Piperine inhibits adipocyte differentiation via dynamic regulation of histone modifications

Bioactive alkaloidal and phenolic phytochemicals as promising epidrugs for diabetes mellitus 2: A review of recent development

Type 2 diabetes (T2D) remains a major chronic metabolic disorder affecting hundreds of millions of the global population, mostly among adults, engendering high rates of morbidity and mortality. It is characterized by complex aetiologies including insulin deficiency and resistance, and hyperglycemia, and these significantly constitute therapeutic challenges. Several pathways have been implicated in its pathophysiology and treatment including the epigenetic regulatory mechanism, notably, deoxyribonucleic acid (DNA) methylation/demethylation, histone modification, non-coding ribonucleic acid (ncRNA) modulation and other relevant pathways. Many studies have recently documented the implications of phytochemicals on the aforementioned biomarkers in the pathogenesis and treatment of T2D. In this review, the cellular and molecular mechanisms of the epigenetic effects of some bioactive alkaloidal and phenolic phytochemicals as potential therapeutic alternatives for T2D have been overviewed from the recent literature (2019-2024). From the survey, the natural product-based compounds, C1-C32 were curated as potent epigenetic modulators for T2D. Their cellular and molecular mechanisms of anti-T2D activities with relevant epigenetic biomarkers were revealed. Although, more comprehensive experimental analyses are observably required for validating their activity and toxicological indices. Thus, perspectives and challenges were enumerated for such demanding future translational studies. The review reveals advances in scientific efforts towards reversing the global trend of T2D through epigenetic phytotherapeutics.

Epigenetic effects of herbal medicine

Epigenetic memory is essential for life that governs the predefined functional features of cells. Recent evidence has indicated that the epigenetic modification provides a potential link to gene expression changes that may be involved in the development of various chronic diseases, and targeting the epigenome becomes a plausible method for treating diseases. Traditional herbal medicine has gradually entered the vision of researchers due to its low toxicity and its effectiveness in treating diseases. As a matter of fact, researchers found that the possessed epigenetic modification capacity of herbal medicine had the ability to combat the progression of the disease, such as various types of cancer, diabetes, inflammation, amnesia, liver fibrosis, asthma, and hypertension-induced renal injury. Studies on the epigenetic effects of herbal medicine will provide valuable insights into the molecular mechanisms of human diseases, which may lead to new therapeutic approaches and diagnoses. Thus, this review summarized the impact of herbal medicine and its bioactive components on disease epigenome as examples of how utilization of epigenetic plasticity could be useful as the basis for the future development of targeted therapies in chronic diseases.

Shikonin Binds and Represses PPARγ Activity by Releasing Coactivators and Modulating Histone Methylation Codes

Shikonin, a natural ingredient produced by Lithospermum erythrorhizon, has anti-inflammatory, anti-cancer, and anti-obesity effects. It also inhibits adipocyte differentiation; however, the underlying molecular and epigenetic mechanisms remain unclear. We performed RNA-sequencing of shikonin-treated 3T3-L1 cells. Gene ontology and gene set enrichment analysis showed that shikonin is significantly associated with genes related to adipogenesis, histone modification, and PPARγ. Shikonin treatment downregulated the mRNA expression of PPARγ-responsive genes and rosiglitazone-induced transcriptional activity of PPARγ. Microscale thermophoresis assays showed a KD value 1.4 ± 0.13 μM for binding between shikonin and PPARγ. Glutathione S-transferase pull-down assays exhibited that shikonin blocked the rosiglitazone-dependent association of PPARγ with its coactivator CBP. In addition, shikonin decreased the enrichment of the active histone code H3K4me3 and increased the repressive code H3K27me3 of PPARγ target promoters. Shikonin is a PPARγ antagonist that suppresses adipogenesis by regulating the enrichment of histone codes during adipogenesis. Therefore, it may be used to treat obesity-related disorders via epigenetic changes.

Trained immunity in monocyte/macrophage: Novel mechanism of phytochemicals in the treatment of atherosclerotic cardiovascular disease

Atherosclerosis (AS) is the pathology of atherosclerotic cardiovascular diseases (ASCVD), characterized by persistent chronic inflammation in the vessel wall, in which monocytes/macrophages play a key role. It has been reported that innate immune system cells can assume a persistent proinflammatory state after short stimulation with endogenous atherogenic stimuli. The pathogenesis of AS can be influenced by this persistent hyperactivation of the innate immune system, which is termed trained immunity. Trained immunity has also been implicated as a key pathological mechanism, leading to persistent chronic inflammation in AS. Trained immunity is mediated via epigenetic and metabolic reprogramming and occurs in mature innate immune cells and their bone marrow progenitors. Natural products are promising candidates for novel pharmacological agents that can be used to prevent or treat cardiovascular diseases (CVD). A variety of natural products and agents exhibiting antiatherosclerotic abilities have been reported to potentially interfere with the pharmacological targets of trained immunity. This review describes in as much detail as possible the mechanisms involved in trained immunity and how phytochemicals of this process inhibit AS by affecting trained monocytes/macrophages.

The influence of phytochemicals on cell heterogeneity in chronic inflammation-associated diseases: the prospects of single cell sequencing

Chronic inflammation-associated diseases include, but is not limited to cardiovascular disease, cancer, obesity, diabetes, etc. Cell heterogeneity is a prerequisite for understanding the physiological and pathological development of cell metabolism, and its response to external stimuli. Recently, dietary habits based on phytochemicals became increasingly recognized to play a pivotal role in chronic inflammation. Phytochemicals can relieve chronic inflammation by regulating inflammatory cell differentiation and immune cell response, but the influence of phytochemicals on cell heterogeneity from in vitro and ex vivo studies cannot simulate the complexity of cell differentiation in vivo due to the differences in cell lines and extracellular environment. Therefore, there is no consensus on the regulation mechanism of phytochemicals on chronic diseases based on cell heterogeneity. The purpose of this review is to summarize cell heterogeneity in common chronic inflammation-associated diseases and trace the effects of phytochemicals on cell differentiation in chronic diseases development. More importantly, by discussing the problems and challenges which hinder the study of cell heterogeneity in recent nutritional assessment experiments, we propose new prospects based on the drawbacks of existing research to optimize the research on the regulation mechanism of phytochemicals on chronic diseases. The need to explore precise measurements of cell heterogeneity is a key pillar in understanding the influence of phytochemicals on certain diseases. In the future, deeper understanding of cell-to-cell variation and the impact of food components and their metabolites on cell function by single-cell genomics and epigenomics with the focus on individual differences will open new avenues for the next generation of health care.

A review on the bioavailability, bio-efficacies and novel delivery systems for piperine

As the major naturally occurring alkaloid in pepper with a pungent taste, piperine is known for its beneficial biological functions and therapeutic effects. In this work, the bioavailability and biological activities of piperine were presented and discussed. Novel delivery systems for enhancing the bioavailability of piperine were also reviewed. This study could provide a better understanding of the physiological and biochemical aspects of piperine to be further developed in the food and nutraceutical industries.

The PPARα and PPARγ Epigenetic Landscape in Cancer and Immune and Metabolic Disorders

Peroxisome proliferator-activated receptors (PPARs) are ligand-modulated nuclear receptors that play pivotal roles in nutrient sensing, metabolism, and lipid-related processes. Correct control of their target genes requires tight regulation of the expression of different PPAR isoforms in each tissue, and the dysregulation of PPAR-dependent transcriptional programs is linked to disorders, such as metabolic and immune diseases or cancer. Several PPAR regulators and PPAR-regulated factors are epigenetic effectors, including non-coding RNAs, epigenetic enzymes, histone modifiers, and DNA methyltransferases. In this review, we examine advances in PPARα and PPARγ-related epigenetic regulation in metabolic disorders, including obesity and diabetes, immune disorders, such as sclerosis and lupus, and a variety of cancers, providing new insights into the possible therapeutic exploitation of PPAR epigenetic modulation.

Piperine treating sciatica through regulating inflammation and MiR-520a/P65 pathway

Although the etiology of sciatica remains uncertain, there is increasing evidence that the disease process of sciatica is associated with the levels of inflammatory factors. Piperine, an alkaloid isolated from Piper nigrum, has previously been demonstrated to inhibit inflammation and analgesic effects. The purpose of this study is to verify the regulatory relationship between miR-520a and p65 and to explore how miR-520a/P65 affects the level of cytokines under the action of piperine, so as to play a therapeutic role in sciatica. Through ELISA experiment, we confirmed that four inflammatory factors (IL-1β, TNF-α, IL-10, TGF-β1) can be used as evaluation indexes of sciatica. The differentially expressed miRNA was screened as miR-520a, by microarray technology, and the downstream target of miR-520a was P65 by bioinformatics. Real-time fluorescence quantitative PCR confirmed that the expression of miR-520a was negatively correlated with pro-inflammatory cytokines, positively correlated with anti-inflammatory cytokines and negatively correlated with p65 expression at mRNA level. The expression of p65 was positively correlated with pro-inflammatory cytokines and negatively correlated with anti-inflammatory cytokines at the protein level verified by ELISA and Western blot. HE staining analysis showed that the nerve fibers were repaired by piprine, the vacuoles were significantly reduced, and the degree of nerve fiber damage was also improved. Immunohistochemical analysis showed that the expression of p65 decreased after administration of piperine. Dual-luciferase reporter gene assay confirmed that the luciferase signal decreased significantly after cotransfection of miR-520a mimics and p65 3'UTR recombinant plasmid. To sum up, in the rat model of non-compressed lumbar disc herniation, piperine plays a significant role in analgesia. MiR-520a can specifically and directly target P65, and piperine can promote the expression of miR-520a, then inhibit the expression of p65, down-regulate the pro-inflammatory factors IL-1β and TNF-α, and up-regulate the effects of anti-inflammatory factors IL-10 and TGF-β1, so as to treat sciatica.

Natural products and analogs as preventive agents for metabolic syndrome via peroxisome proliferator-activated receptors: An overview

Natural products and synthetic analogs have drawn much attention as potential therapeutical drugs to treat metabolic syndrome. We reviewed the underlying mechanisms of 32 natural products and analogs with potential pharmacological effects in vitro, and especially in rodent models and/or patients, that usually act on the PPAR pathway, along with other molecular targets. Recent outstanding total syntheses or semisyntheses of these lead compounds are stated. In general, they can activate the transcriptional activity of PPARα, PPARγ, PPARα/γ, PPARβ/δ, PPARα/δ, PPARγ/δ and panPPAR as weak, partial agonists or selective PPARγ modulators (SPPARγM), which may be useful for managing obesity, type 2 diabetes (T2D), dyslipidemia and non-fatty liver disease (NAFLD). Terpenoids is the largest group of compounds that act as potential modulators on PPARs and are comprised from small lipophilic cannabinoids to lipophilic pentacyclic triterpenes and polar saponins. Shikimates-phenylpropanoids include polar heterocyclic flavonoids and phenolic compounds containing at least one C3-C6 unit and usually a double bond on the propyl chain. Quercetin (19), resveratrol (24) and curcumin (27), stand out from this group for exhibiting beneficial effects on patients. Alkaloids, the minor group of potential modulators on PPARs, include berberine (30), which has been widely explored in preclinical and clinical studies for its potential beneficial effects on T2D and dyslipidemia. However, large-scale clinical trials may be warranted for the promising compounds.

Interaction between piperine and genes associated with sciatica and its mechanism based on molecular docking technology and network pharmacology

Abstract

Piperine is the main active component of Piper longum L., which is also the main component of anti-sciatica Mongolian medicine Naru Sanwei pill. It has many pharmacological activities such as anti-inflammatory and immune regulation. This paper aims to preliminarily explore the potential mechanism of piperine in the treatment of sciatica through network pharmacology and molecular docking. TCMSP, ETCM database and literature mining were used to collect the active compounds of Piper longum L. Swiss TargetPrediction and SuperPred server were used to find the targets of compounds. At the same time, CTD database was used to collect the targets of sciatica. Then the above targets were compared and analyzed to select the targets of anti-sciatica in Piper longum L. The Go (gene ontology) annotation and KEGG pathway of the targets were enriched and analyzed by Metascape database platform. The molecular docking between the effective components and the targets was verified by Autodock. After that, the sciatica model of rats was established and treated with piperine. The expression level of inflammatory factors and proteins in the serum and tissues of rat sciatic nerve were detected by ELISA and Western blot. HE staining and immunohistochemistry were carried out on the sciatica tissues of rats. The results showed that Piper longum L. can regulate the development of sciatica and affect the expressions of PPARG and NF-kB1 through its active ingredient piperine, and there is endogenous interaction between PPARG and NF-kB1.

Graphic abstract