Cutaneous oxidative stress

Natural Antioxidant Evaluation: A Review of Detection Methods

Antioxidants have drawn the attention of the scientific community due to being related to the prevention of various degenerative diseases. The antioxidant capacity has been extensively studied in vitro, and different methods have been used to assess its activity. However, the main issues related to studying natural antioxidants are evaluating whether these antioxidants demonstrate a key role in the biological system and assessing their bioavailability in the organism. The majority of outcomes in the literature are controversial due to a lack of method standardization and their proper application. Therefore, this study aims to compile the main issues concerning the natural antioxidant field of study, comparing the most common in vitro methods to evaluate the antioxidant activity of natural compounds, demonstrating the antioxidant activity in biological systems and the role of the main antioxidant enzymes of redox cellular signaling and explaining how the bioavailability of bioactive compounds is evaluated in animal models and human clinical trials.

A new peptide originated from amphibian skin alleviates the ultraviolet B-induced skin photodamage

Although amphibian-derived bioactive peptides have attracted increasing attention for their potential use in the treatment of photodamage, research is still in its infancy. In this study, we obtained a new antioxidant peptide, named OA-GI13 (GIWAPWPPRAGLC), from the skin of the odorous frog Odorrana andersonii and determined its effects on ultraviolet B (UVB)-induced skin photodamage as well as its possible molecular mechanisms. Results showed that OA-GI13 directly scavenged free radicals, maintained the viability of hydrogen peroxide-challenged keratinocytes, promoted the release of superoxide dismutase, catalase, and glutathione, and reduced the level of lactate dehydrogenase. Furthermore, topical application of OA-GI13 in mice alleviated dorsal skin erythema and edema and protected the skin against UVB irradiation by increasing antioxidant levels and decreasing peroxide, malondialdehyde, and 8-hydroxydeoxyguanosine levels. OA-GI13 also alleviated oxidative stress injury in vivo and in vitro, possibly by inhibiting p38 protein phosphorylation. Our study confirmed the anti-photodamage effects of this novel amphibian-derived peptide, thus providing a new molecule for the development of drugs and topical agents for the treatment of skin photodamage.

Ischemia-Modified Albumin—A Potential New Marker of Oxidative Stress in Dermatological Diseases

There is growing evidence that oxidative stress is involved in the pathogenesis of numerous conditions, including dermatological diseases. Various markers are available to assess oxidative stress, but none of these can be considered the ideal marker. Recent studies have shown that ischemia-modified albumin (IMA) is not only an indicator of ischemia, but also a marker of oxidative stress. We have conducted a narrative review to evaluate the role of IMA in dermatological diseases. We have identified 24 original articles that evaluated IMA in skin disorders (psoriasis, acne vulgaris, hidradenitis suppurativa, urticaria, vitiligo and Behcet’s disease) and hair disorders (alopecia areata, androgenetic alopecia and telogen effluvium). The results of the studies analyzed reveal that IMA may be considered a new marker of oxidative stress in dermatological diseases and offer new insights into the pathogenesis of these disorders and the theoretical basis for the development of new, effective, targeted therapies. To the best of our knowledge, this is the first review that gathers up data on the role of IMA in dermatological diseases.

Functionality of apigenin as a potent antioxidant with emphasis on bioavailability, metabolism, action mechanism and in vitro and in vivo studies: A review

Numerous diseases such as cancer, diabetes, cardiovascular, neurodegenerative diseases, etc. are linked with overproduction of reactive oxygen species (ROS) and oxidative stress. Apigenin (5,7,4'-trihydroxyflavone) is a widely distributed flavonoid, responsible for antioxidant potential and chelating redox active metals. Being present as glycosides or polymers, the apigenin degrades to variable amount in the digestive tract; during processing, its activity is also reduced due to high temperature or Fe/Cu addition. Although its metabolism remains elusive, enteric absorption occurs sufficiently to reduce plasma indices of oxidant status. Delayed clearance in plasma and slow liver decomposition enhance its systematic bioavailability. Antioxidant mechanism of apigenin includes: oxidant enzymes inhibition, modulation of redox signaling pathways (NF-kB, Nrf2, MAPK, and P13/Akt), reinforcing enzymatic and nonenzymatic antioxidant, metal chelation, and free radical scavenging. DPPH, ORAC, ABTS, and FRAP are the major in vitro methods for determining the antioxidant potential of apigenin, whereas its protective effects in whole and living cells of animals are examined using in vivo studies. Due to limited information on antioxidant potential of apigenin, its in vitro and in vivo antioxidant effects are, therefore, discussed with action mechanism and interaction with the signaling pathways. This paper concludes that apigenin is a potent antioxidant compound to overcome the difficulties related to oxidative stress and other chronic diseases.

Effects of Ultrasonic-Assisted Extraction on the Yield and the Antioxidative Potential of Bergenia emeiensis Triterpenes

This study was the first designed to evaluate the extraction and antioxidant ability of triterpenes from Bergenia emeiensis rhizomes. The yield of triterpenes from B. emeiensis was mainly affected by the concentration of ethanol, followed by the extraction time, solvent to sample ratio, and the power of ultrasound. Thus, the response surface method was applied to investigate the interaction between the two factors and to optimize the extraction process. The optimal extraction conditions were 210 W, 75% ethanol, 40 min and 25 mL/g with a maximum yield of 229.37 ± 7.16 mg UAE/g. Moreover, the antioxidant ability of triterpenes from B. emeiensis (TBE) was evaluated by determining the scavenging capacity on free radicals and the protection on CHO cells and Caenorhabditis elegans against oxidative stress. The results showed the triterpenes could clear 2,2-Diphenyl-1-picryl-hydrazyl (DPPH) radicals well and had a strong reducing power. In addition, the survival of CHO cells was higher than that of the control group as a result of reducing the reactive oxygen species (ROS) level and promoting the activities of antioxidant enzymes. In addition, TBE could also enhance the survival of C. elegans under H₂O₂ conditions. Therefore, triterpenes from B. emeiensis could be developed into a beneficial potential for antioxidants.

Age Associated Decrease of MT-1 Melatonin Receptor in Human Dermal Skin Fibroblasts Impairs Protection Against UV-Induced DNA Damage

The human body follows a physiological rhythm in response to the day/night cycle which is synchronized with the circadian rhythm through internal clocks. Most cells in the human body, including skin cells, express autonomous clocks and the genes responsible for running those clocks. Melatonin, a ubiquitous small molecular weight hormone, is critical in regulating the sleep cycle and other functions in the body. Melatonin is present in the skin and, in this study, we showed that it has the ability to dose-dependently stimulate PER1 clock gene expression in normal human dermal fibroblasts and normal human epidermal keratinocytes. Then we further evaluated the role of MT-1 melatonin receptor in mediating melatonin actions on human skin using fibroblasts derived from young and old subjects. Using immunocytochemistry, Western blotting and RT-PCR, we confirmed the expression of MT-1 receptor in human skin fibroblasts and demonstrated a dramatic age-dependent decrease in its level in mature fibroblasts. We used siRNA technology to transiently knockdown MT-1 receptor in fibroblasts. In these MT-1 knockdown cells, UV-dependent oxidative stress (H₂O₂ production) was enhanced and DNA damage was also increased, suggesting a critical role of MT-1 receptor in protecting skin cells from UV-induced DNA damage. These studies demonstrate that the melatonin pathway plays a pivotal role in skin aging and damage. Moreover, its correlation with skin circadian rhythm may offer new approaches for decelerating skin aging by modulating the expression of melatonin receptors in human skin.

Increased levels of mitochondrial DNA copy number in patients with vitiligo

BACKGROUND

Oxidative stress is known to be involved in the pathogenesis of autoimmune diseases such as vitiligo. Evidence suggests that the human mitochondrial DNA copy number (mtDNAcn) is vulnerable to damage mediated by oxidative stress. The purpose of this study was to examine and compare peripheral blood mtDNAcn and oxidative DNA damage byproducts (8-hydroxy-2-deoxyguanosine; 8-OHdG) in patients with vitiligo and healthy controls (HCs).

METHODS

The relative mtDNAcn and the oxidative damage (formation of 8-OHdG in mtDNA) of each sample were determined by real-time quantitative PCR. Blood samples were obtained from 56 patients with vitiligo and 46 HCs.

RESULTS

The mean mtDNAcn and the degree of mtDNA damage were higher in patients with vitiligo than in HCs.

CONCLUSION

These data suggest that increase in mtDNAcn and oxidative DNA damage may be involved in the pathogenesis of vitiligo.

Biological Rhythms in the Skin

Circadian rhythms, ≈24 h oscillations in behavior and physiology, are reflected in all cells of the body and function to optimize cellular functions and meet environmental challenges associated with the solar day. This multi-oscillatory network is entrained by the master pacemaker located in the suprachiasmatic nucleus (SCN) of the hypothalamus, which directs an organism's rhythmic expression of physiological functions and behavior via a hierarchical system. This system has been highly conserved throughout evolution and uses transcriptional-translational autoregulatory loops. This master clock, following environmental cues, regulates an organism's sleep pattern, body temperature, cardiac activity and blood pressure, hormone secretion, oxygen consumption and metabolic rate. Mammalian peripheral clocks and clock gene expression have recently been discovered and are present in all nucleated cells in our body. Like other essential organ of the body, the skin also has cycles that are informed by this master regulator. In addition, skin cells have peripheral clocks that can function autonomously. First described in 2000 for skin, this review summarizes some important aspects of a rapidly growing body of research in circadian and ultradian (an oscillation that repeats multiple times during a 24 h period) cutaneous rhythms, including clock mechanisms, functional manifestations, and stimuli that entrain or disrupt normal cycling. Some specific relationships between disrupted clock signaling and consequences to skin health are discussed in more depth in the other invited articles in this IJMS issue on Sleep, Circadian Rhythm and Skin.

Assessment of Antioxidant Potential and Acute Toxicity Studies of Whole Plant Extract of Pergularia Daemia (Forsk)

Background:

Pergularia daemia (Asclepiadacea) is a fetid- smelling perennial herb growing well along the river bang and road sides of India. Naturally the plant has powerful antioxidants including polyphenols, flavanoids, steroids and terpenoids.

Objective:

The aim of this study is to evaluate the in vitro antioxidant potential and to determine the median lethal dose (LD₅₀) of crude ethyl acetate and methanol extracts of Pergularia daemia. The plant Pergularia daemia possess effective scavenging activity against 2, 2' azino bis (3 ethylbenzothiazoline 6 sulfonic acid (ABTS), nitric oxide and reducing power radicals at different concentrations (100, 200, 300, 400 & 500 µg/mL) of both extracts.

Results:

From the above in vitro assay we have exposed that the methanolic extract exert higher antioxidant activity at 400 µg/mL than ethyl acetate extract. Acute toxicity study revealed that the extracts showed no signs of toxicity upto a dose level of 2500 mg/kg b.wt.

Conclusion:

Thus our findings provide that both extracts of Pergularia daemia possess a strong antioxidant capacity and are relatively has high margin of safety.

The determination of the radical power - an in vitro test for the evaluation of cosmetic products

OBJECTIVE

Cosmetic formulations are influenced by environmental impacts and ageing, resulting in rancidity and change of colour and structure. These changes are caused by free radicals (FRs). The sensitivity of cosmetics generating FRs is a metric for its quality and should be determined.

METHODS

Electron spin resonance spectroscopy in combination with UV irradiation tested cosmetics such as creams, milks, lotions and fragrances. The probes were directly measured without expensive preparation.

RESULTS

Nine formulations are tested for its radical generation and ranked corresponding to the radical power. The transformation of the FR properties of three formulations to skin is measured by the radical skin status factor (RSF) method. It shows that the higher the radical power (RP) is, the lower the radical status RSF of skin will be.

CONCLUSION

The knowledge of the sensitivity of cosmetics to generate FRs is necessary for its stabilization and prevention of potential damages to skin. It is a new way in development of cosmetics which has to be considered.

Brazilian consensus on photoprotection

Brazil is a country of continental dimensions with a large heterogeneity of climates and massive mixing of the population. Almost the entire national territory is located between the Equator and the Tropic of Capricorn, and the Earth axial tilt to the south certainly makes Brazil one of the countries of the world with greater extent of land in proximity to the sun. The Brazilian coastline, where most of its population lives, is more than 8,500 km long. Due to geographic characteristics and cultural trends, Brazilians are among the peoples with the highest annual exposure to the sun. Epidemiological data show a continuing increase in the incidence of non-melanoma and melanoma skin cancers. Photoprotection can be understood as a set of measures aimed at reducing sun exposure and at preventing the development of acute and chronic actinic damage. Due to the peculiarities of Brazilian territory and culture, it would not be advisable to replicate the concepts of photoprotection from other developed countries, places with completely different climates and populations. Thus the Brazilian Society of Dermatology has developed the Brazilian Consensus on Photoprotection, the first official document on photoprotection developed in Brazil for Brazilians, with recommendations on matters involving photoprotection.

Polycomponent mesotherapy formulations for the treatment of skin aging and improvement of skin quality

Skin aging can largely be attributed to dermal fibroblast dysfunction and a decrease in their biosynthetic activity. Regardless of the underlying causes, aging fibroblasts begin to produce elements of the extracellular matrix in amounts that are insufficient to maintain the youthful appearance of skin. The goal of mesopreparations is primarily to slow down and correct changes in skin due to aging. The rationale for developing complex polycomponent mesopreparations is based on the principle that aging skin needs to be supplied with the various substrates that are key to the adequate functioning of the fibroblast. The quintessential example of a polycomponent formulation – NCTF^® (New Cellular Treatment Factor) – includes vitamins, minerals, amino acids, nucleotides, coenzymes and antioxidants, as well as hyaluronic acid, designed to help fibroblasts function more efficiently by providing a more optimal environment for biochemical processes and energy generation, as well as resisting the effects of oxidative stress. In vitro experiments suggest that there is a significant increase in the synthetic and prophylactic activity of fibroblasts with treated NCTF, and a significant increase in the ability of cells to resist oxidative stress. The current article looks at the rationale behind the development of polycomponent mesopreparations, using NCTF as an example.

Mechanisms of Photoaging and Cutaneous Photocarcinogenesis, and Photoprotective Strategies with Phytochemicals

Photoaging and photocarcinogenesis are primarily due to solar ultraviolet (UV) radiation, which alters DNA, cellular antioxidant balance, signal transduction pathways, immunology, and the extracellular matrix (ECM). The DNA alterations include UV radiation induced thymine-thymine dimers and loss of tumor suppressor gene p53. UV radiation reduces cellular antioxidant status by generating reactive oxygen species (ROS), and the resultant oxidative stress alters signal transduction pathways such as the mitogen-activated protein kinase (MAPK), the nuclear factor-kappa beta (NF-κB)/p65, the janus kinase (JAK), signal transduction and activation of transcription (STAT) and the nuclear factor erythroid 2-related factor 2 (Nrf2). UV radiation induces pro-inflammatory genes and causes immunosuppression by depleting the number and activity of the epidermal Langerhans cells. Further, UV radiation remodels the ECM by increasing matrixmetalloproteinases (MMP) and reducing structural collagen and elastin. The photoprotective strategies to prevent/treat photoaging and photocarcinogenesis include oral or topical agents that act as sunscreens or counteract the effects of UV radiation on DNA, cellular antioxidant balance, signal transduction pathways, immunology and the ECM. Many of these agents are phytochemical derivatives and include polyphenols and non-polyphenols. The flavonoids are polyphenols and include catechins, isoflavones, proanthocyanidins, and anthocyanins, whereas the non-flavonoids comprise mono phenolic acids and stilbenes. The natural sources of polyphenols include tea, cocoa, grape/wine, soy, pomegranate, and Polypodium leucotomos. The non-phenolic phytochemicals include carotenoids, caffeine and sulphoraphance (SFN). In addition, there are other phytochemical derivatives or whole extracts such as baicalin, flavangenol, raspberry extract, and Photomorphe umbellata with photoprotective activity against UVB radiation, and thereby carcinogenesis.

Skin, reactive oxygen species, and circadian clocks

SIGNIFICANCE

Skin, a complex organ and the body's first line of defense against environmental insults, plays a critical role in maintaining homeostasis in an organism. This balance is maintained through a complex network of cellular machinery and signaling events, including those regulating oxidative stress and circadian rhythms. These regulatory mechanisms have developed integral systems to protect skin cells and to signal to the rest of the body in the event of internal and environmental stresses.

RECENT ADVANCES

Interestingly, several signaling pathways and many bioactive molecules have been found to be involved and even important in the regulation of oxidative stress and circadian rhythms, especially in the skin. It is becoming increasingly evident that these two regulatory systems may, in fact, be interconnected in the regulation of homeostasis. Important examples of molecules that connect the two systems include serotonin, melatonin, vitamin D, and vitamin A.

CRITICAL ISSUES

Excessive reactive oxygen species and/or dysregulation of antioxidant system and circadian rhythms can cause critical errors in maintaining proper barrier function and skin health, as well as overall homeostasis. Unfortunately, the modern lifestyle seems to contribute to increasing alterations in redox balance and circadian rhythms, thereby posing a critical problem for normal functioning of the living system.

FUTURE DIRECTIONS

Since the oxidative stress and circadian rhythm systems seem to have areas of overlap, future research needs to be focused on defining the interactions between these two important systems. This may be especially important in the skin where both systems play critical roles in protecting the whole body.

Effects of solar radiation on the skin

No one would underestimate the importance of sunlight to the evolution of life on the earth and its role in human development. However, all humans - especially individuals who are lightly pigmented or whose occupation or lifestyle exposes them to excessive amounts of sunlight - are potentially susceptible to its deleterious effects. These effects can range from acute biological responses, such as sunburn and skin tanning, to conditions resulting from chronic exposure such as photoaged skin and potentially life-threatening conditions such as skin cancer. The objective of this review is to present a concise and up-to-date perspective on the effects of UVB, UVA, visible, and infrared radiation on cutaneous biochemistry and physiology.