Flavonoids promoting HaCaT migration: II. Molecular mechanism of 4',6,7-trimethoxyisoflavone via NOX2 activation

Plant-based Natural Products for Wound Healing: A Critical Review

Wound healing is an intricate process consisting of four overlapping phases, namely hemostasis, inflammation, proliferation, and remodelling. Effective treatment of wounds depends upon the interaction of appropriate cell types, cell surface receptors, and the extracellular matrix with the therapeutic agents. Several approaches currently used for treating wounds, such as advanced wound dressing, growth factor therapy, stem cell therapy, and gene therapy, are not very effective and lead to impaired healing. Further, repeated use of antibiotics to treat open wounds leads to multi- drug resistance. Today there is considerable interest in plant-based drugs as they are believed to be safe, inexpensive, and more suitable for chronic wounds. For example, a large number of plant- based extracts and their bioactive compounds have been investigated for wound healing. In recent years the structural and mechanistic diversity of natural products have become central players in the search for newer therapeutic agents. In the present review, a thorough critical survey of the traditionally used plant-based drugs used worldwide for wound healing with special reference to the natural products/bioactive compounds isolated and screened is presented. It is hoped that this review will attract the attention of the research community involved in newer drug design and development for wound healing.

Dracorhodin perchlorate enhances wound healing via β-catenin, ERK/p38, and AKT signaling in human HaCaT keratinocytes

Dracorhodin can be isolated from the exudates of the fruit of Daemonorops draco. Previous studies suggested that dracorhodin perchlorate can promote fibroblast proliferation and enhance angiogenesis during wound healing. In the present study, the potential bioactivity of dracorhodin perchlorate in human HaCaT keratinocytes, were investigated in vitro, with specific focus on HaCaT wound healing. The results of in vitro scratch assay demonstrated the progressive closure of the wound after treatment with dracorhodin perchlorate in a time-dependent manner. An MTT assay and propidium iodide exclusion detected using flow cytometry were used to detect cell viability of HaCaT cells. Potential signaling pathways underlying the effects mediated by dracorhodin perchlorate in HaCaT cells were clarified by western blot analysis and kinase activity assays. Dracorhodin perchlorate significantly increased the protein expression levels of β-catenin and activation of AKT, ERK and p38 in HaCaT cells. In addition, dracorhodin perchlorate did not induce HaCaT cell proliferation but promoted cell migration. Other mechanisms may yet be involved in the dracorhodin perchlorate-induced wound healing process of human keratinocytes. In summary, dracorhodin perchlorate may serve to be a potential molecularly-targeted phytochemical that can improve skin wound healing.

Hydrogels containing soybean isoflavone aglycones-rich fraction-loaded nanoemulsions for wound healing treatment - in vitro and in vivo studies

Soybean isoflavone aglycones have been investigated as potential wound healing compounds for topical application. The aim of this study was to evaluate the wound healing properties of a soybean isoflavone aglycones-rich fraction (IAF) when incorporated into lipid nanoemulsions dispersed in acrylic-acid hydrogels. Formulations exhibited a mean droplet size in the sub 200 nm range, negative ζ-potential (-60 mV), and displayed non-Newtonian pseudoplastic behavior. The addition of a gelling agent decreased the IAF release from formulations and improved the retention of these compounds in intact porcine ear skin when compared with a control propylene glycol solution. No IAF were detected in receptor fluid of Franz-type diffusion cells. However, increasing amounts of IAF were noticed in both skin layers and the receptor fluid when the tissue was partially injured (tape stripping), or when the epidermis was completely removed. In vitro studies showed that IAF elicits an increased proliferation and migration of keratinocytes (HaCaT cell line). Subsequently, the healing effect of the formulations was evaluated in a model of dorsal wounds in rats, by assessing the size of the lesions, histology, inflammatory markers, and antioxidant activity. Overall findings demonstrated the potential of IAF-loaded formulations to promote wound healing by increasing angiogenesis by ∼200 %, reducing the lipid oxidation (TBARS) by ∼52 % and the inflammation (TNFα) by ∼35 %, while increasing re-epithelialization by ∼500 %, visualized by the epithelium thickness.

Pathophysiological Effects of Sulfur Mustard on Skin and its Current Treatments: Possible Application of Phytochemicals

BACKGROUND

Sulfur-(SM) and nitrogen (NM)-based mustards are the mutagenic incapacitating compounds which are widely used in vesicating the chemical warfare and cause toxicity in many organs, especially skin. SM, as a potent vesicating agent, contributes to the destruction of skin in dermis and epidermis layers. The progression of the lesion depends on the concentration of SM and the duration of exposure. Body responses start with pruritus, erythema, edema and xerosis, which lead to the accumulation of immune cells in the target sites and recruitment of mast cells and paracrine-mediated activity. Pro-inflammatory effectors are accumulated in the epidermis, hair follicles, and sebaceous glands resulting in the destruction of the basement membrane beneath the epidermis. There is still no satisfactory countermeasure against SM-induced lesions in clinical therapy, and the symptomatic or supportive treatments are routine management approaches.

OBJECTIVE

The current review highlights the recent progression of herbal medicines application in SM-induced injuries through the illustrative examples and also demonstrates their efficacies, properties and mechanism of actions as therapeutic agents.

CONCLUSION

Phytochemicals and herbal extracts with anti-bacterial, anti-inflammatory and antioxidant properties have been recently shown to hold therapeutic promise against the SM-induced cutaneous complications. The present review discusses the possible application of herbal medicines in the healing of SM-induced injuries.

Wound Healing Potential of Chlorogenic Acid and Myricetin-3-O-β-Rhamnoside Isolated from Parrotia persica

Wound healing is a complex physiological process that is controlled by a well-orchestrated cascade of interdependent biochemical and cellular events, which has spurred the development of therapeutics that simultaneously target these active cellular constituents. We assessed the potential of Parrotia persica (Hamamelidaceae) in wound repair by analyzing the regenerative effects of its two main phenolic compounds, myricetin-3-O-β-rhamnoside and chlorogenic acid. To accomplish this, we performed phytochemical profiling and characterized the chemical structure of pure compounds isolated from P. persica, followed by an analysis of the biological effects of myricetin-3-O-β-rhamnoside and chlorogenic acid on three cell types, including keratinocytes, fibroblasts, and endothelial cells. Myricetin-3-O-β-rhamnoside and chlorogenic acid exhibited complementary pro-healing properties. The percentage of keratinocyte wound closure as measured by a scratch assay was four fold faster in the presence of 10 µg/mL chlorogenic acid, as compared to the negative control. On the other hand, myricetin-3-O-β-rhamnoside at 10 µg/mL was more effective in promoting fibroblast migration, demonstrating a two-fold higher rate of closure compared to the negative control group. Both compounds enhanced the capillary-like tube formation of endothelial cells in an in vitro angiogenesis assay. Our results altogether delineate the potential to synergistically accelerate the fibroblastic and remodelling phases of wound repair by administering appropriate amounts of myricetin-3-O-β-rhamnoside and chlorogenic acid.

Anti-inflammatory activity of Crateva adansonii DC on keratinocytes infected by Staphylococcus aureus: From traditional practice to scientific approach using HPTLC-densitometry

ETHNOPHARMACOLIGICAL RELEVANCE

Leaves of Crateva adansonii DC (Capparidaceae), a small bush found in Togo, are widely used in traditional medicine to cure infectious abscesses. Traditional healers of Lomé harvest only budding leaves early in the morning, in specific area in order to prepare their drugs.

AIM OF THE STUDY

The main goal was to validate the ancestral picking practices, and to assess the activity of C. adansonii medicine towards infectious abscesses.

MATERIALS AND METHODS

A phytochemical screening of various C. adansonii leaf samples was performed using an original HPTLC-densitometry protocol and major flavonoids were identified and quantified. C. adansonii samples were collected in different neighborhoods of Lomé, at different harvesting-times and at different ages. Radical scavenging capacity, using DPPH assay, was used to quickly screen all extracts. Extracts were tested for anti-Staphylococcus aureus activity and anti-inflammatory effect on human primary keratinocytes infected by S. aureus. IL6, IL8 and TNFα expression and production were assessed by RT-PCR and ELISA assays.

RESULTS

Using antioxidant activity as selection criteria, optimal extracts were obtained with budding leaves, collected at 5:00am in Djidjolé neighborhood. This extract showed the strongest anti-inflammatory effect on S. aureus-infected keratinocytes by reducing IL6, IL8 and TNFα expression and production. None of the extracts inhibited the growth of S. aureus.

CONCLUSIONS

Those results validate the traditional practices and the potential of C. adansonii as anti-inflammatory drug. Our findings suggest that traditional healers should add to C. adansonii leaves an antibacterial plant of Togo Pharmacopeia, in order to improve abscess healing.

TMF and glycitin act synergistically on keratinocytes and fibroblasts to promote wound healing and anti-scarring activity

Keratinocyte-fibroblast interactions are critical for skin repair after injury. During the proliferative phase of wound healing, proliferation, migration and differentiation of these cells are the major mechanisms leading to tissue remodeling. We have previously reported that glycitin, a major soy isoflavone, stimulates dermal fibroblast proliferation; and the phytochemical, 4′,6,7-trimethoxyisoflavone (TMF), induces migration of HaCaT keratinocyte cells. We therefore investigated whether these compounds display synergistic effects on skin cells during wound healing in vitro and in vivo. Co-treatment with TMF and glycitin synergistically promotes the proliferation and migration of both keratinocytes and dermal fibroblasts, with a 1:1 ratio of these compounds showing the greatest efficacy in our co-culture system. This keratinocyte-fibroblast interaction occurred via the secretion of TGF-β, and the induction of differentiation and proliferation was confirmed in both indirect and direct co-culture assays. In an excisional and burn wound animal model, mice treated with a 1:1 ratio of TMF and glycitin showed faster wound closure, regeneration and scar reduction than even the positive control drug. These data indicate that two isoflavones, TMF and glycitin, act synergistically to promote wound healing and anti-scarring and could potentially be developed together as a bioactive therapeutic for wound treatment.

Oleanolic acid induces migration in Mv1Lu and MDA-MB-231 epithelial cells involving EGF receptor and MAP kinases activation

During wound healing, skin function is restored by the action of several cell types that undergo differentiation, migration, proliferation and/or apoptosis. These dynamics are tightly regulated by the evolution of the extra cellular matrix (ECM) contents along the process. Pharmacologically active flavonoids have shown to exhibit useful physiological properties interesting in pathological states. Among them, oleanolic acid (OA), a pentacyclic triterpene, shows promising properties over wound healing, as increased cell migration in vitro and improved wound resolution in vivo. In this paper, we pursued to disclose the molecular mechanisms underlying those effects, by using an in vitro scratch assay in two epithelial cell lines of different linage: non-malignant mink lung epithelial cells, Mv1Lu; and human breast cancer cells, MDA-MB-231. In every case, we observed that OA clearly enhanced cell migration for in vitro scratch closure. This correlated with the stimulation of molecular pathways related to mitogen-activated protein (MAP) kinases, as ERK1,2 and Jun N-terminal kinase (JNK) 1,2 activation and c-Jun phosphorylation. Moreover, MDA-MB-231 cells treated with OA displayed an altered gene expression profile affecting transcription factor genes (c-JUN) as well as proteins involved in migration and ECM dynamics (PAI1), in line with the development of an epithelial to mesenchymal transition (EMT) status. Strikingly, upon OA treatment, we observed changes in the epidermal growth factor receptor (EGFR) subcellular localization, while interfering with its signalling completely prevented migration effects. This data provides a physiological framework supporting the notion that lipophilic plant extracts used in traditional medicine, might modulate wound healing processes in vivo through its OA contents. The molecular implications of these observations are discussed.

Urban particulate matter down-regulates filaggrin via COX2 expression/PGE2 production leading to skin barrier dysfunction

We explored the regulation of filaggrin, cyclooxygenase 2 (COX2) and prostaglandin E2 (PGE2) expression induced by urban particulate matter (PM) in human keratinocytes. In addition, we investigated the signaling pathways involved in PM-induced effects on COX2/PGE2 and filaggrin. PMs induced increases in COX2 expression and PGE2 production, and decreased filaggrin expression. These effects were attenuated by pretreatment with COX2 inhibitor and PGE2 receptor antagonist, or after transfection with siRNAs of the aryl hydrocarbon receptor (AhR), gp91phox and p47phox. Furthermore, PM-induced generation of reactive oxygen species (ROS) and NADPH oxidase activity was attenuated by pretreatment with an AhR antagonist (AhRI) or antioxidants. Moreover, Nox-dependent ROS generation led to phosphorylation of ERK1/2, p38, and JNK, which then activated the downstream molecules NF-κB and AP-1, respectively. In vivo studies in PMs-treated mice showed that AhRI and apocynin (a Nox2 inhibitor) had anti-inflammatory effects by decreasing COX2 and increasing filaggrin expression. Our results reveal for the first time that PMs-induced ROS generation is mediated through the AhR/p47 phox/NADPH oxidase pathway, which in turn activates ERK1/2, p38/NF-κB and JNK/AP-1, and which ultimately induces COX2 expression and filaggrin downregulation. Up-regulated expression of COX2 and production of PGE2 may lead to impairment of skin barrier function.

A synthetic isoflavone, DCMF, promotes human keratinocyte migration by activating Src/FAK signaling pathway

Flavonoids are plant secondary compounds with various pharmacological properties. We previously showed that one flavonoid, trimethoxyisoflavone (TMF), could promote wound healing by inducing keratinocyte migration. Here, we screened TMF derivatives for enhanced activity and identified one compound, 2',6 Dichloro-7-methoxyisoflavone (DCMF), as most effective at promoting migration in a scratch wound assay. Using the HaCaT keratinocyte cell line, we found DCMF treatment induced phosphorylation of both FAK and Src, and increased keratinocyte migration. DCMF-induced Src kinase could promote activation of ERK, AKT, and p38 signaling pathways, and DCMF-induced secretion of matrix metalloproteinase (MMP)-2 and MMP-9 and partial epithelial-mesenchymal transition (EMT), whereas Src inhibition abolished DCMF-induced EMT. Using an in vivo excisional wound model, we observed improved wound closure and re-epithelialization in DCMF-treated mice, as compared to controls. Collectively, our data demonstrate that DCMF induces cell migration and promotes wound healing through activation of Src/FAK, ERK, AKT, and p38 MAPK signaling.

Cinnamtannin B-1 Promotes Migration of Mesenchymal Stem Cells and Accelerates Wound Healing in Mice

Substances that enhance the migration of mesenchymal stem cells to damaged sites have the potential to improve the effectiveness of tissue repair. We previously found that ethanol extracts of Mallotus philippinensis bark promoted migration of mesenchymal stem cells and improved wound healing in a mouse model. We also demonstrated that bark extracts contain cinnamtannin B-1, a flavonoid with in vitro migratory activity against mesenchymal stem cells. However, the in vivo effects of cinnamtannin B-1 on the migration of mesenchymal stem cells and underlying mechanism of this action remain unknown. Therefore, we examined the effects of cinnamtannin B-1 on in vivo migration of mesenchymal stem cells and wound healing in mice. In addition, we characterized cinnamtannin B-1-induced migration of mesenchymal stem cells pharmacologically and structurally. The mobilization of endogenous mesenchymal stem cells into the blood circulation was enhanced in cinnamtannin B-1-treated mice as shown by flow cytometric analysis of peripheral blood cells. Whole animal imaging analysis using luciferase-expressing mesenchymal stem cells as a tracer revealed that cinnamtannin B-1 increased the homing of mesenchymal stem cells to wounds and accelerated healing in a diabetic mouse model. Additionally, the cinnamtannin B-1-induced migration of mesenchymal stem cells was pharmacologically susceptible to inhibitors of phosphatidylinositol 3-kinase, phospholipase C, lipoxygenase, and purines. Furthermore, biflavonoids with similar structural features to cinnamtannin B-1 also augmented the migration of mesenchymal stem cells by similar pharmacological mechanisms. These results demonstrate that cinnamtannin B-1 promoted mesenchymal stem cell migration in vivo and improved wound healing in mice. Furthermore, the results reveal that cinnamtannin B-1-induced migration of mesenchymal stem cells may be mediated by specific signaling pathways, and the flavonoid skeleton may be relevant to its effects on mesenchymal stem cell migration.

Effects of the novel compound DK223 ([1E,2E-1,2-Bis(6-methoxy-2H-chromen-3-yl)methylene]hydrazine) on migration and proliferation of human keratinocytes and primary dermal fibroblasts

Wound healing plays an important role in protecting the human body from external infection. Cell migration and proliferation of keratinocytes and dermal fibroblasts are essential for proper wound healing. Recently, several studies have demonstrated that secondary compounds produced in plants could affect skin cells migration and proliferation. In this study, we identified a novel compound DK223 ([1E,2E-1,2-bis(6-methoxy-2H-chromen-3-yl)methylene]hydrazine) that concomitantly induced human keratinocyte migration and dermal fibroblast proliferation. We evaluated the regulation of epithelial and mesenchymal protein markers, such as E-cadherin and Vimentin, in human keratinocytes, as well as extracellular matrix (ECM) secretion and metalloproteinase families in dermal fibroblasts. DK223 upregulated keratinocyte migration and significantly increased the epithelial marker E-cadherin in a time-dependent manner. We also found that reactive oxygen species (ROS) increased significantly in keratinocytes after 2 h of DK223 exposure, returning to normal levels after 24 h, which indicated that DK223 had an early shock effect on ROS production. DK223 also stimulated fibroblast proliferation, and induced significant secretion of ECM proteins, such as collagen I, III, and fibronectin. In dermal fibroblasts, DK223 treatment induced TGF-β1, which is involved in a signaling pathway that mediates proliferation. In conclusion, DK223 simultaneously induced both keratinocyte migration via ROS production and fibroblast proliferation via TGF-β1 induction.