A comprehensive in-vitro/in-vivo screening toolbox for the elucidation of glucose homeostasis modulating properties of plant extracts (from roots) and its bioactives

Plant extracts are increasingly recognized for their potential in modulating (postprandial) blood glucose levels. In this context, root extracts are of particular interest due to their high concentrations and often unique spectrum of plant bioactives. To identify new plant species with potential glucose-lowering activity, simple and robust methodologies are often required. For this narrative review, literature was sourced from scientific databases (primarily PubMed) in the period from June 2022 to January 2024. The regulatory targets of glucose homeostasis that could be modulated by bioactive plant compounds were used as search terms, either alone or in combination with the keyword "root extract". As a result, we present a comprehensive methodological toolbox for studying the glucose homeostasis modulating properties of plant extracts and its constituents. The described assays encompass in-vitro investigations involving enzyme inhibition (α-amylase, α-glucosidase, dipeptidyl peptidase 4), assessment of sodium-dependent glucose transporter 1 activity, and evaluation of glucose transporter 4 translocation. Furthermore, we describe a patch-clamp technique to assess the impact of extracts on KATP channels. While validating in-vitro findings in living organisms is imperative, we introduce two screenable in-vivo models (the hen's egg test and Drosophila melanogaster). Given that evaluation of the bioactivity of plant extracts in rodents and humans represents the current gold standard, we include approaches addressing this aspect. In summary, this review offers a systematic guide for screening plant extracts regarding their influence on key regulatory elements of glucose homeostasis, culminating in the assessment of their potential efficacy in-vivo. Moreover, application of the presented toolbox might contribute to further close the knowledge gap on the precise mechanisms of action of plant-derived compounds.

Environmentally benign silver bio-nanomaterials as potent antioxidant, antibacterial, and antidiabetic agents: Green synthesis using Salacia oblonga root extract

Introduction: The use of plant extracts in the green synthesis of metallic nanoparticles is one of the simplest, most practical, economical, and ecologically friendly methods for avoiding the use of toxic chemicals. Method: Silver nanoparticles (AgNPs) were synthesized, employing a high-efficiency, non- toxic, cost-effective, green, and simple technique that included the use of Salacia oblonga root extract (SOR) as a capping agent compared to synthetic nanoparticles. The use of S. oblonga can be seen in traditional medicines for treating diabetes, obesity, rheumatism, gonorrhea, asthma, and hyperglycemia. The objectives of the current study were to green synthesize S. oblonga root extract silver nanoparticles (SOR-AgNPs), characterize them, and study their antioxidant, antibacterial, and antidiabetic activities. Result: The shape of SOR-AgNPs was spherical, at less than 99.8 nm in size, and exhibited a crystalline peak at XRD. The green synthesized SOR-AgNPs showed significant antioxidant properties like DPPH (80.64 μg/mL), reducing power capacity (81.09 ± SEM μg/mL), nitric oxide (96.58 μg/mL), and hydroxyl (58.38 μg/mL) radical scavenging activities. The MIC of SOR-AgNPs was lower in gram-positive bacteria. The SOR-AgNPs have displayed efficient inhibitory activity against α-amylase, with an EC50 of 58.38 μg/mL. Analysis of capping protein around the SOR-AgNPs showed a molecular weight of 30 kDa. Discussion: These SOR-AgNPs could be used as antibacterial and antidiabetic drugs in the future as it is cheap, non-toxic, and environmentally friendly. Bio-fabricated AgNPs had a significant impact on bacterial strains and could be used as a starting point for future antibacterial drug development.

Antimicrobial Activities of Salacia oblonga Wall Leaf and Root Extracts Against Different Bacterial Strains and Fungal Isolates

Antibiotic resistance and the hazardous nature of synthetic drugs is threatening issue in the health sector. The alternative for this problem is to focus on plants that attribute to various compounds that exhibit therapeutic properties. Therefore, the study aims to evaluate the antimicrobial efficacy of Salacia oblonga leaf and root extracts against tested human pathogens. The S. oblonga extracts showed a significant zone of inhibition against bacteria and fungi. The leaf and root extracts of S. oblonga are prepared using low polar to high polar solvents in the Soxhlet apparatus and tested on the selected bacterial and fungal strains. Agar well diffusion and broth dilution methods evaluate antibacterial activity, antifungal activity, and Minimum Inhibitory Concentration (MIC) of extracts. Among the extracts tested, the ethyl acetate extract of root showed more antimicrobial activity against the tested bacterial and fungal strains. The most susceptible bacterial and fungal species against ethyl acetate extract are Micrococcus luteus, Mycobacterium tuberculosis, Microsporum canis, Trichophyton interdigitale, and Microsporum gypseum. The MIC for bacteria ranged from 13.0 to > 200 µg/ml, whereas for fungi, the MIC ranged from 25.9 to > 200 µg/ml. Ethyl acetate extract of root with 100 µg/ml concentration showed 29.1 mm and 28.7 mm zone of inhibition against bacterial strains M. luteus and M. tuberculosis, respectively. The ethyl acetate extract of root with a 100 µg/ml concentration showed 15.8, 15.2, and 15.6 mm zone of inhibition against fungal isolates M. canis, T. interdigitale, and M. gypseum, respectively. The activity of root and leaf extracts increased in a concentration-dependent manner, and further, the compounds isolated from the crude extracts of leaf and root showed antimicrobial activity. Structural elucidation of isolated compounds Lambertic acid and Ferruginol was done using NMR spectroscopy. Reports indicate that Lambertic acid was isolated previously, but the isolation of hydroxy Ferruginol from S. oblonga leaf extract was reported unprecedented.

Polyphenols of Frangula alnus and Peganum harmala Leaves and Associated Biological Activities

Frangula alnus and Peganum harmala populations growing in Saudi Arabia might be rich sources of natural compounds with important biological activities. A high performance liquid chromatography diode array revealed several polyphenols in the leaf extracts for the first time, including p-coumaric acid, rosmarinic acid, chlorogenic acid, ferulic acid, quercitrin, rutoside, quercetin and trifolin in F. alnus; and hydrocaffeic acid, protocatechuic acid, rosmarinic acid, caffeic acid and cynaroside in P. harmala. F. alnus and P. harmala showed strong antioxidant effects attributed to the polyphenolic composition of leaves and reduction of reactive oxygen species (ROS) accumulation. F. alnus and P. harmala leaf extracts showed cytotoxic effects against Jurkat, MCF-7, HeLa, and HT-29 cancer cells using MTT and flow cytometry assays. These activities were attributed to the polyphenolic composition of leaves including quercitrin, trifolin and cymaroside, as well as the activation of caspase family enzymes 2, 6, 8 and 9 in treated cancer cells compared to control. The current findings of this study include a novel comprehensive investigation on the polyphenol composition and anticancer effects of leaf extracts of F. alnus and P. harmala from natural populations in Saudi Arabia.