Effective reduction of post-inflammatory hyperpigmentation with the tyrosinase inhibitor isobutylamido-thiazolyl-resorcinol (Thiamidol)

LC-ESI-UHR-QqTOF-MS/MS profiling and anti-inflammatory potential of the cultivated Opuntia ficus-indica (L.) Mill. and the wild Opuntia stricta (Haw.) Haw. fruits from the Algerian region

Opuntia plants are abundant but still underexplored edible resources of the Algerian region. This work chemically characterizes extracts of different parts of the fruit of the commercial Opuntia ficus-indica (L.) Mill. and the wild Opuntia stricta (Haw.) Haw. growing in Bejaia, and evaluates their anti-inflammatory potential through different cell and cell-free bioassays. The LC-ESI-UHR-QqTOF-MS/MS analysis enabled the identification of 18 compounds, with azelaic acid and 1-O-vanilloyl-β-d-glucose reported here for the first time. Aqueous extracts of seeds were the most effective in scavenging superoxide anion radical (IC50 = 111.08 μg/mL) and presented the best anti-inflammatory potential in LPS-stimulated macrophages (IC50 = 206.30 μg/mL). The pulp of O. stricta suggested potential for addressing post-inflammatory hyperpigmentation, with piscidic and eucomic acids predicted with the strongest binding affinity towards tyrosinase, exhibiting higher scoring values than the reference inhibitor kojic acid. This pioneer study brings valuable perspectives for the pharmacological, nutritional and economic valorization of the wild O. stricta for functional foods.

Treatment of Post-Inflammatory Hyperpigmentation in Skin of Colour: A Systematic Review

Post inflammatory hyperpigmentation (PIH) affects all skin types with a heightened predilection for darker skin tones. Its course is chronic once developed and treatment is often difficult. This systematic review aims to summarize the treatment outcomes for PIH with a focus on skin of colour (SOC) individuals. A literature search was conducted using MEDLINE (from 1946), Embase (from 1974), PubMed, and Cochrane in adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guideline. Results from 48 studies summarized 1356 SOC individuals. The mean age was 29 years (n = 1036) and 78% were female (n = 786). The ethnic prevalence was 70% Black, 27% Asian, and 3% Latin. Overall, 20% were Fitzpatrick skin type (FST) III, 40% FST IV, 34% FST V, and 6% FST VI. Most cases were precipitated by inflammatory conditions (89%) and localized to the face (83%). The most frequently reported interventions were topical retinoids (22%) and laser therapy (17%). Partial improvement was seen in 85% and 66% of participants, respectively. Laser was the only intervention that offered complete resolution in a subgroup of patients (26%); however, there were reported cases of PIH exacerbation following treatment. Chemical peels (9%) and hydroquinone (7%) were among other treatments with less effective outcomes. PIH and its persistence is a prevalent issue, significantly affecting many affected individuals with darker skin tones. Our results show a lack of robust efficacy across all treatment modalities. There is considerable room for improvement in interventions for at-risk populations.

Efficacy of isobutylamido thiazolyl resorcinol for prevention of laser-induced post-inflammatory hyperpigmentation: A randomized, controlled trial

BACKGROUND

Q-switched (QS) Nd: YAG laser is one of the treatment options for solar lentigines (SLs). However, the incidence of post-inflammatory hyperpigmentation (PIH) is a common complication, especially in dark-complexioned skin. Isobutylamido thiazolyl resorcinol (ITR) has been reported as a preventive modality for ultraviolet B (UVB)-induced hyperpigmentation.

AIMS

This study aims to evaluate the efficacy and safety of ITR for the prevention of laser-induced PIH.

PATIENTS/METHODS

A randomized, evaluator-blinded study including 24 subjects with SLs was conducted. Three SLs of each patient were randomized into three groups, which were to apply ITR twice daily, once daily, and no application for 2 weeks. Thereafter, 532-nm QS Nd: YAG laser was performed. Incidence of laser-induced PIH, relative melanin index (RMI), mean luminance score (L*), hyperpigmentation score, and adverse events were recorded for 2 months post-laser.

RESULTS

The incidence of PIH at the 4th week after laser treatment was significantly lower in the ITR twice-daily group compared to the no-application group (20.83% vs. 50%, p = 0.028). There was no statistically significant difference in RMI, mean L*, and hyperpigmentation score between treatments at all visits. No serious adverse events were reported regarding ITR application and laser treatment.

CONCLUSION

Two-week application of ITR prior to QS: Nd YAG laser treatment may potentially reduce the incidence of PIH. A longer duration of application, including after the laser procedure, may be more beneficial for the prevention of laser-induced PIH.

Acne treatment challenges - Recommendations of Latin American expert consensus

BACKGROUND

Acne is a chronic inflammatory disorder of the pilosebaceous unit that is associated with a negative impact on quality of life, causing anxiety, depression, and poor self-esteem. The treatment of acne is not simple and presents some new challenges. This article addresses important issues faced by dermatologists on their daily, some of them specific for Latin America.

OBJECTIVE

To discuss daily practice recommendations when managing acne patients.

METHODS

A literature review was conducted by a group of eight experts with extensive experience in the field of acne. The results of the data review were presented at an initial kick-off meeting to align the consensus topics. Two e-surveys using the Delphi methodology and an interim group webinar meeting were held.

RESULTS

The expert panel reached a consensus on all proposed key statements, providing scientific support to help dermatologists and healthcare providers make acne management decisions on topics that can be challenging in the everyday practice of dermatology, such as the characteristics of Generation Z or the importance of the maintenance phase of adult acne treatment.

CONCLUSION

This article provides current recommendations for managing acne patients. The high level of agreement achieved based on the latest evidence supports the best acne therapeutic choices in both established topics and new important issues that have emerged in recent years, such as the impact of social media, Generation Z characteristics, and transgender male patient specifics.

Exploring the potential of white birch sap: A natural alternative to traditional skin whitening agents with reduced side effects

Common tyrosinase (TYR) inhibitors used in cosmetics, such as hydroquinone, kojic acid, and arbutin, can cause side effects including erythema, skin peeling, and dryness. Therefore, the development of natural whitening agents that offer excellent permeability, minimal irritation, and high safety has become a primary focus in the field of TYR inhibitors. In this study, we demonstrate that White birch sap (WBS), within a safe concentration range, effectively reduces TYR activity and melanin content in both B16F10 mouse melanoma cells and zebrafish larvae. Importantly, WBS exhibits minimal irritation to neutrophils in fluorescent zebrafish and does not affect the behavior of adult zebrafish. Furthermore, WBS downregulates the gene expression levels of microphthalmia-associated transcription factor, TYR, tyrosinase-related protein-1, and tyrosinase-related protein-2 in B16F10 cells. In conclusion, our research confirms that WBS, a naturally derived substance, offers high safety and mild effects, making it a promising candidate for a skin-whitening agent.

Tetrahedral framework nucleic acid loaded with glabridin: A transdermal delivery system applicated to anti-hyperpigmentation

Topical application of tyrosinase inhibitors, such as hydroquinone and arbutin, is the most common clinical treatment for hyperpigmentation. Glabridin (Gla) is a natural isoflavone that inhibits tyrosinase activity, free radical scavenging, and antioxidation. However, its water solubility is poor, and it cannot pass through the human skin barrier alone. Tetrahedral framework nucleic acid (tFNA), a new type of DNA biomaterial, can penetrate cells and tissues and can be used as carriers to deliver small-molecule drugs, polypeptides, and oligonucleotides. This study aimed to develop a compound drug system using tFNA as the carrier to transport Gla and deliver it through the skin to treat pigmentation. Furthermore, we aimed to explore whether tFNA-Gla can effectively alleviate the hyperpigmentation caused by increased melanin production and determine whether tFNA-Gla exerts substantial synergistic effects during treatment. Our results showed that the developed system successfully treated pigmentation by inhibiting regulatory proteins related to melanin production. Furthermore, our findings showed that the system was effective in treating epidermal and superficial dermal diseases. The tFNA-based transdermal drug delivery system can thus develop into novel, effective options for non-invasive drug delivery through the skin barrier.

Investigation into the effect of skin tone modulators and exogenous stress on skin pigmentation utilizing a novel bioengineered skin equivalent

Human skin equivalents (HSEs) are a popular technology due to limitations in animal testing, particularly as they recapitulate aspects of structure and function of human skin. Many HSEs contain two basic cell types to model dermal and epidermal compartments, however this limits their application, particularly when investigating the effect of exogenous stressors on skin health. We describe the development of a novel platform technology that accurately replicates skin pigmentation in vitro. Through incorporation of melanocytes, specialized pigment producing cells, into the basal layer of the epidermis we are able to re-create skin pigmentation in vitro. We observe apical distribution of melanin within keratinocytes and formation of supranuclear caps (SPNCs), only when the epidermal compartment is co-cultured with a dermal compartment, leading to the conclusion that fibroblast support is essential for correct pigment organization. We also evaluate the commonly observed phenomenon that pigmentation darkens with time in vitro, which we further explore through mechanical exfoliation to remove a build-up of melanin deposits in the stratum corneum. Finally, we demonstrate the application of a pigmented HSE to investigate drug modulation of skin tone and protection from UV-induced damage, highlighting the importance of such a model in the wider context of skin biology.

Review of Laser Treatments for Post-Inflammatory Hyperpigmentation in Skin of Color

Post-inflammatory hyperpigmentation is an extremely common disorder of pigmentation in skin of color. It most frequently and severely affects phototypes that are rich in melanin and often has a chronic and unpredictable course. It presents significant treatment challenges and often requires a multi-factorial approach. We review the literature available for the optimal use of laser-based devices in the treatment of post-inflammatory hyperpigmentation, particularly for Fitzpatrick skin phototypes III-VI. For the treatment of post-inflammatory hyperpigmentation in skin of color, lasers remain second line to topical agents based on the variable response, cost, and risk of complications with laser use. For post-inflammatory hyperpigmentation resistant to topicals, laser devices, particularly neodymium:yttrium-aluminum-garnet and fractional photothermolysis systems, can provide adjunctive treatment in skin of color patients when appropriate parameters are used. Future studies would benefit from an objective and consistent assessment to assist with a systematic analysis.

Photoprotection for people with skin of colour: needs and strategies

Skin of colour or pigmented skin has unique characteristics: it has a higher eumelanin-to-pheomelanin ratio, more mature melanosomes, an increased amount of melanin distributed in the upper layers of the epidermis, and more efficient DNA repair compared with lighter skin. However, individuals with skin of colour are at a significant risk of skin damage caused by ultraviolet radiation, including the development of photodermatoses and photoageing changes such as uneven skin tone, and are predisposed to pigmentary disorders. In fact, one of the most common conditions leading to dermatology consultations by patients with skin of colour is photoexacerbated pigmentary disorders. Unfortunately, individuals with skin of colour may be less prone to engage in photoprotective measures, including the use of sunscreens. Physicians are also less likely to prescribe sunscreens for them. There is thus a clear need for better education on photodamage and for more efficient and suitable photoprotection in populations with skin of colour. However, this need has thus far only partially been met, and the development of sunscreen products designed to provide optimal photoprotection for people with skin of colour remains a challenge. Targeted sunscreens for individuals with skin of colour require optimal cosmetic appeal (leaving no white residue and not disrupting skin tone). They should include broad-spectrum [ultraviolet (UV)B/UVA] protection with high sun protection factor, as well as protection against long-wave UVA (UVA1) and visible light, as these wavelengths are capable of inducing or augmenting pigmentary disorders. They may also contain depigmenting agents for patients with pigmentary disorders.

Disorders of hyperpigmentation. Part II. Review of management and treatment options for hyperpigmentation

Key challenges in the management of pigmentary disorders such as melasma and postinflammatory hyperpigmentation are their resistance to treatment, tendency to recur after treatment, and the risk of exacerbating hyperpigmentation with many treatment modalities. The second article in this 2-part continuing medical education series on pigmentary disorders focuses on the evidence behind medical and procedural treatments of dyschromias, including photoprotection, topical lightening agents, oral agents, chemical peels, and laser therapy.

Melasma: The need for tailored photoprotection to improve clinical outcomes

BACKGROUND/PURPOSE

Melasma is a frequent photoexacerbated hyperpigmentary disorder, which can significantly impact on the quality of life. We sought to review the pathogenesis of melasma, and the role of photoprotection in the prevention and treatment of this disorder.

METHODS

We conducted a narrative review of the literature. We performed literature searches with PubMed from January 1990 to December 2021 using the keywords "melasma," "pathogenesis," "ultraviolet radiation," "visible light," "photoprotection," and "sunscreens."

RESULTS

The physiopathology of melasma includes a complex interaction between genetics, sex hormones, and sun exposure. Visible light, in particular high-energy visible light (HEVL), and long-wave UVA (UVA1) play a key role in melasma pathophysiology, and recent research suggests that melasma shares many features with photoaging disorders. Melasma disproportionately affects dark-skinned individuals. Some 30% to 50% of South Americans and Asians, among other ethnicities, can present with melasma. Dark-skinned patients take fewer photoprotective measures. Also, the majority of melasma patients do not adequately follow photoprotection recommendations, including the application of sunscreen. Intensive use of a broad-spectrum sunscreen can prevent melasma in high-risk individuals, can lessen melasma severity (associated or not with depigmenting agents), and can reduce relapses.

CONCLUSIONS

Due to the physiopathology of melasma, sunscreens should be broad-spectrum with high sun protection factor, and provide high protection against UVA1 and VL. Sunscreens should be cosmetically acceptable and leave no white residue. Tinted sunscreens are an excellent choice, as pigments can protect from HEVL and UVA1, and may provide camouflage, but they must offer colors that match the skin tone of each patient.

Advances in Biomedical Functions of Natural Whitening Substances in the Treatment of Skin Pigmentation Diseases

Pigmentation diseases can lead to significant color differences between the affected part and the normal part, resulting in severe psychological and emotional distress among patients. The treatment of pigmentation diseases with good patient compliance is mainly in the form of topical drugs. However, conventional hydroquinone therapy contributes to several pathological conditions, such as erythema, dryness, and skin desquamation, and requires a longer treatment time to show significant results. To address these shortcomings, natural whitening substances represented by kojic acid and arbutin have gradually become the candidate ingredients of traditional local preparations due to their excellent biological safety. This review focuses on several natural whitening substances with potential therapeutic effects in pigmentation disease and their mechanisms, and a thorough discussion has been conducted into the solution methods for the challenges involved in the practical application of natural whitening substances.

Azole inhibitors of mushroom and human tyrosinases: Current advances and prospects of drug development for melanogenic dermatological disorders

Azoles are a famous and promising class of drugs for treatment of a range of ailments especially fungal infections. A wide variety of azole derivatives are also known to exhibit tyrosinase inhibition, some of which possess promising activity with potential for treatment of dermatological disorders such as post-inflammatory hyperpigmentation, nevus, flecks, melasma, and melanoma. Recently, thiazolyl-resorcinol derivatives have demonstrated potent human tyrosinase inhibition with a safe and effective therapeutic profile for treatment of skin hyperpigmentation in humans, which are currently under clinical trials. If approved these derivatives would be the first azole drugs to be used for treatment of skin hyperpigmentation. Although the scientific literature has been witnessing general reviews on tyrosinase inhibitors to date, there is none that specifically and comprehensively discusses azole inhibitors of tyrosinase. Appreciating such potential of azoles, this focused review highlights a wide range of their derivatives with promising mushroom and human tyrosinase inhibitory activities and clinical potential for treatment of melanogenic dermatological disorders. Presently, these disorders have been treated with kojic acid, hydroquinone and other drugs, the design and development of which are based on their ability to inhibit mushroom tyrosinase. The active sites of mushroom and human tyrosinases carry structural differences which affect substrate or inhibitor binding. For this reason, kojic acid and other drugs pose efficacy and safety issues since they were originally developed using mushroom tyrosinase and have been clinically used on human tyrosinase. Design and development of tyrosinase inhibitors should be based on human tyrosinase, however, there are challenges in obtaining the human enzyme and understanding its structure and function. The review discusses these challenges that encompass structural and functional differences between mushroom and human tyrosinases and the manner in which they are inhibited. The review also gauges promising azole derivatives with potential for development of drugs against skin hyperpigmentation by analyzing and comparing their tyrosinase inhibitory activities against mushroom and human tyrosinases, computational data, and clinical profile where available. It aims to lay groundwork for development of new azole drugs for treatment of skin hyperpigmentation, melanoma, and related dermatological disorders.

Management of post-inflammatory hyperpigmentation in skin of color: A short review

Post-inflammatory hyperpigmentation (PIH) is a common cosmetic complaint affecting patient quality of life. PIH has been proven to disproportionately affect skin of color. While several treatment options exist, special consideration must be given when managing PIH in patients of color, as topical treatments and aesthetic procedures, such as chemical peels and lasers, may either exacerbate or prove ineffective against PIH.

Inhibitory activities of grape bioactive compounds against enzymes linked with human diseases

A quest for identification of novel, safe and efficient natural compounds, as additives in the modern food and cosmetic industries, has been prompted by concerns about toxicity and side effects of synthetic products. Plant phenolic compounds are one of the most documented natural products due to their multifarious biological applications. Grape (Vitis vinifera) is an important source of phenolic compounds such as phenolic acids, tannins, quinones, coumarins and, most importantly, flavonoids/flavones. This review crisply encapsulates enzyme inhibitory activities of various grape polyphenols towards different key human-ailment-associated enzymes: xanthine oxidase (gout), tyrosinase (hyperpigmentation), α-amylase and α-glucosidase (diabetes mellitus), pancreatic lipase (obesity), cholinesterase (Alzheimer's disease), angiotensin i-converting enzymes (hypertension), α-synuclein (Parkinson's disease) and histone deacetylase (various diseases). The review also depicts the enzyme inhibitory mechanism of various grape polyphenols and briefly discusses their stature as potential therapeutic and drug development candidates. KEY POINTS: • Nineteen major bioactive polyphenols from the grape/grape products and their disease targets are presented • Sixty-two important polyphenols as enzyme inhibitors from grape/grape products are presented • A thorough description and graphical presentation of biological significance of polyphenols against various diseases.

Hyperpigmentation: Looking beyond hydroquinone

Hyperpigmentation is the most common complaint in the age group 40-45 years, seeking consultation for skin disorders. Hydroquinone is a commonly used depigmenting agent in clinical practice for treating hyperpigmentation. Prolonged use of hydroquinone has been associated with cancer risk and exogenous ochronosis. The CARES (The Coronavirus Aid, Relief, and Economic Security Act) Act of 2020 has instituted significant changes to hydroquinone containing OTC (over the counter) products, and consequently, many hydroquinone-based OTC products had to be withdrawn from the market. Henceforth, products containing hydroquinone would need US Food and Drug Administration approval via new drug application pathways for commercialization. Alternative treatment options to hydroquinone in clinical practice are reviewed in this paper with regard to their safety and efficacy vis a vis hydroquinone. Also, new potential treatment options such as thiamidol, Polypodium leucotomos, and glutathione are discussed. The review shows that these alternative depigmenting agents can be rationally combined to achieve desired treatment goals in the management of hyperpigmentation.

Thiamidol® in moderate-to-severe melasma: 24-week, randomized, double-blind, vehicle-controlled clinical study with subsequent regression phase

Thiamidol^® was the most potent inhibitor of human tyrosinase out of 50 000 screened substances. In vivo, it was well tolerated and improved melasma significantly. This was the first 24-week, randomized, double-blind, vehicle-controlled, cosmetic clinical study to assess the efficacy and tolerability of thiamidol in moderate-to-severe melasma of phototype III-V subjects with subsequent regression phase. Females allocated to verum (n = 23), applied daily Dual Serum followed either by Day Care SPF30 in the morning or by Night Care in the evening, all containing Thiamidol. The vehicle group (25 females) followed the same skin care routine using the corresponding vehicle formulations. Subjects came back for a follow-up visit 13-20 weeks after treatment (regression phase). Assessments included clinical photography, Melasma Area and Severity Index (MASI), skin lightness, quality of life, and tolerability. Baseline demographics and hyperpigmentation were well balanced across the treatment groups. Clinical photography and MASI improved with Thiamidol significantly versus baseline (p < 0.001) and vehicle (p < 0.001-0.043) at all time points up to treatment end. At follow-up, the MASI was still significantly lower than at baseline but similar for verum and vehicle. Skin lightness and quality of life improved significantly versus baseline without significant differences between verum and vehicle. This study demonstrated that Thiamidol is well tolerated and superior in improving melasma compared to baseline and vehicle over a treatment period of 24 weeks.

Efficacy and safety of topical isobutylamido thiazolyl resorcinol (Thiamidol) vs. 4% hydroquinone cream for facial melasma: an evaluator-blinded, randomized controlled trial

BACKGROUND

Melasma can be refractory to treatment, and relapses are frequent. Thiamidol is a new potent tyrosinase inhibitor that has been found effective as a cosmeceutical for the depigmenting of melasma.

OBJECTIVE

This study compared the efficacy and tolerability of topical 0.2% Thiamidol vs. 4% hydroquinone for facial melasma.

METHODS

Fifty women with facial melasma participated in a randomized, evaluator-blinded, controlled study from September through November 2020. Patients were randomly assigned to apply a double layer of 0.2% Thiamidol twice a day or 4% hydroquinone cream at bedtime, for 90 days. Both groups received tinted sunscreen (sun protection factor 60, PPD 20). The primary outcome was the change from the baseline Modified Melasma Area Seve:rity Index (mMASI) score. Secondary outcomes were improvements in the patients' quality of life [Melasma Quality of Life Index (MELASQoL)], colourimetry, and Global Aesthetic Improvement Scale (GAIS) evaluation.

RESULTS

One participant, from the hydroquinone group, did not complete the study (unrelated to adverse effects). The mean (SD) age of the participants was 43 (6) years, and 86% were phototypes III-IV. Both groups exhibited a reduction in mMASI, MELASQoL, and colour contrast scores (P < 0.01). The mean [95% confidence interval (CI 95%)] reductions of the mMASI scores were 43% (35-50%) for Thiamidol and 33% (23-42%) for hydroquinone. There was no difference between the groups in the reductions in mMASI, MELASQoL, colourimetric contrast and GAIS scores (P ≥ 0.09). The GAIS analysis resulted in an improvement of 84% (CI: 95% 67-97%) for participants in the Thiamidol group and 74% (CI: 95% 61-93%) for those in the hydroquinone group. There were only mild adverse effects in the Thiamidol group, but allergic contact dermatitis was evidenced in two (8%) participants.

CONCLUSION

The melasma improvement achieved using 0.2% Thiamidol did not differ from that of 4% hydroquinone cream. Thiamidol can be considered a suitable option for melasma patients with poor tolerability or treatment failure with hydroquinone.