Topical retinoids in the treatment of photoaging

Topical retinoids: Novel derivatives, nano lipid-based carriers, and combinations to improve chemical instability and skin irritation

BACKGROUND

Retinoids, defined as synthetic or natural derivatives of vitamin A, have been extensively studied as anti-aging molecules that are widely applied in cosmetics. However, due to their physicochemical property, retinoids are highly unstable and extremely sensitive to light, oxygen, and temperature. Moreover, topical application of retinoids often leads to cutaneous irritation. These instabilities and irritant properties of retinoids limit their application in cosmetic and pharmaceutical products.

AIM

Our study aimed to provide a systematic review to summarize the mechanisms underlying the instability and irritant properties of retinoids, as well as recent developments in addressing these challenges.

METHODS

A comprehensive PubMed search was conducted using the following keywords: retinoids, chemical instability, skin irritation, retinoid derivatives, nano lipid-based carriers, liposomes, penetration-enhancer vesicles, ethosomes, niosomes, nanoemulsions, solid lipid nanoparticles, vitamins, soothing and hydrating agents, antioxidants and metal chelator and retinol combinations. Relevant researches published between 1968 and 2023 and studies related to these reports were reviewed.

RESULTS

The development of new retinoid derivatives, the utilization of new delivery systems like nano lipid-based carriers and the combination with other compounds like vitamins, soothing agents, antioxidants and metal chelator have been explored to improve the stability, bioavailability, and toxicity of the retinoid family.

CONCLUSIONS

Through advancements in formulation techniques, structure modification of retinoid derivatives and development of novel nano lipid-based carriers, the chemical instability and skin irritation of retinoids has been mitigated, ensuring their efficacy and potency over extended periods.

Formulation and Skin Permeation of Active-Loaded Lipid Nanoparticles: Evaluation and Screening by Synergizing Molecular Dynamics Simulations and Experiments

Encapsulation into nanoparticles (NPs) is a potential method to deliver pharmaceutical/cosmetic actives deep into the skin. However, understanding the NP formulations and underlying mechanism of active delivery to skin has scarcely been studied. We report a simulation platform that screens, evaluates, formulates, and provides atomic-resolution interpretation of NP-based formulations, and reveals the active permeation mechanism from NPs to skin. First, three actives, namely, ferulic acid (FA), clotrimazole (CZE), and tretinoin (TTN), and five lipid excipients' (Compritol, Precirol, Geleol, Gelot, Gelucire) combinations were screened by MD simulations for the best pairs. For each suggested pair, the actual active and lipid compositions for the synthesis of stable NP formulations were then obtained by experiments. MD simulations demonstrate that in NP formulations, FA and CZE actives are present at the surface of the NPs, whereas TTN actives are present at both the surface and interior of the NP core. The NP shapes obtained by simulation perfectly match with experiments. For each NP, separate MD simulations illustrate that active-loaded NPs approach the skin surface quickly, and then actives translocate from NP surface to skin surface followed by penetration of NPs through skin. The driving force for the translocation which initiates during the penetration process, is the stronger active-skin interaction compared to active-NP interaction. Permeation free energy indicates spontaneous transfer of actives from solution phase to the surface of the skin bilayer. The free energy barriers are increased in the order of FA < TTN < CZE. Significantly lower diffusions of actives are obtained in the main barrier region compared to bulk, and the average diffusion coefficients of actives are in the same order of magnitude (∼10^-6 cm²/s). The estimated permeability coefficients (log P) of actives are mainly governed by free energy barriers. The study would facilitate the development of novel lipid-based NP formulations for personal-care/pharmaceutical applications.

Spectroscopy of Retinoic Acid at the Air-Water Interface

The spectroscopy of all-trans-retinoic acid (ATRA), an important molecule of biological origin that can be found in nature, is investigated at the air-water interface using UV-Vis and IR reflection spectroscopy. We employ a UV-Vis reflection absorption spectroscopy (RAS) experiment along with infrared reflection absorption spectroscopy (IR-RAS) to probe ATRA at the air-water interface. We elucidate the factors influencing the spectroscopy of ATRA at the air-water interface and compare its spectra at the water surface with results of bulk samples obtained with conventional spectroscopic methods and computational chemistry. Monolayers of pure ATRA as well as mixed ATRA with stearic-d₃₅ acid were prepared, and the spectroscopy reveals that ATRA forms J-aggregates with itself, causing a significant redshift of its S₀ to S₁ electronic transition. Pure ATRA monolayers are found to be unstable at the air-water interface and are lost from the surface over time due to the formation of aggregates. The mixture of ATRA and stearic-d₃₅ acid has been shown to stabilize the monolayers and inhibit the loss of surface ATRA. On the basis of our observations, we propose that ATRA could be a significant photosensitizer in natural aqueous environments.

Evolution of the use of antioxidants in anti-ageing cosmetics

OBJECTIVE

Skin health and beauty are a cornerstone of general well-being in humans. Anti-ageing cosmetics are used to provide a healthy and youthful appearance. Among the different cosmetic actives, antioxidants are incorporated in anti-ageing products due to their beneficial effects in preventing and minimizing the signs of skin ageing. This work aims to understand how anti-ageing formulations changed in the past 7 years regarding pure antioxidants composition.

METHODS

Data were collected from anti-ageing formulations commercialized in main stores and pharmacies in the Portuguese market. The study started on 2011 and was updated with products launched or whose composition has been renewed on 2013, 2015 or 2018.

RESULTS

Ascorbic acid and tocopherol and their derivatives were consistently the most used antioxidants in anti-ageing formulations; followed by niacinamide and retinyl palmitate. Seven ascorbic acid derivatives are currently used in anti-ageing formulations while only three tocopherol derivatives were identified in this study. Several combinations of antioxidants were routinely found, mainly tocopherol (or tocopherol derivatives) with other antioxidants and tocopherol with tocopherol derivatives. We have not identified emerging antioxidants with great impact in anti-ageing formulations even though niacinamide and retinyl palmitate exhibited over 10% more usage in 2018.

CONCLUSION

This insight is relevant to the cosmetic industry providing a better understanding of the scientific-based formulation of modern cosmetics and supports the need for innovative antioxidants in anti-ageing cosmetics.

Investigation on Toxicity and Teratogenicity in Rats of a Retinoid-Polyamine Conjugate with Potent Anti-Inflammatory Properties

Previous studies have shown that N(1),N(12)-bis(all-trans-retinoyl)spermine (RASP), a retinoid analog, inhibits RNase P activity and angiogenesis in the chicken embryo chorioallantoic membrane, demonstrates anti-tumor activity on prostate cancer cells, and acts as anti-inflammatory agent, being more effective and less toxic than all-trans retinoic acid. In an attempt to further characterize the biological profile of RASP, we tested its effects on organ toxicity and teratogenicity by daily oral gavage of RASP at a level of 50 mg/Kg of body weight in two generations of rats. We found that this compound does not induce changes to the body growth, the appearance of physical features, and the animal's reflexes. Additionally, no substantial histopathological lesions were found in brain, heart, lung, thymus, liver, thyroid gland, adrenal gland, pituitary gland, kidneys, spleen, skin, femora, prostate, testis, epididymis, vagina, uterus, and ovaries of RASP-treated animals. These results suggest RASP, as a promising lead compound for the treatment of several dermatological disorders and certain cancer types, has apparently minimal toxic side-effects as revealed in this two-generation reproduction study in rats.

Antiageing Mechanisms of a Standardized Supercritical CO 2 Preparation of Black Jack (Bidens pilosa L.) in Human Fibroblasts and Skin Fragments

The use of topical retinoids to treat skin disorders and ageing can induce local reactions, while oral retinoids are potent teratogens and produce several unwanted effects. This way, efforts to explore complementary care resources should be supported. Based on this, we evaluate the antiageing effects of a supercritical CO₂ extract from Bidens pilosa L. (BPE-CO₂A) containing a standardized multicomponent mixture of phytol, linolenic, palmitic, linoleic, and oleic acids. BPE-CO₂A was assessed for its effects on human dermal fibroblasts (TGF-β1 and FGF levels using ELISA; collagen, elastin, and glycosaminoglycan by colorimetric assays, and mRNA expression of RXR, RAR, and EGFr by qRT-PCR) and human skin fragments (RAR, RXR, collagen, elastin, and glycosaminoglycan by immunohistochemical analysis). Levels of extracellular matrix elements, TGF-β1 and FGF, and EGFr gene expression were significantly increased by BPE-CO₂A. The modulation of RXR and RAR was positively demonstrated after the treatment with BPE-CO₂A or phytol, a component of BPE-CO₂A. The effects produced by BPE-CO₂A were similar to or better than those produced by retinol and retinoic acid. The ability to stimulate extracellular matrix elements, increase growth factors, and modulate retinoid and rexinoid receptors provides a basis for the development of preparation containing BPE-CO₂A as an antiageing/skin-repair agent.

Characterization of alcohol dehydrogenase from Kangiella koreensis and its application to production of all-trans-retinol

A recombinant alcohol dehydrogenase (ADH) from Kangiella koreensis was purified as a 40 kDa dimer with a specific activity of 21.3 nmol min(-1) mg(-1), a K m of 1.8 μM, and a k cat of 1.7 min(-1) for all-trans-retinal using NADH as cofactor. The enzyme showed activity for all-trans-retinol using NAD (+) as a cofactor. The reaction conditions for all-trans-retinol production were optimal at pH 6.5 and 60 °C, 2 g enzyme l(-1), and 2,200 mg all-trans-retinal l(-1) in the presence of 5% (v/v) methanol, 1% (w/v) hydroquinone, and 10 mM NADH. Under optimized conditions, the ADH produced 600 mg all-trans-retinol l(-1) after 3 h, with a conversion yield of 27.3% (w/w) and a productivity of 200 mg l(-1) h(-1). This is the first report of the characterization of a bacterial ADH for all-trans-retinal and the biotechnological production of all-trans-retinol using ADH.

Topical retinoids in skin ageing: a focused update with reference to sun-induced epidermal vitamin A deficiency

Vitamin A is an important constituent of the epidermis, where it plays a crucial role in epidermal turnover. A deficiency of epidermal vitamin A may be the consequence of nutritional vitamin A deficiency, exposure to sunlight or any UV source, oxidative stress or chronological ageing. As a consequence, any treatment aiming at increasing epidermal vitamin A would exert a protective effect against these deleterious conditions. Retinoids may counteract some deleterious actions of UV radiation by physical and biological mechanisms. Topical natural retinoic acid precursors such as retinaldehyde or retinol are less irritant than acidic retinoids and may prevent epidermal vitamin A deficiency due to nutritional deficiency, exposure to sunlight or any condition leading to free radical production. Retinoids may be combined with other compounds with complementary actions against ageing, nutritional deficiency and cancer, such as antioxidants, to potentiate their beneficial effects in the skin.

Pathway analysis for drug repositioning based on public database mining

Sixteen FDA-approved drugs were investigated to elucidate their mechanisms of action (MOAs) and clinical functions by pathway analysis based on retrieved drug targets interacting with or affected by the investigated drugs. Protein and gene targets and associated pathways were obtained by data-mining of public databases including the MMDB, PubChem BioAssay, GEO DataSets, and the BioSystems databases. Entrez E-Utilities were applied, and in-house Ruby scripts were developed for data retrieval and pathway analysis to identify and evaluate relevant pathways common to the retrieved drug targets. Pathways pertinent to clinical uses or MOAs were obtained for most drugs. Interestingly, some drugs identified pathways responsible for other diseases than their current therapeutic uses, and these pathways were verified retrospectively by in vitro tests, in vivo tests, or clinical trials. The pathway enrichment analysis based on drug target information from public databases could provide a novel approach for elucidating drug MOAs and repositioning, therefore benefiting the discovery of new therapeutic treatments for diseases.

Favre-Racouchot syndrome in a 39-year old female following radiation therapy

BACKGROUND

Favre-Racouchot syndrome is a cutaneous disease characterized by nodules, cysts, and comedones that typically develops on sun-exposed areas of the face. This syndrome most commonly affects white males between the ages of 40 and 60 years and is frequently associated with chronic sun exposure and, more recently, chronic cigarette smoking.

OBJECTIVE

We report a case of Favre-Racouchot syndrome in a 39-year-old female who received 6 weeks of radiation therapy to treat a grade 3 oligodendroglioma.

RESULTS AND CONCLUSION

Although there have been previously reported cases of Favre-Racouchot syndrome following radiation therapy, this case is unique given the young age of the patient and extent of involvement.

Fusion genes in solid tumors: an emerging target for cancer diagnosis and treatment

Studies over the past decades have uncovered fusion genes, a class of oncogenes that provide immense diagnostic and therapeutic advantages because of their tumor-specific expression. Originally associated with hemotologic cancers, fusion genes have recently been discovered in a wide array of solid tumors, including sarcomas, carcinomas, and tumors of the central nervous system. Fusion genes are attractive as both therapeutic targets and diagnostic tools due to their inherent expression in tumor tissue alone. Therefore, the discovery and elucidation of fusion genes in various cancer types may provide more effective therapies in the future for cancer patients.

Cosmeceuticals: practical applications

Cosmeceuticals are topically applied products that are more than merely cosmetic, yet are not true drugs that have undergone rigorous placebo controlled studies for safety and efficacy. There are many review articles that outline the theoretical biologic and clinical actions of these cosmeceuticals and their various ingredients. This article reviews how to incorporate various cosmeceuticals into the treatment regime of patients, depending on the diagnosis and therapies chosen. The practical application of when, why, and on whom to use different products will enable dermatologists to improve the methodology of product selection and, ultimately, improve patient's clinical results.

Retinoids in cosmeceuticals

Retinoids are natural and synthetic vitamin A derivatives. They are lipophilic molecules and easily penetrate the epidermis. Their biologically active forms can modulate the expression of genes involved in cellular differentiation and proliferation. Retinoic acid (tretinoin), its 13-cis isomer isotretinoin, as well as various synthetic retinoids are used for therapeutic purposes, whereas retinaldehyde, retinol, and retinyl esters, because of their controlled conversion to retinoic acid or their direct receptor-independent biologic action, can be used as cosmeceuticals. These natural retinoic acid precursors are thus expected to be helpful in (i) renewing epidermal cells, (ii) acting as UV filters, (iii) preventing oxidative stress, (iv) controlling cutaneous bacterial flora, and (v) improving skin aging and photoaging. Retinol and retinyl esters are not irritant, whereas demonstrating only a modest clinical efficiency. On the other hand, retinaldehyde, which is fairly well tolerated, seems to be the most efficient cosmeceutical retinoid; it has significant efficiency toward oxidative stress, cutaneous bacterial flora, epidermis renewing, and photoaging.