Combining large-spot low-fluence 1064-nm and fractional 1064-nm picosecond lasers for promoting protective melanosome autophagy via the PI3K/Akt/mTOR signalling pathway for the treatment of melasma.

Melasma is a common condition of hyperpigmented facial skin. Picosecond lasers are reported to be effective for the treatment of melasma. We aimed to identify the most effective therapeutic mode and elucidate the potential molecular mechanisms of picosecond lasers for the treatment of melasma. Female Kunming mice with melasma-like conditions were treated using four different picosecond laser modes. Concurrently, in vitro experiments were conducted to assess changes in melanin and autophagy in mouse melanoma B16-F10 cells treated with these laser modes. Changes in melanin in mouse skin were detected via Fontana-Masson staining, and melanin particles were evaluated in B16-F10 cells. Real-time polymerase chain reaction and western blotting were used to analyse the expression levels of melanosome and autophagy-related messenger ribonucleic acid (mRNA) and proteins. A combination of large-spot low-fluence 1064-nm and fractional 1064-nm picosecond lasers resulted insignificant decreases in melanin as well as in mRNA and protein expression of melanin-synthesizing enzymes (TYR, TRP-1 and MITF). This combination also led to increased expression of the autophagy-related proteins, Beclin1 and ATG5, with a marked decrease in p62 expression. Intervention with the PI3K activator, 740 Y-P, increased TYR, TRP-1, MITF, p-PI3K, p-AKT, p-mTOR and p62 expression but decreased the expression of LC3, ATG5 and Beclin1. A combination of large-spot low-fluence 1064-nm and fractional 1064-nm picosecond lasers proved more effective and safer. It inhibits melanin production, downregulates the PI3K/AKT/mTOR pathway, enhances melanocyte autophagy and accelerates melanin metabolism, thereby reducing melanin content.

Definition of refractory melasma and its treatment: a review.

Although patients with refractory melasma have been treated using various methods, there is still no precise definition or summary of the therapies. To define refractory melasma and conduct a review of the treatments, we searched for relevant publications in PubMed, Web of Science, and the Cochrane Library, and a total of 35 references were obtained. Refractory melasma can be roughly defined as an ineffective treatment for melasma, including topical bleaching agents, chemical peels, laser therapy, microdermabrasion for more than six months, or chemical peels treated more than six times. Meanwhile, physicians should be careful when treating patients with darker skin and dermal or mixed types of melasma since these individuals do not respond well to treatment. Lasers combined with other methods, especially different types of lasers or topical agents, are considered more effective than monotherapy. Oral tranexamic acid (TXA) is a prospective cure for refractory melasma. Other methods include a combination of chemical peels, microneedling, or injections with additional therapies. In conclusion, we were able to provide a rough definition of refractory melasma and list the available therapies. According to the literature, the most prevalent treatment is laser combination therapy. However, laser treatment should be considered only after topical agents and chemical peeling have failed. Considering its side effects, efficacy, and safety, oral TXA may be a better option, but more research is needed to make a firm conclusion. Moreover, maintenance therapy is required after treatment.

755-nm picosecond laser plus topical 20% azelaic acid compared to topical 20% azelaic acid alone for the treatment of melasma: a randomized, split-face and controlled trial.

PURPOSE: Melasma remains a refractory skin condition that needs to be actively explored. Azelaic acid has been used for decades as a topical agent to improve melasma through multiple mechanisms, however, there is a lack of research on its combination with laser therapy. This study evaluated the effectiveness of isolated treatment with topical 20% azelaic acid and its combination with 755-nm picosecond laser in facial melasma patients. METHODS: A randomized, evaluator-blinded, controlled study was conducted on 30 subjects with facial melasma in a single center from October 2021 to April 2022. All subjects received topical 20% azelaic acid cream (AA) for 24 weeks, and after 4 weeks, a hemiface was randomly assigned to receive 755-nm picosecond (PS) laser therapy once every 4 weeks for 3 treatments. Treatment efficacy was determined by mMASI score evaluations, dermoscopic assessment, reflectance confocal microscopy (RCM) assessments and patient's satisfaction assessments (PSA). RESULTS: Treatment with 20% azelaic acid, with or without picosecond laser therapy, significantly reduced the hemi-mMASI score (P < 0.0001) and resulted in higher patient satisfaction. Improvements in dermoscopic and RCM assessments were observed in both sides of the face over time, with no difference between the two sides. RCM exhibited better dentritic cell improvement in the combined treatment side. No patients had serious adverse effects at the end of treatment or during the follow-up period. CONCLUSION: The additional use of picosecond laser therapy showed no clinical difference except for subtle differences detected by RCM assessments.The study was registered in the Chinese Clinical Trial Registry (ChiCTR2100051294; 18 September 2021).

Review of Fractional Nonablative Lasers for the Treatment of Dermatologic Conditions in Darker Skin Phototypes.

BACKGROUND: Fractional nonablative lasers (NAFLs) have demonstrated efficacy and safety for treating dermatologic conditions in patients with darker skin phototypes. Nonablative lasers are preferred in darker skin tones due to lower risk of postinflammatory hyperpigmentation. OBJECTIVE: This review aims to identify the ideal laser options and parameters for treating common dermatologic conditions in patients with skin types IV-VI. MATERIALS AND METHODS: A comprehensive literature search was conducted on PubMed in May 2023. Of 1,065 articles were identified, and 40 articles met the inclusion criteria. The studies were classified based on design, dermatologic condition, and skin phototype of patients, and assigned levels of evidence according to the Modified Criteria of the Oxford Center of Evidence Based Medicine. RESULTS: Strong level 1 evidence supports the treatment of melasma and atrophic scars using NAFL. Moderate level 2 evidence was found for using NAFL in acne vulgaris, striae, and skin rejuvenation; 45% of the studies examined skin types III-IV, 20% III-V, 7.5% II-IV, 5% II-V, 5% IV alone, and 2.5% I-IV. CONCLUSION: Further research is needed to determine the optimal treatment modalities and parameters for skin types V and VI. Appropriate device selection and conservative treatment settings are crucial for optimizing outcomes and minimizing adverse events.

Does Systemic Metformin Have a Role in Treating Melasma?

BACKGROUND: Melasma is a common pigmentary condition that affects the patients' quality of life and all the prescribed treatment options till now are not satisfactory, especially in dark-skinned patients. OBJECTIVE: To evaluate the efficacy and safety of systemic metformin (1,000 mg and 500 mg) combined with trichloroacetic acid (TCA) peeling versus TCA alone in the treatment of melasma. PATIENTS AND METHODS: The study included 60 melasma patients divided into 3 groups: Group A received systemic metformin (1000 mg/d), Group B received systemic metformin (500 mg/d) and Group C received placebo. The 3 treatment groups were treated by TCA 25% over the whole face bimonthly for a total of 6 sessions. Melasma area and severity index (MASI), and Melasma impact Quality of life Scale (MELASQOL) were used to assess the outcome. RESULTS: There was a statistically significant decrease in the MASI, and the MELASQOL in the 3 studied groups after treatment with significantly better improvement in Group (A) than Group (C) ( p = .045). CONCLUSION: Systemic metformin is a safe and promising therapeutic option for treating melasma.

Combination of 5% cysteamine and 4% nicotinamide in melasma: Efficacy, tolerability, and safety.

BACKGROUND: Melasma is a chronic dermatosis that impacts the patient's quality of life and can present considerable challenges in terms of effective treatment. OBJECTIVE: To evaluate the effectiveness, tolerability, and safety of 5% cysteamine combined with 4% nicotinamide in female subjects with melasma. METHODS: This single-center, single-arm, prospective, open-label study evaluated patients with melasma using a combination cream of 5% cysteamine and 4% nicotinamide in a progressive regimen (60 min in the first month, 120 min in the second month, and 180 min in the third month). RESULTS: Overall, 35 treated subjects exhibited reduced modified Melasma Area and Severity Index (mMASI) (p < 0.001) and decreased MelasQoL scores (p < 0.001), accompanied by improved brightness, luminosity, homogeneity, and spot intensity (p < 0.001). Photographic and colorimetric analysis revealed smaller spots and improved homogeneity. LIMITATIONS: Adherence to progressive daily treatment could not be evaluated long-term. CONCLUSION: A combination cream comprising 5% cysteamine and 4% nicotinamide was effective, tolerable, and safe for treating melasma.

Efficacy and Safety of Ablative Fractional Laser in Melasma: A Meta-analysis and Systematic Review.

Melasma is a common acquired skin pigmentation disorder. The treatment is urgent but challenging. Ablative fractional laser (AFL) can improve pigmentation, but the efficacy and potential side effects are still debatable. This study aimed to evaluate the efficacy and safety of ablative fractional lasers in the treatment of melasma. A comprehensive systematic search of literature published before June 20, 2023, was conducted on online databases, including PubMed, Embase, Cochrane Library, and Web of Science. The data obtained were analyzed using Review Manager 5.4 software. Fourteen randomized controlled trials, comprising 527 patients, were included. Compared to the drug alone, the combination of AFL and the drug showed improved therapeutic efficacy in the melasma area and severity index (MASI) (MD = 1.54, 95% CI [0.16, 2.92], P = 0.03) and physician global assessment (RR = 1.61, 95% CI [1.08, 2.41], P = 0.02). However, no statistically significant results were found in patient self-assessment (RR = 1.56, 95% CI [0.88, 2.76], P = 0.12). As an individual therapy, AFL is not superior to any other lasers in terms of MASI (MD = 2.66, 95% CI [-1.32, 6.64], P = 0.19) or melanin index (MD = -7.06, 95% CI [-45.09, 30.97], P = 0.72). Common adverse events included transient erythema, burning, edema, and superficial crusting. Only a few patients experienced reversible post-inflammatory hyperpigmentation, herpes labialis, and acne breakouts. These results support the application of AFL as a viable treatment option for melasma, particularly in refractory and severe cases. Rational parameterization or combination therapy may lead to significant clinical improvement with fewer complications.

Cysteamine Isobionic-Amide Complex Versus Kligman's Formula for the Treatment of Melasma: Equal Efficacy and Rapid Onset of Action.

BACKGROUND: Modified Kligman's formula (mKF) is the gold standard treatment for melasma; however, its prolonged use is not recommended due to side effects. Cysteamine is a potent, safe, and effective depigmenting agent. Here, we conducted a double-blind, randomized, and placebo-controlled clinical trial to assess the efficacy of cysteamine isobionic-amide -- a complex with enhanced depigmenting efficacy -- and compared it to mKF for the treatment of melasma. METHODS: This study involved a total of 80 patients divided into 3 groups: cysteamine-isobionic amide, placebo, or mKF. The modified Melasma Area Severity Index (mMASI) score and spectrophotometric evaluation were conducted at baseline, week 4, week 8, and week 16. Dermatological assessment, patients’ feedback, and satisfaction including quality-of-life scores were also collected. RESULTS: At week 4, cysteamine isobionic-amide and mKF groups showed an equivalent onset of action in terms of mMASI and skin pigmentation contrast reduction. The 2 groups significantly reduced melasma severity and improved the overall skin condition with a comparable efficacy at week 16. Quality of life of melasma patients was significantly improved in the cysteamine isobionic-amide group at week 8 and further at week 16 (P<0.001) compared to the mKF group. Patients’ feedback and satisfaction were higher with the cysteamine isobionic-amide product compared to mKF. CONCLUSION: Cysteamine isobionic-amide provided a rapid onset of action and was as effective as the mKF for the treatment of melasma. The data suggest that cysteamine isobionic-amide could potentially be an acceptable alternative to mKF for the long-term treatment of melasma. J Drugs Dermatol. 2024;23(2):9-16.  doi:10.36849/JDD.7428.

Melanoma of the central nervous system based on neurocutaneous melanocytosis in childhood: A rare but fatal condition.

BACKGROUND: Melanomas of the central nervous system (CNS) based on neurocutaneous melanocytosis (NCM) are exceptionally rare in childhood and have been described only sporadically. Rapidly progressive disease may represent a major challenge for treating physicians, especially given the limited knowledge about this condition. This analysis aimed to increase knowledge about the occurrence and treatment of these malignancies. PROCEDURE: Data on diagnosis, treatment, and outcome of patients aged 0-18 years with CNS melanoma based on NCM recorded in the German Registry for Rare Pediatric Tumors (STEP registry) were analyzed. Additionally, published case reports on this condition were analyzed. RESULTS: In STEP, five patients with leptomeningeal melanoma based on NCM were identified, with a median age at melanoma diagnosis of 3.7 years. Various multimodal treatments were performed: (partial) resection (n = 4), irradiation (n = 2), trametinib (n = 3), different cytostatics (n = 2), and anti-GD2 immunotherapy (n = 1). All patients died between 0.3 and 0.8 years after diagnosis. Including published case reports, 27 patients were identified with a median age of 2.8 years at melanoma diagnosis (range: 0.2-16.6). Fourteen of 16 cases with reported data had a NRAS alteration (88%), particularly NRAS p.Q61K (85%). In the expanded cohort, no patient survived longer than 1 year after diagnosis despite multimodal therapy (including trametinib; n = 9), with a median survival of 0.4 years (range 0.1-0.9). CONCLUSIONS: CNS melanomas based on NCM in childhood are aggressive malignancies without curative treatment to date. Therapeutic approaches must be individualized. Genetic tumor sequencing is essential to improve understanding of tumorigenesis and potentially identify new therapeutic targets.

Comparison of 755-nm picosecond alexandrite laser versus 1064-nm Q-switched Nd:YAG laser for melasma: A randomized, split-face controlled, 2-year follow-up study.

OBJECTIVES: Pulsed laser treatment of melasma has shown some promising results. To compare the effectiveness and safety of 755-nm picosecond alexandrite laser (PSAL) fitted with diffractive lens array (DLA) versus 1064-nm Q-switched neodynimum:yttrium aluminum garnet laser (QSNYL) for the treatment of melasma. METHODS: We conducted a randomized, split face controlled, 2-year follow-up study. Each face was divided into two parts, each side receiving three treatments with either PSAL or QSNYL at 1 month intervals. Modified Melasma Area Severity Index scores (mMASI), pain scores, patient satisfaction and adverse events were recorded. In vivo reflectance confocal microscopy (RCM) images were acquired. RESULTS: Twenty subjects were enrolled and three dropped out. At 6 months, mMASI scores were significantly lower than baseline for QSNYL sides (p = 0.022), with no statistically significant difference between PSAL sides before and after treatment, PSAL sides versus QSNYL sides, or patient satisfaction scores. QSNYL treatment was associated with less pain (p = 0.014). No serious adverse events were reported. In the PSAL sides RCM showed a large number of dendritic melanocytes infiltrated in the dermis at 2 weeks and 4 weeks after treatment. Ten patients (58.82%) reported recurrence or exacerbation at 2-year follow-up with no statistically significant difference between the two lasers. CONCLUSIONS: QSNYL demonstrated short term clinical efficacy for melasma, but did not provide any additional benefit compared to PSAL with DLA. QSNYL was associated with less pain. There was a high recurrence rate at 2-year follow-up. RCM allowed the detection of cellular changes in melasma lesions.

Clinicopathologic profiles of canine ocular melanosis: A comparative study between cairn terriers and non-cairn terriers.

OBJECTIVES: To identify canine breeds at risk for ocular melanosis and to compare the clinical and histologic features between affected Cairn Terriers (CTs) and non-Cairn Terriers (NCTs). DESIGN: Relative risk (RR) analysis and retrospective cohort study of dogs histologically diagnosed with ocular melanosis. PROCEDURES: The COPLOW archive was searched for globe submissions diagnosed with ocular melanosis. Six hundred fifty globes were included, and RR analysis was performed to identify at-risk NCT breeds. A cohort of 360 CT and NCT globes diagnosed from 2013 to 2023 were included in the retrospective cohort study. Clinical data were collected from submission forms, medical records, and follow-up surveys. One hundred fifty-seven submissions underwent masked histologic review. Immunohistochemical staining for CD204 was performed to determine the predominance of melanophages in affected uvea from five NCTs. RESULTS: At-risk NCT breeds included the Boxer, Labrador Retriever, and French Bulldog. Glaucoma was the reported reason for enucleation in 79.4% of submissions. At enucleation, clinical features less prevalent in NCTs than CTs included pigmentary abnormalities in the contralateral eye (33.7% vs. 63.1%, p = .0008) and abnormal episcleral/scleral pigmentation in the enucleated globe (25.4% vs. 53.6%, p = .0008). Histologic involvement of the episclera was also less frequent in NCTs than in CTs (39.7% vs. 76.9%, p = .008). Concurrent melanocytic neoplasms arising in melanosis were more common in NCTs (24.4%) than CTs (3.9%). Melanophages were not predominant in any samples evaluated immunohistochemically. CONCLUSIONS: Several popular NCT breeds carry risk for ocular melanosis, and some clinicopathologic disease features may differ from those described in CTs.

Comparing the Efficacy and Tolerability of Moderate to Severe Hyperpigmentation and Skin Unevenness.

Dyschromia is the result of irregular facial pigmentation. These cutaneous manifestations can have a significant impact on the quality of life of those affected, especially among females and skin of color. In this randomized, double-blinded, two-cell, single-center, 16-week clinical study, all subjects had moderate to severe (scores 4-9 on the modified Griffiths Scale) hyperpigmentation and skin unevenness of the face such that approximately 20% of subjects had post-inflammatory hyperpigmentation (PIH), 40% had overall mottled hyperpigmentation, and 40% had superficial melasma (Superficial Melasma was determined by Wood's Lamp Assessment). Study participants received either Product A (proprietary new formulation - Cysteamine HSA) or Product B (current marketed product - Cyspera®) and used the test product either in the morning or at night, beginning with every other day application, and then advanced to every day, or as tolerated. The results revealed that both Product A (Cysteamine HSA) and Product B (Cyspera®) had statistically significant improvement in facial hyperpigmentation and skin unevenness, however, Product A (Cysteamine HSA) had better tolerability results for scaling, peeling, burning, stinging, erythema, and dryness, indicating that Product A (Cysteamine HSA) outperformed Product B (Cyspera®). J Drugs Dermatol. 2024;23(1):1260-1265.     doi:10.36849/JDD.7584.

Markers of Oxidative Stress and Tyrosinase Activity in Melasma Patients: A Biochemical Investigation.

BACKGROUND: Melasma is a skin hyperpigmentary disorder that develops over time. Genetic factors, oxidative stress, female sex hormones, and UV light may all play a role in the disorder's progression. AIMS: To compare the levels of oxidative stress and tyrosinase activity in melasma patients with healthy volunteers. METHODS: After written consent, 130 patients were enrolled in a case-control study. 65 cases were of melasma disorder, and 65 were served as control. Homogenized skin tissues were taken and used to estimate superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), glutathione peroxidase (GPx) (antioxidants), malondialdehyde (MDA) and tyrosine hydroxylase (TH). RESULTS: Melasma patients had lower basal levels of systemic antioxidants than healthy subjects. Tyrosinase activity was shown to be greater in lesional skin than in non-lesional skin. In controls, there was a good positive relationship between TH and MDA and an excellent negative relationship between GPx and GSH. In melasma patients, there were significant associations between CAT, GPx, SOD and MDA. CONCLUSIONS: Increased oxidative stress may affect tyrosinase activity and eumelanin synthesis via the anabolic pathway of melanin synthesis, according to our findings. In conclusion, we discovered a negative relationship between antioxidants and tyrosinase activity.

Missense mutation of NRAS is associated with malignant progression in neurocutaneous melanosis.

Neurocutaneous melanosis (NCM) is a rare congenital neurocutaneous syndrome characterized by congenital melanocytic nevus of skin and abnormal proliferation of leptomeningeal melanocytes. Early acquisition of post-zygotic somatic mutations has been postulated to underlie the pathogenesis of NCM. The pathogenesis of NCM remains to be fully elucidated, and treatment options have not been established. Here, we report for the first time, multiregional genomic analyses in a 3-year-old autopsied girl with leptomeningeal melanomatosis associated with NCM, in which a ventriculo-peritoneal (VP) shunt was inserted for the treatment of hydrocephalus. The patient expired six months after the onset due to respiratory failure caused by abdominal dissemination via VP shunt. We performed multiregional exome sequencing to identify genomic differences among brain and abdominal tumors, nevus, and normal tissues. A total of 87 somatic mutations were found in 71 genes, with a significantly large number of gene mutations found in the tumor site. The genetic alterations detected in the nevus were only few and not shared with other sites. Three mutations, namely GNAQ R183Q, S1PR3 G89S and NRAS G12V, considered pathogenic, were found, although S1PR3 mutations have not been previously reported in melanocytic tumors. GNAQ and S1PR3 mutations were shared in both tumor and normal sites. Moreover, the mutant allele frequencies of the two mutations were markedly higher in tumor sites than in normal sites, with copy-neutral loss-of-heterozygosity (CN-LOH) occurring in tumor. NRAS mutation was found only in the abdominal tumor and was thought to be responsible for malignant progression in the present case. Multiregional comprehensive genetic analysis may lead to discovering novel driver mutations associated with tumorigenesis and targeted therapy.

Urinary Bladder "Melanosis": A Case Report and Review of the Literature.

Melanosis of the urinary bladder, so-called melanosis vesicae, is a rare condition characterized by dark, velvety bladder mucosa observed by cystoscopy examination. Up to 20 examples have been reported in the English literature, and the etiology of this disease still needs to be discovered. We present an 82-year-old woman with a history of pelvic organ prolapse-associated urinary symptoms. The patient was found to have pigmented urinary bladder mucosa on cystoscopy and underwent a total hysterectomy and bladder mucosal biopsy. Histologically, pigmented granules were evident in the bladder stroma and epithelium, highlighted by Periodic Acid-Schiff (PAS) stain, suggestive of lipofuscin in nature. We outline the diagnostic features of bladder melanosis, discuss the diagnostic mimickers, and thoroughly review the literature on the subject.

Photobiomodulation for melasma treatment: Integrative review and state of the art.

PURPOSE: Photobiomodulation therapy (PBM) is a versatile technique for treating skin diseases. Melasma, a chronic hyperpigmentation condition, has recently been associated with vascular features and dermal photoaging and poses significant management challenges. We review the recent literature on melasma etiology and the evidence supporting PBM as a therapeutic modality for melasma treatment. METHODS: We conducted a comprehensive literature search in three different databases from May to August 2023, focusing on studies published in the past 10 years. The inclusion criteria comprised full-text studies investigating low-power lasers and/or light-emitting diodes (LEDs) in in vitro or in vivo models, as well as clinical trials. We excluded studies discussing alternative melasma therapies or lacking experimental data. We identified additional studies by searching the reference lists of the selected articles. RESULTS: We identified nine relevant studies. Clinical studies, in agreement with in vitro experiments and animal models, suggest that PBM effectively reduces melasma-associated hyperpigmentation. Specific wavelengths (red: 630 nm; amber: 585 and 590 nm; infrared: 830 and 850 nm) at radiant exposures between 1 and 20 J/cm2 exert modulatory effects on tyrosinase activity, gene expression, and protein synthesis of melanocytic pathway components, and thus significantly reduce the melanin content. Additionally, PBM is effective in improving the dermal structure and reducing erythema and neovascularization, features recently identified as pathological components of melasma. CONCLUSION: PBM emerges as a promising, contemporary, and non-invasive procedure for treating melasma. Beyond its role in inhibiting melanogenesis, PBM shows potential in reducing erythema and vascularization and improving dermal conditions. However, robust and well-designed clinical trials are needed to determine optimal light parameters and to evaluate the effects of PBM on melasma thoroughly.

Guide to tinted sunscreens in skin of color.

Disorders of hyperpigmentation, such as melasma and post-inflammatory hyperpigmentation, disproportionately affect skin of color and have a profound impact on quality of life. Exposure to ultraviolet light (UVL) is a well-documented factor in these disorders. However, recent studies show that visible light (VL) is a significant and underrecognized contributor to hyperpigmentation, especially in skin of color. Our objective is to review the role of VL in disorders of hyperpigmentation and that of tinted sunscreens in protecting against VL. Tinted sunscreens containing iron oxides should be recommended over nontinted sunscreens for patients prone to disorders of hyperpigmentation, as iron oxides protect against VL in addition to UVL. Tinted sunscreens are more effective than nontinted sunscreens in preventing melasma relapses and reducing hyperpigmentation, and they may also enhance the depigmenting efficacy of topical hydroquinone. In the search for an ideal tinted sunscreen for a particular patient, several factors must be considered, including a broad spectrum with adequate coverage of both UVL and VL, tint, formulation texture, active ingredients, and cost. VL is increasingly recognized as a major contributor of hyperpigmentation, and adequate treatment for disorders of hyperpigmentation should include protection against VL. Tinted sunscreens are ideal but require consideration of cosmesis, efficacy, and affordability.

Preparation of paeoniflorin-glycyrrhizic acid complex transethosome gel and its preventive and therapeutic effects on melasma.

Paeoniflorin (PF) and glycyrrhizic acid (GL) have skin beautifying effects of anti-inflammation, anti-oxidation, inhibition of melanin formation, and reduction of skin pigmentation. To improve the transdermal permeability of PF and GL in transdermal drug delivery system (TDDS) and enhance their anti-melasma efficacy, PF-GL transethosome (PF-GL-TE) was prepared by ethanol injection method, and finally gelled with carbomer-940 to form PF-GL-TE gel. Consequently, the obtained PF-GL-TE is small and uniform, with an average particle size and a PDI value of about 167.9 nm and 0.102. PF-GL-TE gel showed sustained release behavior and high transdermal permeability in vitro release and transdermal tests. Meanwhile, PF-GL-TE gel played significant preventive effects on melasma induced by progesterone injection and ultraviolet radiation B (UVB) irradiation. According to the results of H&E staining and Masson staining of rat skin, PF-GL-TE gel can alleviate the skin inflammation of and reduce the loss of collagen fibers of back skin in the melasma model rats. Compared with the PF-GL mixture gel, PF-GL-TE gel significantly attenuated the oxidative damage of liver and skin by increasing the activity of SOD and reducing the content of MDA. The results of Western blot showed that PF-GL-TE gel might down-regulate melanin-related proteins expressions of MITF/TYR/TRP1 and TRP2 to prevent and treat melasma. These findings indicate that PF-GL-TE gel is an effective TDDS for delivering PF and GL into the skin, providing a promising preparation for effective prevention and treatment of melasma.