Apigenin restores impairment of autophagy and downregulation of unfolded protein response regulatory proteins in keratinocytes exposed to ultraviolet B radiation

Honey Phytochemicals: Bioactive Agents With Therapeutic Potential for Dermatological Disorders

Honey has been reported to have a range of biological activities including antimicrobial, immunomodulatory, and wound healing effects. Indeed, medical-grade honey is currently used in hospitals for the clinical management of wound infections. Honey is also of scientific interest for its therapeutic effects on other dermatological disorders such as atopic dermatitis, rosacea, and skin cancer. Recent studies have uncovered that honey contains a range of phytochemicals including flavonoids, dicarboxylic acids, coumarins, and phenolic acids. In this review, PubMed was used to search the scientific literature on the biological properties of honey phytochemicals in relation to dermatological disorders and to evaluate their potential as bioactive agents, drugs, or cosmeceuticals for the treatment of skin disease. The review revealed that phytochemicals found in honey have antimicrobial, anti-inflammatory, antiaging, antioxidant, anticancer, depigmenting, photoprotective, wound healing, and skin barrier enhancing properties. Although further high-quality studies are required to establish clinical efficacy, these findings suggest that honey phytochemicals may have the potential to be used as bioactive agents for the management of a range of dermatological disorders including wounds, psoriasis, atopic dermatitis, vitiligo, rosacea, and skin cancer.

A comprehensive review of apigenin a dietary flavonoid: biological sources, nutraceutical prospects, chemistry and pharmacological insights and health benefits

A multitude of plant-derived bioactive compounds have shown significant promise in preventing chronic illnesses, with flavonoids constituting a substantial class of naturally occurring polyphenolic compounds. Apigenin, a flavone identified as 4',5,7-trihydroxyflavone, holds immense promise as a preventative agent against chronic illnesses. Despite its extensive research and recognized nutraceutical value, its therapeutic application remains underexplored, necessitating further clinical investigations. This review delves into the biological sources, nutraceutical prospects, chemistry, pharmacological insights, and health benefits of apigenin. Through multifaceted analytical studies, we explore its diverse pharmacological profile and potential therapeutic applications across various health domains. The manuscript comprehensively examines apigenin's role as a neuroprotective , anti-inflammatory compound, and a potent antioxidant agent. Additionally, its efficacy in combating cardiovascular diseases, anti-diabetic properties, and anticancer potential has been discussed. Furthermore, the antimicrobial attributes and the challenges surrounding its bioavailability, particularly from herbal supplements have been addressed. Available in diverse forms including tablets, capsules, solid dispersions, co-crystals, inclusion complexes and nano formulations. Additionally, it is prevalent as a nutraceutical supplement in herbal formulations. While strides have been made in overcoming pharmacokinetic hurdles, further research into apigenin's clinical effectiveness and bioavailability from herbal supplements remains imperative for its widespread utilization in preventive medicine.

Natural Compounds in Non-Melanoma Skin Cancer: Prevention and Treatment

The elevated occurrence of non-melanoma skin cancer (NMSC) and the adverse effects associated with available treatments adversely impact the quality of life in multiple dimensions. In connection with this, there is a necessity for alternative approaches characterized by increased tolerance and lower side effects. Natural compounds could be employed due to their safety profile and effectiveness for inflammatory and neoplastic skin diseases. These anti-cancer drugs are often derived from natural sources such as marine, zoonotic, and botanical origins. Natural compounds should exhibit anti-carcinogenic actions through various pathways, influencing apoptosis potentiation, cell proliferation inhibition, and metastasis suppression. This review provides an overview of natural compounds used in cancer chemotherapies, chemoprevention, and promotion of skin regeneration, including polyphenolic compounds, flavonoids, vitamins, alkaloids, terpenoids, isothiocyanates, cannabinoids, carotenoids, and ceramides.

Endoplasmic reticulum stress in skin aging induced by UVB

Aging is a normal and complex biological process. Skin is located in the most superficial layer of the body, and its degree of aging directly reflects the aging level of the body. Endoplasmic reticulum stress refers to the aggregation of unfolded or misfolded proteins in the endoplasmic reticulum and the disruption of the calcium ion balance when cells are stimulated by external stimuli. Mild endoplasmic reticulum stress can cause a series of protective mechanisms, including the unfolded protein response, while sustained high intensity stimulation leads to endoplasmic reticulum stress and eventually apoptosis. Photoaging caused by ultraviolet radiation is an important stimulus in skin aging. Many studies have focused on oxidative stress, but increasing evidence shows that endoplasmic reticulum stress plays an important role in photoaging. This paper reviews the development and mechanism of endoplasmic reticulum stress (ERS) in skin photoaging, and provides research directions for targeting the ERS pathway to slow aging.

Autophagy-related LncRNA PRDM10-DT responds to UVB radiation in keratinocytes

Ultraviolet (UV)-B radiation is a major environmental risk factor that is responsible for the development and progression of many skin disorders. Autophagy is the process of degradation and recycling of damaged cytoplasmic organelles, macromolecular aggregates, and long-lived proteins. Previously, we found that the autophagy inducer apigenin restored UVB-impaired autophagy and the cellular response by downregulating the expression of autophagy-related genes such as ATG5. To explore long noncoding RNAs (lncRNAs) involved in regulating these autophagy-related genes, in this study, we assessed the expression profiles of lncRNAs and mRNAs using a microarray in human epidermal keratinocytes (HEKs) treated with or without apigenin after UVB radiation. The expression levels of 80 selected autophagy-related genes and related lncRNAs were confirmed by quantitative real-time polymerase chain reaction (qRT‒PCR). The lncRNA PRDM10-DT was proposed to regulate IRGM based on the ceRNA and coexpression pattern and was demonstrated to be involved in autophagy regulation, proliferation and migration of HEKs by qRT‒PCR, Western blotting, colony formation and scratch wound assays, respectively. These findings suggest an autophagy-related lncRNA in response to UVB radiation that promotes the proliferation and migration of HEKs through inducing autophagy by competing microRNAs for IRGM.

The Role of Nutraceuticals and Functional Foods in Skin Cancer: Mechanisms and Therapeutic Potential

Skin cancer is a prevalent type of cancer worldwide and has a high growth rate compared to other diseases. Although modern targeted therapies have improved the management of cutaneous neoplasms, there is an urgent requirement for a safer, more affordable, and effective chemoprevention and treatment strategy for skin cancer. Nutraceuticals, which are natural substances derived from food, have emerged as a potential alternative or adjunctive treatment option. In this review, we explore the current evidence on the use of omega-3 fatty acids and polyphenols (curcumin, epigallocatechin gallate, apigenin, resveratrol, and genistein) for the treatment of melanoma and non-melanoma skin cancer (NMSC), as well as in their prevention. We discuss the mechanisms of action of the aforementioned nutraceuticals and their probable therapeutic benefits in skin cancer. Omega-3 fatty acids, curcumin, epigallocatechin gallate, apigenin, resveratrol, and genistein have several properties, among which are anti-inflammatory and anti-tumor, which can help to prevent and treat skin cancer. However, their effectiveness is limited due to poor bioavailability. Nanoparticles and other delivery systems can improve their absorption and targeting. More research is needed to evaluate their safety and effectiveness as a natural approach to skin cancer prevention and treatment. These compounds should not replace conventional cancer treatments, but may be used as complementary therapy under the guidance of a healthcare professional.

Investigation of UV-treated mesenchymal stem cells in an in vitro wound model

This study examines the effects of ultraviolet-induced adipose tissue-derived mesenchymal stem cells and their supernatants on wound healing regarding cell viability, percentage of wound healing, released cytokine, and growth factors. It has been reported in previous studies that mesenchymal stem cells are resistant to ultraviolet light and have a protective effect on skin cells against ultraviolet-induced damage. At the same time, there are many studies in the literature about the positive effects of cytokines and growth factors secreted by mesenchymal stem cells. Based on this information, the effects of ultraviolet-induced adipose-derived stem cells and supernatants containing their secreted cytokines and growth factors on an in vitro two-dimensional wound model created with two different cell lines were investigated in this study. It was determined from the results that the highest cell viability and the least apoptotic staining were 100 mJ in mesenchymal stem cells (**p < 0.01). Furthermore, analysis of cytokines and growth factors collected from supernatants also supported 100 mJ as the optimal ultraviolet dose. It was observed that cells treated with ultraviolet and their supernatants significantly increased cell viability and wound-healing rate over time compared to other groups. In conclusion, with this study, it has been shown that adipose-derived stem cells exposed to ultraviolet light can have an important use in wound healing, both with their potential and with the more cytokines and growth factors they secrete. However, further analysis and animal experiments should be performed before clinical use.

Digested Cinnamon (Cinnamomum verum J. Presl) Bark Extract Modulates Claudin-2 Gene Expression and Protein Levels under TNFα/IL-1β Inflammatory Stimulus

Epigenetic changes, host-gut microbiota interactions, and environmental factors contribute to inflammatory bowel disease (IBD) onset and progression. A healthy lifestyle may help to slow down the chronic or remitting/relapsing intestinal tract inflammation characteristic of IBD. In this scenario, the employment of a nutritional strategy to prevent the onset or supplement disease therapies included functional food consumption. Its formulation consists of the addition of a phytoextract enriched in bioactive molecules. A good candidate as an ingredient is the Cinnamon verum aqueous extract. Indeed, this extract, subjected to a process of gastrointestinal digestion simulation (INFOGEST), exhibits beneficial antioxidant and anti-inflammatory properties in an in vitro model of the inflamed intestinal barrier. Here, we deepen the study of the mechanisms related to the effect of digested cinnamon extract pre-treatment, showing a correlation between transepithelial electrical resistance (TEER) decrement and alterations in claudin-2 expression under Tumor necrosis factor-α/Interleukin-1β (TNF-α/IL-1) β cytokine administration. Our results show that pre-treatment with cinnamon extract prevents TEER loss by claudin-2 protein level regulation, influencing both gene transcription and autophagy-mediated degradation. Hence, cinnamon polyphenols and their metabolites probably work as mediators in gene regulation and receptor/pathway activation, leading to an adaptive response against renewed insults.

Handelin protects human skin keratinocytes against ultraviolet B-induced photodamage via autophagy activation by regulating the AMPK-mTOR signaling pathway

Handelin is a natural ingredient extracted from Chrysanthemum boreale flowers that has been shown to decrease stress-related cell death, prolong lifespan, and promote anti-photoaging. However, whether handelin inhibits ultraviolet (UV) B stress-induced photodamage remains unclear. In the present study, we investigate whether handelin has protective properties on skin keratinocytes under UVB irradiation. Human immortalized keratinocytes (HaCaT keratinocytes) were pretreated with handelin for 12 h before UVB irradiation. The results indicated that handelin protects keratinocytes against UVB-induced photodamage by activating autophagy. However, the photoprotective effect of handelin was suppressed by an autophagic inhibitor (wortmannin) or the transfection of keratinocytes with a small interfering RNA targeting ATG5. Notably, handelin reduced mammalian target of rapamycin (mTOR) activity in UVB-irradiated cells in a manner similar to that shown by the mTOR inhibitor rapamycin. Adenosine monophosphate-activated protein kinase (AMPK) activity was also induced by handelin in UVB-damaged keratinocytes. Finally, certain effects of handelin, including autophagy induction, mTOR activity inhibition, AMPK activation, and reduction of cytotoxicity, were suppressed by an AMPK inhibitor (compound C). Our data suggest that handelin effectively prevents photodamage by protecting skin keratinocytes against UVB-induced cytotoxicity via the regulation of AMPK/mTOR-mediated autophagy. These findings provide novel insights that can aid the development of therapeutic agents against UVB-induced keratinocyte photodamage.

Exploration of binding mechanism of apigenin to pepsin: Spectroscopic analysis, molecular docking, enzyme activity and antioxidant assays

Pepsin plays an important role in nutrient metabolism. Apigenin (AP) is a beneficial polyphenol to human health. To enhance the bioavailability of AP and elucidate the inhibitory effect of AP on pepsin, the interaction mechanism of AP with pepsin was investigated using spectroscopic analysis and molecular docking, and the activity of pepsin and antioxidant activity of AP was also evaluated. Specifically, AP performed static quenching of pepsin and had only one binding site on pepsin. More interestingly, the interaction between AP and pepsin was spontaneous, while hydrogen bonds and van der Waals forces were the main binding forces. Generally, synchronous and three-dimensional fluorescence confirmed that AP induced the conformational changes of pepsin, and molecular docking proved the above results and illustrated the specific binding patterns. Specifically, AP inhibited the activity of pepsin, while pepsin decreased the antioxidant activity of AP. These results provided useful information for elucidating the interactions between AP and pepsin.

Ultraviolet Light, Unfolded Protein Response and Autophagy†

The endoplasmic reticulum (ER) plays an important role in the regulation of protein synthesis. Alterations in the folding capacity of the ER induce stress, which activates three ER sensors that mediate the unfolded protein response (UPR). Components of the pathways regulated by these sensors have been shown to regulate autophagy. The last corresponds to a mechanism of self-eating and recycling important for proper cell maintenance. Ultraviolet radiation (UV) is an external damaging stimulus that is known for inducing oxidative stress, and DNA, lipid and protein damage. Many controversies exist regarding the role of UV-inducing ER stress or autophagy. However, a connection between the three of them has not been addressed. In this review, we will discuss the contradictory theories regarding the relationships between UV radiation with the induction of ER stress and autophagy, as well as hypothetic connections between UV, ER stress and autophagy.

Apigenin and its dermatological applications: A comprehensive review

Apigenin is one of the abundant flavonoids in fruits and vegetables of human diet with several demonstrated health benefits. The aim of the present study is to provide an overview of the current evidence regarding the effect of apigenin on different dermatological complications. Electronic databases including PubMed, Scopus, and Web of Science were searched to retrieve all papers assessing the dermatological effects of apigenin. Preclinical studies support beneficial effects of apigenin on UV-induced skin damage, vitiligo, dermatitis, wounds, skin aging, and some types of skin cancer. The compound mostly acts via inhibition of inflammation through suppression of pro-inflammatory cytokines and intracellular inflammatory mediators, as well as antioxidant properties such as improvement of endogenous antioxidant defense mechanisms. There are also some studies for the design and development of novel drug delivery systems for apigenin to improve its oral and topical bioavailability. Nevertheless, no clinical study has evaluated apigenin as a natural supplement for skin conditions. Considering the benefits of apigenin in preclinical models of dermatological disorders, as well as the acceptable safety of this compound, apigenin may be a future candidate to be used in dermatological disorders. Future clinical studies are needed to further confirm the safety and efficacy of apigenin in skin care products.

Pharmacological Properties of 4', 5, 7-Trihydroxyflavone (Apigenin) and Its Impact on Cell Signaling Pathways

Plant bioactive compounds, particularly apigenin, have therapeutic potential and functional activities that aid in the prevention of infectious diseases in many mammalian bodies and promote tumor growth inhibition. Apigenin is a flavonoid with low toxicities and numerous bioactive properties due to which it has been considered as a traditional medicine for decades. Apigenin shows synergistic effects in combined treatment with sorafenib in the HepG2 human cell line (HCC) in less time and statistically reduces the viability of tumor cells, migration, gene expression and apoptosis. The combination of anti-cancerous drugs with apigenin has shown health promoting potential against various cancers. It can prevent cell mobility, maintain the cell cycle and stimulate the immune system. Apigenin also suppresses mTOR activity and raises the UVB-induced phagocytosis and reduces the cancerous cell proliferation and growth. It also has a high safety threshold, and active (anti-cancer) doses can be gained by consuming a vegetable and apigenin rich diet. Apigenin also boosted autophagosome formation, decreased cell proliferation and activated autophagy by preventing the activity of the PI3K pathway, specifically in HepG2 cells. This paper provides an updated overview of apigenin's beneficial anti-inflammatory, antibacterial, antiviral, and anticancer effects, making it a step in the right direction for therapeutics. This study also critically analyzed the effect of apigenin on cancer cell signaling pathways including the PI3K/AKT/MTOR, JAK/STAT, NF-κB and ERK/MAPK pathways.

Trehalose Protects Keratinocytes against Ultraviolet B Radiation by Activating Autophagy via Regulating TIMP3 and ATG9A

Trehalose, a natural disaccharide, is synthesized by many organisms when cells are exposed to stressful stimuli. On the basis of its ability to modulate autophagy, trehalose has been considered an innovative drug for ameliorating many diseases, but its molecular mechanism is not well described. Previous findings demonstrated that trehalose plays a photoprotective role against ultraviolet (UV) B-induced damage through autophagy induction in keratinocytes. In this study, coimmunoprecipitation, label-free quantitative proteomic and parallel reaction monitoring, and western blot analysis demonstrated that trehalose promotes the interaction between tissue inhibitor of metalloproteinase (TIMP) 3 and Beclin1. Western blot and immunofluorescence staining analysis suggested that trehalose increases ATG9A localization in lysosomes and decreases its localization in the endoplasmic reticulum. Furthermore, in the presence or absence of UVB radiation, we evaluated the influence of TIMP3 and ATG9A small interfering RNA (siRNA) on the effect of trehalose on autophagy, cell death, migration, or interleukin-8 expression in keratinocytes, including HaCaT, A431, and human epidermal keratinocytes. The results revealed that in HaCaT cells, TIMP3 and ATG9A siRNA resulted in attenuation of trehalose-induced autophagy and inhibited cell death. In A431 cells, TIMP3 and ATG9A siRNA led to attenuation of trehalose-induced autophagy and cell death and inhibited migration. In human epidermal keratinocytes, trehalose-induced autophagy and inhibition of the interleukin-8 expression were blocked by ATG9A but not TIMP3 siRNA. In addition, the results of quantitative real-time PCR and immunohistochemistry analysis demonstrated the abnormal expression of TIMP3 and ATG9A in actinic keratosis and cutaneous squamous cell carcinoma skin tissues. These findings suggest the protective effects of trehalose in normal keratinocytes and its inhibitory effects on cancerous keratinocytes, possibly mediated by activation of autophagy and regulation of TIMP3 and ATG9A, providing the mechanistic basis for the potential use of trehalose in the prevention or treatment of UVB-induced skin diseases.

Role of Induced Programmed Cell Death in the Chemopreventive Potential of Apigenin

The flavonoid apigenin (4′,5,7-trihydroxyflavone), which is one of the most widely distributed phytochemicals in the plant kingdom, is one of the most thoroughly investigated phenolic components. Previous studies have attributed the physiological effects of apigenin to its anti-allergic, antibacterial, antidiabetic, anti-inflammatory, antioxidant, antiviral, and blood-pressure-lowering properties, and its documented anticancer properties have been attributed to the induction of apoptosis and autophagy, the inhibition of inflammation, angiogenesis, and cell proliferation, and the regulation of cellular responses to oxidative stress and DNA damage. The most well-known mechanism for the compound’s anticancer effects in human cancer cell lines is apoptosis, followed by autophagy, and studies have also reported that apigenin induces novel cell death mechanisms, such as necroptosis and ferroptosis. Therefore, the aim of this paper is to review the therapeutic potential of apigenin as a chemopreventive agent, as well as the roles of programmed cell death mechanisms in the compound’s chemopreventive properties.

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.

Polyphenol-Mediated Autophagy in Cancer: Evidence of In Vitro and In Vivo Studies

One of the hallmarks of cellular transformation is the altered mechanism of cell death. There are three main types of cell death, characterized by different morphological and biochemical features, namely apoptosis (type I), autophagic cell death (type II) and necrosis (type III). Autophagy, or self-eating, is a tightly regulated process involved in stress responses, and it is a lysosomal degradation process. The role of autophagy in cancer is controversial and has been associated with both the induction and the inhibition of tumor growth. Autophagy can exert tumor suppression through the degradation of oncogenic proteins, suppression of inflammation, chronic tissue damage and ultimately by preventing mutations and genetic instability. On the other hand, tumor cells activate autophagy for survival in cellular stress conditions. Thus, autophagy modulation could represent a promising therapeutic strategy for cancer. Several studies have shown that polyphenols, natural compounds found in foods and beverages of plant origin, can efficiently modulate autophagy in several types of cancer. In this review, we summarize the current knowledge on the effects of polyphenols on autophagy, highlighting the conceptual benefits or drawbacks and subtle cell-specific effects of polyphenols for envisioning future therapies employing polyphenols as chemoadjuvants.

Apigenin Protects Mouse Retina against Oxidative Damage by Regulating the Nrf2 Pathway and Autophagy

Oxidative stress is a critical factor in the pathology of age-related macular degeneration (AMD). Apigenin (AP) is a flavonoid with an outstanding antioxidant activity. We had previously observed that AP protected APRE-19 cells against oxidative injury in vitro. However, AP has poor water and fat solubility, which determines its low oral bioavailability. In this study, we prepared the solid dispersion of apigenin (AP-SD). The solubility and dissolution of AP-SD was significantly better than that of the original drug, so the oral bioavailability in rats was better than that of the original drug. Then, the effects of AP-SD on the retina of a model mouse with dry AMD were assessed by fundus autofluorescence (FAF), optical coherence tomography (OCT), and electron microscopy; the results revealed that AP-SD alleviated retinopathy. Further research found that AP-SD promoted the nuclear translocation of Nrf2 and increased expression levels of the Nrf2 and target genes HO-1 and NQO-1. AP-SD enhanced the activities of SOD and GSH-Px and decreased the levels of ROS and MDA. Furthermore, AP-SD upregulated the expressions of p62 and LC3II in an Nrf2-dependent manner. However, these effects of AP-SD were observed only in the retina of Nrf2 WT mice, not in Nrf2 KO mice. In addition, the therapeutic effect of AP-SD was dose dependent, and AP did not work. In conclusion, AP-SD significantly enhanced the bioavailability of the original drug and reduced retinal oxidative injury in the model mouse of dry AMD in vivo. The results of the underlying mechanism showed that AP-SD upregulated the expression of antioxidant enzymes through the Nrf2 pathway and upregulated autophagy, thus inhibiting retinal oxidative damage. AP-SD may be a potential compound for the treatment of dry AMD.