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 reviews 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.

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.

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-β-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.

Purpose: Obesity and associated metabolic disorders represent a major global health challenge. The objective of this study was to determine the efficacy of a Multifaceted Lifestyle Program (MLP, combining dietary advice and supplementation with dietary fibre, probiotics and chromium) on weight, body composition and markers of metabolic health in overweight adults. Methods: Fifty-seven overweight adults (BMI 25–29.9 kg/m ² , aged 19–65 years) participated in an 8-week intervention trial, with 50 completing the study. Participants were randomised into three groups (A–C): A: placebo (rice powder; control); B: MLP + BioPB (an equal part blend of carrageenan, konjac and cellulose); and C: MLP + P (psyllium fibre). The primary outcome was changes in anthropometric and metabolic health indices at 4 and 8 weeks. The secondary outcome was the effect of the different fibres. Results: At week 4, participants receiving MLP + P and MLP + BioPB exhibited significant reductions ( p < 0.001) in body weight (− 4.8 kg; and − 5.1 kg, respectively), BMI (− 1.7 kg/m ² and − 1.7 kg/m ² , respectively), body fat mass (− 3.7 kg and − 4.2 kg) and visceral fat scores (− 1.9 and − 2.4). Some lean tissue mass loss was also evident. These changes were sustained for 4 weeks post-intervention. MLP + P and MLP + BioPB showed differing effects on blood lipids and inflammatory markers: reductions in cholesterol and LDL-cholesterol were greater and more persistent in the MLP + BioPB group, whereas the CRP levels (high CRP levels are linked to inflammation and metabolic disorders) were significantly reduced in the MLP + P group only. Significant improvements were also observed in the liver and kidney functions. No notable changes were observed in any parameters in the control group. Conclusion: The MLP, incorporating fibre supplementation, produced clinically significant improvements in body weight, BMI and body fat in overweight adults, offering a practical strategy for managing obesity. Importantly, the type of dietary fibre used had distinct metabolic effects, underscoring the need for tailored fibre interventions to optimise metabolic health.