Abscisic acid identification in Okra, Abelmoschus esculentus L. (Moench): perspective nutraceutical use for the treatment of diabetes

Function and Mechanism of Abscisic Acid on Microglia-Induced Neuroinflammation in Parkinson's Disease

Parkinson's disease (PD), as a neurologically implemented disease with complex etiological factors, has a complex and variable pathogenesis. Accompanying further research, neuroinflammation has been found to be one of the possible factors in its pathogenesis. Microglia, as intrinsic immune cells in the brain, play an important role in maintaining microenvironmental homeostasis in the brain. However, over-activation of neurotoxic microglia in PD promotes neuroinflammation, which further increases dopaminergic (DA) neuronal damage and exacerbates the disease process. Therefore, targeting and regulating the functional state of microglia is expected to be a potential avenue for PD treatment. In addition, plant extracts have shown great potential in the treatment of neurodegenerative disorders due to their abundant resources, mild effects, and the presence of multiple active ingredients. However, it is worth noting that some natural products have certain toxic side effects, so it is necessary to pay attention to distinguish medicinal ingredients and usage and dosage when using to avoid aggravating the progression of diseases. In this review, the roles of microglia with different functional states in PD and the related pathways inducing microglia to transform into neuroprotective states are described. At the same time, it is discussed that abscisic acid (ABA) may regulate the polarization of microglia by targeting them, promote their transformation into neuroprotective state, reduce the neuroinflammatory response in PD, and provide a new idea for the treatment of PD and the selection of drugs.

Abscisic acid ameliorates d-galactose -induced aging in mice by modulating AMPK-SIRT1-p53 pathway and intestinal flora

Abscisic acid (ABA) is a plant hormone with various biological activities. Aging is a natural process accompanied by cognitive and physiological decline, and aging and its associated diseases pose a serious threat to public health, but its mechanisms remain insufficient. Therefore, the purpose of this study was to investigate the ameliorative effects of ABA on d-galactose (D-Gal)-induced aging in mice and to delve into its molecular mechanisms. Aging model was es-tablished by theintraperitoneal injection of D-Gal. We evaluated the oxidative stress by measuring superoxide dismutase (SOD), malondialdehyde (MDA), catalase (CAT) levels in serum. Proteins content in brain were determined by Western blot. D-Gal-induced brain damage was monitored by measuring the levels of acetylcholinesterase (AChE) content and hematoxylin-eosin staining (H&E). To evaluate the effects of ABA on aging, we measured the gut microbiota. The results demonstrated that ABA increased SOD, CAT and AChE, decreased MDA level. H&E staining showed that ABA could improve D-Gal-induced damage. In addition, ABA regulated the B-cell-lymphoma-2 (BCL-2) family and Phosphatidylinositol 3-kinase/Protein kinase B (PI3K/AKT) signaling pathway, while further regulating the acetylation of p53 protein by modulating the AMPK pathway and activating SIRT1 protein, thereby inhibiting the apoptosis of brain neurons and thus regulating the aging process. Interestingly, ABA improved the ratio of intestinal bacteria involved in regulating multiple metabolic pathways in the aging process, such as Bacteroides, Firmicutes, Lactobacillus and Ak-kermansia. In conclusion, the present study suggests that ABA may be responsible for improving and delaying the aging process by enhancing antioxidant activity, anti-apoptosis and regulating intestinal flora.

The effect of Abelmoschus esculentus L. (Okra) extract supplementation on glycaemic control, inflammation, kidney function and expression of PPAR-α, PPAR-γ, TGF-β and Nrf-2 genes in patients with diabetic nephropathy: a triple-blind, randomised, placebo-controlled trial

The present study was carried out to evaluate the effects of okra extract supplementation on kidney function, glycaemic control, inflammation and gene expression in patients with diabetic nephropathy (DN). A total of sixty-four DN patients based on the inclusion and exclusion criteria were recruited in this triple-blind placebo-controlled randomised clinical trial. Participants were randomly allocated to receive a 125-mg capsule of dried okra extract (DOE) (n 32) or placebo (n 32) for 10 weeks. At the baseline and endpoint of the trial, kidney function, glycaemic indices, inflammation and gene expression were evaluated. Statistical analysis showed that fasting blood glucose, HbA1c and insulin resistance significantly reduced in the DOE group although between-group analysis did not show any significant difference. Also, no significant difference was observed in urine protein, urine creatinine and high-sensitivity C-reactive protein between the two groups. Furthermore, gene expression of PPAR-α, PPAR-γ, transforming growth factor-beta and Nrf-2 did not affect the end of the trial in comparison with the baseline. According to the present study, DOE did not have impressive effects on kidney function, inflammation, glycaemic management and gene expression in patients with DN.

Targeting Metabolic Diseases: The Role of Nutraceuticals in Modulating Oxidative Stress and Inflammation

The escalating prevalence of metabolic and cardiometabolic disorders, often characterized by oxidative stress and chronic inflammation, poses significant health challenges globally. As the traditional therapeutic approaches may sometimes fall short in managing these health conditions, attention is growing toward nutraceuticals worldwide; with compounds being obtained from natural sources with potential therapeutic beneficial effects being shown to potentially support and, in some cases, replace pharmacological treatments, especially for individuals who do not qualify for conventional pharmacological treatments. This review delves into the burgeoning field of nutraceutical-based pharmacological modulation as a promising strategy for attenuating oxidative stress and inflammation in metabolic and cardiometabolic disorders. Drawing from an extensive body of research, the review showcases various nutraceutical agents, such as polyphenols, omega-3 fatty acids, and antioxidants, which exhibit antioxidative and anti-inflammatory properties. All these can be classified as novel nutraceutical-based drugs that are capable of regulating pathways to mitigate oxidative-stress- and inflammation-associated metabolic diseases. By exploring the mechanisms through which nutraceuticals interact with oxidative stress pathways and immune responses, this review highlights their potential to restore redox balance and temper chronic inflammation. Additionally, the challenges and prospects of nutraceutical-based interventions are discussed, encompassing bioavailability enhancement, personalized treatment approaches, and clinical translation. Through a comprehensive analysis of the latest scientific reports, this article underscores the potential of nutraceutical-based pharmacological treatment modulation as a novel avenue to fight oxidative stress and inflammation in the complex landscape of metabolic disorders, particularly accentuating their impact on cardiovascular health.

A Review: Pharmacological Activity and Phytochemical Profile of Abelmoschus esculentus (2010-2022)

Abelmoschus esculentus L. Moench (okra) which belongs to the family Malvaceae is a commonly consumed vegetable that consists of the seed component which is rich in polyphenolic compounds. The aim of this study is to highlight the chemical and biological diversity of A. esculentus. This plant contains many vitamins, minerals, proteins and carbohydrates in addition to flavonoids, terpenes, phenolic compounds and sterols. These variations in the chemical composition resulted in different therapeutic activities including antidiabetic, hypolipidemic, antioxidant, antimicrobial, anticancer, wound healing, hepatoprotective, immunomodulator, neuroprotective, and gastroprotective activities in addition to cardioprotective activity.

The ABA/LANCL Hormone/Receptor System in the Control of Glycemia, of Cardiomyocyte Energy Metabolism, and in Neuroprotection: A New Ally in the Treatment of Diabetes Mellitus?

Abscisic acid (ABA), long known as a plant stress hormone, is present and functionally active in organisms other than those pertaining to the land plant kingdom, including cyanobacteria, fungi, algae, protozoan parasites, lower Metazoa, and mammals. The ancient, cross-kingdom role of this stress hormone allows ABA and its signaling pathway to control cell responses to environmental stimuli in diverse organisms such as marine sponges, higher plants, and humans. Recent advances in our knowledge about the physiological role of ABA and of its mammalian receptors in the control of energy metabolism and mitochondrial function in myocytes, adipocytes, and neuronal cells allow us to foresee therapeutic applications for ABA in the fields of pre-diabetes, diabetes, and cardio- and neuro-protection. Vegetal extracts titrated in their ABA content have shown both efficacy and tolerability in preliminary clinical studies. As the prevalence of glucose intolerance, diabetes, and cardiovascular and neurodegenerative diseases is steadily increasing in both industrialized and rapidly developing countries, new and cost-efficient therapeutics to combat these ailments are much needed to ensure disease-free aging for the current and future working generations.

Effects of okra (Abelmoschus esculentus (L.) Moench) on glycemic markers in animal models of diabetes: A systematic review

ETHNOPHARMACOLOGICAL RELEVANCE

Okra (Abelmoschus esculentus (L.) Moench) is traditionally used by different populations of Africa, América, Asia, and Europa to control diabetes. Although its action has been evaluated in several preclinical rodent trials, they have not been systematically analyzed.

OBJECTIVE

To evaluate the effectiveness of using okra in the treatment of diabetes in experimental rodent models.

MATERIAL AND METHODS

Controlled and randomized rodent animal trials with induced diabetes published between January 2000 and January 2021 were searched in the PubMed, Scopus, Scielo, and Web of Science databases. The search strategy included studies comprising the descriptors: animal species, diabetes induction method, intervention time, part of okra fruit used (whole, seeds, or peels), and dose as well as observed effects on biochemical and metabolic parameters. The systematic review was carried out according to the PRISMA statement, Cochrane bias risk tool (SYRCLE's RoB tool), and registered for systematic review protocols (PROSPERO).

RESULTS

A total of 326 articles were identified and after the exclusion of studies with gestational animal models, non-rodent animals, and non-diabetic animals, 11 studies involving 388 rodents were selected for the synthesis of results. The diabetes induction methods included streptozotocin, streptozotocin-nicotinamide, alloxan monohydrate, insulin resistance by high-fat diets or formulation described in AIN - 76, and feeding with high-fat food. Both Wistar albino rats, Sprague-Dawley males, and rats of both sexes of the Long-Evans lineage as well as male albino mice and C57BL females were included in the experiments. Studies showed that extracts of the fruit, the fresh fruit, or its various fractions had positive effects on the following markers: glycated hemoglobin, cholesterol, HOMA-IR, oral glucose tolerance test, and blood glucose, in acute (2 and 24 h), and chronic (up to 4 months) treatment.

CONCLUSION

An important hypoglycemic effect of okra in its various fractions on induced diabetes was observed by different authors. Moreover, okra promoted improvement in metabolic markers such as insulin sensitivity, lipid profile, and bodyweight loss.

In Vitro and In Vivo Evaluation of the Antidiabetic Activity of Solidago virgaurea Extracts

Background

Solidago virgaurea (Asteraceae) has been used for more than 700 years for treating cystitis, chronic nephritis, urolithiasis, rheumatism, and inflammatory diseases. However, the antidiabetic activity of Solidago virgaurea has been rarely studied.

Methods

Three extracts of Solidago virgaurea were prepared, and their antidiabetic potentials were evaluated by various cell-free, cell-based, and in vivo studies.

Results

We found that the Solidago virgaurea contained multiple bioactive phytochemicals based on the GC-MS analysis. The Solidago virgaurea extracts effectively inhibited the functions of the carbohydrate digestive enzyme (α-glucosidase) and protein tyrosine phosphatase 1B (PTP1B), as well as decreased the amount of advanced glycation end products (AGEs). In the L6 myotubes, the Solidago virgaurea methanolic extract remarkably enhanced the glucose uptake via the upregulation of glucose transporter type 4 (GLUT4). The extract also significantly downregulated the expression of PTP1B. In the streptozotocin-nicotinamide induced diabetic mice, the daily intraperitoneal injection of 100 mg/kg Solidago virgaurea methanolic extract for 24 days, substantially lowered the postprandial blood glucose level with no obvious toxicity. The extract's anti-hyperglycemic effect was comparable to that of the glibenclamide treatment.

Conclusion

Our findings suggested that the Solidago virgaurea extract might have great potential in the prevention and treatment of diabetes.

Abelmoschus esculentus (L.) Moench Pod Extract Revealed Antagonistic Effect against the Synergistic Antidiabetic Activity of Metformin and Acarbose upon Concomitant Administration in Glucose-Induced Hyperglycemic Mice

Abelmoschus esculentus (L.) Moench, commonly known as okra, is one of the most widely used vegetable crops currently used for diabetes treatment as well. It is thought that the large amount of soluble dietary fibers present in okra is responsible for the slowing of the absorption of glucose from the gut. However, its role in concomitant administration with commonly prescribed medications, including metformin (MET) and acarbose (ACR) for diabetes, is unclear. Therefore, this study assessed the effect of A. esculentus pod extract (AEE) administered concomitantly with MET and ACR in the glucose-induced hyperglycemic mice model. The AEE was prepared using green okra pods. In this experiment, each male Swiss Webster mouse was administered a 2.5 gm/kg/BW dose of glucose via gastric lavage to induce hyperglycemia. The experimental animals were divided into five groups: (i) negative control, (ii) positive control, (iii) MET only, (iv) MET and ACR, and (v) MET, ACR, and AEE. The orally administered doses of the MET, ACR, and the extract were 150 mg/kg/BW, 15 mg/kg/BW, and 0.2 mL/kg/BW, respectively. We found that MET only and a combination of MET and ACR reduced glucose levels significantly (p < 0.01) compared to the positive control. On the other hand, when MET, ACR, and AEE were administered simultaneously, the synergistic antihyperglycemic action of the MET and ACR was diminished. After 150 min, the blood glucose level was 4.50 ± 0.189 mmol/L (iv) and 6.58 ± 0.172 mmol/L (v). This study suggests that taking AEE concurrently with MET and ACR would reduce the effectiveness of antidiabetic drugs; thereby, concomitant administration of these antidiabetic agents is not recommended. This study provides an essential basis for decision-making about the consumption of AEE with conventional medicine. Further study is required to find the molecular insight of drug interactions in combination therapy of medicinal plants for diabetes.

Spatial variations in the biochemical potential of okra [Abelmoschus esculentus L. (Moench)] leaf and fruit under field conditions

Okra (Abelmoschus esculentus L. (Moench) plays a significant role in humans nutrition because its fresh leaves, stems, flowers, pods and seeds, are used for multiple purposes. The present study attempted to determine the spatial variations in biochemical attributes of osmoprotectants and the oxidative defense system of okra plants. Samples of soil and okra plants (leaves and fruits) were collected from three different locations: Faisalabad region-1 (7 JB-I), Faisalabad region-2 (7 JB-II) and Pindi Bhattian. Chlorophyll contents, glycine betaine (GB), ascorbic acid (AsA), total phenolics, hydrogen peroxide (H₂O₂), proline, and malondialdehyde (MDA) contents were analyzed in the leaves and fruits of okra plants. Soil analyses showed that pH, electrical conductivity (EC), phosphorus (P), potassium (K), iron (Fe), and saturation of soil were higher in Faisalabad region 2, while organic matter, sand, Zn, and Cu were higher in the Pindi Bhattian region. The results from okra leaves showed that Pindi Bhattian had higher chlorophyll a, GB and H₂O₂ contents, while Faisalabad region 1 had a higher ratio of chlorophyll a/b compared to the other regions. However, Faisalabad regions 2 and 1 had higher leaf phenolic contents, Faisalabad regions 1 and 2 showed higher leaf proline contents, and Faisalabad region 2 possessed higher AsA and MDA contents. Analyses of okra fruits showed that Faisalabad region 2 had higher chlorophyll a and total chlorophyll contents, while Faisalabad region 1 had higher chlorophyll b contents. Faisalabad region 2 and Pindi Bhattian had higher ratios of chlorophyll a/b, and Faisalabad region 1 showed higher phenolic, AsA, H₂O₂, and MDA contents of okra fruit, whereas the Faisalabad regions exhibited higher proline and GB contents than the Pindi Bhattian region. Overall, okra leaves and fruits showed better responses in the Faisalabad regions, and these results may be used to screen for okra cultivars with better tolerance under different environmental conditions.

Multi-Targeted Molecular Docking, Pharmacokinetics, and Drug-Likeness Evaluation of Okra-Derived Ligand Abscisic Acid Targeting Signaling Proteins Involved in the Development of Diabetes

Diabetes mellitus is a global threat affecting millions of people of different age groups. In recent years, the development of naturally derived anti-diabetic agents has gained popularity. Okra is a common vegetable containing important bioactive components such as abscisic acid (ABA). ABA, a phytohormone, has been shown to elicit potent anti-diabetic effects in mouse models. Keeping its anti-diabetic potential in mind, in silico study was performed to explore its role in inhibiting proteins relevant to diabetes mellitus- 11β-hydroxysteroid dehydrogenase (11β-HSD1), aldose reductase, glucokinase, glutamine-fructose-6-phosphate amidotransferase (GFAT), peroxisome proliferator-activated receptor-gamma (PPAR-gamma), and Sirtuin family of NAD(+)-dependent protein deacetylases 6 (SIRT6). A comparative study of the ABA-protein docked complex with already known inhibitors of these proteins relevant to diabetes was compared to explore the inhibitory potential. Calculation of molecular binding energy (ΔG), inhibition constant (pKi), and prediction of pharmacokinetics and pharmacodynamics properties were performed. The molecular docking investigation of ABA with 11-HSD1, GFAT, PPAR-gamma, and SIRT6 revealed considerably low binding energy (ΔG from −8.1 to −7.3 Kcal/mol) and predicted inhibition constant (pKi from 6.01 to 5.21 µM). The ADMET study revealed that ABA is a promising drug candidate without any hazardous effect following all current drug-likeness guidelines such as Lipinski, Ghose, Veber, Egan, and Muegge.

Okra (Abelmoschus esculentus L.) as a Potential Functional Food Source of Mucilage and Bioactive Compounds with Technological Applications and Health Benefits

Abelmoschus esculentus has fruit popularly known as okra and belongs to the Malvaceae family. It is commonly used in cooking but also in traditional medicine in the treatment of worms, dysentery, inflammation, and also irritation of the stomach, intestines, and kidneys, as it is a potential functional food. Its mucilage is a highly viscous polysaccharide that is mostly composed of monosaccharides D-galactose, L-rhamnose, and galacturonic acid, as well as proteins and minerals. The functional properties of okra mucilage have been widely studied, mainly for its potential antidiabetic activity; thus, its use as adjuvant or nutraceutical therapy for diabetes is very promising. Due to its rheological properties, it is a potential resource for pharmaceutical and food applications. Okra mucilage can be extracted by several methods, which can directly influence its physicochemical characteristics and biological activity. Features such as low cost, non-toxicity, biocompatibility, and high availability in nature arouse the interest of researchers for the study of okra mucilage. The survey of research on the applications of okra mucilage highlights the importance of using this promising source of bioactive compounds with interesting technological properties. The potential of okra as a functional food, the properties of okra mucilage, and its technological applications are discussed in this review.

Silymarin from Silybum marianum by Naviglio's extractor: a new and very efficient approach

The aim of this work is to compare new and traditional extraction methods to obtain silymarin from Silybum marianum, a biennial herbaceous plant of the Asteraceae family, present throughout the Mediterranean basin and used to treat several diseases. Silymarin primarily contains flavonolignans and flavonoids and is used in some pharmaceutical preparations to improve of liver function and as a protective against some hepatotoxins. In six extracts obtained by new and traditional extraction methods, the total contents of silymarin and its main flavonolignans, total phenols and condensed tannins were evaluated in addition to their respective antioxidant capacities. By the Naviglio extractor, that is a rapid solid-liquid dynamic extraction method, it is possible to obtain a fraction quantitatively more abundant than other methods, and with a lower content of tannins and phenolic compounds but with a higher content of flavonolignans, rare and expensive, and therefore easier to separate and purify.

Biological efficacy of zinc oxide nanoparticles against diabetes: a preliminary study conducted in mice

The antidiabetic, hypoglycemic and oral glucose tolerance test (OGTT) activities of zinc oxide nanoparticles (ZnONPs) were assessed in mice. ZnONPs were prepared by reacting Zn(NO3)2.6H2O and NaOH solution at 70°C with continuous stirring and then characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) techniques. Diabetes was induced by the intraperitoneal injection of streptozotocin (STZ) in mice, and then the blood glucose levels were determined by the glucose oxidase method. The experimental results revealed that ZnONPs suggestively (p<0.001) declined the blood glucose levels (39.79%), while these reductions were 38.78% for the cotreatment of ZnONPs and insulin, and 48.60% for insulin, respectively. In the hypoglycemic study, ZnONPs (8 and 14 mg/kg b.w) reduced approximately 25.13 and 29.15% of blood glucose levels, respectively. A similar reduction was found in the OGTT test, which is also a dose- and time-dependent manner. Overall, ZnONPs possess a potential antidiabetic activity, which could be validated by further mechanistic studies.

Structure, antioxidant property and protection on PC12 of a polysaccharide isolated and screened from Abelmoschus esculentus L.Moench (okra)

AeP-P-2, a pectic polysaccharide, was extracted from the fruit pod of okra. It composed of rhamnose (Rha), arabinose (Ara), glucose (Glc), galactose (Gal) and galacturonic acid (GalA) with the ratio of 4.75:2.01:1.00:4.91:7.24. The main structural feature of AeP-P-2 are 1,4-linked galacturonan units (homogalacturonan backbone) and (1 → 2) and (1 → 2,4) linked Rha (rhamnogalacturonan I region). And the other side chains contained →1)-linked Ara, (1 → 5)-linked Ara, (1 → 4)-linked Glc, (1 → 6)-linked Gal, (1 → 4)-linked Rha, (1 → 2,4)-linked Rha, →1)-linked Ara and →1)-linked Gal. When the concentration of AeP-P-2 was 3.2 mg/mL, the scavenging rates on DPPH·, ABTS, O^2-· and ·OH reached to 61.88%, 87.10%, 52.17% and 60.32%, respectively. AeP-P-2 also could protect PC12 cells from the damage of H₂O₂ and reduce apoptosis caused by oxidative damage by decreasing the level of ROS. The findings indicated that okra was a functional vegetable and AeP-P-2 was worth studying and developing into antioxidant component.

Isolation and Characterisation of Two Quercetin Glucosides with Potent Anti-Reactive Oxygen Species (ROS) Activity and an Olean-12-en Triterpene Glucoside from the Fruit of Abelmoschus esculentus (L.) Moench

Abelmoschus esculentus (Okra) is used in the traditional treatment of cancer, hyperlipidaemia and hyperglycaemia. We, therefore, investigated its composition and potential cytotoxic or antioxidant properties that might underlie its phytotherapeutic applications. Its methanolic fruit extract yielded compounds 1, 2 and 3, identified through NMR, UV and MS analyses as olean-12-en-3-O-β-d-glucopyranoside, isoquercitrin (quercetin glucoside) and 5,7,3',4'-tetrahydroxy-flavonol-3-O-[β-d-glucopyranosyl-(1→6)]-β-d-glucopyranoside (quercetin diglucoside), respectively. Following 48 h exposure, oleanene glucoside was mildly toxic to the HeLa and the MRC5-SV2 cancer cells, isoquercitrin was not toxic except at 100 μg/ml in HeLa, and quercetin diglucoside elicited no toxicity. In a 2',7'-dichlorofluorescein diacetate (DCFDA) assay of intracellular levels of reactive oxygen species (ROS), hydrogen peroxide increased ROS levels, an effect not affected by oleanene glucoside but protected against by isoquercitrin and quercetin diglucoside, with IC₅₀ values, respectively, of 2.7±0.5 μg/ml and 1.9±0.2 μg/ml (3 h post-treatment) and 2.0±0.8 μg/ml and 1.5±0.4 μg/ml (24 h post-treatment.) This is the first report of this oleanene skeleton triterpenoid in the plant. The work provides some insight into why the plant is included in remedies for cancers, cardiovascular complications and diabetes, and reveals it as a potential source of novel therapeutics.

Structural Properties, Bioactivities, and Applications of Polysaccharides from Okra [Abelmoschus esculentus (L.) Moench]: A Review

Okra [Abelmoschus esculentus (L.) Moench], as a kind of nutritive vegetable, is rich in flavonoids, polyphenols, polysaccharides, amino acids, and other bioactive substances and has various biological activities. As one of main bioactive components, okra polysaccharides (OPs), mainly comprising pectic polysaccharides, have various biological activities. OPs have been extensively investigated in recent years. Many studies characterized structures of OPs obtained by different extraction methods, which were confirmed to be rhamnogalacturonan-I-type polysaccharides in most cases. OPs have a thick and slimy texture, suggesting that they can be a promising source of texture modifiers for complex food matrices. They have various biological activities, such as antioxidant activity, immunomodulatory activity, hypoglycaemic activity, and improving intestinal function. Therefore, OPs may potentially serve as novel immunomodulators or an adjuvant for diabetic nephropathy. Up to now, there is no specific summary on the research progress of OPs. In this paper, the latest research progress on the extraction, purification, characterization, rheological properties, biological activities, and applications of OPs is reviewed, to provide the reference for the processing and comprehensive utilization of OPs in the future.

Natural products in diabetes research: quantitative literature analysis

The current study aimed to identify which natural products and which research directions are related to the major contributors to academic journals for diabetes therapy. Bibliometric data were extracted from the Web of Science online database using the search string TOPIC = (''natural product*' OR ''natural compound*' OR ''natural molecule*' OR 'phytochemical*' OR ''secondary metabolite*') AND TS = ('diabet*') and analysed by a bibliometric software, VOSviewer. The search yielded 3694 publications, which were collectively cited 80,791 times, with an H-index of 117 and 21.9 citations per publication on average. The top-contributing countries were India, the USA, China, South Korea and Brazil. Curcumin, flavanone, resveratrol, carotenoid, polyphenols, flavonol, flavone and berberine were the most frequently cited natural products or compound classes. Our results provide a brief overview of the major directions of natural product research in diabetes up to now and hint on promising avenues for future research.

The effect of okra (Abelmoschus esculentus) on lipid profiles and glycemic indices in Type 2 diabetic adults: Randomized double blinded trials

The aim of the present study was to investigate the effect of okra consumption on serum levels of lipid profiles and glycemic indices in Type 2 diabetic (T2D) patients. The present study was a randomized, double-blinded clinical trial, carried out in Kerman, Iran. Sixty T2D patients were randomized into intervention and control groups and received 10 g okra powder blended in 150 g conventional yogurt or conventional yogurt alone, along with dinner and lunch, for 8 weeks. Glycemic markers and lipid profile were assessed, as well as anthropometric measures, at the beginning and end of study. The findings showed that 8 weeks okra consumption resulted in a significant decrease in fasting plasma glucose (-15.61 ± 19.44 vs. -3.40 ± 24.78; p = .02), homeostatic model of assessment for insulin resistance (-1.17 ± 1.61 vs. -0.14 ± 1.64; p = .01), quantitative insulin sensitivity check index (0.01 ± 0.007 vs. 0.00 ± 0.01; p = .004), triacylglycerol (-22.30 ± 32.46 vs. -3.86 ± 30.57; p = .001), total cholesterol (-10.23 ± 10.36 vs. -2.03 ± 13.94; p = .004), low-density lipoprotein cholesterol (LDL-C; -8.15 ± 10.01 vs. -2.31 ± 9.37; p = .02), and LDL-C/high-density lipoprotein cholesterol (HDL-C) ratio (-0.28 ± 0.37 vs. -0.08 ± 0.24; p = .01). No significant difference was observed between groups in HDL-C, glycated hemoglobin, fasting insulin levels, and anthropometric measures. The present study suggests that okra consumption can elicit improvements in lipid profile, as well as glycemic markers, among T2D patients.

A Pilot Screening of Agro-Food Waste Products as Sources of Nutraceutical Formulations to Improve Simulated Postprandial Glycaemia and Insulinaemia in Healthy Subjects

The control of glucose homeostasis is the main goal for both the prevention and management of diabetes and pre-diabetes. Numerous drugs are available, despite their side effects. This is constantly leading people to be inclined to natural alternative treatments. Evidence indicates antioxidant-based nutraceuticals as an optimal tool for the glycaemic control. Currently, a great interest has been focused on the valorisation of agro-food by-products as sources of bioactive compounds including polyphenols. In this sense, we tested the efficacy of novel nutraceutical products based on polyphenolic extract from nectarines (NecP), tomato peels (TP), and olive leaves (EOL) on glycaemic and insulinemic responses. The three formulations contained, respectively, 0.007 mg abscisic acid (ABA)/g, 0.5 mg carotenoids/g, and 150 mg oleuropein/g. Twenty healthy subjects consumed a regular glucose solution (RG) or a treatment beverage (TB) obtained by mixing RG with the individual formulations (TB NecP, TB EOL, and TB TP), separately, and on different days. All three formulations significantly lowered the 30 min glucose plasma peak (p < 0.05 for all); similarly, NecP and TP also significantly lowered the 30 min insulin plasma peak (p < 0.05 for all). These results may lead to the hypothesis of a formulation of a multi-component nutraceutical with a synergistic efficacy for the glycaemic control.

Ready to Use Therapeutical Beverages: Focus on Functional Beverages Containing Probiotics, Prebiotics and Synbiotics

The growing global interest in functional foods containing nutrients capable of adding possible beneficial health effects is rapidly increasing both interest and consumer demand. In particular, functionalized beverages for their potential positive effect on health e.g., decreasing cholesterol level, lowering sugar, high fiber content, ability to enhance the immune system, and help digestion, have recently received special attention. Among the different beverages available on the market, probiotic dairy and non-dairy products have attracted much attention because of their affordable cost and their numerous therapeutic activities. Fermented milk and yogurt are currently worth €46 billion, with 77% of the market reported in Europe, North America, and Asia. Consumption of dairy beverages has some limitations due for example to lactose intolerance and allergy to milk proteins, thereby leading consumers to use non-dairy beverages such as fruit, grains, and vegetable juices to add probiotics to diet as well as driving the manufacturers to food matrices-based beverages containing probiotic cultures. The purpose of this review article is to evaluate the therapeutic performance and properties of dairy and non-dairy beverages in terms of probiotic, prebiotic, and synbiotic activities.

Multiple Cell Signalling Pathways of Human Proinsulin C-Peptide in Vasculopathy Protection

A major hallmark of diabetes is a constant high blood glucose level (hyperglycaemia), resulting in endothelial dysfunction. Transient or prolonged hyperglycemia can cause diabetic vasculopathy, a secondary systemic damage. C-Peptide is a product of cleavage of proinsulin by a serine protease that occurs within the pancreatic β-cells, being secreted in similar amounts as insulin. The biological activity of human C-peptide is instrumental in the prevention of diabetic neuropathy, nephropathy and other vascular complications. The main feature of type 1 diabetes mellitus is the lack of insulin and of C-peptide, but the progressive β-cell loss is also observed in later stage of type 2 diabetes mellitus. C-peptide has multifaceted effects in animals and diabetic patients due to the activation of multiple cell signalling pathways, highlighting p38 mitogen-activated protein kinase and extracellular signal-regulated kinase ½, Akt, as well as endothelial nitric oxide production. Recent works highlight the role of C-peptide in the prevention and amelioration of diabetes and also in organ-specific complications. Benefits of C-peptide in microangiopathy and vasculopathy have been shown through conservation of vascular function, and also in the prevention of endothelial cell death, microvascular permeability, neointima formation, and in vascular inflammation. Improvement of microvascular blood flow by replacing a physiological amount of C-peptide, in several tissues of diabetic animals and humans, mainly in nerve tissue, myocardium, skeletal muscle, and kidney has been described. A review of the multiple cell signalling pathways of human proinsulin C-peptide in vasculopathy protection is proposed, where the approaches to move beyond the state of the art in the development of innovative and effective therapeutic options of diabetic neuropathy and nephropathy are discussed.