The discovery of novel isoflavone pan peroxisome proliferator-activated receptor agonists

Metabolites of endophytic fungi isolated from leaves of Bauhinia variegata exhibit antioxidant activity and agonist activity on peroxisome proliferator-activated receptors α, β/δ and γ

Diabetes mellitus is a metabolic disorder that affects millions of people worldwide and is linked to oxidative stress and inflammation. Thiazolidinediones (TZD) improve insulin sensitization and glucose homeostasis mediated by the activation of peroxisome proliferator-activated receptors γ (PPARγ) in patients with type 2 diabetes. However, their use is associated with severe adverse effects such as loss of bone mass, retention of body fluids, liver and heart problems, and increased risk of bladder cancer. Partial PPARγ agonists can promote the beneficial effects of thiazolidinediones with fewer adverse effects. Endophytic fungi colonize plant tissues and have a particularly active metabolism caused by the interaction with them, which leads to the production of natural products with significant biological effects that may be like that of the colonized plant. Here, we identify seven endophytic fungi isolated from Bauhinia variegata leaves that have antioxidant activities. Also, one of the extracts presented pan-agonist activity on PPAR, and another showed activity in PPARα and PPARβ/δ. A better understanding of this relationship could help to comprehend the mechanism of action of antioxidants in treating diabetes and its complications. Moreover, compounds with these capabilities to reduce oxidative stress and activate the receptor that promotes glucose homeostasis are promising candidates in treatment of diabetes.

Ameliorative effects of Portulaca oleracea L. (purslane) on the metabolic syndrome: A review

ETHNOPHARMACOLOGICAL RELEVANCE

The metabolic syndrome, which comprises hyperglycemia, dyslipidemia, abdominal obesity, and hypertension, is a worldwide problem. This disorder is a significant risk factor for insulin resistance, diabetes mellitus, cardiovascular disease incidence, and mortality. The value of herbs and natural products in the treatment of human ailments has been documented in several inquiries. An annual herbaceous plant called Portulaca oleracea L. (purslane) is used both as a traditional medicine and an edible plant to treat various ailments including gastrointestinal diseases and liver inflammation. Purslane contains a variety of secondary metabolites such as organic acids, flavonoids, terpenoids, and alkaloids.

AIM OF THE STUDY

In the current work, our team aims to shed light on the potential efficacy of purslane and its main components in treating metabolic syndrome and its complications.

STUDY DESIGN

Scopus, Google Scholar, and PubMed databases have been used to gather the most relevant in vitro, in vivo studies, and clinical trials from the time of inception up to February 2022.

RESULTS

The effects of purslane on metabolism are among its most significant pharmacological properties. In patients with metabolic syndrome, purslane could significantly lower blood glucose and balance lipid profiles. This indicates that purslane might have a potential role in the management of metabolic syndrome through different underlying mechanisms including antioxidant, anti-inflammatory, anti-hyperlipidemic, anti-obesity, and antidiabetic.

CONCLUSION

According to previous investigations, purslane can control metabolic syndrome and its complications. However, further preclinical and clinical studies are required to approve the advantageous effects of purslane on metabolic syndrome.

Quantitative determination of isoflavonoids in Ononis species by UPLC-UV-DAD

INTRODUCTION

The root of the Ononis species has been used internally and externally in ethnomedicine for centuries and contains biologically valuable isoflavonoid compounds. Therefore, it is important to obtain quantitative information about the isoflavonoid profile of these plants.

OBJECTIVES

In this article we aimed to develop an optimised sample preparation protocol alongside a validated method for the quantitative measurement of isoflavones, isoflavanones and pterocarpans in the form of glucosides and aglycones, in order to compare the specialised metabolites of Ononis spinosa L. and O. arvensis L.

MATERIAL AND METHODS

Quantitative determination was carried out by the means of ultra-performance liquid chromatography coupled with ultraviolet diode-array detection (UPLC-UV-DAD).

RESULTS

An optimised sample preparation method was developed to transform malonyl glucosides to their glucosidic forms. Chromatographic methods were created for the baseline separation of isoflavones, isoflavanones and pterocarpans alongside with their glucosides. Altogether 12 compounds were evaluated quantitatively in samples of O. spinosa and O. arvensis.

CONCLUSION

As a result, no characteristic change could be observed between the two species regarding their isoflavonoid pattern.

Molecules Isolated from Mexican Hypoglycemic Plants: A Review

Like in many developing countries, in Mexico, the use of medicinal plants is a common practice. Based on our own field experience, there are at least 800 plants used for treating diabetes nowadays. Thus, their investigation is essential. In this context, this work aims to provide a comprehensive and critical review of the molecules isolated from Mexican hypoglycemic plants, including their source and target tested. In the last few years, some researchers have focused on the study of Mexican hypoglycemic plants. Most works describe the hypoglycemic effect or the mechanism of action of the whole extract, as well as the phytochemical profile of the tested extract. Herein, we analyzed 85 studies encompassing 40 hypoglycemic plants and 86 active compounds belonging to different classes of natural products: 28 flavonoids, 25 aromatic compounds, other than flavonoids, four steroids, 23 terpenoids, 4 oligosaccharides, and 1 polyalcohol. These compounds have shown to inhibit α-glucosidases, increase insulin secretion levels, increase insulin sensitivity, and block hepatic glucose output. Almost half of these molecules are not common metabolites, with a narrow taxonomic distribution, which makes them more interesting as lead molecules. Altogether, this analysis provides a necessary inventory useful for future testing of these active molecules against different hypoglycemic targets, to get a better insight into the already described mechanisms, and overall, to contribute to the knowledge of Mexican medicinal plants.

Isolation and Biological Properties of the Natural Flavonoids Pectolinarin and Pectolinarigenin-A Review

Flavonoids are metabolites widely distributed in plants and commonly present in foods, such as fruits and vegetables. Pectolinarin, which belongs to the flavone subclass, has attracted considerable attention due to its presence in many medicinal plants. It has turned out to be a good biological agent especially due to its antioxidant, anti-inflammatory, antidiabetic, and antitumor activities, evaluated both in vitro and in vivo. Its aglycone, the metabolite pectolinarigenin, is also known for a series of biological properties including anti-inflammatory and antidiabetic effects. In the first overview on the two metabolites here presented, their collection, isolation and the results of their biological evaluation are reported.

Bioactive flavonoids in medicinal plants: Structure, activity and biological fate

Flavonoids, a class of polyphenol secondary metabolites, are presented broadly in plants and diets. They are believed to have various bioactive effects including anti-viral, anti-inflammatory, cardioprotective, anti-diabetic, anti-cancer, anti-aging, etc. Their basic structures consist of C₆-C₃-C₆ rings with different substitution patterns to produce a series of subclass compounds, and correlations between chemical structures and bioactivities have been studied before. Given their poor bioavailability, however, information about associations between structure and biological fate is limited and urgently needed. This review therefore attempts to bring some order into relationships between structure, activity as well as pharmacokinetics of bioactive flavonoids.

Synthetic and natural Peroxisome Proliferator-Activated Receptor (PPAR) agonists as candidates for the therapy of the metabolic syndrome

INTRODUCTION

Peroxisome proliferator-activated receptors (PPARs) are the molecular targets of hypolipidemic and insulin-sensitizing drugs and implicated in a multitude of processes that fine-tune the functions of all organs in vertebrates. As transcription factors they sense endogenous and exogenous lipid signaling molecules and convert these signals into intricate gene responses that impact health and disease. The PPARs act as modulators of cellular, organ, and systemic processes, such as lipid and carbohydrate metabolism, making them valuable for understanding body homeostasis influenced by nutrition and exercise. Areas covered: This review concentrates on synthetic and natural PPAR ligands and how they have helped reveal many aspects of the transcriptional control of complex processes important in health. Expert opinion: The three PPARs have complementary roles in the fine-tuning of most fundamental body functions, especially energy metabolism. Understanding their inter-relatedness using ligands that simultaneously modulate the activity of more than one of these receptors is a major goal. This approach may provide essential knowledge for the development of dual or pan-PPAR agonists or antagonists as potential new health-promoting agents and for nutritional approaches to prevent metabolic diseases.

Bavachinin, as a novel natural pan-PPAR agonist, exhibits unique synergistic effects with synthetic PPAR-γ and PPAR-α agonists on carbohydrate and lipid metabolism in db/db and diet-induced obese mice

AIMS/HYPOTHESIS

Pan-peroxisome proliferator-activated receptor (PPAR) agonists have long been sought as therapeutics against the metabolic syndrome, but current PPAR agonists show limited efficacy and adverse effects. Natural herbs provide a structurally untapped resource to prevent and treat complicated metabolic syndrome.

METHODS

Natural PPAR agonists were screened using reporter gene, competitive binding and 3T3-L1 pre-adipocyte differentiation assays in vitro. The effects on metabolic phenotypes were verified in db/db and diet-induced obese mice. In addition, potentially synergistic actions of bavachinin (BVC, a novel natural pan-PPAR agonist from the fruit of the traditional Chinese glucose-lowering herb malaytea scurfpea) and synthetic PPAR agonists were studied through nuclear magnetic resonance, molecular docking, reporter gene assays and mouse studies.

RESULTS

BVC exhibited glucose-lowering properties without inducing weight gain and hepatotoxicity. Importantly, BVC synergised with thiazolidinediones, which are synthetic PPAR-γ agonists, and fibrates, which are PPAR-α agonists, to induce PPAR transcriptional activity, as well as to lower glucose and triacylglycerol levels in db/db mice. We further found that BVC occupies a novel alternative binding site in addition to the canonical site of synthetic agonists of PPAR, and that the synthetic PPAR-γ agonist rosiglitazone can block BVC binding to this canonical site but not to the alternative site.

CONCLUSIONS/INTERPRETATION

This is the first report of a synergistic glucose- and lipid-lowering effect of BVC and synthetic agonists induced by unique binding with PPAR-γ or -α. This combination may improve the efficacy and decrease the toxicity of marketed drugs for use as adjunctive therapy to treat the metabolic syndrome.

The role of PPARγ-mediated signalling in skin biology and pathology: new targets and opportunities for clinical dermatology

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that modulate the expression of multiple different genes involved in the regulation of lipid, glucose and amino acid metabolism. PPARs and cognate ligands also regulate important cellular functions, including cell proliferation and differentiation, as well as inflammatory responses. This includes a role in mediating skin and pilosebaceous unit homoeostasis: PPARs appear to be essential for maintaining skin barrier permeability, inhibit keratinocyte cell growth, promote keratinocyte terminal differentiation and regulate skin inflammation. They also may have protective effects on human hair follicle (HFs) epithelial stem cells, while defects in PPARγ-mediated signalling may promote the death of these stem cells and thus facilitate the development of cicatricial alopecia (lichen planopilaris). Overall, however, selected PPARγ modulators appear to act as hair growth inhibitors that reduce the proliferation and promote apoptosis of hair matrix keratinocytes. The fact that commonly prescribed PPARγ-modulatory drugs of the thiazolidine-2,4-dione class can exhibit a battery of adverse cutaneous effects underscores the importance of distinguishing beneficial from clinically undesired cutaneous activities of PPARγ ligands and to better understand on the molecular level how PPARγ-regulated cutaneous lipid metabolism and PPARγ-mediated signalling impact on human skin physiology and pathology. Surely, the therapeutic potential that endogenous and exogenous PPARγ modulators may possess in selected skin diseases, ranging from chronic inflammatory hyperproliferative dermatoses like psoriasis and atopic dermatitis, via scarring alopecia and acne can only be harnessed if the complexities of PPARγ signalling in human skin and its appendages are systematically dissected.

4',6-dimethoxyisoflavone-7-O-β-D-glucopyranoside (wistin) is a peroxisome proliferator-activated receptor γ (PPARγ) agonist that stimulates adipocyte differentiation

Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-dependent transcription factor that directly activates the expression of adipocyte-specific genes, and is universally accepted as the master regulator for adipocyte differentiation. Using a PPARγ luciferase reporter assay system, we showed that 4',6-dimethoxyisoflavone-7-O-β-D-glucopyranoside (wistin) dose-dependently activates PPARγ. Treatment with wistin enhanced the marker of adipocyte differentiation, such as triglyceride accumulation in 3T3-L1 cells. Real-time quantitative polymerase chain reaction showed that wistin increased the expression of PPARγ2 messenger RNA. Moreover, the addition of wistin upregulated the expression of PPARγ-target genes, aP2 and adiponectin in 3T3-L1 cells. To our knowledge, wistin is the first isoflavonoid O-glycoside that exhibits PPARγ agonist activity.

Hypoglycemic, antihyperglycemic, and antioxidant effects of the edible plant Anoda cristata

ETHNOPHARMACOLOGICAL RELEVANCE

Some studies refer that the entire plant of Anoda cristata is consumed as food and medicine; in particular for treating diabetes, inflammation, fever, cough, and wounds. The aim of this study was to establish the preclinical efficacy of Anoda cristata as hypoglycemic and/or antihyperglycemic agent using well-known animal models.

MATERIALS AND METHODS

The acute toxicity was analyzed by the Lorke method. Acute hypoglycemic as well as oral glucose and sucrose tolerance tests were used to determine the hypoglycemic and antihyperglycemic action of Anoda cristata. Several preparations of the plant, including a mucilage (M), an aqueous (T-AE), a free mucilage aqueous (FM-AE), and an organic (OE) extracts, were tested in healthy and NA-STZ-hyperglycemic mice. Glibenclamide (15mg/kg), acarbose (5mg/kg ) and metformin (200mg/kg) were used as positive controls. The major compounds acacetin (1) and diosmetin (2), isolated from an infusion of the plant applying chromatographic methods, were evaluated as hypoglycemic agents using the same assays. The FM-AE was tested also in rats with metabolic syndrome induced by a high-fructose fed. Finally some assays were performed to determine the antioxidant capacity of the FM-AE in vitro.

RESULTS

The results demonstrated that the extracts and compounds from Anoda cristata were effective for reducing blood glucose levels in healthy and NA-STZ-hyperglycemic mice when compared with vehicle groups (p<0.05). The FM-AE exerted also positive effect over different biochemical parameters altered in rats with metabolic syndrome induced by a fructose diet. FM-AE has also antioxidant action effectively trapping ONOO(-) and ROO(•) radicals. The major flavonoids isolated from the plant, namely acacetin (1) and diosmetin (2), caused significant hypoglycemic effect and possessed antioxidant activity.

CONCLUSION

Anoda cristata is effective to diminish glucose levels in vivo and to ameliorate different disorders related with the metabolic syndrome in rats. According to the results, the efficacy of Anoda cristata preparations could be due to the presence of active principles with different mode of actions at the molecular level, including α-glycosidases inhibitors, insulin secretagogues, glucose entrapment and radical trapping agents.

An unexpected three-component reaction of 2-alkylenecyclobutanone and N′-(2-alkynylbenzylidene)hydrazide with water

A silver(i)-catalyzed three-component reaction of 2-alkylenecyclobutanone, N′-(2-alkynylbenzylidene)hydrazide with water gives rise to 3-(pyrazolo[5,1-a]isoquinolin-1-yl)propanoic acids in good yields through 6-endo cyclization, [3 + 2] cycloaddition, and rearrangement.

Flavones: an important scaffold for medicinal chemistry

Flavones have antioxidant, anti-proliferative, anti-tumor, anti-microbial, estrogenic, acetyl cholinesterase, anti-inflammatory activities and are also used in cancer, cardiovascular disease, neurodegenerative disorders, etc. Also, flavonoids are found to have an effect on several mammalian enzymes like protein kinases that regulate multiple cell signaling pathways and alterations in multiple cellular signaling pathways are frequently found in many diseases. Flavones have been an indispensable anchor for the development of new therapeutic agents. The majority of metabolic diseases are speculated to originate from oxidative stress, and it is therefore significant that recent studies have shown the positive effect of flavones on diseases related to oxidative stress. Due to the wide range of biological activities of flavones, their structure-activity relationships have generated interest among medicinal chemists. The outstanding development of flavones derivatives in diverse diseases in very short span of time proves its magnitude for medicinal chemistry research. The present review gives detail about the structural requirement of flavone derivatives for various pharmacological activities. This information may provide an opportunity to scientists of medicinal chemistry discipline to design selective, optimize as well as poly-functional flavone derivatives for the treatment of multi-factorial diseases.