Diosmetin and Its Glycoside, Diosmin, Improve Atopic Dermatitis- Like Lesions in 2,4-Dinitrochlorobenzene-Induced Murine Models

Anti-Inflammatory Properties of the Citrus Flavonoid Diosmetin: An Updated Review of Experimental Models

Inflammation is an essential contributor to various human diseases. Diosmetin (3',5,7-trihydroxy-4'-methoxyflavone), a citrus flavonoid, can be used as an anti-inflammatory agent. All the information in this article was collected from various research papers from online scientific databases such as PubMed and Web of Science. These studies have demonstrated that diosmetin can slow down the progression of inflammation by inhibiting the production of inflammatory mediators through modulating related pathways, predominantly the nuclear factor-κB (NF-κB) signaling pathway. In this review, we discuss the anti-inflammatory properties of diosmetin in cellular and animal models of various inflammatory diseases for the first time. We have identified some deficiencies in current research and offer suggestions for further advancement. In conclusion, accumulating evidence so far suggests a very important role for diosmetin in the treatment of various inflammatory disorders and suggests it is a candidate worthy of in-depth investigation.

The Role of Diet and Nutrition in Allergic Diseases

Allergic diseases are a set of chronic inflammatory disorders of lung, skin, and nose epithelium characterized by aberrant IgE and Th2 cytokine-mediated immune responses to exposed allergens. The prevalence of allergic diseases, including asthma, allergic rhinitis, and atopic dermatitis, has increased dramatically worldwide in the past several decades. Evidence suggests that diet and nutrition play a key role in the development and severity of allergic diseases. Dietary components can differentially regulate allergic inflammation pathways through host and gut microbiota-derived metabolites, therefore influencing allergy outcomes in positive or negative ways. A broad range of nutrients and dietary components (vitamins A, D, and E, minerals Zn, Iron, and Se, dietary fiber, fatty acids, and phytochemicals) are found to be effective in the prevention or treatment of allergic diseases through the suppression of type 2 inflammation. This paper aims to review recent advances in the role of diet and nutrition in the etiology of allergies, nutritional regulation of allergic inflammation, and clinical findings about nutrient supplementation in treating allergic diseases. The current literature suggests the potential efficacy of plant-based diets in reducing allergic symptoms. Further clinical trials are warranted to examine the potential beneficial effects of plant-based diets and anti-allergic nutrients in the prevention and management of allergic diseases.

Citrus By-Products as a Valuable Source of Biologically Active Compounds with Promising Pharmaceutical, Biological and Biomedical Potential

Citrus fruits processing results in the generation of huge amounts of citrus by-products, mainly peels, pulp, membranes, and seeds. Although they represent a major concern from both economical and environmental aspects, it is very important to emphasize that these by-products contain a rich source of value-added bioactive compounds with a wide spectrum of applications in the food, cosmetic, and pharmaceutical industries. The primary aim of this review is to highlight the great potential of isolated phytochemicals and extracts of individual citrus by-products with bioactive properties (e.g., antitumor, antimicrobial, antiviral, antidiabetic, antioxidant, and other beneficial activities with health-promoting abilities) and their potential in pharmaceutical, biomedical, and biological applications. This review on citrus by-products contains the following parts: structural and chemical characteristics; the utilization of citrus by-products; bioactivities of the present waxes and carotenoids, essential oils, pectins, and phenolic compounds; and citrus by-product formulations with enhanced biocactivities. A summary of the recent developments in applying citrus by-products for the treatment of different diseases and the protection of human health is also provided, emphasizing innovative methods for bioaccessibility enhancements (e.g., extract/component encapsulation, synthesis of biomass-derived nanoparticles, nanocarriers, or biofilm preparation). Based on the representative phytochemical groups, an evaluation of the recent studies of the past six years (from 2018 to 2023) reporting specific biological and health-promoting activities of citrus-based by-products is also provided. Finally, this review discusses advanced and modern approaches in pharmaceutical/biological formulations and drug delivery (e.g., carbon precursors for the preparation of nanoparticles with promising antimicrobial activity, the production of fluorescent nanoparticles with potential application as antitumor agents, and in cellular imaging). The recent studies implementing nanotechnology in food science and biotechnology could bring about new insights into providing innovative solutions for new pharmaceutical and medical discoveries.

The macrophage polarization in inflammatory dermatosis and its potential drug candidates

Inflammatory dermatosis is characterized by persistent inflammatory infiltration and hard repair of diseased skin. As a member of the human innate immune cells, macrophages usually show different phenotypes in different diseases. The macrophage phenotype (M1/M2) imbalance caused by the increase of M1 macrophages or the decrease of M2 macrophages is common in inflammatory dermatosis. In recent years, with the deepening research on inflammatory skin diseases, more and more natural medicines/traditional Chinese medicines (TCMs), represented by Shikonin and Angelica Dahurica, have shown their therapeutic effects by affecting the polarization of macrophages. This review introduced macrophage polarization in different inflammatory dermatosis, such as psoriasis. Then summarized the natural medicines/TCMs that have potential therapeutic effects so far and introduced their mechanisms of action and the proteins/signal pathways involved. We found that the TCMs with therapeutic effects listed in this review are closely related to the theory of five flavors and four properties of Chinese medicinal, and most of them are bitter, acrid and sweet. Bitter TCMs have antipyretic, anti-inflammatory and antibacterial effects, which may improve the persistent inflammation of M1 macrophage infiltration. Acrid TCMs have the effect of promoting blood circulation, while sweet TCMs have the effect of nourishing. These 2 flavors may accelerate the repair of skin lesions of inflammatory dermatosis by affecting M2 macrophages. In conclusion, we hope to provide sufficient knowledge for natural medicine research and the development of inflammatory dermatosis related to macrophage phenotype imbalance.

Diosmin and its glycocalyx restorative and anti-inflammatory effects on injured blood vessels

The endothelium, a crucial homeostatic organ, regulates vascular permeability and tone. Under physiological conditions, endothelial stimulation induces vasodilator endothelial nitric oxide (eNO) release and prevents adhesion molecule accessibility and leukocyte adhesion and migration into vessel walls. Endothelium dysfunction is a principal event in cardiovascular disorders, including atherosclerosis. Minimal attention is given to an important endothelial cell structure, the endothelial glycocalyx (GCX), a negatively charged heterogeneous polysaccharide that serves as a protective covering for endothelial cells and enables endothelial cells to transduce mechanical stimuli into various biological and chemical activities. Endothelial GCX shedding thus plays a role in endothelial dysfunction, for example by increasing vascular permeability and decreasing vessel tone. Consequently, there is increasing interest in developing therapies that focus on GCX repair to limit downstream endothelium dysfunction and prevent further downstream cardiovascular events. Here, we present diosmin (3',5,7-trihydroxy-4'-methoxyflavone-7-rhamnoglucoside), a flavone glycoside of diosmetin, which downregulates adhesive molecule expression, decreases inflammation and capillary permeability, and upregulates eNO expression. Due to these pleiotropic effects of diosmin on the vasculature, a possible unidentified mechanism of action is through GCX restoration. We hypothesize that diosmin positively affects GCX integrity along with GCX-related endothelial functions. Our hypothesis was tested in a partial ligation left carotid artery (LCA) mouse model, where the right carotid artery was the control for each mouse. Diosmin (50 mg/kg) was administered daily for 7 days, 72 h after ligation. Within the ligated mice LCAs, diosmin treatment elevated the activated eNO synthase level, inhibited inflammatory cell uptake, decreased vessel wall thickness, increased vessel diameter, and increased GCX coverage of the vessel wall. ELISA showed a decrease in hyaluronan concentration in plasma samples of diosmin-treated mice, signifying reduced GCX shedding. In summary, diosmin supported endothelial GCX integrity, to which we attribute diosmin's preservation of endothelial function as indicated by attenuated expression of inflammatory factors and restored vascular tone.

Lobelia chinensis Extract and Its Active Compound, Diosmetin, Improve Atopic Dermatitis by Reinforcing Skin Barrier Function through SPINK5/LEKTI Regulation

The skin acts as a mechanical barrier that protects the body from the exterior environment, and skin barrier function is attributed to the stratum corneum (SC), which is composed of keratinocytes and skin lipids. Skin barrier homeostasis is maintained by a delicate balance between the differentiation and exfoliation of keratinocytes, and keratinocyte desquamation is regulated by members of the serine protease kalikrein (KLK) family and their endogenous inhibitor SPINK5/LEKTI (serine protease inhibitor Kazal type 5/lympho-epithelial Kazal-type-related inhibitor). Furthermore, SPINK5/LEKTI deficiency is involved in impaired skin barrier function caused by KLK over-activation. We sought to determine whether increased SPINK5/LEKTI expression ameliorates atopic dermatitis (AD) by strengthening skin barrier function using the ethanol extract of Lobelia chinensis (LCE) and its active compound, diosmetin, by treating human keratinocytes with UVB and using a DNCB-induced murine model of atopic dermatitis. LCE or diosmetin dose-dependently increased the transcriptional activation of SPINK5 promoter and prevented DNCB-induced skin barrier damage by modulating events downstream of SPINK5, that is, KLK, PAR2 (protease activated receptor 2), and TSLP (thymic stromal lymphopoietin). LCE or diosmetin normalized immune response in DNCB treated SKH-1 hairless mice as determined by reductions in serum immunoglobulin E and interleukin-4 levels and numbers of lesion-infiltrating mast cells. Our results suggest that LCE and diosmetin are good candidates for the treatment of skin barrier-disrupting diseases such as Netherton syndrome or AD, and that they do so by regulating SPINK5/LEKTI.

Potential Natural Biomolecules Targeting JAK/STAT/SOCS Signaling in the Management of Atopic Dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease caused by the dysregulation of cytokines and other immune mediators. JAK/STAT is a classical signal transduction pathway involved in various biological processes, and its dysregulation contributes to the key aspects of AD pathogenesis. Suppressor of cytokine signaling (SOCS) proteins negatively regulate the immune-related inflammatory responses mediated by the JAK/STAT pathway. JAK/STAT-mediated production of cytokines including IL-4, IL-13, IL-31, and TSLP inhibits the expression of important skin barrier proteins and triggers pruritus in AD. The expression of SOCS proteins regulates the JAK-mediated cytokines and facilitates maintaining the skin barrier disruptions seen in AD. STATs are crucial in dendritic-cell-activated Th2 cell differentiation in the skin, releasing inflammatory cytokines, indicating that AD is a Th2-mediated skin disorder. SOCS proteins aid in balancing Th1/Th2 cells and, moreover, regulate the onset and maintenance of Th2-mediated allergic responses by reducing the Th2 cell activation and differentiation. SOCS proteins play a pivotal role in inflammatory cytokine-signaling events that act via the JAK/STAT pathway. Therapies relying on natural products and derived biomolecules have proven beneficial in AD when compared with the synthetic regimen. In this review, we focused on the available literature on the potential natural-product-derived biomolecules targeting JAK/STAT/SOCS signaling, mainly emphasizing the SOCS family of proteins (SOCS1, SOCS3, and SOCS5) acting as negative regulators in modulating JAK/STAT-mediated responses in AD pathogenesis and other inflammatory disorders.

Diosmetin Affects Gene Expression on Human Lung Adenocarcinoma Cells

Objective

This study was aimed at investigating the effects of diosmetin (a natural flavonoid) on the gene expression of human lung adenocarcinoma (LUAD) cells.

Methods

HCC827 and A549 cells were used. MTT and colony formation assay were used to investigate the effects of diosmetin on cell proliferation and colony forming activity. The expression of mRNA, microRNA, and lncRNA in HCC827 and A549 cell lines after diosmetin treatment was measured using DNA microarray, microRNA chromatin immunoprecipitation assay (ChIP), and long noncoding RNA (lncRNA) ChIP. Part of the results were cross-validated by quantitative reverse transcription PCR (RT-qPCR), while some others were analyzed using bioinformatic tools.

Results

Diosmetin inhibited proliferation and colony formation of HCC827 and A549 cells. Investigation on gene expression profiles of A549 and HCC827 cells revealed that compared with the control group, diosmetin can up- or downregulated the expression of mRNAs, microRNAs, and lncRNAs. The top three candidates in each RNA category were cross-validated by RT-qPCR, from which single peaks were observed in the melt curves, showing a great specificity. After a comprehensive selection of the results from the mRNA ChIP, we performed GO and KEGG functional clustering analyses on the differentially expressed genes.

Conclusion

Diosmetin treatment induced gene expression of A549 and HCC827 cells. Our results will provide guidance for development of new diagnostic and therapeutic targets.

A comprehensive review of natural products against atopic dermatitis: Flavonoids, alkaloids, terpenes, glycosides and other compounds

Atopic dermatitis (AD) is considered a great challenge for human communities and imposes both physiological and mental burdens on patients. Natural products have widely been used to treat a wide range of diseases, including cancer, gastrointestinal diseases, asthma, neurological disorders, and infections. To seek potential natural products against AD, in the current review, we searched the terms "atopic dermatitis" and "natural product" in Pubmed, Medline, Web of Science，Science Direct, Embase, EBSCO, CINAHL, ACS. The results show that many natural products, especially puerarin, ferulic acid and ginsenosides, cound protect against AD. Meanwhile, we discussed the therapeutic mechanisms and showed that the natural products exert their anti-inflammatory effects by suppressing the quantity and activity of many inflammatory cell types and cytokines, including neutrophils, monocytes, lymphocytes, Langerhans cells, interleukins (ILs, including IL-1α, IL-1β, IL-4), TNF-α, and TSLP, IgE. via inhibition of JAK/STAT, MAPKs and NF-κB signaling pathways, thereby, halting the inflammatory cascade. Future investigations should focus on studies with more reflective of the clinical characteristics and demographics, so as to develop natural products that will be hopefully available for the treatment of human AD disease.