Honokiol suppresses 2,6-dinitrochlorobenzene-induced atopic dermatitis in mice

Delivery Strategies, Structural Modification, and Pharmacological Mechanisms of Honokiol: A Comprehensive Review

Honokiol (HK) is a traditional Chinese herbal bioactive compound that originates mainly from the Magnolia species, traditionally used to treat anxiety and stroke, as well as alleviation of flu symptoms. This natural product and its derivatives displayed diverse biological activities, including anticancer, antioxidant, anti-inflammatory, neuroprotective, and antimicrobial activities. However, its poor bioavailability and pharmacological activity require primary consideration in the development of HK-based drugs. Recent innovative HK formulations based on the nanotechnology approach allowed for improvement in both bioavailability and therapeutic efficacy. Chemical derivation and drug combination are also effective strategies to ameliorate the drawbacks of HK. In recent years, studies on HK derivatives and compositions have made great progress in the treatment of cancer, inflammation, bacterial infection, cardiovascular, and cerebrovascular diseases, demonstrating better activity than HK. The objective of this review is an examination of the recent developments in the field of pharmacological activity of HK and its drug-related issues, and approaches to improve its physicochemical and biological properties, including solubility, stability, and bioavailability. Recent patents and the ongoing clinical trials in HK are also summarized.

Inhibition of Ca2+-permeable TRPV3 and inflammatory cytokine release by honokiol and magnolol in human epidermal keratinocytes

Transient receptor potential vanilloid-3 (TRPV3) ion channels are prominently expressed in keratinocytes, playing a vital role in skin functions. Honokiol and magnolol (H&M) the primary bioactive constituents in Magnolia officinalis extract, demonstrate anti-inflammatory and skin-protective properties. Nevertheless, the underlying mechanism regarding their effect on Ca2+-permeable ion channels remain unclear. Our purpose in this study is to investigate the effect of H&M on TRPV3 and cytokine release in normal human epidermal keratinocytes (NHEKs), including its gain-of-function (GOF) mutants (G573S and G573C) associated with Olmstead syndrome. We performed whole-cell patch-clamp, fura-2 spectrofluorimetry to investigate channels activity, CCK-8 assay to analyze cell death and enzyme-linked immunosorbent assay to assess the cytokine release from NHEKs. H&M inhibited the TRPV3 current (ITRPV3) and cytosolic calcium increase in NHEKs, HEK293T cells overexpressing hTRPV3 and its GOF mutants. Moreover, the release of pro-inflammatory cytokines (interleukin-6 and -8) from keratinocytes stimulated by TRPV3 agonist was effectively suppressed by H&M. Our findings provide insights into the mechanism underlying the anti-inflammatory effects of H&M, highlighting their potential in treating skin diseases.

Inhibitory Effect of Oroxylin A in a Mouse Model of Atopic Dermatitis

Scutellaria baicalensis has long been used in Asian traditional medicine to prevent and treat suppurative dermatitis, allergic diseases, inflammation, hyperlipemia, and arteriosclerosis. Oroxylin A is a flavone present in Scutellaria baicalensis. Because the root extracts of Scutellaria baicalensis have been shown to have anti-dermatitis effects, the authors investigated the effects of oroxylin A on chemically induced atopic dermatitis (AD) in an in vivo AD model induced by 1-chloro-2,4-dinitrobenzene (CDNB) in BALB/c mice. CDNB-induced skin hypertrophy and accumulation of mast cells in the epidermis and dermis were significantly decreased by oroxylin A. Increased serum levels of immunoglobulin E, as well as pro-inflammatory chemokines and cytokines in the skin and lymph nodes, were significantly decreased by oroxylin A. Suppression of immune responses in the skin and lymph nodes by oroxylin A decreased the symptoms of AD. Thus, these results proved that oroxylin A is an effective component of Scutellaria baicalensis for treating the symptoms of AD.

Integrated transcriptomic and metabolomic analyses of DNCB-induced atopic dermatitis in mice

AIMS

Atopic dermatitis (AD) is a common chronic inflammatory skin disorder that affects up to 20 % of children and 10 % of adults worldwide; however, the exact molecular mechanisms remain largely unknown.

MATERIALS AND METHODS

In this study, we used integrated transcriptomic and metabolomic analyses to study the potential mechanisms of 1-chloro-2,4-dinitrobenzene (DNCB)-induced AD-like skin lesions.

KEY FINDINGS

We found that DNCB induced AD-like skin lesions, including phenotypical and histomorphological alterations and transcriptional and metabolic alterations in mice. A total of 3413 differentially expressed metabolites were detected between DNCB-induced AD-like mice and healthy controls, which includes metabolites in taurine and hypotaurine metabolism, phenylalanine metabolism, biosynthesis of unsaturated fatty acids, tryptophan metabolism, arachidonic acid metabolism, pantothenate and CoA biosynthesis, pyrimidine metabolism, and glycerophospholipid metabolism pathways. Furthermore, the differentially expressed genes associated (DEGs) with these metabolic pathways were analyzed using RNA sequencing (RNA-seq), and we found that the expression of pyrimidine metabolism-associated genes was significantly increased. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that the glycolysis/gluconeogenesis, glucagon signaling pathway and pentose phosphate pathway-associated metabolic genes were dramatically altered.

SIGNIFICANCE

Our results explain the possible mechanism of AD at the gene and metabolite levels and provide potential targets for the development of clinical drugs for AD.

Possible Mechanisms of Oxidative Stress-Induced Skin Cellular Senescence, Inflammation, and Cancer and the Therapeutic Potential of Plant Polyphenols

As the greatest defense organ of the body, the skin is exposed to endogenous and external stressors that produce reactive oxygen species (ROS). When the antioxidant system of the body fails to eliminate ROS, oxidative stress is initiated, which results in skin cellular senescence, inflammation, and cancer. Two main possible mechanisms underlie oxidative stress-induced skin cellular senescence, inflammation, and cancer. One mechanism is that ROS directly degrade biological macromolecules, including proteins, DNA, and lipids, that are essential for cell metabolism, survival, and genetics. Another one is that ROS mediate signaling pathways, such as MAPK, JAK/STAT, PI3K/AKT/mTOR, NF-κB, Nrf2, and SIRT1/FOXO, affecting cytokine release and enzyme expression. As natural antioxidants, plant polyphenols are safe and exhibit a therapeutic potential. We here discuss in detail the therapeutic potential of selected polyphenolic compounds and outline relevant molecular targets. Polyphenols selected here for study according to their structural classification include curcumin, catechins, resveratrol, quercetin, ellagic acid, and procyanidins. Finally, the latest delivery of plant polyphenols to the skin (taking curcumin as an example) and the current status of clinical research are summarized, providing a theoretical foundation for future clinical research and the generation of new pharmaceuticals and cosmetics.