Abrus precatorius Leaf Extract Stimulates Insulin-mediated Muscle Glucose Uptake: In vitro Studies and Phytochemical Analysis.

Diabetes mellitus, linked with insulin resistance and hyperglycaemia, is a leading cause of mortality. Glucose uptake through glucose transporter type 4, especially in skeletal muscle, is crucial for maintaining euglycaemia and is a key pathway targeted by antidiabetic medication. Abrus precatorius is a medicinal plant with demonstrated antihyperglycaemic activity in animal models, but its mechanisms are unclear.This study evaluated the effect of a 50% ethanolic (v/v) A. precatorius leaf extract on (1) insulin-stimulated glucose uptake and (2) related gene expression in differentiated C2C12 myotubes using rosiglitazone as a positive control, and (3) generated a comprehensive phytochemical profile of A. precatorius leaf extract using liquid chromatography-high resolution mass spectrometry to elucidate its antidiabetic compounds. A. precatorius leaf extract significantly increased insulin-stimulated glucose uptake, and insulin receptor substrate 1 and Akt substrate of 160 kDa gene expression; however, it had no effect on glucose transporter type 4 gene expression. At 250 µg/mL A. precatorius leaf extract, the increase in glucose uptake was significantly higher than 1 µM rosiglitazone. Fifty-five phytochemicals (primarily polyphenols, triterpenoids, saponins, and alkaloids) were putatively identified, including 24 that have not previously been reported from A. precatorius leaves. Abrusin, precatorin I, glycyrrhizin, hemiphloin, isohemiphloin, hispidulin 4'-O-ß-D-glucopyranoside, homoplantaginin, and cirsimaritin were putatively identified as known major compounds previously reported from A. precatorius leaf extract. A. precatorius leaves contain antidiabetic phytochemicals and enhance insulin-stimulated glucose uptake in myotubes via the protein kinase B/phosphoinositide 3-kinase pathway by regulating insulin receptor substrate 1 and Akt substrate of 160 kDa gene expression. Therefore, A. precatorius leaves may improve skeletal muscle insulin sensitivity and hyperglycaemia. Additionally, it is a valuable source of bioactive phytochemicals with potential therapeutic use for diabetes.

A Pharmacological Perspective on Plant-derived Bioactive Molecules for Epilepsy.

Epilepsy is a related chronic neurological condition of a predisposition for recurrent epileptic seizures, with various manifestations and causes. Although there are antiepileptic drugs, complementary natural therapies are widely used. The purpose of this systematic review was to analyze the antiepileptic/anticonvulsant pharmacological properties of plant-food derived bioactive molecules. In this regard, a systematic review of the PubMed database was made based on the inclusion criteria. Natural compounds/herbs with scientifically proven antiepileptic properties were selected. Experimental pharmacological studies in vitro and in vivo have shown that flavonoids, alkaloids and terpenoids may have anticonvulsant mechanisms similar to the new generation antiepileptic drugs. The relationships of structure-anticonvulsant effect, pharmacological models, seizure-inducing factors and response, effective dose were also analyzed and discussed. The results of in vitro and in vivo pharmacological studies analyzed in this systematic review support the clinical importance of plant-food-derived bioactive molecules for the complementary treatment of epilepsy. Thus, are opened new perspectives to develop new natural anticonvulsant drugs.

Screening natural product extracts for potential enzyme inhibitors: protocols, and the standardisation of the usage of blanks in α-amylase, α-glucosidase and lipase assays.

BACKGROUND: Enzyme assays have widespread applications in drug discovery from plants to natural products. The appropriate use of blanks in enzyme assays is important for assay baseline-correction, and the correction of false signals associated with background matrix interferences. However, the blank-correction procedures reported in published literature are highly inconsistent. We investigated the influence of using different types of blanks on the final calculated activity/inhibition results for three enzymes of significance in diabetes and obesity; α-glucosidase, α-amylase, and lipase. This is the first study to examine how different blank-correcting methods affect enzyme assay results. Although assays targeting the above enzymes are common in the literature, there is a scarcity of detailed published protocols. Therefore, we have provided comprehensive, step-by-step protocols for α-glucosidase-, α-amylase- and lipase-inhibition assays that can be performed in 96-well format in a simple, fast, and resource-efficient manner with clear instructions for blank-correction and calculation of results. RESULTS: In the three assays analysed here, using only a buffer blank underestimated the enzyme inhibitory potential of the test sample. In the absorbance-based α-glucosidase assay, enzyme inhibition was underestimated when a sample blank was omitted for the coloured plant extracts. Similarly, in the fluorescence-based α-amylase and lipase assays, enzyme inhibition was underestimated when a substrate blank was omitted. For all three assays, method six [Raw Data - (Substrate + Sample Blank)] enabled the correction of interferences due to the buffer, sample, and substrate without double-blanking, and eliminated the need to add substrate to each sample blank. CONCLUSION: The choice of blanks and blank-correction methods contribute to the variability of assay results and the likelihood of underestimating the enzyme inhibitory potential of a test sample. This highlights the importance of standardising the use of blanks and the reporting of blank-correction procedures in published studies in order to ensure the accuracy and reproducibility of results, and avoid overlooked opportunities in drug discovery research due to inadvertent underestimation of enzyme inhibitory potential of test samples resulting from unsuitable blank-correction. Based on our assessments, we recommend method six [RD - (Su + SaB)] as a suitable method for blank-correction of raw data in enzyme assays.

Impact of Natural Compounds on Neurodegenerative Disorders: From Preclinical to Pharmacotherapeutics.

Among the major neurodegenerative disorders (NDDs), Alzheimer's disease (AD) and Parkinson's disease (PD), are a huge socioeconomic burden. Over many centuries, people have sought a cure for NDDs from the natural herbals. Many medicinal plants and their secondary metabolites are reported with the ability to alleviate the symptoms of NDDs. The major mechanisms identified, through which phytochemicals exert their neuroprotective effects and potential maintenance of neurological health in ageing, include antioxidant, anti-inflammatory, antithrombotic, antiapoptotic, acetylcholinesterase and monoamine oxidase inhibition and neurotrophic activities. This article review the mechanisms of action of some of the major herbal products with potential in the treatment of NDDs according to their molecular targets, as well as their regional sources (Asia, America and Africa). A number of studies demonstrated the beneficial properties of plant extracts or their bioactive compounds against NDDs. Herbal products may potentially offer new treatment options for patients with NDDs, which is a cheaper and culturally suitable alternative to conventional therapies for millions of people in the world with age-related NDDs.

Understanding glycaemic control and current approaches for screening antidiabetic natural products from evidence-based medicinal plants.

Type 2 Diabetes Mellitus has reached epidemic proportions as a result of over-nutrition and increasingly sedentary lifestyles. Current therapies, although effective, are not without limitations. These limitations, the alarming increase in the prevalence of diabetes, and the soaring cost of managing diabetes and its complications underscores an urgent need for safer, more efficient and affordable alternative treatments. Over 1200 plant species are reported in ethnomedicine for treating diabetes and these represents an important and promising source for the identification of novel antidiabetic compounds. Evaluating medicinal plants for desirable bioactivity goes hand-in-hand with methods in analytical biochemistry for separating and identifying lead compounds. This review aims to provide a comprehensive summary of current methods used in antidiabetic plant research to form a useful resource for researchers beginning in the field. The review summarises the current understanding of blood glucose regulation and the general mechanisms of action of current antidiabetic medications, and combines knowledge on common experimental approaches for screening plant extracts for antidiabetic activity and currently available analytical methods and technologies for the separation and identification of bioactive natural products. Common in vivo animal models, in vitro models, in silico methods and biochemical assays used for testing the antidiabetic effects of plants are discussed with a particular emphasis on in vitro methods such as cell-based bioassays for screening insulin secretagogues and insulinomimetics. Enzyme inhibition assays and molecular docking are also highlighted. The role of metabolomics, metabolite profiling, and dereplication of data for the high-throughput discovery of novel antidiabetic agents is reviewed. Finally, this review also summarises sample preparation techniques such as liquid-liquid extraction, solid phase extraction, and supercritical fluid extraction, and the critical function of nuclear magnetic resonance and high resolution liquid chromatography-mass spectrometry for the dereplication, putative identification and structure elucidation of natural compounds from evidence-based medicinal plants.