Trichloroacetic acid model to accurately capture the efficacy of treatments for postinflammatory hyperpigmentation

Synthesis and new skin-relevant properties of the salicylic acid ester of bakuchiol

Bakusylan (bakuchiol salicylate) is a bipartite compound obtained by merging two skin-active entities with complementary bioactivities-bakuchiol and salicylic acid-for the purpose of generating a new class of functional retinoids with enhanced skin benefits. Here, we describe its preparation process and report that pure bakusylan exhibits potential for an improved permeation through the stratum corneum, enhances type IV collagen gene expression in organotypic skin substitutes containing both epidermal and dermal layers, and upregulates this protein in adult human dermal fibroblast cultures. The mechanism of action underlying these effects appears to involve the components of the IP3K/Akt signaling pathway selectively implicated in the maintenance of skin integrity, further underlying the suitability of this ester for skin care applications requiring enhanced cutaneous permeation targeting the dermal-epidermal junction.

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.

Applications of bakuchiol in dermatology: Systematic review of the literature

BACKGROUND

Bakuchiol (BAK), a meroterpene phenol abundant in the plant Psoralea corylifolia, is an emerging cosmeceutical agent with promising anti-aging, anti-inflammatory, and antibacterial properties. The trend for "clean" skincare products and search for anti-aging retinoid alternatives have poised BAK as a "must-have" ingredient in skincare.

AIMS

Our aim was to review the data for the applications of BAK in dermatology.

METHODS

This is a systematic review of PubMed.

RESULTS

Thirty articles matched our search terms ["Bakuchiol" and "Dermatology"] or ["Bakuchiol" and "Skin"] of which one did not meet inclusion criteria, 16 were pre-clinical studies, seven clinical studies, three commentaries, two narrative reviews, and one report on adverse events. BAK has been mostly studied for its effects on photoaging, acne, and post-inflammatory hyperpigmentation (PIH), showing beneficial results comparable to those achieved by topical retinoids. While having no structural resemblance to retinoids, BAK can function as a retinol analog, through retinol-like regulation of gene expression. In in vivo studies, BAK was used alone or in combination with other products resulting in a significant reduction in photodamage, hyperpigmentation, wrinkle scores, and acne severity. Additionally, in vitro studies hinted at its anti-cancer properties by inhibiting epidermal growth factor induced neoplastic cell transformation. Also, demonstrated potential applications in psoriasis by normalizing keratinocyte activity and in pigmentary disorders through inhibition of melanogenesis. There was one adverse event case reported of contact dermatitis in the literature.

CONCLUSIONS

Bakuchiol is a retinol alternative with anti-aging, antibacterial, and anti-inflammatory properties. Additional studies are warranted to better understand its applications in dermatology.

An in vivo model of postinflammatory hyperpigmentation and erythema: clinical, colorimetric and molecular characteristics

BACKGROUND

Postinflammatory hyperpigmentation (PIH) is a common, acquired pigmentary disorder of the skin associated with significant quality-of-life impairment, especially in individuals with skin of colour. Current treatment for PIH is limited, largely due to a poor understanding of disease pathogenesis and the lack of a representative disease model.

OBJECTIVES

This study is intended to further develop, update and validate our previously designed in vivo model of acne-induced PIH/postinflammatory erythema (PIE) using different concentrations of trichloroacetic acid (TCA), a medium-depth chemical peel.

METHODS

Twenty-nine patients with skin types II-VI and clinician-confirmed presence of two or more truncal acne pustules and PIH/PIE were included. On the basis of Investigator's Global Assessment (IGA), clinical polarized photography (CPP), colorimetry and Skindex, we experimentally determined an optimum TCA concentration and assessed our model's ability to exhibit a dose-response relationship between degree of inciting insult and severity of resulting pigmentation. We also performed differential microRNA profiling and pathway analysis to explore the potential of microRNAs as molecular adjuncts to our model.

RESULTS

Application of TCA 30% produced lesions indistinguishable from acne-induced PIH and PIE lesions on the basis of colorimetry data without causing epidermal necrosis. Application of progressively increasing TCA doses from 20% to 30% resulted in concentration-dependent increases in CPP, IGA and colorimetry scores at all timepoints during the study. miRNA-31 and miRNA-23b may play a role in PIH pathogenesis, although further validation is required.

CONCLUSIONS

Our TCA-based in vivo model, using TCA concentrations between 20% and 30% with an optimum of 30%, enables the quantitative assessment of the pigmentary response to varying degrees of cutaneous inflammation in a fashion that mirrors natural acne-induced PIH and PIE.

Management of hyperpigmentation: Current treatments and emerging therapies

Hyperpigmentation of the skin refers to a dermatological condition which alters the color of the skin, making it discolored or darkened. The treatments for hyperpigmentation disorders often take very long to show results and have poor patient compliance. The first-line treatment for hyperpigmentation involves topical formulations of conventional agents such as hydroquinone, kojic acid, and glycolic acid followed by oral formulations of therapeutic agents such as tranexamic acid, melatonin, and cysteamine hydrochloride. The second-line approaches include chemical peels and laser therapy given under the observation of expert professionals. However, these therapies pose certain limitations and adverse effects such as erythema, skin peeling, and drying and require long treatment duration to show visible effects. These shortcomings of the conventional treatments provided scope for further research on newer alternatives for managing hyperpigmentation. Some of these therapies include novel formulations such as solid lipid nanocarriers, liposomes, phytochemicals, platelet-rich plasma, microneedling. This review focuses on elaborating on several hyperpigmentation disorders and their mechanisms, the current, novel and emerging treatment options for management of hyperpigmentation.