Several lines of antioxidant defense against oxidative stress: antioxidant enzymes, nanomaterials with multiple enzyme-mimicking activities, and low-molecular-weight antioxidants

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are well recognized for playing a dual role, since they can be either deleterious or beneficial to biological systems. An imbalance between ROS production and elimination is termed oxidative stress, a critical factor and common denominator of many chronic diseases such as cancer, cardiovascular diseases, metabolic diseases, neurological disorders (Alzheimer's and Parkinson's diseases), and other disorders. To counteract the harmful effects of ROS, organisms have evolved a complex, three-line antioxidant defense system. The first-line defense mechanism is the most efficient and involves antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). This line of defense plays an irreplaceable role in the dismutation of superoxide radicals (O2•-) and hydrogen peroxide (H2O2). The removal of superoxide radicals by SOD prevents the formation of the much more damaging peroxynitrite ONOO- (O2•-  + NO• → ONOO-) and maintains the physiologically relevant level of nitric oxide (NO•), an important molecule in neurotransmission, inflammation, and vasodilation. The second-line antioxidant defense pathway involves exogenous diet-derived small-molecule antioxidants. The third-line antioxidant defense is ensured by the repair or removal of oxidized proteins and other biomolecules by a variety of enzyme systems. This review briefly discusses the endogenous (mitochondria, NADPH, xanthine oxidase (XO), Fenton reaction) and exogenous (e.g., smoking, radiation, drugs, pollution) sources of ROS (superoxide radical, hydrogen peroxide, hydroxyl radical, peroxyl radical, hypochlorous acid, peroxynitrite). Attention has been given to the first-line antioxidant defense system provided by SOD, CAT, and GPx. The chemical and molecular mechanisms of antioxidant enzymes, enzyme-related diseases (cancer, cardiovascular, lung, metabolic, and neurological diseases), and the role of enzymes (e.g., GPx4) in cellular processes such as ferroptosis are discussed. Potential therapeutic applications of enzyme mimics and recent progress in metal-based (copper, iron, cobalt, molybdenum, cerium) and nonmetal (carbon)-based nanomaterials with enzyme-like activities (nanozymes) are also discussed. Moreover, attention has been given to the mechanisms of action of low-molecular-weight antioxidants (vitamin C (ascorbate), vitamin E (alpha-tocopherol), carotenoids (e.g., β-carotene, lycopene, lutein), flavonoids (e.g., quercetin, anthocyanins, epicatechin), and glutathione (GSH)), the activation of transcription factors such as Nrf2, and the protection against chronic diseases. Given that there is a discrepancy between preclinical and clinical studies, approaches that may result in greater pharmacological and clinical success of low-molecular-weight antioxidant therapies are also subject to discussion.

Spectroscopic insight on impact of environment on natural photoprotectants

Biomimicry has become a key player in researching new materials for a whole range of applications. In this study, we have taken a crude extract from the red algae Palmaria palmata containing mycosporine-like amino acids - a photoprotective family of molecules. We have applied the crude extract onto a surface to assess if photoprotection, and more broadly, light-to-heat conversion, is retained; we found it is. Considering sunscreens as a specific application, we have performed transmission and reflection terahertz spectroscopy of the extract and glycerol to demonstrate how one can monitor stability in real-world applications.

Examining the substituent effect on mycosporine-inspired ultraviolet filters

Current organic ultraviolet (UV) filters found in sunscreen formulations suffer a number of drawbacks. In this work, we have synthesised four biomimetic molecules built on the mycosporine molecular scaffold (a natural UV filter) with varying substituents at one of the carbons on the ring and investigated their photoprotective properties. From our findings, we infer design guidelines which may have a direct result on the production of next generation UV filters.

A Perspective on Femtosecond Pump-Probe Spectroscopy in the Development of Future Sunscreens

Given the negative impacts of overexposure to ultraviolet radiation (UVR) on humans, sunscreens have become a widely used product. Certain ingredients within sunscreens are responsible for photoprotection and these are known, collectively herein, as ultraviolet (UV) filters. Generally speaking, organic UV filters work by absorbing the potentially harmful UVR and dissipating this energy as harmless heat. This process happens on picosecond time scales and so femtosecond pump–probe spectroscopy (FPPS) is an ideal technique for tracking this energy conversion in real time. Coupling FPPS with complementary techniques, including steady-state spectroscopy and computational methods, can provide a detailed mechanistic picture of how UV filters provide photoprotection. As such, FPPS is crucial in aiding the future design of UV filters. This Perspective sheds light on the advancements made over the past two years on both approved and nature-inspired UV filters. Moreover, we suggest where FPPS can be further utilized within sunscreen applications for future considerations.

Prospective Evaluation of the Efficacy of a Food Supplement in Increasing Photoprotection and Improving Selective Markers Related to Skin Photo-Ageing

INTRODUCTION

Skin exposure to ultraviolet radiation (UVR) can cause oxidative stress, particularly in the absence of adequate protective measures or in individuals with a sensitive skin type. Most commonly, protection from UVR entails the use of topical sunscreens. Sunscreens, however, have various limitations. The objective of this study was to evaluate the efficacy and tolerability of an oral food supplement containing a combination of actives with mainly antioxidative properties (vitamins A, C, D3, E, selenium, lycopene, lutein, as well as green tea, polypodium and grape extracts) in the context of photoprotection.

METHODS

Photoprotective efficacy was assessed in a 12-week-long, open, prospective and monocentric clinical study with 30 subjects (27 women and 3 men) having a Fitzpatrick skin type I-III and manifesting clinical ageing signs. The study included several visits (14, 28, 56, and 84 days after starting supplement intake), in which photoprotection was evaluated by the measurement of the minimal erythema dose (MED), while the antioxidant capacity of the skin was assessed through ferric reducing antioxidant power (FRAP) and malondialdehyde (MDA) assays. Additionally, several skin parameters (including radiance, elasticity, and moisture) were evaluated. Product evaluation was performed throughout the length of the study by means of a self-assessment questionnaire, and safety was monitored through a self-recording of all observed adverse reactions.

RESULTS

The MED levels increased significantly compared to baseline throughout the study visits, reaching an increase of + 8.1% at T84, p < 0.001. FRAP results also indicated a significant increase in the antioxidant capacity of the skin compared to baseline (+ 22.7% at T84, p < 0.001), while the MDA assay showed a significant decrease in MDA concentration compared to baseline (- 6.4% at T84, p < 0.001) which, in line with the FRAP results, indicated enhanced antioxidative protection of the skin. All assessed skin parameters, including radiance (+ 36.1% at T84, p < 0.001), gross elasticity (+ 13.2% at T84, p < 0.001), net elasticity (+ 28.0% at T84, p < 0.001), and moisture (+ 13.8% at T84, p < 0.001) were also significantly improved. The product was well tolerated as no adverse events were attributed by the investigators to the use of the product. Additionally, the global score obtained from the self-assessment questionnaires provided overwhelmingly positive feedback from the study subjects.

CONCLUSIONS

The food supplement evaluated in this study was effective and well-tolerated by the subjects, demonstrating a beneficial effect in terms of photoprotection, enhancing the antioxidative status of the skin and improving general skin condition.

TRIAL REGISTRATION

Retrospectively registered 3rd October 2019, ISRCTN18121679.

Topical Use of Quercetin-Loaded Chitosan Nanoparticles Against Ultraviolet B Radiation

Ultraviolet radiation is a major risk factor for human skin damage, especially solar ultraviolet-B (UVB) which can induce inflammation, photoaging, and skin cancer. Quercetin (Qu), one of flavonoid family members, has showed protective effects against UVB radiation. However, its application for topical use is limited by low hydrophilicity and poor percutaneous absorption. Herein, we found that Qu, if entrapped into TPP-Chitosan nanoparticles (TCs), can be efficiently uptake by HaCaT cells and easily permeate through the epidermis layer, meanwhile display better stability and low cytotoxicity. We also found that Qu-loaded TCs (QTCs) could notably enhance the effect of Qu on inhibiting the NF-kB/COX-2 signaling pathway as well as ameliorating the skin edema caused by UVB radiation. Therefore, this study provided a method to get rid of Qu's low hydrophilicity, enhance its percutaneous absorption and retention in the skin, and further improve its anti-UVB effect, and demonstrated that Qu-loaded chitosan nanoparticles can be used as the therapeutic agent for topical use against UVB radiation.

Disparities by Sexual Orientation in Frequent Engagement in Cancer-Related Risk Behaviors: A 12-Year Follow-Up

OBJECTIVES

We examined sexual-orientation disparities in frequent engagement in cancer-related risk indicators of tobacco, alcohol, diet and physical activity, ultraviolet radiation, and sexually transmitted infections (STIs).

METHODS

We used longitudinal data from the national Growing Up Today Study (1999-2010). Of the analytic sample (n = 9958), 1.8% were lesbian or gay (LG), 1.6% bisexual (BI), 12.1% mostly heterosexual (MH), and 84.5% completely heterosexual (CH).

RESULTS

More sexual minorities (LGs, BIs, and MHs) than CHs frequently engaged in multiple cancer-related risk behaviors (33%, 29%, 28%, and 19%, respectively). Sexual-minority young women, especially BI and MH, more frequently engaged over time in substance use and diet and physical activity risk than CH women. More young gay than CH men frequently engaged over time in vomiting for weight control (odds ratio [OR] = 3.2; 95% confidence interval [CI] = 1.1, 9.4), being physically inactive (OR = 1.7; 95% CI = 1.2, 2.4), and using tanning booths (OR = 4.7; 95% CI = 3.0, 7.4), and had a higher prevalence of ever having an STI (OR = 3.5; 95% CI = 2.0, 6.4). Individual analyses were generally comparable to the group-level analyses.

CONCLUSIONS

Young sexual minorities are at risk for cancer through frequent exposure to cancer-related risk behaviors over time. Long-term, longitudinal studies and surveillance data are essential and warranted to track frequent engagement in the risk behaviors and cancer-related morbidity and mortality.

Review of natural compounds for potential skin cancer treatment

Most anti-cancer drugs are derived from natural resources such as marine, microbial and botanical sources. Cutaneous malignant melanoma is the most aggressive form of skin cancer, with a high mortality rate. Various treatments for malignant melanoma are available, but due to the development of multi-drug resistance, current or emerging chemotherapies have a relatively low success rates. This emphasizes the importance of discovering new compounds that are both safe and effective against melanoma. In vitro testing of melanoma cell lines and murine melanoma models offers the opportunity for identifying mechanisms of action of plant derived compounds and extracts. Common anti-melanoma effects of natural compounds include potentiating apoptosis, inhibiting cell proliferation and inhibiting metastasis. There are different mechanisms and pathways responsible for anti-melanoma actions of medicinal compounds such as promotion of caspase activity, inhibition of angiogenesis and inhibition of the effects of tumor promoting proteins such as PI3-K, Bcl-2, STAT3 and MMPs. This review thus aims at providing an overview of anti-cancer compounds, derived from natural sources, that are currently used in cancer chemotherapies, or that have been reported to show anti-melanoma, or anti-skin cancer activities. Phytochemicals that are discussed in this review include flavonoids, carotenoids, terpenoids, vitamins, sulforaphane, some polyphenols and crude plant extracts.

Beyond obesity and lifestyle: a review of 21st century chronic disease determinants

The obesity epidemic and associated chronic diseases are often attributed to modern lifestyles. The term "lifestyle" however, ignores broader social, economic, and environmental determinants while inadvertently "blaming the victim." Seen more eclectically, lifestyle encompasses distal, medial, and proximal determinants. Hence any analysis of causality should include all these levels. The term "anthropogens," or "…man-made environments, their by-products and/or lifestyles encouraged by these, some of which may be detrimental to human health" provides a monocausal focus for chronic diseases similar to that which the germ theory afforded infectious diseases. Anthropogens have in common an ability to induce a form of chronic, low-level systemic inflammation ("metaflammation"). A review of anthropogens, based on inducers with a metaflammatory association, is conducted here, together with the evidence for each in connection with a number of chronic diseases. This suggests a broader view of lifestyle and a focus on determinants, rather than obesity and lifestyle per se as the specific causes of modern chronic disease. Under such an analysis, obesity is seen more as "a canary in a mineshaft" signaling problems in the broader environment, suggesting that population obesity management should be focused more upstream if chronic diseases are to be better managed.

Promotion of Sun-Protective Behaviors

Promoting sun-protective behaviors is important because decreased exposure to ultraviolet radiation (UVR) reduces the risk of skin cancer. However, many individuals deliberately engage in overexposure to UVR for cosmetic purposes. Due to this and other factors, the need for prevention programs is clear. Several efficacious prevention strategies have been developed for the health care setting.