AGEs Blocker™ (Goji Berry, Fig, and Korean Mint Mixed Extract) Inhibits Skin Aging Caused by Streptozotocin-Induced Glycation in Hairless Mice

Synthetic and Natural Agents Targeting Advanced Glycation End-Products for Skin Anti-Aging: A Comprehensive Review of Experimental and Clinical Studies

Advanced glycation end-products (AGEs) cause blood vessel damage and induce diabetic complications in various organs, such as the eyes, kidneys, nerves, and skin. As glycation stress causes aesthetic, physical, and functional changes in the skin, glycation-targeting skin anti-aging strategies are attracting attention in cosmetology and dermatology. The primary goal of this review is to understand the significance of glycation-induced skin aging and to examine the therapeutic potential of glycation-targeting strategies. This study covers experimental and clinical studies exploring various interventions to attenuate glycation-induced skin aging. Glycation stress decreases the viability of cells in culture media, the cell-mediated contraction of collagen lattices in reconstructed skin models, and the expression of fibrillin-1 at the dermo-epidermal junction in the skin explants. It also increases cross-links in tail tendon collagen in animals, prolonging its breakdown time. However, these changes are attenuated by several synthetic and natural agents. Animal and clinical studies have shown that dietary or topical administration of agents with antiglycation or antioxidant activity can attenuate changes in AGE levels (measured by skin autofluorescence) and skin aging parameters (e.g., skin color, wrinkles, elasticity, hydration, dermal density) induced by chronological aging, diabetes, high-carbohydrate diets, ultraviolet radiation, or oxidative stress. Therefore, the accumulating experimental and clinical evidence supports that dietary supplements or topical formulations containing one or more synthetic and natural antiglycation agents may help mitigate skin aging induced by AGEs.

Functional Observation Battery Test for Single Intravenous Caffeine Exposure in Male ICR Mice

This study investigated the behavioral responses of male Institute for Cancer Research (ICR) mice to intravenous caffeine exposure via a functional observation battery (FOB) test. Thirty-two experimental mice were randomly assigned to four groups (n = 8 per group) and received intravenous caffeine at a dose of 0, 5, 10, or 20 mg/kg. Functional behaviors were observed at 0, 0.25, 1.5, 6, and 24 h after intravenous caffeine administration. Among the hand-held observations, the ease of removal from the cage and the ease of handling were significantly altered in all caffeine-exposed mice in both a dose-dependent and a time-dependent manner. In terms of physiological responses, both stimulus responses and locomotor activities were significantly affected by intravenous caffeine exposure. Specifically, the tail pinch response was significantly impaired in half of the mice in the 10 mg/kg and 20 mg/kg groups. Moreover, the rearing count decreased in the 10 mg/kg group at 1.5 to 6 h and in the 20 mg/kg group at 1.5 h after intravenous caffeine exposure. Furthermore, locomotor activity was markedly increased 0.25 h after intravenous caffeine administration in the 20 mg/kg group. These findings clearly indicate that intravenous caffeine exposure significantly impacts functional behaviors, as assessed by an FOB test, which is consistent with widely accepted safety pharmacology testing guidelines.

Respiratory Responses to a Single Oral Dose of Caffeine in Male Sprague-Dawley Rats

Caffeine is a key component of beverages such as coffee and tea and has effects on the cardiovascular and respiratory systems, prompting a variety of physiological changes. In our previous study, intravenously administered caffeine at high concentrations significantly influenced respiratory rates. However, comparative research on the potential adverse effects of caffeine consumption on the respiratory system is limited. To address this issue, in this study, we focused on evaluating the effects of orally administered caffeine (0, 2, 6, and 20 mg/kg) on the respiratory system of 6-week-old male Sprague-Dawley rats. We measured the respiratory rate, tidal volume, and minute volume following the guidelines set forth by the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use, specifically adhering to Harmonized Tripartite Guideline S7A for Safety Pharmacology Studies for Human Pharmaceuticals. Caffeine administration led to a notable increase in both the respiratory rate and the tidal volume. Conversely, a marked reduction in minute volume was recorded between 0.5 and 2 h following caffeine administration in doses exceeding 6 mg/kg.

Fermented Fish Collagen Diminished Photoaging-Related Collagen Decrease by Attenuating AGE-RAGE Binding Activity

Ultraviolet (UV) irradiation causes skin wrinkles and decreases elasticity. UV also increases binding between advanced glycation end products (AGEs) and the receptor for AGEs (RAGE), resulting in increased inflammation and activation of NF-κB. We evaluated whether fermented fish collagen (FC) could decrease photoaging via decreasing AGE-RAGE binding activity, which was associated with decreased TNF-α and NF-κB levels in UV-irradiated keratinocytes and animal skin. In the UV-irradiated keratinocytes, AGE-RAGE binding activity and TNF-α secretion levels were increased, and FC decreased these. Additionally, AGE-RAGE binding activity and TNF-α secretion levels were attenuated by soluble RAGE (RAGE inhibitor) in the UV-irradiated keratinocytes. FC decreased AGE-RAGE binding activity, TNF-α levels, and translocation of NF-κB in the UV-irradiated skin. Furthermore, FC decreased the expression of matrix metalloproteinases 1/3/9, which degrades collagen fibers, and Smad7, which inhibits Smad2/3, in UV-irradiated skin. FC increased Smad2/3 and collagen fiber accumulation. FC also increases skin moisture and elasticity. In conclusion, FC could attenuate skin photoaging via decreasing AGE-RAGE binding activity and its downstream signals such as TNF-α and NF-κB.

Matrix Metalloproteinases on Skin Photoaging

BACKGROUND

Skin aging is characterized by an imbalance between the generation and degradation of extracellular matrix molecules (ECM). Matrix metalloproteinases (MMPs) are the primary enzymes responsible for ECM breakdown. Intrinsic and extrinsic stimuli can induce different MMPs. However, there is limited literature especially on the summary of skin MMPs and potential inhibitors.

OBJECTIVE

We aim to focus on the upregulation of MMP expression or activity in skin cells following exposure to UV radiation. We also would like to offer valuable insights into potential clinical applications of MMP inhibitors for mitigating skin aging.

METHODS

This article presents the summary of prior research, which involved an extensive literature search across diverse academic databases including Web of Science and PubMed.

RESULTS

Our findings offer a comprehensive insight into the effects of MMPs on skin aging after UV irradiation, including their substrate preferences and distinct roles in this process. Additionally, a comprehensive list of natural plant and animal extracts, proteins, polypeptides, amino acids, as well as natural and synthetic compounds that serve as inhibitors for MMPs is compiled.

CONCLUSION

Skin aging is a complex process influenced by environmental factors and MMPs. Research focuses on UV-induced skin damage and the formation of Advanced Glycosylation End Products (AGEs), leading to wrinkles and impaired functionality. Inhibiting MMPs is crucial for maintaining youthful skin. Natural sources of MMP inhibitor substances, such as extracts from plants and animals, offer a safer approach to obtain inhibitors through dietary supplements. Studying isolated active ingredients can contribute to developing targeted MMP inhibitors.

The effects of advanced glycation end-products on skin and potential anti-glycation strategies

The advanced glycation end-products (AGEs) are produced through non-enzymatic glycation between reducing sugars and free amino groups, such as proteins, lipids or nucleic acids. AGEs can enter the body through daily dietary intake and can also be generated internally via normal metabolism and external stimuli. AGEs bind to cell surface receptors for AGEs, triggering oxidative stress and inflammation responses that lead to skin ageing and various diseases. Evidence shows that AGEs contribute to skin dysfunction and ageing. This review introduces the basic information, the sources, the metabolism and absorption of AGEs. We also summarise the detrimental mechanisms of AGEs to skin ageing and other chronic diseases. For the potential strategies for counteracting AGEs to skin and other organs, we summarised the pathways that could be utilised to resist glycation. Chemical and natural-derived anti-glycation approaches are overviewed. This work offers an understanding of AGEs to skin ageing and other chronic diseases and may provide perspectives for the development of anti-glycation strategies.