase Catalytic Activity: A Review

Obesity is a disease of epidemic proportions with a concerning increasing trend. Regarded as one of the main sources of energy, lipids can also represent a big part of an unnecessary intake of calories and be, therefore, directly related to the problem of obesity. Pancreatic lipase is an enzyme that is essential in the absorption and digestion of dietary fats and has been explored as an alternative for the reduction of fat absorption and consequent weigh loss.Literature describes a great variability of methodologies and experimental conditions used in research to evaluate the in vitro inhibitory activity of compounds against pancreatic lipase. However, in an attempt to choose the best approach, it is necessary to know all the reaction conditions and understand how these can affect the enzymatic assay.The objective of this review is to understand and summarize the methodologies and respective experimental conditions that are mainly used to evaluate pancreatic lipase catalytic activity.156 studies were included in this work and a detailed description of the most commonly used UV/Vis spectrophotometric and fluorimetric instrumental techniques are presented, including a discussion regarding the differences found in the parameters used in both techniques, namely enzyme, substrate, buffer solutions, kinetics conditions, temperature and pH.This works shows that both UV/Vis spectrophotometry and fluorimetry are useful instrumental techniques for the evaluation of pancreatic lipase catalytic activity, presenting several advantages and limitations, which make the choice of parameters and experimental conditions a crucial decision to obtain the most reliable results.

The Impact of Za'atar Antioxidant Compounds on the Gut Microbiota and Gastrointestinal Disorders: Insights for Future Clinical Applications

Since the gut microbiota plays a pivotal role in host homeostasis and energy balance, changes in its composition can be associated with disease states through the promotion of immune-mediated inflammatory disorders and increasing intestinal permeability, ultimately leading to the impairment of intestinal barrier function. Za'atar is one of the most popular plant-based foods in the Eastern Mediterranean region. Za'atar is a mixture of different plant leaves, fruits, and seeds and contains hundreds of antioxidant compounds, especially polyphenols, and fiber, with pre-clinical and clinical evidence suggesting health-promoting effects in cardiovascular and metabolic disease. Za'atar compounds have also been studied from a gastrointestinal perspective, concerning both gut microbiota and gastrointestinal diseases. Antioxidants such as Za'atar polyphenols may provide beneficial effects in the complex interplay between the diet, gut microbiota, and intestinal permeability. To our knowledge, no studies have reported the effects of the whole Za'atar mixture, however, based on the pre-clinical studies published on components and single compounds found in Za'atar, we provide a clinical overview of the possible effects on the gastrointestinal tract, focusing mainly on carvacrol, rosmarinic acid, gallic acid, and other polyphenols. We also cover the potential clinical applications of Za'atar mixture as a possible nutraceutical in disorders involving the gastrointestinal tract.

Investigation of Enzyme Inhibitory Activities, Antioxidant Activities, and Chemical Properties of Pistacia vera Leaves Using LC-QTOF-MS and RP-HPLC

Since the leaves of some Pistacia species are used in traditional folk medicine for diabetes, this study investigated the in vitro antidiabetic effect (α-glucosidase and α-amylase) of Pistacia vera leaves. Additionally, the current study investigated the antihypercholesterolemic (cholesterol esterase), antiobesity (pancreatic lipase), and antioxidant activities (i.e., total antioxidant capacity, DPPH (2,2-Diphenyl-1-picrylhydrazyl) radical scavenging activity, metal chelating activity, and ferric-reducing antioxidant power) of P. vera leaves. The aqueous-alcoholic leaf extract inhibited α-amylase, α-glucosidase, and pancreatic lipase with the half-maximal inhibitory concentration values of 7.74 ± 0.72, 11.08 ± 3.96, and 168.43 ± 26.10 µg/mL, respectively. It was determined that the crude extract had high DPPH radical scavenging activity, ferric-reducing power, and moderate metal chelating activity. The ethyl acetate (EtOAc) subextract obtained by the liquid-liquid fractionation of the crude extract showed potent α-amylase and α-glucosidase inhibitory activities. The EtOAc subextract (5.794 ± 0.027 g/100 g subextract) was standardized by reversed-phase high-performance liquid chromatography based on β-pentagalloyl glucose, which showed inhibitory effects on both amylase and glucosidase enzymes. Fifteen compounds, seven of which are organic acid derivatives and eight of which are flavonoids, were identified by liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) analysis in the crude extract of P. vera leaves. Seven of the fifteen phenolic compounds detected in the crude extract by LC-QTOF-MS have both glucosidase and amylase inhibitory effects. As a result, P. vera leaves can be a potential source for compounds with high antioxidant effects that show inhibitory effects on enzymes involved in carbohydrate digestion in the prevention and treatment of diabetes or can be evaluated as a standardized extract.

Amentoflavone-Enriched Selaginella rossii Warb. Suppresses Body Weight and Hyperglycemia by Inhibiting Intestinal Lipid Absorption in Mice Fed a High-Fat Diet

Many Selaginellaceae species are used as traditional medicines in Asia. This study is the first to investigate the anti-obesity and anti-diabetic effects of Selaginella rossii (SR) in high-fat diet (HFD)–fed C57BL/6J mice. Seven-day oral administration of ethanol extract (100 mg/kg/day) or ethyl acetate (EtOAc) extract (50 mg/kg/day) from SR improved oral fat tolerance by inhibiting intestinal lipid absorption; 10-week long-term administration of the EtOAc extract markedly reduced HFD-induced body weight gain and hyperglycemia by reducing adipocyte hypertrophy, glucose levels, HbA1c, and plasma insulin levels. Treatment with SR extracts reduced the expression of intestinal lipid absorption-related genes, including Cd36, fatty acid-binding protein 6, ATP-binding cassette subfamily G member 8, NPC1 like intracellular cholesterol transporter 1, and ATP-binding cassette subfamily A member 1. In addition, the EtOAc extract increased the expression of protein absorption–related solute carrier family genes, including Slc15a1, Slc8a2, and Slc6a9. SR extracts reduced HFD-induced hepatic steatosis by suppressing fatty acid transport to hepatocytes and hepatic lipid accumulation. Furthermore, amentoflavone (AMF), the primary compound in SR extracts, reduced intestinal lipid absorption by inhibiting fatty acid transport in HFD-fed mice. AMF-enriched SR extracts effectively protected against HFD-induced body weight gain and hyperglycemia by inhibiting intestinal lipid absorption.

Investigation of Antidiabetic Effect of Pistacia atlantica Leaves by Activity-Guided Fractionation and Phytochemical Content Analysis by LC-QTOF-MS

In this study, the antidiabetic, antiobesity, antioxidant, and antihyperlipidemic effects potential of Pistacia atlantica Desf. leaves were evaluated by in vitro methods. The effects of the leaves of the plant on pancreatic lipase, pancreatic cholesterol esterase, and PTP1B enzymes were investigated for the first time and it was observed that leaf methanol extract (IC₅₀: 123.67 ± 0.40 μg/ml) and n-hexane sub-extract (IC₅₀: 61.03 ± 0.11 μg/ml) had much stronger effects on pancreatic cholesterol esterase enzyme than simvastatin (IC₅₀: 142.30 ± 5.67 μg/ml). The methanolic extract of P. atlantica leaves exerted strong inhibitory effect on the enzymes (α-amylase and α-glucosidase) effective on carbohydrate digestion. It was thought that the methanol extract could provide significant benefits against oxidative stress in diabetes mellitus since it showed antioxidant activities (DPPH radical scavenging activity and reducing power) as strong as reference compounds (ascorbic acid and quercetin). Qualitative and quantitative analyzes of rutin (0.328 ± 0.000 g/100 g dry extract), methyl gallate (5.245 ± 0.014 g/100 g dry extract), quercetin-3-O-glucoside (0.231 ± 0.000 g/100 g dry extract), and gallic acid (0.528 ± 0.127 g/100 g dry extract) in methanol extract were performed by RP-HPLC. The phytochemical content of the active sub-fraction obtained from the leaf methanol extract by activity-guided fractionation and column chromatography studies was characterized by LC-QTOF-MS. The presence of trigalloylglucose, digalloylglucose, and methyl gallate in the G6 coded sub-fraction obtained by chromatographic techniques from the ethyl acetate sub-extract, which has the highest inhibitory effect on α-amylase and α-glucosidase enzymes, was determined by LC-QTOF-MS. In addition to the G5 coded subfraction, a strong α-glucosidase enzyme inhibitory activity was also observed in the G6 coded sub-fraction, and methyl gallate, methyl digallate, 2″-O-galloyl-quercetin-3-O-hexoside, and myricetin-3-O-hexoside were identified in this sub-fraction. This study displayed that the methanol extract of P. atlantica leaves could be a potential source for bioactive compounds with antidiabetic effects by showing inhibitory effects on enzymes involved in carbohydrate digestion.

Standardization of Juniperus macrocarpa Sibt. & Sm. and Juniperus excelsa M. Bieb. Extracts with Carbohydrate Digestive Enzyme Inhibitory and Antioxidant Activities

Juniperus species growing in Turkey are used for various medicinal purposes in traditional folk medicine. We aimed to evaluate in-vitro antidiabetic (α-glucosidase and α-amylase inhibition assays), antiobesity (pancreatic lipase inhibition assay), and antioxidant (ABTS and DPPH radical scavenging activities, ferric reducing activity, metal chelating activity, and phosphomolybdenum assay) activities of the extracts obtained from branches, leaves, and fruits of Juniperus macrocarpa and Juniperus excelsa. The branch (IC₅₀ = 67.1 ± 1.7 µg/mL) and leaf ethyl acetate extracts (IC₅₀ = 83.4 ± 0.8 µg/mL) of J. macrocarpa exhibited the strongest activity on the α-glucosidase enzyme. Besides that, J. excelsa leaf methanol extract exerted remarkable α-amylase inhibitory activity (IC₅₀ = 950.1 ± 3.5 µg/mL). Only J. macrocarpa branch and J. excelsa leaf ethyl acetate extract slightly inhibited pancreatic lipase enzyme with 2963.3 ± 736.4 and 2343 ± 557.8 µg/mL IC₅₀ values, respectively. The RP-HPLC-DAD analysis results demonstrated that the more active J. macrocarpa extracts are richer in agathisflavone, amentoflavone, and umbelliferone than J. excelsa extracts. With this study, it is concluded that J. macrocarpa branch and leaf ethyl acetate extracts may be a new source of α-glucosidase enzyme inhibitory activity and agathisflavone, amentoflavone can be used in the standardization of the extracts.

Rhus coriaria L., a new candidate for controlling metabolic syndrome: a systematic review

OBJECTIVES

Rhus coriaria L. (RC) is a deciduous shrub with several pharmacological activities. Evidence of the effects of RC on weight, hyperlipidaemia, hypertension and diabetes mellitus have been presented in this study. Books, thesis and internet-based resources such as PubMed, Web of Science, Scopus, EMBASE, Cochrane, Ovid and Google Scholar were searched for the English, Arabic and Persian literature from 1966 to 2020 (December). The keywords were Rhus coriaria L., Sumac, metabolic syndrome and all its medical conditions (hyperlipidaemia, hypertension, obesity and diabetes mellitus). The inclusion criteria were full-text animal and human studies conducted on RC to evaluate its efficacy on any components of metabolic syndrome (MetS). Jadad scale was used to assess the quality of evidence.

KEY FINDINGS

Reviewing 23 relevant studies demonstrated that RC is able to decrease the level of blood glucose, glycated haemoglobin, serum insulin and insulin resistance. Studies on hyperlipidaemia and obesity have very contradicting results, and there is no definite conclusion on the effect of RC on lipid profile. However, the hypotensive and effect of RC was confirmed in the existing studies.

SUMMARY

According to the literature, RC can be considered as a promising curative candidate for MetS. However, further studies with larger sample size and higher methodological quality are needed.

Insight into the α-glucosidase-inhibiting mechanism of β-PGG, a commonly occurring polyphenol in diets

1,2,3,4,6-Penta-O-galloyl-β-D-glucopyranose (β-PGG) is a compound commonly available in vegetables and fruits. It exhibited potential inhibition of α-glucosidase and hypoglycemic effect in vivo. This study explored its dynamics properties inhibiting α-glucosidase by Lineweaver - Burk plots, spectral analysis, docking analysis, and molecular dynamics simulations. β-PGG showed a mix-type inhibition when it was interacting with α-glucosidase. The fluorescence quenching indicated that the PGG-glucosidase complex formed in a spontaneous exothermic process and was driven by enthalpy. The synchronous fluorescence and ECD spectra indicate that β-PGG induced and changed the enzyme conformation in the complex formation. Docking results revealed multiple hydrogen bonds between the phenols and the amino acid residues. Further dynamic simulations indicated that the residues Asp345, Phe153, Arg435, Glu300, Pro305, and Phe296 played a more critical role in the interactions between β-PGG and α-glucosidase.