Ginkgo biloba extract protects human melanocytes from H2 O2 -induced oxidative stress by activating Nrf2

Comparison of various excimer laser (EL) combination therapies for vitiligo: a systematic review and network meta-analysis

AIM

This study aimed to compare the efficacy and safety of excimer laser (EL)-based combination regimens in improving repigmentation.

METHODS

A comprehensive search was conducted in PubMed, Web of Science, Cochrane Library, and Embase on July 1, 2023, to include randomized controlled trials of EL combination treatments for vitiligo that met the criteria. The primary outcome measure was a repigmentation rate ≥ 75%, and the secondary outcome measures were a repigmentation rate of ≤ 25% and adverse events.

RESULTS

Eleven studies involving 348 patients were included. Network Meta-Analysis showed that EL combined with antioxidants (SUCRA = 98.8%), EL combined with calcipotriol (SUCRA = 59.8%) and EL combined with tacalcitol (SUCRA = 59.6%) were the three optimal interventions achieving repigmentation rates ≥ 75%. EL alone (SUCRA = 77.6%), EL combined with tacalcitol (SUCRA = 61.7%) and EL combined with antioxidants (SUCRA = 57.2%) were the three interventions with the highest rates of treatment failure. Adverse events in all groups mainly included erythema, burning sensation and hyperpigmentation. Based on the results of the current study, EL combination therapies were safe with mild adverse events.

CONCLUSION

EL combined with antioxidants was the preferred regimen for vitiligo, whereas EL alone was the regimen with the highest rate of treatment failure in vitiligo.

From traditional medicine to nanomedicine: potential of Ginkgo biloba extracts in treating inflammatory skin diseases

The use of plant extracts as a potential cure for various conditions has moved from traditional medicine to evidence-based medicine. Skin diseases have been addressed since time immemorial using plant extracts through observational and traditional knowledge and passed on through generations. With the advent of modern techniques, the molecular mechanisms of action of plant extracts/isolates are being deciphered with more precision, and more nanomedicine-based therapies are being studied to improve their therapeutic efficacy and stability. The leaves and seeds of Ginkgo biloba (G. biloba), an ancient medicinal tree species, have been used in Chinese herbal medicine for thousands of years. G. biloba extracts have been widely studied as a neuroprotective and anti-ischaemic drug for ischaemia-reperfusion injuries in the heart, lungs, brain, kidneys, and other organs. However, the use of G. biloba can be accompanied with side effects and drug interactions. Although, there is now a growing interest for its use in skincare, the mechanisms of action of the extract are not fully understood and vital aspects of G. biloba, such as its neuroprotective and angiogenic properties contributing to the treatment of inflammatory skin diseases and skin ageing, are yet to be investigated. This review critically discusses the mechanisms of action of different constituents of G. biloba extracts linked to their potential interference in the molecular mechanisms underlying the pathogenesis of inflammatory skin diseases. In addition to its ability to act on oxidative stress, G. biloba can regulate angiogenesis through its compounds such as ginkgetin or ginkgolide K, which either inhibit aberrant angiogenesis in eczema/psoriasis or increase microcirculation during skin ageing. G. biloba may also contribute to the control of pruritus in atopic dermatitis via a neuroprotective and anti-inflammatory mechanism by suppressing JAK2/STAT3 signalling pathways. This review also highlights nanomedicine strategies to decrease the side effects and enhance the efficacy of the extracts. Similar strategies have been successfully used for anticancer molecules in targeted chemotherapy and iron delivery in anaemia treatment.

The molecular mechanisms of ginkgo (Ginkgo biloba) activity in signaling pathways: A comprehensive review

BACKGROUND

One of the most unique plants that have ever grown on the planet is Ginkgo biloba L., a member of the Ginkgoaceae family with no close living relatives. The existence of several differently structured components of G. biloba has increased the chemical variety of herbal therapy. Numerous studies that investigated the biochemical characteristics of G. biloba suggest this plant as a potential treatment for many illnesses.

PURPOSE

Review the molecular mechanisms involved in the signaling pathways of G. biloba activity in varied circumstances and its potential as a novel treatment for various illnesses.

METHODS

Studies focusing on the molecular processes and signaling pathways of compounds and extracts of G. biloba were found and summarized using the proper keywords and operators from Google Scholar, PubMed, Web of Science, and Scopus without time restrictions.

RESULTS

G. biloba exerts its effects through its anti-inflammatory, anti-apoptotic, anti-cancer, neuroprotective, cardioprotective, hepatoprotective, antiviral, antibacterial, pulmoprotective, renoprotective, anti-osteoporosis, anti-melanogenic, retinoprotective, otoprotective, adipogenic, and anti-adipogenic properties. The most important mechanisms involved in these actions are altering the elevation of ROS formation, inhibiting NADPH oxidases activation, altering the expression of antioxidant enzymes, downregulating MAPKs (p38 MAPK and ERK, and JNK) and AP-1, increasing cAMP, inactivating Stat5, activating the AMPK signaling pathway, affecting Stat3/JAK2, NF-κB, Nrf-2, mTOR, HGF/c-Met, Wnt/β-catenin and BMP signaling pathways, and changing the mitochondrial transmembrane potential, the Bax/Bcl-2 ratio, the release of Cyc from mitochondria to cytosol, the protein cleavage of caspases 3, 7, 8, 9, and 12, poly (ADP-ribose) polymerase, and MMPs levels.

CONCLUSIONS

G. biloba and its components have gained attention in recent years for their therapeutic benefits, such as their anti-inflammatory, antioxidant, anti-apoptotic, and apoptotic effects. By understanding their molecular mechanisms and signaling pathways, potential novel medicines might be developed in response to the rising public desire for new therapies.

Resveratrol improves meat quality traits by activating the lncRNAs-KEAP1-NRF2 axis in pigs

This research aims at uncovering the effects and investigating the molecular mechanisms of dietary resveratrol (RES) supplementation on antioxidant capacity and meat quality of pigs. In this study, 20 μM RES could activate the KEAP1-NRF2 antioxidant defense pathway in response to oxidative stress in porcine skeletal muscle satellite cells was firstly found. Then, twenty-four healthy crossbred castrated boars were allocated to 4 treatments that were fed with a basal diet (control) and a basal diet supplemented with 200 mg, 400 mg or 600 mg RES per Kilogram (kg) of feed for 41 days, respectively. 400 and 600 mg/kg RES-supplemented diet can effectively improve the meat quality traits and activities of antioxidizing enzymes via the KEAP1-NRF2 signaling pathway of pigs. The molecular dynamic simulation further revealed that RES could directly binding to KEAP1 to reduce the tightness of KEAP1-NRF2 protein-protein interaction. More importantly, dietary supplementation of RES also improves antioxidant capacity through a series of KEAP1-NRF2 pathway-related lncRNAs were found by RNA sequencing (RNA-seq). Altogether, this study demonstrated that RES improves meat quality traits by effectively increasing antioxidant levels via the lncRNA-KEAP1-NRF2 axis in vivo and/or in vitro. These results provide new insights into the molecular mechanisms by which RES, as a nutritional agent, regulates antioxidant capacity and improves meat quality in pigs.

Drug-induced liver injury and anti-hepatotoxic effect of herbal compounds: a metabolic mechanism perspective

BACKGROUND

Drug-induced liver injury (DILI) is the most challenging and thought-provoking liver problem for hepatologists owing to unregulated medication usage in medical practices, nutritional supplements, and botanicals. Due to underreporting, analysis, and identification issues, clinically evaluated medication hepatotoxicity is prevalent yet hard to quantify.

PURPOSE

This review's primary objective is to thoroughly compare pharmaceutical drugs and herbal compounds that have undergone clinical trials, focusing on their metabolic mechanisms contributing to the onset of liver illnesses and their hepatoprotective effects.

METHODS

The data was gathered from several online sources, such as PubMed, Scopus, Google Scholar, and Web of Science, using appropriate keywords.

RESULTS

The prevalence of conventional and herbal medicine is rising. A comprehensive understanding of the metabolic mechanism is necessary to mitigate the hepatotoxicity induced by drugs and facilitate the incorporation or substitution of herbal medicine instead of pharmaceuticals. Moreover, pre-clinical pharmacological research has the potential to facilitate the development of natural products as therapeutic agents, displaying promising possibilities for their eventual clinical implementation.

CONCLUSIONS

Acetaminophen, isoniazid, rifampicin, diclofenac, and pyrogallol have been identified as the most often reported synthetic drugs that produce hepatotoxicity by oxidative stress, inflammation, apoptosis, and fibrosis during the last several decades. Due to their ability to downregulate many factors (such as cytokines) and activate several enzyme/enzyme systems, herbal substances (such as Gingko biloba extract, curcumin, resveratrol, and silymarin) provide superior protection against harmful mechanisms which induce hepatotoxicity with fewer adverse effects than their synthetic counterparts.

Polysaccharides from Brasenia schreberi with Great Antioxidant Ability and the Potential Application in Yogurt

Brasenia schreberi is a widely consumed aquatic plant, yet the knowledge regarding its bioactive components, particularly polysaccharides, remains limited. Therefore, this study aimed to optimize the extraction process of polysaccharides from B. schreberi using the response surface method (RSM). Additionally, we characterized the polysaccharides using various methods and assessed their antioxidant capabilities both in vitro and in vivo, employing cell cultures and Caenorhabditis elegans. Furthermore, these polysaccharides were incorporated into a unique yogurt formulation. Our findings demonstrated that hot water extraction was the most suitable method for extracting polysaccharides from B. schreberi, yielding samples with high sugar content, significant antioxidant capacity, and a well-defined spatial structure. Moreover, pectinase was employed for polysaccharide digestion, achieving an enzymolysis rate of 10.02% under optimized conditions using RSM. Notably, the results indicated that these polysaccharides could protect cells from oxidative stress by reducing apoptosis. Surprisingly, at a concentration of 250 μg/mL, the polysaccharides significantly increased the survival rate of C. elegans from 31.05% to 82.3%. Further qPCR results revealed that the polysaccharides protected C. elegans by up-regulating the daf-16 gene and down-regulating mTOR and insulin pathways, demonstrating remarkable antioxidant abilities. Upon addition to the yogurt, the polysaccharides significantly enhanced the water retention, viscosity, and viability of lactic acid bacteria. These outcomes underscore the potential of polysaccharides from B. schreberi as a valuable addition to novel yogurt formulations, thereby providing additional theoretical support for the utilization of B. schreberi.

Oxidative Stress and Potential Antioxidant Therapies in Vitiligo: A Narrative Review

Vitiligo is a chronic skin disorder characterised by the loss of melanocytes and subsequent skin depigmentation. Although many theories have been proposed in the literature, none alone explains the pathogenesis of vitiligo. Oxidative stress has been identified as a potential factor in the pathogenesis of vitiligo. A growing body of evidence suggests that antioxidant therapies may offer a promising approach to managing this condition. This review summarises the potential mechanisms of oxidative stress and the types of melanocyte death in vitiligo. We also provide a brief overview of the most commonly studied antioxidants. Melanocytes in vitiligo are thought to be damaged by an accumulation of reactive oxygen species to destroy the structural and functional integrity of their DNA, lipids, and proteins. Various causes, including exogenous and endogenous stress factors, an imbalance between prooxidants and antioxidants, disruption of antioxidant pathways, and gene polymorphisms, lead to the overproduction of reactive oxygen species. Although necroptosis, pyroptosis, ferroptosis, and oxeiptosis are newer types of cell death that may contribute to the pathophysiology of vitiligo, apoptosis remains the most studied cell death mechanism in vitiligo. According to studies, vitamin E helps to treat lipid peroxidation of the skin caused by psoralen ultra-violet A treatment. In addition, Polypodium leucotomos increased the efficacy of psoralen ultra-violet A or narrow-band ultraviolet B therapy. Our review provides valuable insights into the potential role of oxidative stress in pathogenesis and antioxidant-based supporting therapies in treating vitiligo, offering a promising avenue for further research and the development of effective treatment strategies.

The PI3K-Akt-mTOR and Associated Signaling Pathways as Molecular Drivers of Immune-Mediated Inflammatory Skin Diseases: Update on Therapeutic Strategy Using Natural and Synthetic Compounds

The dysregulated phosphatidylinositol-3-kinase (PI3K)-Akt-mammalian target of rapamycin (mTOR) signaling pathway has been implicated in various immune-mediated inflammatory and hyperproliferative dermatoses such as acne, atopic dermatitis, alopecia, psoriasis, wounds, and vitiligo, and is associated with poor treatment outcomes. Improved comprehension of the consequences of the dysregulated PI3K/Akt/mTOR pathway in patients with inflammatory dermatoses has resulted in the development of novel therapeutic approaches. Nonetheless, more studies are necessary to validate the regulatory role of this pathway and to create more effective preventive and treatment methods for a wide range of inflammatory skin diseases. Several studies have revealed that certain natural products and synthetic compounds can obstruct the expression/activity of PI3K/Akt/mTOR, underscoring their potential in managing common and persistent skin inflammatory disorders. This review summarizes recent advances in understanding the role of the activated PI3K/Akt/mTOR pathway and associated components in immune-mediated inflammatory dermatoses and discusses the potential of bioactive natural products, synthetic scaffolds, and biologic agents in their prevention and treatment. However, further research is necessary to validate the regulatory role of this pathway and develop more effective therapies for inflammatory skin disorders.

The Use of Herbal Medicine in the Treatment of Vitiligo: An Updated Review

Vitiligo is a chronic disease of unknown etiology that causes progressive cutaneous depigmentation. Current pharmacological treatments have limited success and present significant risks. Many efforts have been made in recent years to explore new anti-vitiligo therapeutic strategies, including herbal-based therapies. The objective of the present review is to provide an updated overview on the most frequently used medicinal plants in the treatment of vitiligo. A bibliographical search was carried out in scientific databases Pubmed, Scifinder, Scopus, Google Scholar, and Medline up to October 2021 using the descriptors vitiligo, herbal, medicinal plants, and alternative therapies. In our search, the highest number of published studies comprise plants commonly used in traditional herbal medicine, highlighting the usefulness of ethnopharmacology in the discovery of new therapeutic agents. The review outlines current understanding and provides an insight into the role of psoralens and khellin (photosensitizing agents obtained from plants such as Cullen corylifolium or Ammi visnaga). The paper also describes other traditional herbs such as Ginkgo biloba, Phlebodium aureum, Piper nigrum, Picrorhiza kurroa, and Baccharoides anthelmintica that can likewise act as potential therapeutical agents. Based on our findings, photosensitizing agents in combination with phototherapy, the association of oral Phebodium aureum with phototherapies as well as oral G. biloba in monotherapy showed greater scientific evidence as therapeutic options. The research results emphasize that further investigation in this area is merited. More long-term follow up clinical trials and higher quality randomized trials are needed.

The Role of Oxidative Stress in Vitiligo: An Update on Its Pathogenesis and Therapeutic Implications

Vitiligo is an autoimmune skin disorder caused by dysfunctional pigment-producing melanocytes which are attacked by immune cells. Oxidative stress is considered to play a crucial role in activating consequent autoimmune responses related to vitiligo. Melanin synthesis by melanocytes is the main intracellular stressor, producing reactive oxygen species (ROS). Under normal physiological conditions, the antioxidative nuclear factor erythroid 2-related factor 2 (Nrf2) pathway functions as a crucial mediator for cells to resist oxidative stress. In pathological situations, such as with antioxidant defects or under inflammation, ROS accumulate and cause cell damage. Herein, we summarize events at the cellular level under excessive ROS in vitiligo and highlight exposure to melanocyte-specific antigens that trigger immune responses. Such responses lead to functional impairment and the death of melanocytes, which sequentially increase melanocyte cytotoxicity through both innate and adaptive immunity. This report provides new perspectives and advances our understanding of interrelationships between oxidative stress and autoimmunity in the pathogenesis of vitiligo. We describe progress with targeted antioxidant therapy, with the aim of providing potential therapeutic approaches.

Effects of dietary Ginkgo biloba leaf extract on growth performance, immunity and environmental stress tolerance of Penaeus vannamei

Ginkgo biloba leaf extract (GBE) has been extensively used in the treatment of diseases due to its anti-inflammatory, antioxidant, and immunomodulatory effects. In aquaculture, GBE is widely used as a feed additive, which is important to enhance the immunity of aquatic animals. The current study evaluated the effects of adding GBE to the diet of Penaeus vannamei (P. vannamei) under intensive aquaculture. The GBE0 (control group), GBE1, GBE2, and GBE4 groups were fed a commercial feed supplemented with 0.0, 1.0, 2.0, and 4.0 g/kg GBE for 21 days, respectively. The results showed that dietary GBE could alleviate hepatopancreas tissue damage and improve the survival rate of shrimp, and dietary 2 g/kg GBE could significantly increase the total hemocyte count (THC), the hemocyanin content, the antioxidant gene's expression, and the activity of their encoded enzymes in P. vannamei. Furthermore, transcriptome data revealed that immunity-related genes were upregulated in the GBE2 group compared with the GBE0 group after 21 days of culture. Drug metabolism-cytochrome P450, sphingolipid metabolism, linoleic acid metabolism, glycerolipid metabolism, fat digestion and protein digestion and absorption pathways were significantly enriched, according to KEGG results. Surprisingly, all of the above KEGG-enriched pathways were significantly upregulated. These findings demonstrated that supplementing P. vannamei with 2 g/kg GBE improved its environmental adaptability by improving immunity, lipid metabolism, and detoxification. In this study, a comprehensive evaluation of the effects of dietary GBE on the intensive aquaculture of P. vannamei was conducted to provide a reference for the healthy culture of P. vannamei.

Modified rougan decoction alleviates lipopolysaccharide-enrofloxacin-induced hepatotoxicity via activating the Nrf2/ARE pathway in chicken

Liver injury plays a heavy burden on the chicken industry. Although modified rougan decoction is a prescription for the treatment of liver disease based on the classical prescription of rougan decoction (containing peony and licorice). However, the effect and mechanism of modified rougan decoction on the liver remain unclear. In this study, the effects of the water extracts (MRGD) and the alcohol precipitates of water extracts (MRGDE) against lipopolysaccharide-enrofloxacin (LPS-ENR)-induced hepatotoxicity were discussed in vivo and in vitro. The isolated hepatocytes and 128 one-day-old Hyline chickens were considered research objects. The indices of liver injury and oxidative stress were evaluated by hematoxylin and eosin (H&E) stained and the assay kits, and the nuclear erythroid 2-related factor 2 (Nrf2)/antioxidant responsive element (ARE) pathway was detected by the RT-PCR, western blot, and immunofluorescence tests. All data were analyzed using the IBM SPSS 20.0 software. In vivo, the structural integrity of the liver was maintained, AST, ALT, and MDA levels were decreased, and antioxidant enzymes were increased, confirming that the oxidative stress was reduced and liver injury was alleviated. Correspondingly, MRGD and MRGDE were observed to improve cell viability and decrease lactate dehydrogenase (LDH) in vitro, and the cell oxidative damage was reduced. In addition, the nuclear translocation of Nrf2 was improved significantly, and the mRNA and protein expression levels of the related genes were upregulated. In conclusion, MRGD and MRGDE can exert a protective effect against LPS-ENR-induced hepatotoxicity by activating the Nrf2/ARE pathway, which might be a potential therapeutic prescription for preventing or treating liver injury. Notably, no significant difference was found between the 2 extracts, suggesting that a depth extraction method did not always improve the efficacy of natural medicine. Our results provided new insights into finding effective hepatoprotective medicine.

Immunometabolism in the pathogenesis of vitiligo

Vitiligo is a common depigmenting skin disorder characterized by the selective loss of melanocytes. Autoimmunity, genetic, environmental, and biochemical etiology have been proposed in vitiligo pathogenesis. However, the exact molecular mechanisms of vitiligo development and progression are unclear, particularly for immunometabolism. Sporadic studies have suggested mitochondrial dysfunction, enhanced oxidative stress, and specific defects in other metabolic pathways can promote dysregulation of innate and adaptive immune responses in vitiligo. These abnormalities appear to be driven by genetic and epigenetic factors modulated by stochastic events. In addition, glucose and lipid abnormalities in metabolism have been associated with vitiligo. Specific skin cell populations are also involved in the critical role of dysregulation of metabolic pathways, including melanocytes, keratinocytes, and tissue-resident memory T cells in vitiligo pathogenesis. Novel therapeutic treatments are also raised based on the abnormalities of immunometabolism. This review summarizes the current knowledge on immunometabolism reprogramming in the pathogenesis of vitiligo and novel treatment options.

NRF2, a crucial modulator of skin cells protection against vitiligo, psoriasis, and cancer

The skin represents a physical barrier between the organism and the environment that has evolved to confer protection against biological, chemical, and physical insults. The inner layer, known as dermis, is constituted by connective tissue and different types of immune cells whereas the outer layer, the epidermis, is composed by different layers of keratinocytes and an abundant number of melanocytes, localized in the stratum basale of the epidermis. Oxidative stress is a common alteration of inflammatory skin disorders such as vitiligo, dermatitis, or psoriasis but can also play a causal role in skin carcinogenesis and tumor progression. Nuclear factor (erythroid-derived 2)-like 2 (NRF2) has emerged as a crucial regulator of cell defense mechanisms activating complex transcriptional programs that facilitate reactive oxygen species detoxification, repair oxidative damage and prevent xenobiotic-induced toxicity. Accumulating evidence suggests that the keratinocytes, melanocytes, and other skin cell types express high levels of NRF2, which is known to play a pivotal role in the skin homeostasis, differentiation, and metabolism during normal and pathologic conditions. In the present review, we summarize the current evidence linking NRF2 to skin pathophysiology and we discuss some recent modulators of NRF2 activity that have shown a therapeutic efficacy in skin protection against tumor initiation and common inflammatory skin conditions such as vitiligo or psoriasis, with a particular emphasis on natural compounds.

Natural product, bilobalide, improves joint health in rabbits with osteoarthritis by anti-matrix degradation and antioxidant activities

Osteoarthritis (OA) is a common chronic musculoskeletal disease reported in veterinary clinics that severely reduces the quality of life of animals. The natural product, bilobalide, has positive effects on chondroprotection but its exact mechanism of action is unclear. This study aimed to investigate the antioxidant and anti-matrix degradation activities of bilobalide in a rabbit model of OA and its protective effects on joints. We also investigated the possible mechanisms underlying these effects. The rabbit OA model was established by intra-articular injection of 4% papain. Thirty healthy male New Zealand rabbits were randomly divided into control, untreated OA, Cel (100 mg/kg celecoxib intervention as a positive control), BB-L and BB-H (40 mg /kg and 80 mg /kg bilobalide gavage treatment, respectively) groups. Two weeks after surgical induction, bilobalide or celecoxib was administered by gavage daily for 8 weeks. After 8 weeks of bilobalide intervention, cartilage macroscopic observation and histopathological images showed alleviation of cartilage damage after bilobalide treatment, and the Osteoarthritis Research Society International (OARSI) score was significantly lower than that in the OA group. Bilobalide reduced the expression of metalloproteinase 3 (MMP-3) and MMP-13 in cartilage tissue of OA rabbits and reversed the levels of serum C-telopeptides of type II collagen (CTX-II), cartilage oligomeric matrix protein (COMP), interleukin 1(IL-1), and tumor necrosis factor (TNF-α). Bilobalide (80 mg/kg) could improve the biomechanical properties and microstructural changes in subchondral bone in the early stage of OA in rabbits, thereby delaying subchondral bone damage. Mechanistically, bilobalide exerted antioxidant and anti-matrix degradation effects by upregulating the oxidative stress signaling Nrf2/HO-1 pathway and inhibiting cartilage degeneration in rabbit OA. We thus speculate that bilobalide supplements recovery from OA damage.

Research Progress on Targeted Antioxidant Therapy and Vitiligo

Vitiligo is a common acquired depigmenting disease characterized by the loss of functional melanocytes and epidermal melanin. Vitiligo has a long treatment cycle and slow results, which is one of the most difficult challenges for skin diseases. Oxidative stress plays an important role as an initiating and driving factor in the pathogenesis of vitiligo. Antioxidant therapy has recently become a research hotspot in vitiligo treatment. A series of antioxidants has been discovered and applied to the treatment of vitiligo, which has returned satisfactory results. This article briefly reviews the relationship between oxidative stress and vitiligo. We also describe the progress of targeted antioxidant therapy in vitiligo, with the aim of providing a reference for new drug development and treatment options for this condition.

Methylcobalamin Protects Melanocytes from H2O2-Induced Oxidative Stress by Activating the Nrf2/HO-1 Pathway

Purpose

Oxidative stress is considered a major determinant in the pathogenesis of vitiligo. Methylcobalamin (MeCbl) is an activated form of vitamin B12 that regulates inflammatory factors, counters oxidative stress, and reduces apoptosis in many disease models. However, the specific mechanism of MeCbl repigmentation against vitiligo is unknown. In this study, we explored the effect of MeCbl on melanocytes following hydrogen peroxide (H₂O₂)-induced oxidative stress.

Methods

We established an oxidative stress model using the immortalized human normal melanocyte cell line PIG1. We used a Cell Counting Kit-8 (CCK-8) to detect drug cytotoxicity, and we measured the melanin content of cells using the NaOH method. Intracellular oxidative damage was assessed by flow cytometry and antioxidant enzyme detection kits. In addition, we assessed the presence of apoptosis by flow cytometry and Western blots. We explored the underlying mechanisms of MeCbl during oxidative stress in melanocytes by analyzing the results of experiments based on real-time quantitative polymerase chain reaction (RT-qPCR), Western blotting, and laser scanning confocal immunofluorescence microscopy. Finally, we repeated the experiments after applying an inhibitor to block the Nrf2 pathway.

Results

We found that MeCbl treatment enhanced cell viability, increased melanin content, reduced intracellular reactive oxygen species (ROS) accumulation, increased the activities of antioxidant enzyme superoxide dismutase (SOD) and catalase (CAT), reduced melanocyte apoptosis, and up-regulated the expression of the Nrf2/HO-1 pathway. Moreover, the protective effects of MeCbl were significantly weakened after inhibiting the Nrf2/HO-1 pathway.

Conclusion

Our results indicate that MeCbl attenuated the H₂O₂-induced oxidative stress in melanocytes by activating the Nrf2/HO-1 pathway, this suggests that MeCbl may be an effective treatment against vitiligo.

The Potential Antioxidant Activity and Characterization of Bioactive Compounds of Stahlianthus involucratus

Stahlianthus involucratus (S. involucratus) has anti-inflammatory, antinociceptive, and antipyretic activities; however, there are no literature reports on its antioxidant capacity. This study presents a comparative assessment of the polyphenols contents, flavonoids contents, and antioxidant activity of the aqueous and methanol extracts of S. involucratus (ASI and MSI). Moreover, the expression of oxidative stress-related genes in H₂O₂-induced H9c2 cells pretreated with the MSI was measured by RT-qPCR, and furthermore, MSI were characterized by UHPLC-Q-Orbitrap-MS/MS. The results indicated that the MSI had higher antioxidant contents and antioxidant capacity, and MSI could inhibit H₂O₂-induced oxidative stress in H9c2 cells by activating the Nrf2/HO-1 pathway. UHPLC-Q-Orbitrap-MS/MS characterized 15 phenolic compounds from the MSI. In conclusion, S. involucratus has the potential antioxidant capacity.

Current evidence to support the therapeutic potential of flavonoids in oxidative stress-related dermatoses

BACKGROUND

Skin, as a crucial external defense organ, is more vulnerable to oxidative stress (OS) insult, reactive oxygen species (ROS)-mediated OS in particular. OS results from a redox imbalance caused by various extrinsic stimuli and occurs once the oxidants production overwhelming the antioxidants capacity, through mediating in DNA damage, lipid peroxidation (LPO), protein oxidation and a serial of signaling pathways activation/inactivation, thereby offering favorable conditions for the occurrence and development of numerous diseases especially some dermatoses, e.g. psoriasis, vitiligo, skin photodamage, skin cancer, systemic sclerosis (SSc), chloasma, atopic dermatitis (AD), pemphigus, etc. Targeting OS molecular mechanism, a variety of anti-OS agents emerge, in which flavonoids, natural plant extracts, stand out.

OBJECTIVES

To discuss the possible mechanisms of OS mediating in dermatoses and summarize the properties of flavonoids as well as their applications in OS-related skin disorders.

METHODS

Published papers on flavonoids and OS-related skin diseases were collected and reviewed via database searching on PubMed, MEDLINE and Embase, etc.

RESULTS

It has been confirmed that flavonoids, belonging to polyphenols, are a class of plant secondary metabolites widely distributed in various plants and possess diverse bioactivities especially their potent antioxidant capacity. Moreover, flavonoids benefit to suppress OS via eliminating free radicals and mediating the corresponding signals, further excellently working in the prevention and management of OS-related skin diseases.

CONCLUSION

Flavonoids have the potential therapeutic effects on oxidative stress-related dermatoses. However, more studies on specific mechanism as well as the dosage of flavonoids are needed in future.

Vitiligo: What's old, what's new

Vitiligo is an acquired pigmentary disorder afflicting 0.5-2% of the world population for both sexes and all races with a capricious and unpredictable course. It has a complex etiology and varies in its manifestation, progression and response to treatment. Even if the precise aetiology and pathobiology of the disease are complex and still debated, recent evidence supports that vitiligo is a T CD8+ cell-mediated autoimmune disease triggered by oxidative stress. To date no clinical, biological and histological criteria allow us to establish the prognosis with certainty. The choice of the best therapy for adult and childhood vitiligo is based on various factors, such as the patient's age, psychological condition and expectations, distribution and extension of skin lesions, type of vitiligo (stable or not) and availability and cost of therapeutic options. Since vitiligo has a deep psychological impact on patients and their quality of life, treating the disease is very important. As dermatologists, we have important goals in the treatment of vitiligo patients: stabilization of the disease progression, repigmentation of the lesions and especially the persistence of the aforementioned repigmentation. Although several medical and surgical therapeutic options have been proposed, no definite cure has yet been developed and the long-term persistence of repigmentation is unpredictable. We review the different therapeutic options with particular attention on the recurrence rate.

Stem Cell Therapy Offers a Possible Safe and Promising Alternative Approach for Treating Vitiligo: A Review

BACKGROUND

Normal skin pigmentation pattern is an extremely important component of the appearance of a person, as it can be a significant factor in the social context of any person. A condition known as vitiligo is caused by the death of melanocytes leading to pigmentation loss in the skin. This affects all races across the globe and sometimes leads to social avoidance as in some communities, it is stigmatized. Although there are different pathobiological processes suspected because of the different underlying causes of vitiligo, autoimmunity and oxidative stress are suspected to be the most probable ones.

OBJECTIVE

In this review, we present an overview of the underlying mechanisms causing and developing the disease. Also, some of the most successful treatments along with the clinical applications of Mesenchymal Stem Cells (MSCs) as a comprehensive approach for treating this condition will be covered.

RESULTS

Autoreactive CD8+ T-cells are the primary suspect considered to be responsible for the destruction of melanocytes. Therefore, topical use of autoimmune inhibitors including those derived from MSCs, thanks to their immune-modulatory properties, have been reported to be successful in the promotion of repigmentation. MSCs can suppress the proliferation of CD8+T via the NKG2D pathway while inducing T-cell apoptosis. The use of pharmacological agents for reducing cellular oxidative stress with the help of topical application of antioxidants and growth factors also have been in use. Intravenous administration of MSCs has been shown to regulate the level of reactive oxidative species (ROS) in a mice model. Growth factors derived from platelet-rich-plasma (PRP) or from MSCs caused rapid tissue regeneration.

CONCLUSIONS

Finally, MSC therapy also has been shown to stimulate the mobilization of healthy melanocytes, leading to successful repigmentation of skin lesions in vitiligo patients.

Mechanisms of melanocyte death in vitiligo

Vitiligo is an autoimmune depigment disease results from extensive melanocytes destruction. The destruction of melanocyte is thought to be of multifactorial causation. Genome-wide associated studies have identified single-nucleotide polymorphisms in a panel of susceptible loci as risk factors in melanocyte death. But vitiligo onset can't be solely attributed to a susceptive genetic background. Oxidative stress triggered by elevated levels of reactive oxygen species accounts for melanocytic molecular and organelle dysfunction, a minority of melanocyte demise, and melanocyte-specific antigens exposure. Of note, the self-responsive immune function directly contributes to the bulk of melanocyte deaths in vitiligo. The aberrantly heightened innate immunity, type-1-skewed T helper, and incompetent regulatory T cells tip the balance toward autoreaction and CD8+ cytotoxic T lymphocytes finally execute the killing of melanocytes, possibly alarmed by resident memory T cells. In addition to the well-established apoptosis and necrosis, we discuss several death modalities like oxeiptosis, ferroptosis, and necroptosis that are probably employed in melanocyte destruction. This review focuses on the various mechanisms of melanocytic death in vitiligo pathogenesis to demonstrate a panorama of that. We hope to provide new insights into vitiligo pathogenesis and treatment strategies by the review.

A Systematic Review of Nutrition, Supplement, and Herbal-Based Adjunctive Therapies for Vitiligo

Background: Vitiligo is an autoimmune skin condition that affects people globally anywhere, from <0.1% to more than 8% of individuals. The disease destroys skin melanocytes, resulting in a patchy depigmentation of the skin. About 50% of all patients develop the disease before their 20s. Methods: We systematically searched the literature and reviewed the evidence for the use of nutritional supplements and diet in the management of vitiligo. Embase and Medline were searched for diet, herbal, and nutrition-based clinical studies. Additional filters were applied that looked for controlled trial or randomized controlled trial and article or article in press or letter and English and clinical study. We selected clinical studies in humans that showed how diet or natural supplements can improve the symptoms of vitiligo in all of our searches. Results: There were 62 manuscripts that resulted from the PubMed search and 259 from the Embase search. A final of 26 studies were reviewed, and other supplemental case and case-control studies were used to introduce diet components that may influence either exacerbation or amelioration of vitiligo. Possible mechanisms of action are introduced for natural and supplemental interventions. Conclusion: Some of the supplements reviewed include Gingko biloba, oral Polypodium leucotomos, alpha lipoic acid, vitamins B12, D, and E, folic acid, phenylalanine, canthaxanthin, Nigella sativa oil, and other combined herbal bio-actives. Overall, the growing evidence is promising, but more studies are needed in this area to further explore the impact that supplements and diet can have on vitiligo management. The most promising therapies included oral phenylalanine as adjuvant therapy with UVA therapy, oral G. biloba as monotherapy, both of which can be used with other traditional therapies, and oral P. leucotomos with phototherapy or photochemotherapy.

Nuclear factor erythroid 2-related factor 2 (Nrf2) as a potential therapeutic target for vitiligo

Vitiligo is an autoimmune disease of the skin which causes loss of melanocytes from the epidermis. Recently, it is demonstrated that oxidative stress (OS) plays a significant role in the immuno-pathogenesis of vitiligo. A major mechanism in the cellular defense against OS is activation of the nuclear factor erythroid2-related factor (Nrf2)-Kelch-like ECH-associated protein 1(Keap1)-antioxidant responsive element (ARE) signaling pathway. Recently it has been shown that vitiligo melanocytes have impaired Nrf2-ARE signaling. A number of drugs including those known as Nrf2 activators and those known to possess effects to activate Nrf2, have been used in treating vitiligo with certain therapeutic effects. Also, studies have shown that a number of compounds can protect melanocytes against OS via activating Nrf2. These compounds may be considered as candidates for developing new drugs for vitiligo in the future. Nrf2 can be considered as a potential therapeutic target for vitiligo.

Curcumin Protects Human Trophoblast HTR8/SVneo Cells from H2O2-Induced Oxidative Stress by Activating Nrf2 Signaling Pathway

Pregnancy complications are associated with oxidative stress induced by accumulation of trophoblastic ROS in the placenta. We employed the human trophoblast HTR8/SVneo cell line to determine the effect of curcumin pre-treatment on H₂O₂-induced oxidative damage in HTR8/Sveo cells. Cells were pretreated with 2.5 or 5 μM curcumin for 24 h, and then incubated with 400 μM H₂O₂ for another 24 h. The results showed that H₂O₂ decreased the cell viability and induced excessive accumulation of reactive oxygen species (ROS) in HTR8/Sveo cells. Curcumin pre-treatment effectively protected HTR8/SVneo cells against oxidative stress-induced apoptosis via increasing Bcl-2/Bax ratio and decreasing the protein expression level of cleaved-caspase 3. Moreover, curcumin pre-treatment alleviated the excessive oxidative stress by enhancing the activity of antioxidative enzymes. The antioxidant effect of curcumin was achieved by activating Nrf2 and its downstream antioxidant proteins. In addition, knockdown of Nrf2 by Nrf2-siRNA transfection abolished the protective effects of curcumin on HTR8/SVneo cells against oxidative damage. Taken together, our results show that curcumin could protect HTR8/SVneo cells from H₂O₂-induced oxidative stress by activating Nrf2 signaling pathway.

Ginkgo biloba extract protects human melanocytes from H2 O2 -induced oxidative stress by activating Nrf2

Vitiligo is a common skin depigmenting disorder characterized by the loss of functional melanocytes. Its pathogenesis is complicated and oxidative stress plays a critical role in the development of vitiligo. Thus, antioxidant therapy is a promising therapeutic strategy to prevent or even reverse the progression of depigmentation. Ginkgo biloba extract EGb761 has been confirmed to have protective effects on neurons against oxidative stress. Notably, several clinical trials have shown that patients with stable vitiligo achieved repigmentation after taking EGb761. However, the exact mechanism underlying the protective effects of EGb761 on melanocytes against oxidative stress has not been fully elucidated. In the present study, we found that EGb761 effectively protected melanocytes against oxidative stress‐induced apoptosis and alleviated the excessive accumulation of reactive oxygen species (ROS) and lipid peroxidation by enhancing the activity of antioxidative enzymes. Furthermore, the antioxidative effect of EGb761 was achieved by activating Nrf2 and its downstream antioxidative genes. In addition, interfering Nrf2 with siRNA abolished the protective effects of EGb761 on melanocytes against oxidative damage. In conclusion, our study proves that EGb761 could protect melanocytes from H₂O₂‐induced oxidative stress by activating Nrf2. Therefore, EGb761 is supposed to be a potential therapeutic agent for vitiligo.