Skin whitening agents: medicinal chemistry perspective of tyrosinase inhibitors

Isolation, Purification and Tyrosinase Inhibitory Activity of Anthocyanins and Their Novel Degradation Compounds from Solanum tuberosum L

To explore the composition of anthocyanins and expand their biological activities, anthocyanins were systematically isolated and purified from tubers of Solanum tuberosum L., and their tyrosinase inhibitory activity was investigated. In this study, two new anthocyanin degradation compounds, norpetanin (9) and 4-O-(p-coumaryl) rhamnose (10), along with 17 known anthocyanins and their derivatives, were isolated and purified from an acid-ethanolic extract of fresh purple potato tubers. Their structures were elucidated via 1D and 2D NMR and HR-ESI-MS and compared with those reported in the literature. The extracts were evaluated for anthocyanins and their derivatives using a tyrosinase inhibitor screening kit and molecular docking technology, and the results showed that petanin, norpetanin, 4-O-(p-coumaryl) rhamnose, and lyciruthephenylpropanoid D/E possessed tyrosinase inhibitory activity, with 50% inhibiting concentration (IC50) values of 122.37 ± 8.03, 115.53 ± 7.51, 335.03 ± 12.99, and 156.27 ± 11.22 μM (Mean ± SEM, n = 3), respectively. Furthermore, petanin was validated against melanogenesis in zebrafish; it was found that it could significantly inhibit melanin pigmentation (p < 0.001), and the inhibition rate of melanin was 17% compared with the normal group. This finding may provide potential treatments for diseases with abnormal melanin production, and high-quality raw materials for whitening cosmetics.

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.

Pulp or Peel? Comparative Analysis of the Phytochemical Content and Selected Cosmetic-Related Properties of Annona cherimola L., Diospyros kaki Thumb., Cydonia oblonga Mill. and Fortunella margarita Swingle Pulp and Peel Extracts

Fruit peels might be a valuable source of active ingredients for cosmetics, leading to more sustainable usage of plant by-products. The aim of the study was to evaluate the phytochemical content and selected biological properties of hydroglycolic extracts from peels and pulps of Annona cherimola, Diospyros kaki, Cydonia oblonga, and Fortunella margarita as potential cosmetic ingredients. Peel and pulp extracts were compared for their antiradical activity (using DPPH and ABTS radical scavenging assays), skin-lightening potential (tyrosinase inhibitory assay), sun protection factor (SPF), and cytotoxicity toward human fibroblast, keratinocyte, and melanoma cell lines. The total content of polyphenols and/or flavonoids was significantly higher in peel than in pulp extracts, and the composition of particular active compounds was also markedly different. The HPLC-MS fingerprinting revealed the presence of catechin, epicatechin and rutoside in the peel of D. kaki, whereas kaempferol glucoside and procyanidin A were present only in the pulp. In A. cherimola, catechin, epicatechin and rutoside were identified only in the peel of the fruit, whereas procyanidins were traced only in the pulp extracts. Quercetin and luteolinidin were found to be characteristic compounds of F. margarita peel extract. Naringenin and hesperidin were found only in the pulp of F. margarita. The most significant compositional variety between the peel and pulp extracts was observed for C. oblonga: Peel extracts contained a higher number of active components (e.g., vicenin-2, kaempferol rutinoside, or kaempferol galactoside) than pulp extract. The radical scavenging potential of peel extracts was higher than of the pulp extracts. D. kaki and F. margarita peel and pulp extracts inhibited mushroom and murine tyrosinases at comparable levels. The C. oblonga pulp extract was a more potent mushroom tyrosinase inhibitor than the peel extract. Peel extract of A. cherimola inhibited mushroom tyrosinase but activated the murine enzyme. F. margarita pulp and peel extracts showed the highest in vitro SPF. A. cherimola, D. kaki, and F. margarita extracts were not cytotoxic for fibroblasts and keratinocytes up to a concentration of 2% (v/v) and the peel extracts were cytotoxic for A375 melanoma cells. To summarize, peel extracts from all analyzed fruit showed comparable or better cosmetic-related properties than pulp extracts and might be considered multifunctional active ingredients of skin lightening, anti-aging, and protective cosmetics.

Screening of Key Components for Melanogenesis Inhibition of Polygonum cuspidatum Extract Based on the Spectrum-Effect Relationship and Molecular Docking

Polygonum cuspidatum (PC) extract has been listed in the "Catalog of Used Cosmetic Ingredients (2021 Edition)", which can inhibit melanogenesis, thus exerting a whitening effect, and has been widely used in cosmetics. However, there are currently no quality standards for PC extract used in cosmetics, and the bioactive components associated with anti-melanogenesis remain unclear. In view of this, the present study was the first to investigate the spectrum-effect relationship between fingerprints of PC extract and melanogenesis inhibition. Ten batches of PC extract fingerprints were established by HPLC. Pearson's correlation analysis, gray correlation analysis (GRA) and orthogonal partial least squares regression analysis (OPLSR) were used to screen out resveratrol, emodin and physcion as the main whitening active ingredients using the inhibition of tyrosinase in B16F10 cells as the pharmacological index. Then, the melanogenesis inhibitory effects of the above three components were verified by tyrosinase inhibition and a melanin content assay in B16F10 cells. The interaction between small molecules and proteins was investigated by the molecular docking method, and it was confirmed by quantitative real-time PCR (qRT-PCR) that resveratrol, emodin and physcion significantly down-regulated the transcript levels of melanogenesis-related factors. In conclusion, this study established a general model combining HPLC fingerprinting and melanogenesis inhibition and also analyzed the spectrum-effect relationship of PC extract, which provided theoretical support for the quality control of PC extract in whitening cosmetics.

Synthesis and Tyrosinase Inhibitory Activity of Novel Benzimidazole/Thiazolidin-4-one Hybrid Derivatives

In this study, novel 3-(phenylamino)thiazolidin-4-one 2 a-d and 3-(phenyl)thiazolidin-4-one 3 a-g derivatives which are having benzimidazole moiety were synthesized and their tyrosinase inhibitory activity were investigated. The structures of the target compounds were elucidated using 1 H/13 C-NMR, IR and MS. The structure of 2 b was also characterized using HSQC NMR technique. Among the target compounds, 3 b-g demonstrated stronger tyrosinase inhibitory activity (IC50 values for 3 b-g ranged from 80.93 to 119.20 μM), compared to the positive control kojic acid (IC50 : 125.08 μM). With IC50 value of 80.93 μM, 5-(2-(4-(1H-benzimidazol-1-yl)phenyl)-4-oxothiazolidin-3-yl)-2-methylbenzenesulfonamide 3 g was found to be the most active derivative of the series. Molecular docking studies were conducted to elucidate the binding interactions between compounds and tyrosinase. The MTT assay studies used to determine the cytotoxicity of 3 b-g showed that 3 c, 3 d, 3 f and 3 g were not cytotoxic in the range of 0-200 μM. Considering its tyrosinase inhibitory activity and cytotoxic effect, 3 g exhibits promising potential for further research and development as a novel tyrosinase inhibitor.

2,4,6-Triphenyl-1-hexene, an Anti-Melanogenic Compound from Marine-Derived Bacillus sp. APmarine135

Although melanin protects against ultraviolet radiation, its overproduction causes freckles and senile lentigines. Recently, various biological effects of metabolites derived from marine microorganisms have been highlighted due to their potential for biological and pharmacological applications. In this study, we discovered the anti-melanogenic effect of Bacillus sp. APmarine135 and verified the skin-whitening effect. Fractions of APmarine135 showed the melanin synthesis inhibition effect in B16 melanoma cells, and 2,4,6-triphenyl-1-hexene was identified as an active compound. The melanogenic capacity of 2,4,6-triphenyl-1-hexene (1) was investigated by assessing the intracellular melanin content in B16 cells. Treatment with 5 ppm of 2,4,6-triphenyl-1-hexene (1) for 72 h suppressed the α-melanocyte-stimulating hormone (α-MSH)-induced intracellular melanin increase to the same level as in the untreated control group. Additionally, 2,4,6-triphenyl-1-hexene (1) treatment suppressed the activity of tyrosinase, the rate-limiting enzyme for melanogenesis. Moreover, 2,4,6-triphenyl-1-hexene (1) treatment downregulated tyrosinase, Tyrp-1, and Tyrp-2 expression by inhibiting the microphthalmia-associated transcription factor (MITF). Furthermore, 2,4,6-triphenyl-1-hexene (1) treatment decreased the melanin content in the three-dimensional (3D) human-pigmented epidermis model MelanoDerm and exerted skin-whitening effects. Mechanistically, 2,4,6-triphenyl-1-hexene (1) exerted anti-melanogenic effects by suppressing tyrosinase, Tyrp-1, and Tyrp-2 expression and activities via inhibition of the MITF. Collectively, these findings suggest that 2,4,6-triphenyl-1-hexene (1) is a promising anti-melanogenic agent in the cosmetic industry.

Clinical effect of Pediococcus acidilactici PMC48 on hyperpigmented skin

BACKGROUND

The excessive production and accumulation of melanin in the epidermal skin layer can result in skin hyperpigmentation and darkening. Current technologies for regulating melanin are based on inhibiting melanin biosynthesis. They have low effectiveness and safety issues.

AIMS

This study aimed to evaluate the potential role of Pediococcus acidilactici PMC48 as a probiotic strain in medicines and cosmetics for skin treatment.

MATERIALS AND METHODS

Meanwhile, our research team has reported that P. acidilactici PMC48 strain isolated from sesame leaf kimchi can directly decompose the already synthesized melanin. It can also inhibit melanin biosynthesis. In the present study, we investigated the skin-whitening effect of this strain by arranging an 8-week clinical trial with 22 participants. PMC48 was applied to each participant's artificially UV-induced tanned skin in the clinical trial. Its whitening effect was investigated based on visual evaluation, skin brightness, and melanin index.

RESULTS

PMC48 showed a significant effect on the artificially induced pigmented skin. The color intensity of the tanned skin was decreased by 47.647%, and skin brightness was increased by 8.098% after the treatment period. PMC48 also significantly decreased the melanin index by 11.818%, indicating its tyrosinase inhibition capacity. Also, PMC48 improved skin moisture content level by 20.943%. Additionally, 16S rRNA-based amplicon sequencing analysis showed a distinct increase in Lactobacillaceae in the skin by up to 11.2% at the family level without affecting other skin microbiota. Furthermore, it showed no toxicity in in vitro or in vivo analyses.

DISCUSSION

These results indicate that P. acidilactici PMC48 is a promising probiotic strain that can be used to develop medicines and cosmetic products to solve skin-related problems.

CONCLUSIONS

These results demonstrate that P. acidilactici PMC48 can be a potential probiotic for the cosmetic industry against different skin disorders.

Valorization of biomass polyphenols as potential tyrosinase inhibitors

Tyrosinases (TYRs; EC 1.14.18.1) catalyze two sequential oxidative reactions of the melanin biosynthesis pathway and play an important role in mammalian pigmentation and enzymatic browning of fruit and vegetables. Inhibition of TYR activity is therefore an attractive target for new drugs and/or food ingredients. In addition, increasing evidence suggests that TYR regulation could be a novel target for treatments of cancer and Parkinson's disease. Biomasses, notably industrial byproducts and biowaste, are good sustainable sources of phytochemicals that may be valorized into bioactive compounds including TYR inhibitors. This review presents potential applications of biomass-derived polyphenols targeting TYR inhibition. Insights into structure-activity relationships of several polyphenols and their glycosides are highlighted. Finally, some remarks and perspectives on research into new TYR inhibitors from biomass waste are provided.

Biochemical and In Silico Studies on Triazole Derivatives as Tyrosinase Inhibitors: Potential Treatment of Hyperpigmentation Related Skin Disorders

INTRODUCTION

Tyrosinase is a versatile, glycosylated copper-containing oxidase enzyme that mainly catalyzes the biosynthesis of melanin in mammals. Its overexpression leads to the formation of excess melanin, resulting in hyperpigmentary skin disorders, such as dark spots, melasma, freckles, etc. Therefore, inhibition of tyrosinase is a therapeutic approach for the treatment of hyperpigmentation.

METHODS

The current study focused on evaluating tyrosinase inhibitory activities of triazole derivatives 1-20, bearing different substituents on the phenyl ring. 17 derivatives have shown a potent tyrosinase inhibition with IC50 values between 1.6 to 13 μM, as compared to the standard drug, i.e., kojic acid (IC50 = 24.1 ± 0.5 μM). Particularly, compounds 11 and 15 displayed 12 times more potent inhibitory effects than the kojic acid.

RESULTS

The structure-activity relationship revealed that substituting halogens at the C-4 position of the benzene ring renders remarkable anti-tyrosinase activities. Compounds 1-3 and 8 showed a competitive type of inhibition, while compounds 5, 11, and 15 showed a non-competitive mode of inhibition. Next, we performed molecular docking analyses to study the binding modes and interactions between the ligands (inhibitors) and the active site of the tyrosinase enzyme (receptor). Besides this, we have assessed the toxicity profile of inhibitors on the BJ human fibroblast cell line.

CONCLUSION

The majority of the newly identified tyrosinase inhibitors were found to be noncytotoxic. The results presented herein form the basis of further studies on triazole derivatives as potential drug leads against tyrosinase-related diseases.

Comparative Studies on the Photoreactivity, Efficacy, and Safety of Depigmenting Agents

Depigmenting products are increasingly used to counteract skin hyperpigmentation and related psychosocial issues. This study aimed to compare different depigmenting agents-4-butylresorcinol; bakuchiol; tranexamic acid; ascorbyl glucoside; α-arbutin; and ascorbic acid-for photoreactivity; tyrosinase inhibition; and safety. Photoreactivity was assessed using the Reactive Oxygen Species assay. In vitro tyrosinase inhibition was compared, and cell viability was assessed in B-16V melanocytes to evaluate safety. Results showed 4-butylresorcinol, ascorbyl glucoside, and α-arbutin are non-photoreactive, while for ascorbic acid and bakuchiol it was not possible to reach conclusive results due to the lack of specificity of the ROS assay. 4-Butylresorcinol, acting as a competitive inhibitor, displayed potent tyrosinase inhibition, followed by ascorbic acid and bakuchiol. Both 4-butylresorcinol and bakuchiol reduced cell viability in a concentration-dependent manner. The insights obtained in this work support the development of depigmenting products by providing useful scientific guidance on the photostability, tyrosinase inhibitory efficacy, and skin safety of depigmenting agents.

Assessment and computational bioevaluation of heavy metals from selected cosmetic products

Heavy metal toxicity in environment has been an increasing issue for last decades, though now the attention has diverted to presence of heavy metals in cosmetic products. The aim of this study was to determine the concentration of selected heavy metals in cosmetic products (lipsticks and foundations) using ICP-OES. Health risk assessment was done by using hazard quotient (HQ) and hazard index (HI). HQ for lipsticks was below the safe limit (HQ = < 1) while for foundations it exceeded the safe limit (HQ = >1). Mostly, mercury (Hg) and iron (Fe) were found to be exceeding the permissible limit, the allowed limits are Hg, 1 ppm; Fe, 10 ppm; Cd, 0.3 ppm; and Cr, 1 ppm. Iron was found to be highest in lipsticks (123.86 ± 1.05 ppm) as well as in foundations (34.52 ± 0.08 ppm). Health risk assessment was done by using hazard quotient (HQ) and hazard index (HI). HQ for lipsticks was below the safe limit (HQ = < 1) while for foundations it exceeded the safe limit (HQ = >1). To understand the binding pattern of heavy metals to skin targets, molecular docking studies were carried out. This revealed the potentially harmful behavior of these heavy metals on the skin. This will provide new direction for the structural changes of consistence and activity of macromolecules in our body. Research proved that prolonged use of cosmetic products containing heavy metals can be harmful and sometimes fatal to human life as these heavy metals can penetrate through the skin and target the skin enzymes, disrupting their normal function leading to various skin related issues such as dermatitis (itching, redness, burning) hence the monitoring of cosmetic products is necessary for safety of human being.

Synergistic impact of arbutin and kaempferol-7-O-α-L-rhamnopyranoside from Nephelium lappaceum L. on whitening efficacy and stability of cosmetic formulations

Four flavonoid glycosides, namely quercetin-3-O-rhamnoside (1), kaempferol-3-O-β-D-glucopyranosyl (2), kaempferol-7-O-α-L-rhamnopyranoside (3), and kaempferol-3-O-β-D-glucopyranosyl-7-O-α-L-rhamnopyranoside (4), from Nephelium lappaceum L. seeds were evaluated for their efficacy against melanin inhibition in B16F10 melanoma cells and tyrosinase inhibition. Among them, kaempferol-7-O-α-L-rhamnopyranoside (3) displayed the highest potency in both activities without any significant cytotoxicity. The combination of compound 3 and arbutin in specific proportions demonstrated a synergistic effect (CI < 1) in inhibiting melanin production in B16F10 cells and tyrosinase inhibition. Additionally, a cosmetic formulation containing compound 3 and arbutin as active ingredients exhibited favorable stability under accelerated storage conditions. Quantitative analysis indicated that compound 3 and arbutin levels in the formulation were above 90% after one month of storage. Determination of the formulation's shelf life using the Q10 method, estimating it to be around 5.2 months from the date of manufacture. The synergy between arbutin and kaempferol-7-O-α-L-rhamnopyranoside (3) extracted from N. lappaceum substantially enhances both the whitening effectiveness and the stability of cosmetic formulations.

Synthesis, in silico modelling, and in vitro biological evaluation of substituted pyrazole derivatives as potential anti-skin cancer, anti-tyrosinase, and antioxidant agents

Twenty-five azole compounds (P1-P25) were synthesised using regioselective base-metal catalysed and microwave-assisted approaches, fully characterised by high-resolution mass spectrometry (HRMS), nuclear magnetic resonance (NMR), and infrared spectra (IR) analyses, and evaluated for anticancer, anti-tyrosinase, and anti-oxidant activities in silico and in vitro. P25 exhibited potent anticancer activity against cells of four skin cancer (SC) lines, with selectivity for melanoma (A375, SK-Mel-28) or non-melanoma (A431, SCC-12) SC cells over non-cancerous HaCaT-keratinocytes. Clonogenic, scratch-wound, and immunoblotting assay data were consistent with anti-proliferative results, expression profiling therewith implicating intrinsic and extrinsic apoptosis activation. In a mushroom tyrosinase inhibition assay, P14 was most potent among the compounds (half-maximal inhibitory concentration where 50% of cells are dead, IC50 15.9 μM), with activity greater than arbutin and kojic acid. Also, P6 exhibited noteworthy free radical-scavenging activity. Furthermore, in silico docking and absorption, distribution, metabolism, excretion, and toxicity (ADMET) simulations predicted prominent-phenotypic actives to engage diverse cancer/hyperpigmentation-related targets with relatively high affinities. Altogether, promising early-stage hits were identified - some with multiple activities - warranting further hit-to-lead optimisation chemistry with further biological evaluations, towards identifying new skin-cancer and skin-pigmentation renormalising agents.

Tripeptides conjugated with thiosemicarbazones: new inhibitors of tyrosinase for cosmeceutical use

The development of skin-care products is recently growing. Cosmetic formulas containing active ingredients with proven efficacy, namely cosmeceuticals, are based on various compounds, including peptides. Different whitening agents featuring anti-tyrosinase activity have been applied in the cosmeceutical field. Despite their availability, their applicability is often limited due to several drawbacks including toxicity, lack of stability, and other factors. In this work, we present the inhibitory effect on diphenolase activity of thiosemicarbazone (TSC)-peptide conjugates. Tripeptides FFY, FWY, and FYY were conjugated with three TSCs bearing one or two aromatic rings via amide bond formation in a solid phase. Compounds were then examined as tyrosinase and melanogenesis inhibitors in murine melanoma B16F0 cell line, followed by the cytotoxicity assays of these cells. In silico investigations explained the differences in the activity, observed among tested compounds. Mushroom tyrosinase was inhibited by TSC1-conjugates at micromolar level, with IC₅₀ lower than this for kojic acid, a widely used reference compound. Up to now, this is the first report regarding thiosemicarbazones conjugated with tripeptides, synthesised for the purpose of tyrosinase inhibition.

Synthesizing biomaterials in living organisms

Living organisms fabricate biomacromolecules such as DNA, RNA, and proteins by the self-assembly process. The research on the mechanism of biomacromolecule formation also inspires the exploration of in vivo synthesized biomaterials. By elaborate design, artificial building blocks or precursors can self-assemble or polymerize into functional biomaterials within living organisms. In recent decades, these so-called in vivo synthesized biomaterials have achieved extensive applications in cell-fate manipulation, disease theranostics, bioanalysis, cellular surface engineering, and tissue regeneration. In this review, we classify strategies for in vivo synthesis into non-covalent, covalent, and genetic types. The development of these approaches is based on the chemical principles of supramolecular chemistry and synthetic chemistry, biological cues such as enzymes and microenvironments, and the means of synthetic biology. By summarizing the design principles in detail, some insights into the challenges and opportunities in this field are provided to  enlighten further research.

Investigation of Structure-Activity Relationships for Benzoyl and Cinnamoyl Piperazine/Piperidine Amides as Tyrosinase Inhibitors

Melanin is a substance that plays important roles in several organisms. Its function as an antioxidant and metal-complexing agent makes tyrosinase, the key enzyme that controls melanogenesis, an interesting target for designing inhibitors. In this article, we report a set of piperazine/piperidine amides of benzoic and cinnamic acid derivatives as tyrosinase inhibitors with improved potency and drug-likeness. The most potent compound 5b showed a pIC50 of 4.99 in the monophenolase assay, and only compound 3a showed reasonable potency in the diphenolase assay (pIC50, 4.18). These activities are not correlated to antiradical activity, suggesting that the activity is dependent on competition with the substrates. Molecular docking studies indicated that the benzyl substituent of 5b and other analogues perform important interactions in the enzyme that may explain the higher potency of these compounds. Moreover, the compounds present adequate lipophilicity and skin permeability and no relevant cytotoxicity (CC50 > 200 μM) to mammalian cells.

Exploring Major Flavonoid Phytochemicals from Nelumbo nucifera Gaertn. as Potential Skin Anti-Aging Agents: In Silico and In Vitro Evaluations

Nelumbo nucifera Gaertn., an aquatic medicinal plant (Nelumbonaceae family), has a history of use in traditional medicine across various regions. Our previous study demonstrated the skin anti-aging potential of its stamen ethanolic extract by effectively inhibiting collagenase and tyrosinase enzymes. While the major constituents of this extract are well documented, there is a lack of research on the individual compounds' abilities to inhibit skin aging enzymes. Therefore, this study aimed to evaluate the anti-aging potential of the primary flavonoids found in N. nucifera using both in silico and in vitro approaches. Our initial step involved molecular docking to identify compounds with the potential to inhibit collagenase, elastase, and tyrosinase. Among the seven flavonoids studied, kaempferol-3-O-robinobioside (Kae-3-Rob) emerged as the most promising candidate, exhibiting the highest docking scores for three skin aging-related enzymes. Subsequent enzyme-based inhibition assays confirmed that Kae-3-Rob displayed robust inhibitory activity against collagenase (58.24 ± 8.27%), elastase (26.29 ± 7.16%), and tyrosinase (69.84 ± 6.07%). Furthermore, we conducted extensive 200-ns molecular dynamics (MD) simulations, revealing the stability of the complexes formed between Kae-3-Rob and each enzyme along the MD simulation time. MM/PBSA-based binding free energy calculations indicated the considerably stronger binding affinity of Kae-3-Rob for collagenase and tyrosinase compared to elastase, which was related to the greater percentage of hydrogen bond occupations. These computational findings were consistent with the relatively high inhibitory activity of Kae-3-Rob against collagenase and tyrosinase observed in our in vitro experiment. In conclusion, the results obtained from this comprehensive study suggest that Kae-3-Rob, a key flavonoid from N. nucifera, holds significant potential as a source of bioactive compounds for anti-aging cosmeceutical and other phytopharmaceutical application.

Thiazolopyrimidine derivatives as novel class of small molecule tyrosinase inhibitor

Tyrosinase, the rate-limiting enzyme of melanogenesis, plays a crucial role in hyperpigmentation. As a result, in this study, a novel class of thiazolopyrimidine derivatives was developed and synthesized as tyrosinase inhibitor. The structure of derivatives was characterized using various spectroscopy techniques, including FTIR, Mass, 1H-NMR, and 13C-NMR. Next, the inhibitory activities of all derivatives were examined against tyrosinase, and, 6a as the most potent compound, exhibited an IC50 value of 28.50 µM. Furthermore, the kinetic study of 6a was performed to better understand the inhibitory mechanism and its type of inhibition. The UV/Vis spectra analysis was also executed to provide valuable evidence supporting the inhibitory mechanism of compound 6a in the context of tyrosinase inhibition. Also, molecular docking and dynamic molecular study of 6a were executed to study its interactions within the enzyme's binding site.

Natural tyrosinase enzyme inhibitors: A path from melanin to melanoma and its reported pharmacological activities

The skin containing melanin pigment acts as a protective barrier and counteracts the UVR and other environmental stressors to maintain or restore disrupted cutaneous homeostasis. The production of melanin pigment is dependent on tyrosine levels. L-tyrosine and L-dihydroxyphenylalanine (L-DOPA) can serve both as a substrates and intermediates of melanin synthetic pathway and as inducers and positive regulators of melanogenesis. The biosynthesis of melanin is stimulated upon exposure to UVR, which can also stimulate local production of hormonal factors, which can stimulate melanoma development by altering the chemical properties of eu- and pheomelanin. The process of melanogenesis can be altered by several pathways. One involves activation of POMC, with the production of POMC peptides including MSH and ACTH, which increase intracellular cAMP levels, which activates the MITF, and helps to stimulate tyrosinase (TYR) expression and activity. Defects in OCA1 to 4 affects melanogenic activity via posttranslational modifications resulting in proteasomal degradation and reducing pigmentation. Further, altering, the MITF factor, helps to regulate the expression of MRGE in melanoma, and helps to increase the TYR glycosylation in ER. CRH stimulates POMC peptides that regulate melanogenesis and also by itself can stimulate melanogenesis. The POMC, P53, ACTH, MSH, MC1R, MITF, and 6-BH4 are found to be important regulators for pigmentation. Melanogenesis can affect melanoma behaviour and inhibit immune responses. Therefore, we reviewed natural products that would alter melanin production. Our special focus was on targeting melanin synthesis and TYR enzyme activity to inhibit melanogenesis as an adjuvant therapy of melanotic melanoma. Furthermore, this review also outlines the current updated pharmacological studies targeting the TYR enzyme from natural sources and its consequential effects on melanin production.

Fenchone and camphor: Main natural compounds from Lavandula stoechas L., expediting multiple in vitro biological activities

Lavandula stoechas, a Mediterranean plant, renowned in traditional medicine for its health benefits, is also arousing strong interest associated with its essential oils (EOs) with promising therapeutic properties. The aim of this study was to analyze the chemical composition of the plant, as well as to study its major activities, including antioxidant, anti-diabetic, dermatoprotective, anti-inflammatory, and antibacterial effects, focusing on its major molecules. Using the GC-MS method, the main compounds identified in L. stoechas EO (LSEO) were fenchone (31.81 %) and camphor (29.60 %), followed by terpineol (13.14 %) and menthone (8.96 %). To assess their antioxidant activity, three in vitro methods were used (DPPH, FRAP, and ABTS). The results revealed that LSEO exhibited the best antiradical property (54 ± 62 μg/mL) according to the DPPH test, while fenchone demonstrated the highest antioxidant capacity (87 ± 92 μg/mL) in the FRAP test, and camphor displayed the highest antioxidant capacity (96 ± 32 μg/mL) in the ABTS test. However, these results were lower than those obtained by Trolox used as a reference. In addition, study also explored the anti-diabetic potential of LSEO and its major compounds by evaluating their inhibitory activity towards two digestive enzymes, α-glucosidase and α-amylase. Camphor (76.92 ± 2.43 μg/mL) and fenchone (69.03 ± 2.31 μg/mL) exhibited the best inhibitory activities for α-amylase and α-glucosidase assays, respectively. Interestingly, all elements of the study exerted activities superior to those of acarbose, regardless of the test performed. In contrast, the evaluation of the dermatoprotective potential was carried out in vitro by targeting two enzymes involved in cutaneous processes, tyrosinase and elastase. In this light, fenchone (53.14 ± 3.06 μg/mL) and camphor (48.39 ± 1.92 μg/mL) were the most active against tyrosinase and elastase, respectively. It should be noted that the effect of both molecules, as well as that of LSEO, ranged between 53.14 ± 3.06 and 97.45 ± 5.22 μg/mL, which was significantly lower than the standard, quercetin (IC50 of 246.90 ± 2 0.54 μg/mL) against tyrosinase. Furthermore, the anti-inflammatory potential of these elements has been studied by evaluating their ability to inhibit lipooxygenase (LOX), a class of enzymes involved in the inflammatory process in the human body. As a result, the LSEO demonstrated a remarkable effect with an IC50 of 6.34 ± 1.29 μg/mL, which was almost comparable to the standard, quercetin (IC50 = 3.93 ± 0.45 μg/mL). Concerning the antibacterial potential, we carried out a quantitative analysis of the various products tested, revealing a bactericidal activity of the LSEO against the strain L. monocytogenes ATCC 13932 at a minimum effective concentration (MIC = CMB = 0.25). Overall, LSEOs offer significant potential as a source of natural antioxidants, and antidiabetic and anti-inflammatory agents, as well as dermatoprotective and antibacterial compounds. Its major molecules, fenchone and camphor, showed promising activity in these areas of study, making it a valuable candidate for future research and development in the field of natural medicine.

Peptide OA-VI12 restrains melanogenesis in B16 cells and C57B/6 mouse ear skin via the miR-122-5p/Mitf/Tyr axis

Excessive melanogenesis leads to hyperpigmentation, which is one of the common skin conditions in humans. Existing whitening cosmetics cannot meet market needs due to their inherent limitations. Thus, the development of novel skin-whitening agents continues to be a challenge. The peptide OA-VI12 from the skin of amphibians at high altitude has attracted attention due to its remarkable anti light damage activity. However, whether OA-VI12 has the skin-whitening effect of inhibiting melanogenesis is still. Mouse melanoma cells (B16) were used to study the effect of OA-VI12 on cell viability and melanin content. The pigmentation model of C57B/6 mouse ear skin was induced by UVB and treated with OA-VI12. Melanin staining was used to observe the degree of pigmentation. MicroRNA sequencing, quantitative real-time PCR (qRT-PCR), immunofluorescence analysis and Western blot were used to detect the change of factor expression. Double luciferase gene report experiment was used to prove the regulatory relationship between miRNA and target genes. OA-VI12 has no effect on the viability of B16 cells in the concentration range of 1-100 μM and significantly inhibits the melanin content of B16 cells. Topical application of OA-VI12, which exerted transdermal potency, prevented UVB-induced pigmentation of ear skin. MicroRNA sequencing and double luciferase reporter analysis results showed that miR-122-5p, which directly regulated microphthalmia-associated transcription factor (Mitf), had significantly different expression before and after treatment with OA-VI12. Mitf is a simple helix loop and leucine zipper transcription factor that regulates tyrosinase (Tyr) expression by binding to the M-box promoter element of Tyr. qRT-PCR, immunofluorescence analysis and Western blot showed that OA-VI12 up-regulated the expression of miR-122-5p and inhibited the expression of Mitf and Tyr. The effects of OA-VI12 on melanogenesis inhibition in vitro and in vivo may involve the miR-122-5p/Mitf/tyr axis. OA-VI12 represents the first report on a natural amphibian-derived peptide with skin-whitening capacity and the first report of miR-122-5p as a target for regulating melanogenesis, thereby demonstrating its potential as a novel skin-whitening agent and highlighting amphibian-derived peptides as an underdeveloped resource.

The Potential of Mangifera indica L. Peel Extract to Be Revalued in Cosmetic Applications

The constant growth of the cosmetic industry, together with the scientific evidence of the beneficial properties of phytochemicals, has generated great interest in the incorporation of bioactive extracts in cosmetic formulations. This study aims to evaluate the bioactive potential of a mango peel extract for its incorporation into cosmetic formulations. For this purpose, several assays were conducted: phytochemical characterization; total phenolic content (TPC) and antioxidant potential; free-radical scavenging capacity; and skin aging-related enzyme inhibition. In addition, the extract was incorporated into a gel formulation, and a preliminary stability study was conducted where the accelerated (temperature ramp, centrifugation, and heating/cooling cycles) and long-term (storage in light and dark for three months) stability of the mango peel formulations were evaluated. The characterization results showed the annotation of 71 compounds, gallotannins being the most representative group. In addition, the mango peel extract was shown to be effective against the •NO radical with an IC50 of 7.5 mg/L and against the hyaluronidase and xanthine oxidase enzymes with IC50 of 27 mg/L and 2 mg/L, respectively. The formulations incorporating the extract were stable during the stability study. The results demonstrate that mango peel extract can be a by-product to be revalorized as a promising cosmetic ingredient.

Tocotrienol-Rich Fraction Attenuates Blue Light-Induced Oxidative Stress and Melanogenesis in B16-F1 Melanocytes via Anti-Oxidative and Anti-Tyrosinase Properties

Our skin is constantly exposed to blue light (BL), which is abundant in sunlight and emitted by digital devices. Prolonged exposure to BL can lead to oxidative stress-induced damages and skin hyperpigmentation. For this study, we used a cell line-based model to examine the protective effects of tocotrienol-rich fraction (TRF) on BL-induced oxidative stress and hyperpigmentation in B16-F1 melanocytes. Alpha-tocopherol (αTP) was used as a comparator. Molecular assays such as cell viability assay, flow cytometry, western blotting, fluorescence imaging, melanin and tyrosinase analysis were performed. Our results showed that TRF effectively suppressed the formation of reactive oxygen species and preserved the mitochondrial membrane potential. Additionally, TRF exhibited anti-apoptotic properties by reducing the activation of the p38 mitogen-activated protein kinase molecule and downregulating the expression of cleaved caspase-3. Moreover, TRF modulated tyrosinase activity, resulting in a lowered rate of melanogenesis and reduced melanin production. In contrast, αTP did not exhibit significant protective effects against skin damages and pigmentation in BL-induced B16-F1 cells. Therefore, this study indicates that TRF may offer superior protective effects over αTP against the effects of BL on melanocytes. These findings demonstrate the potential of TRF as a protective natural ingredient that acts against BL-induced skin damages and hyperpigmentation via its anti-oxidative and anti-melanogenic properties.

Extremophilic Solutions: The Role of Deinoxanthin in Counteracting UV-Induced Skin Harm

This research delved into the protective capacities of deinoxanthin, a carotenoid present in Deinococcus radiodurans, against UVA- and UVB-mediated skin damage using human fibroblast foreskin cells (HFF-1). Using the MTT assay, HFF-1 cells treated with 10 µM DNX displayed 20% and 31.7% higher viability than the positive (Vitamin C-treated) and negative (DNX-untreated) control groups, respectively, upon 100 mJ/cm2 UVB exposure. At 24 J/cm2 UVA, 20 µM DNX-treated cells showed 80.6% viability, exceeding the positive and negative control groups by 28.6% and 33.6%, respectively. Flow cytometry analysis revealed that cells treated with DNX and exposed to 24 J/cm2 UVA exhibited a 69.32% reduction in apoptotic processes compared to untreated cells. Similarly, when exposed to 100 mJ/cm2 UVB, DNX-treated cells demonstrated a 72.35% decrease in apoptotic processes relative to their untreated counterparts. DNX also displayed dose-dependent inhibition on tyrosinase activity. The study emphasized DNX's antioxidative capacity, evident in its modulation of superoxide dismutase activity and measurements of Malondialdehyde and intracellular reactive oxygen species levels. DNX-treated cells exhibited higher hydroxyproline levels, suggesting healthier collagen production. Additionally, the wound-healing assay method confirmed an accelerated healing rate in DNX-treated cells. Conclusively, DNX offers significant protection against UV-induced skin damage, emphasizing its potential for skincare and therapeutics.

Chemical composition, antioxidant and anti-tyrosinase potentials of Acacia cyclops trunk bark using in vitro and in silico approaches

The purpose of this paper was to evaluate the phytochemical profile of Acacia cyclops trunk bark methanol extract using LC-MS/MS, as well as to assess its antioxidant and anti-tyrosinase activities. Thus, total phenolic and flavonoid contents of the studied extract were established and 19 compounds were detected and quantified. In addition of their antioxidant potential against DPPH and ABTS assays, in vitro and in silico studies were adopted to evaluate tyrosinase inhibitory property of A. cyclops extract. Methanol trunk bark extract showed significant total phenolic content, antioxidant potential in terms of free radical scavenging, as well as an interesting tyrosinase inhibitory action (IC50= 05.12 ± 0.41 μg/mL). The molecular docking analysis and the drug-likeness prediction of the major selected compounds supported the significant anti-tyrosinase activity of the studied extract. The obtained results suggest that A. cyclops extract could be a promising candidate in the treatment of skin hyperpigmentation disorders.

LC-MS and NMR Based Plant Metabolomics: A Comprehensive Phytochemical Investigation of Symphytum anatolicum

The application of metabolomics to the study of plants is growing because of the current development of analytical techniques. The most commonly used analytical technology driving plant metabolomics studies is Mass Spectrometry (MS) coupled to liquid chromatography (LC). In recent years, Nuclear Magnetic Resonance (NMR) spectroscopy, not requiring a previous chromatographic separation, has been receiving growing attention for metabolite fingerprinting of natural extracts. Herein, an integrated LC-MS and 1H NMR metabolomic approach provided a comprehensive phytochemical characterization of Symphytum anatolicum whole plant, taking into account both primary and specialized metabolites. Moreover, the NMR analyses provided direct quantitative information. Species belonging to the Symphytum genus, known as comfrey, have shown several biological activities including anti-inflammatory, analgesic, hepatoprotective, antifungal, and antibacterial. The LC-MS profile showed the presence of 21 main specialized metabolites, belonging to the classes of flavonoids, phenylpropanoids, salvianols, and oxylipins. The 1H NMR spectrum revealed the occurrence of metabolites including organic acids, phenolics, flavonoids, sugars, and amino acids. A quantitative analysis of these metabolites was performed and their concentration was obtained with respect to the known concentration of TSP, by means of the software package Chenomx which allows quantification of individual components in the NMR spectra. Furthermore, the phenolic content, antioxidant activity, glucosidase, and tyrosinase inhibitory activity of S. anatolicum extract were evaluated. The resulting bioactivity profile suggests how S. anatolicum represents a source of metabolites with health-promoting activity.

Discovery of new functions of food proteins and their structural development for multifunctional applications

Proteins and peptides derived from various food sources are used in a variety of applications, including functional foods, pharmaceuticals, and cosmetics. The three-dimensional structure of proteins provides useful insights into their functions and essential information for the creation of proteins with new functions. In this review, a series of functional conversion technologies based on protein structural information derived from foods traditionally consumed in Japan, such as natto (fermented soybeans) and rice, are introduced. For natto, we first identified 2 types of Bacillus subtilis-derived endolytic and exolytic enzymes with different modes of action on soybean cell wall polysaccharides and then focused on the technology used to create an endolytic enzyme from an exolytic enzyme. By applying this technology, a method for creating novel bioactive peptides from rice seed proteins was established. The modified peptides created could provide diverse options for the production of substances such as pharmaceuticals and cosmetic materials.

Rational design of an N-terminal cysteine-containing tetrapeptide that inhibits tyrosinase and evaluation of its mechanism of action

There has been a resurgence of interest in bioactive peptides as therapeutic agents. This is particularly interesting for tyrosinase, which can be inhibited by thiol-containing peptides. This work demonstrates that an N-terminal cysteine-containing tetrapeptide can be rationally designed to inhibit tyrosinase activity in vitro and in cells. The tetrapeptide cysteine (C), arginine (R), asparagine (N) and leucine (L) or CRNL is a potent inhibitor of tyrosinase activity with an IC50 value of 39.62 ± 6.21 μM, which is comparable to currently used tyrosinase inhibitors. Through structure-activity studies and computational modeling, we demonstrate the peptide interacts with the enzyme via electrostatic (R with E322), hydrogen bonding (N with N260) and hydrophobic (L with V248) intermolecular interactions and that a combination of these is required for potent activity. Moreover, copper chelating activity might be one of the mechanisms of tyrosinase inhibition by CRNL. Kinetic studies show that tetrapeptide is a competitive inhibitor with two-step irreversible inhibition. In addition, CRNL had no toxicity and could reduce melanin levels in the murine melanoma cell line (B16F1). Overall, CRNL is a very promising candidate for hyperpigmentation treatment.

Aspacochioside C from Asparagus cochinchinensis attenuates eumelanin synthesis via inhibition of TRP2 expression

Aspacochioside C (ACC) is a steroidal saponin isolated from Asparagus cochinchinensis. Steroidal saponins, such as pseudoprotodioscin and dioscin, are known to inhibit melanogenesis, but the role of ACC in melanogenesis remains unknown. Due to the toxic effect of the commonly used skin whitening agents like arbutin, kojic acid and α-lipoic acid alternative plant products are recentlybeen studied for their anti-hypergmentation effect. This study explores the role of ACC in melanogenesis in both in vivo and in vitro models. Here, we for the first time demonstrate that ACC attenuated α-MSH- and UVB-induced eumelanin production by inhibiting tyrosinase-related protein (TRP)-2 protein expression in both murine B16F10 and human melanoma MNT1 cells. However, ACC had no significant effect on pheomelanin concentration. ACC also decreased the pigmentation density in zebrafish embryos, which indicates that ACC targets TRP2 and inhibits eumelanin synthesis. Our results demonstrate that ACC inhibits TRP2, thereby attenuating eumelanin synthesis both in in vitro and in vivo zebrafish model. Therefore, ACC can potentially be used as an anti-melanogenic agent for both aesthetic and pharmaceutical purposes.

In Vitro and In Vivo Antimelanogenesis Effects of Leaf Essential Oil from Agathis dammara

Agathis species are widely distributed around Southeast Asia, Australasia, South Pacific islands, and etc. Traditionally, Agathis species have been used as the folk medicines, the common ethnopharmacological uses of Agathis genus are the treatments of headache and myalgia. This study aims to investigate the chemical composition of Agathis dammara (Lamb.) Rich. leaf essential oil and to explore its antimelanogenesis effect. The chemical constituents of leaf essential oil are analyzed using gas chromatography-mass spectrometry (GC-MS), the major constituents of leaf essential oil are sesquiterpenoids. The major constituents are δ-cadinene (16.12%), followed by γ-gurjunene (15.57%), 16-kaurene (12.43%), β-caryophyllene (8.58%), germacrene D (8.53%), and γ-cadinene (5.33%). As for the in vitro antityrosinase activity, leaf essential oil inhibit the tyrosinase activity of mushroom when the substrate is 3,4-dihydroxyphenylalanine (L-DOPA). Leaf essential oil prevents tyrosinase from acting as diphenolase and catalyzing L-DOPA to dopaquinone, and converting into dark melanin pigments. A. dammara leaf essential oil also exhibits the in vivo antimelanogenesis effect, leaf essential oil reduces 43.48% of melanin formation in zebrafish embryos at the concentration of 50 μg/mL. Results reveal A. dammara leaf essential oil has the potential for developing the skin whitening drug and depigmentation ingredient for hyperpigmentary disorders.

Design, synthesis, spectroscopic characterizations, in vitro pancreatic lipase as well as tyrosinase inhibition evaluations and in silico analysis of novel aryl sulfonate-naphthalene hybrids

One of the primary purposes of this study is to synthesize new aryl sulfonate-naphthalene hybrid structures possessing divergent electron-withdrawing and electron-releasing functional groups. Following the improved reaction conditions, we successfully gathered ten distinct sulfonate derivatives (3a-j) with good yields. The synthesized naphthalene-based sulfonate derivatives were then characterized using appropriate analytical methods (FT-IR, 1H-NMR, 13C-NMR, HRMS, and elemental analysis). Additionally, in vitro and in silico enzyme inhibitory properties of the prepared aryl sulfonate-naphthalene hybrid structures were evaluated against pancreatic lipase and tyrosinase enzymes. Corresponding in vitro enzyme activity investigations revealed that the produced compounds inhibit pancreatic lipase and tyrosinase enzymes significantly. According to the lowest IC50 values, 3h (95.3 ± 4.0 µM) demonstrated the most effective inhibition against pancreatic lipase, whereas 3a (40.8 ± 3.3 µM) was found as the most effective inhibition against the tyrosinase. According to in silico studies, 3a exhibited the highest affinity value (-9.9 kcal/mol) against pancreatic lipase, whereas 3f demonstrated the best affinity value (-8.7 kcal/mol) against tyrosinase.Furthermore, we investigated various structural and physicochemical properties of the target molecules, namely frontier orbital' (HOMO, LUMO, and bandgap) energies (including their corresponding contour plots), global reactivity descriptors (ionization energy and electron affinity), and electronegativity values gathered from ground-state (GS) density functional theory (DFT) calculations. These investigations demonstrated that the observed electrostatic interactions effectively contributed to the studied molecules' experimentally demonstrated enzyme inhibition potential. Also, ADMET studies were evaluated to enlighten the molecular interactions of the compounds with the enzymes.Communicated by Ramaswamy H. Sarma.

Skincare potential of a sustainable postbiotic extract produced through sugarcane straw fermentation by Saccharomyces cerevisiae

Postbiotics are defined as a "preparation of inanimate microorganisms and/or their components that confers a health benefit on the host." They can be produced by fermentation, using culture media with glucose (carbon source), and lactic acid bacteria of the genus Lactobacillus, and/or yeast, mainly Saccharomyces cerevisiae as fermentative microorganisms. Postbiotics comprise different metabolites, and have important biological properties (antioxidant, anti-inflammatory, etc.), thus their cosmetic application should be considered. During this work, the postbiotics production was carried out by fermentation with sugarcane straw, as a source of carbon and phenolic compounds, and as a sustainable process to obtain bioactive extracts. For the production of postbiotics, a saccharification process was carried out with cellulase at 55°C for 24 h. Fermentation was performed sequentially after saccharification at 30°C, for 72 h, using S. cerevisiae. The cells-free extract was characterized regarding its composition, antioxidant activity, and skincare potential. Its use was safe at concentrations below ~20 mg mL-1 (extract's dry weight in deionized water) for keratinocytes and ~ 7.5 mg mL-1 for fibroblasts. It showed antioxidant activity, with ABTS IC50 of 1.88 mg mL-1 , and inhibited elastase and tyrosinase activities by 83.4% and 42.4%, respectively, at the maximum concentration tested (20 mg mL-1 ). In addition, it promoted the production of cytokeratin 14, and demonstrated anti-inflammatory activity at a concentration of 10 mg mL-1 . In the skin microbiota of human volunteers, the extract inhibited Cutibacterium acnes and the Malassezia genus. Shortly, postbiotics were successfully produced using sugarcane straw, and showed bioactive properties that potentiate their use in cosmetic/skincare products.

Discovery of amphotericin B, an antifungal drug as tyrosinase inhibitor with potent anti-melanogenic activity

Tyrosinase, a rate-limiting enzyme for melanin production, has been the most efficient target for the development of depigmenting agents. Although hydroquinone, kojic acid, and arbutin are the most well-known tyrosinase inhibitors, their adverse effects are inevitable. In the present study, an in silico drug repositioning combined with experimental validation was performed to search for novel potent tyrosinase inhibitors. Docking-based virtual screening results revealed that, among the 3210 FDA-approved drugs available in the ZINC database, amphotericin B, an antifungal drug exhibited the highest binding efficiency against human tyrosinase. Results from tyrosinase inhibition assay demonstrated that amphotericin B could inhibit the activity of mushroom and cellular tyrosinases, especially from MNT-1 human melanoma cells. Molecular modeling results revealed that amphotericin B/human tyrosinase complex exhibited high stability in an aqueous environment. Melanin assay results demonstrated that amphotericin B significantly suppressed melanin production in α-MSH-induced B16F10 murine melanoma and MNT-1 human melanoma cell lines better than the known inhibitor, kojic acid. Mechanistically, amphotericin B treatment significantly activated ERK and Akt signaling pathways, resulting in the decreased expression of MITF and tyrosinase. The obtained results may pursue pre-clinical and clinical studies to examine the possibility of using amphotericin B as an alternative treatment for hyperpigmentation disorders.

Photosensitizers-Loaded Nanocarriers for Enhancement of Photodynamic Therapy in Melanoma Treatment

Malignant melanoma poses a significant global health burden. It is the most aggressive and lethal form of skin cancer, attributed to various risk factors such as UV radiation exposure, genetic modifications, chemical carcinogens, immunosuppression, and fair complexion. Photodynamic therapy is a promising minimally invasive treatment that uses light to activate a photosensitizer, resulting in the formation of reactive oxygen species, which ultimately promote cell death. When selecting photosensitizers for melanoma photodynamic therapy, the presence of melanin should be considered. Melanin absorbs visible radiation similar to most photosensitizers and has antioxidant properties, which undermines the reactive species generated in photodynamic therapy processes. These characteristics have led to further research for new photosensitizing platforms to ensure better treatment results. The development of photosensitizers has advanced with the use of nanotechnology, which plays a crucial role in enhancing solubility, optical absorption, and tumour targeting. This paper reviews the current approaches (that use the synergistic effect of different photosensitizers, nanocarriers, chemotherapeutic agents) in the photodynamic therapy of melanoma.

The Role of Probiotics in Skin Health and Related Gut-Skin Axis: A Review

Aging skin, wrinkles, pigmentation, and dryness are problems that plague people, and researchers are working to solve them. Recent studies have shown that intestinal microbiota homeostasis can influence skin health, demonstrating the existence of a gut-skin axis. Recently, improving skin health through probiotic interventions has been proposed, and micro-ecological skin care is becoming a popular concept. By regulating skin health and gut-skin axis interactions, probiotics can be used as potential management tools to suppress and improve skin diseases in multiple ways, including decreasing oxidative stress, suppressing inflammatory responses, and keeping immune effects. The purpose of this paper is to provide a comprehensive review of the application and mechanisms of probiotic-mediated gut microbiota homeostasis in skin care and to offer a theoretical basis for the application of probiotics in skin care.

Azelaic Acid Versus Hydroquinone for Managing Patients With Melasma: Systematic Review and Meta-Analysis of Randomized Controlled Trials

Melasma, a commonly acquired hyperpigmentation skin condition, is usually treated with topical agents as the first line of management. This systematic review and meta-analysis aimed to assess the efficacy and safety of azelaic acid versus hydroquinone in treating melasma patients. We conducted a comprehensive search across four online databases (PubMed, Scopus, Web of Science, and Cochrane Library) from the time of their creation until May 28, 2023. We considered randomized controlled studies comparing hydroquinone with azelaic acid for the treatment of melasma patients. We used the Cochrane Risk of Bias tool 2 to evaluate the risk of bias. The mean difference (MD) for continuous variables and the risk ratio (RR) for categorical variables, with a 95% confidence interval (CI) were pooled. Six studies were included, with a total of 673 patients with melasma. The azelaic acid had a lower mean change in melasma area severity index (MASI) than the hydroquinone group [MD= -1.23, 95% CI (-2.05, -0.40), P=0.004]. No difference was observed regarding the improvement via the objective response scale, the reduction in pigmentation, or the adverse events reported. However, despite not being statistically significantly different, there was a trend towards having more good responses in the azelaic acid group. Azelaic acid may be better than hydroquinone in reducing melasma severity (measured by MASI). However, larger studies with long-term follow-up are needed to validate these findings.

Anti-tyrosinase and antimelanogenic effect of cinnamic acid derivatives from Prunus mahaleb L.: Phenolic composition, isolation, identification and inhibitory activity

ETHNOPHARMACOLOGICAL RELEVANCE

The traditional use of Prunus species against skin diseases and especially for skin lightning cosmeceutical purposes is widespread in many cultures. Prunus mahaleb L. is a well known food plant and used in the baking industry for flavoring. The fruit kernels (endocarp) are used in India for hyperpigmentation.

AIM OF THE STUDY

To investigate the chemical composition with the antimelanogenesis effect of P. mahaleb seed and kernel extracts and isolated compounds.

MATERIALS AND METHODS

Isolation studies performed from the methanol extracts obtained from kernels and structures were determined using NMR and MS analysis. Antimelanogenesis effect was determined by mushroom tyrosinase assay, cellular tyrosinase assay and melanin content assay using B16F10 murine melanoma cells.

RESULTS

Five cinnamic acid derivatives were isolated and their structures (2-O-β-glucopyranosyloxy-4-methoxy-hydrocinnamic acid (1), cis-melilotoside (2), dihydromelilotoside (3), trans-melilotoside (4), 2-O-β-glucosyloxy-4-methoxy trans-cinnamic acid (5)) were elucidated using advanced spectroscopic methods. Mushroom tyrosinase enzyme inhibition of extracts, fractions and pure compounds obtained from P. mahaleb kernels were investigated and structure-activity relationship revealed. According to a detailed, comprehensive and validated LC-MS/MS technique analysis, vanilic acid (41.407 mg/g), protocatechuic acid (8.992 mg/g) and ferulic acid (4.962 mg/g) in the kernel ethylacetate fraction; quinic acid (14.183 mg/g), fumaric acid (8.349 mg/g) and aconitic acid (5.574 mg/g) were found as major phenolic compounds in the water fraction. The correlation of trace element copper content in extracts and fractions with mushroom enzyme activity was determined. By examining the enzyme kinetics of the compounds with effective cinnamic acid derivatives, inhibition types and enzyme binding constants K_i were calculated. Compounds 1,3 and 5 exhibited high noncompetitive tyrosinase inhibitory activity against L-tyrosine substrates, with IC₅₀ values of 0.22, 0.31 and 0.37 mM respectively. In addition compounds 1, 3 and 5 showed dose-dependent inhibitory effects on intracellular tyrosinase and melanin levels in α-melanocyte-stimulating hormone (α-MSH)-induced B16F10 melanoma cells.

CONCLUSIONS

Potent tyrosinase inhibitory compounds and extracts of P. mahaleb kernels suggest that it could be a new, non-toxic and inexpensive resource for the cosmeceutical industry and in skin diseases associated with hyperpigmentation.

Harnessing the Value of Tripolium pannonicum and Crithmum maritimum Halophyte Biomass through Integrated Green Biorefinery

Bioactive extracts are often the target fractions in bioprospecting, and halophyte plants could provide a potential source of feedstock for high-value applications as a part of integrated biorefineries. Tripolium pannonicum (Jacq.) Dobrocz. (sea aster) and Crithmum maritimum L. (sea fennel) are edible plants suggested for biosaline halophyte-based agriculture. After food production and harvesting of fresh leaves for food, the inedible plant fractions could be utilized to produce extracts rich in bioactive phytochemicals to maximize feedstock application and increase the economic feasibility of biomass processing to bioenergy. This study analyzed fresh juice and extracts from screw-pressed sea aster and sea fennel for their different phenolic compounds and pigment concentrations. Antioxidant and enzyme inhibition activities were also tested in vitro. Extracts from sea aster and sea fennel had phenolic contents up to 45.2 mgGAE/gDM and 64.7 mgGAE/gDM, respectively, and exhibited >70% antioxidant activity in several assays. Ethanol extracts also showed >70% inhibition activity against acetylcholinesterase and >50% inhibition of tyrosinase and α-glucosidase. Therefore, these species can be seen as potential feedstocks for further investigations.

Secondary Metabolites from the Cultures of Medicinal Mushroom Vanderbylia robiniophila and Their Tyrosinase Inhibitory Activities

Vanderbylia robiniophila (Huaier in Chinese) has been used as a traditional herbal medicine in China for over 1600 years. However, the secondary metabolites of V. robiniophila have not been systematically examined. Corresponding chemical investigation in this study led to the discovery of two new compounds, (22E, 24R)-6β, 7α-dimethoxyergosta-8(14), 22-diene-3β, 5α-diol (1) and vanderbyliolide A (8), along with eight known ones (2-7, 9-10). Their structures were determined by extensive spectroscopic analyses and electronic circular dichroism (ECD) calculations. The tyrosinase inhibitory activity of all isolated compounds was evaluated, and compound 10 showed a potential tyrosinase inhibitory effect with an IC₅₀ value of 60.47 ± 2.63 μM. Kinetic studies of the inhibition reactions suggested that 10 provides the inhibitory ability on tyrosinase in an uncompetitive way.

Phytochemical Profiling, Antioxidant and Tyrosinase Regulatory Activities of Extracts from Herb, Leaf and In Vitro Culture of Achillea millefolium (Yarrow)

Achillea millefolium L. is one of the most known medicinal plants with a broad spectrum of applications in the treatment of inflammation, pain, microbial infections and gastrointestinal disorders. In recent years, the extracts from A. millefolium have also been applied in cosmetics with cleansing, moisturizing, shooting, conditioning and skin-lightening properties. The growing demand for naturally derived active substances, worsening environmental pollution and excessive use of natural resources are causing increased interest in the development of alternative methods for the production of plant-based ingredients. In vitro plant cultures are an eco-friendly tool for continuous production of desired plant metabolites, with increasing applicability in cosmetics and dietary supplements. The purpose of the study was to compare phytochemical composition and antioxidant and tyrosinase inhibitory properties of aqueous and hydroethanolic extracts from A. millefolium obtained from field conditions (AmL and AmH extracts) and in vitro cultures (AmIV extracts). In vitro microshoot cultures of A. millefolium were obtained directly from seeds and harvested following 3 weeks of culture. Extracts prepared in water, 50% ethanol and 96% ethanol were compared for the total polyphenolic content, phytochemical content using the ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-hr-qTOF/MS), antioxidant activity by DPPH scavenging assay and the influence on the activity of mushroom and murine tyrosinases. The phytochemical content of AmIV extracts was significantly different from AmL and AmH extracts. Most of the polyphenolic compounds identified in AmL and AmH extracts were present in AmIV extracts only in trace amounts and the major constituents presented in AmIV extracts were fatty acids. The total content of polyphenols in AmIV exceeded 0.25 mg GAE/g of dried extract, whereas AmL and AmH extracts contained from 0.46 ± 0.01 to 2.63 ± 0.11 mg GAE/g of dried extract, depending on the solvent used. The low content of polyphenols was most likely responsible for the low antioxidant activity of AmIV extracts (IC₅₀ values in DPPH scavenging assay >400 µg/mL) and the lack of tyrosinase inhibitory properties. AmIV extracts increased the activity of mushroom tyrosinase and tyrosinase present in B16F10 murine melanoma cells, whereas AmL and AmH extracts showed significant inhibitory potential. The presented data indicated that microshoot cultures of A. millefolium require further experimental research before they can be implemented as a valuable raw material for the cosmetics industry.

Evaluation of phytochemicals of Poria cocos against tyrosinase protein: a virtual screening, pharmacoinformatics and molecular dynamics study

Tyrosinase inhibitors are commonly used in the pharmaceutical and cosmetic industries for skin lightening and hypopigmentation. The current inhibitors of tyrosinase induce strong safety concerns which necessitate the discovery of new inhibitors. Natural compounds are a promising solution to discover potential candidate for anti-melanogenic activity as they possess less safety concerns and high therapeutic effect. The current study aimed to screen and identify potential phytochemicals from Poria cocos for tyrosinase inhibition. The phytochemicals were obtained from the Traditional Chinese Medicine System Pharmacology Database and screened for druglikeness score and toxicity class and then subjected to in-silico virtual screening and molecular dynamics. 7,9-(11)-Dehydropachymic acid established hydrogen interaction with the tyrosinase protein and was found to be highly stable as validated with MD simulations. The pharmacokinetic results showed that this compound has adequate toxicity and ADME profile that can be exploited for anti-melanogenic effects. Our study identified 7,9-(11)-dehydropachymic acid as an efficient candidate for tyrosinase inhibition.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03626-8.

Synthesis and biological evaluation of new kojic acid-1,3,4-oxadiazole hybrids as tyrosinase inhibitors and their application in the anti-browning of fresh-cut mushrooms

In the food industry, inhibition of tyrosinase activity is considered as one of the main means to prevent browning. Therefore, fourteen kojic acid-1,3,4-oxadiazole hybrids (5a-5n) were prepared and tested for their tyrosinase inhibitory effects. Among them, 5f (IC₅₀ = 5.32 ± 0.58 μM) has the best anti-tyrosinase activity and was 9 times higher than that of kojic acid (IC₅₀ = 49.77 ± 1.19 μM). Additionally, the inhibitory mechanism was studied by copper-chelating assay, ultraviolet spectrophotometry, fluorescence quenching, molecular docking, etc. The results had shown that 5f could not only bind to the copper ion in the active region of tyrosinase but also change the secondary structure of tyrosinase. Combined with the outstanding anti-browning effect and low cytotoxicity of 5f, it is concluded that these title derivatives could be used as the leading molecules in the development of new anti-browning agents.

Activity and potential mechanisms of action of persimmon tannins according to their structures: A review

One distinguishing feature of the persimmon, that differentiates it from other fruits, is its high proanthocyanidins content, known as persimmon tannin (PT). Despite the poor absorption of PT in the small intestine, results from animal studies demonstrate that PT has many health benefits. Our goal in this review is to summarize the literature that elucidates the relationship between PT structure and activity. In addition, we also summarize the potential mechanisms underlying the health benefits that result from PT consumption; this includes the hypolipidemic, hypoglycemic, antioxidant, anti-inflammatory, antiradiation, antibacterial and antiviral, detoxification effects on snake venom, and the absorption of heavy metals and dyes. Studies show that PT is a structurally distinct proanthocyanidins that exhibits a high degree of polymerization. It is galloylation-rich and possesses unique A-type interflavan linkages in addition to the more common B-type interflavan bonds. Thus, PT is converted into oligomeric proanthocyanidins by depolymerization strategies, including the nucleophilic substitution reaction, acid hydrolysis, and hydrogenolysis. In addition, multiple health benefits exerted by PT mainly involve the inactivation of lipogenic and intracellular inflammatory signaling pathways, activation of the fatty acid oxidation signaling pathway, regulation of gut microbiota, and highly absorptive properties.

Topical Application of No-Ozone Cold Plasma in Combination with Vitamin C Reduced Skin Redness and Pigmentation of UV-Irradiated Mice

Ultraviolet (UV) is the main cause of sunburn on the skin as it induces erythema and accelerates pigmentation. Vitamin C is one of the most frequently used compounds to reduce UV-induced skin pigmentation, but it has limitations in absorption through the skin. In this study, we tested whether a no-ozone cold plasma (NCP) treatment can improve UV-irradiated skin by helping the action of Vitamin C. For this, among five groups of HRM-2 hairless mice, four groups of mice were subjected to UVB irradiation, and three groups of UVB-treated mice were treated with NCP, Vitamin C, and NCP + Vitamin C, respectively. For evaluating the effect of each treatment, the melanin and erythema index was measured during animal experiments. Histological changes were monitored by performing H&E and MTS and IHC against tyrosinase and melanin. As a result, the naturally recovered mice showed a 28-point decrease in the melanin index, whereas a decrease of around 88, 74.3, and 106 points was detected in NCP-, Vitamin C-, and NCP + vitamin C-treated mice, respectively. Likewise, only a 39-point reduction in the erythema index was monitored in naturally recovered mice, but the NCP-, vitamin C-, and NCP + vitamin C-treated mice showed a 87.3-, 77-, and 111-point reduction, respectively. Interestingly, the skin tissues of the mice treated with NCP in combination with Vitamin C mostly recovered from UVB-induced damage. Altogether, this study elucidated the beneficial effect of the treatment of NCP in combination with Vitamin C on the UVB-irradiated skin, which might be helpful for treating sunburn on the skin.

Substrate specificity of polyphenol oxidase and its selectivity towards polyphenols: Unlocking the browning mechanism of fresh lotus root (Nelumbo nucifera Gaertn.)

Polyphenol oxidase (PPO) causes the browning of lotus roots (LR), negatively affecting their nutrition and shelf-life. This study aimed to explore the specific selectivity of PPO toward polyphenol substrates, thus unlocking the browning mechanism of fresh LR. Results showed that two highly homologous PPOs were identified in LR and exhibited the highest catalytic activity at 35 ℃ and pH 6.5. Furthermore, the substrate specificity study revealed (-)-epigallocatechin had the lowest Km among the polyphenols identified in LR, while (+)-catechin showed the highest Vmax. The molecular docking further clarified that (-)-epigallocatechin exhibited lower docking energy and formed more hydrogen bonds and Pi-Alkyl interactions with LR PPO than (+)-catechin, while (+)-catechin entered the active cavity of PPO more quickly due to its smaller structure, both of which enhance their affinity to PPO. Thus, (+)-catechin and (-)-epigallocatechin are the most specific substrates responsible for the browning mechanism of fresh LR.

Neuromelanin: Its role in the pathogenesis of idiopathic Parkinson's disease and potential as a therapeutic target

Parkinson's disease is an increasingly prevalent condition that involves the marked loss of dopaminergic neurons in the substantia nigra pars compacta. These neurons pigmented with neuromelanin along with other regions of the brain are almost exclusively victims of neurodegeneration in the disease. The link between neuromelanin and Parkinson's disease has been widely studied for decades. While many studies have outlined the pigment's neuroprotective function as a potent free radical scavenger, antioxidant, and ion-chelator, it has also been observed to play a role in cell death due to mitochondrial dysfunction and oxidative stress, especially in the parkinsonian disease state. This is due to the damaging effects of neuromelanin precursors, neuromelanin-related ion dysregulation and intra- and extraneuronal neuromelanin accumulation. Current and emerging therapeutic endeavours guided by these pathological processes may include antioxidant therapy, proteostasis enhancement, ion chelation and neuromelanin-targeted immunotherapy to prevent the accumulation, formation and effects of neuromelanin and oxidative neuromelanin precursors. Some of these therapeutic strategies are already in nascent stages, while others have produced mixed results in clinical trials. This review aims to provide an update on how neuromelanin and neuromelanin-related substances may be linked to the pathogenesis of Parkinson's disease and how future therapeutic strategies may be able to hamper or prevent neuromelanin-related pathological processes and ultimately modify disease progression in Parkinson's.

Photoprotective and Anti-Aging Properties of the Apical Frond Extracts from the Mediterranean Seaweed Ericaria amentacea

There is a growing interest in using brown algal extracts thanks to the bioactive substances they produce for adaptation to the marine benthic environment. We evaluated the anti-aging and photoprotective properties of two types of extracts (50%-ethanol and DMSO) obtained from different portions, i.e., apices and thalli, of the brown seaweed, Ericaria amentacea. The apices of this alga, which grow and develop reproductive structures during summer when solar radiation is at its peak, were postulated to be rich in antioxidant compounds. We determined the chemical composition and pharmacological effects of their extracts and compared them to the thallus-derived extracts. All the extracts contained polyphenols, flavonoids and antioxidants and showed significant biological activities. The hydroalcoholic apices extracts demonstrated the highest pharmacological potential, likely due to the higher content of meroditerpene molecular species. They blocked toxicity in UV-exposed HaCaT keratinocytes and L929 fibroblasts and abated the oxidative stress and the production of pro-inflammatory cytokines, typically released after sunburns. Furthermore, the extracts showed anti-tyrosinase and anti-hydrolytic skin enzyme activity, counteracting the collagenase and hyaluronidase degrading activities and possibly slowing down the formation of uneven pigmentation and wrinkles in aging skin. In conclusion, the E. amentacea apices derivatives constitute ideal components for counteracting sunburn symptoms and for cosmetic anti-aging lotions.

Screening of Tyrosinase, Xanthine Oxidase, and α-Glucosidase Inhibitors from Polygoni Cuspidati Rhizoma et Radix by Ultrafiltration and HPLC Analysis

Polygoni Cuspidati Rhizoma et Radix (PCR), the rhizome and root of Polygonum cuspidatum Sieb. et Zucc., has been used as an herbal medicine for a long time. In this study, the ultrafiltration combined with high performance liquid chromatography (UF-HPLC) method was developed to screen tyrosinase (TYR), α-glucosidase (α-GLU), and xanthine oxidase (XOD) inhibitors from PCR. Firstly, the inhibitory activity of 50% methanol PCR extract on TYR, α-GLU, XOD, and acetylcholinesterase (ACHE) was tested. The extract showed a good inhibition on the enzymes, except for ACHE. Therefore, UF-HPLC experiments were carried out to screen TYR, α-GLU, and XOD inhibitors from PCR extract. Seven potential bioactive components were discovered, including methylgallate (1), 1,6-di-O-galloyl-D-glucose (2), polydatin-4'-O-D-glucoside (3), resveratrol-4'-O-D-glucoside (4), polydatin (5), malonyl glucoside resveratrol (6), and resveratrol-5-O-D-glucoside (7). Most of them were found as enzyme inhibitors from PCR for the first time, except polydatin (5), which had been reported as an α-GLUI in PCR in the literature. Finally, molecular docking analysis was applied to validate the interactions of these seven potential active components with the enzymes. Compounds 1-7 were proven as TYR inhibitors, compounds 2, 4-7 were identified as XOD inhibitors, and compounds 4-6 were confirmed as α-GLU inhibitors. In short, the current study provides a good reference for the screening of enzyme inhibitors through UF-HPLC, and provides scientific data for future studies of PCR.

Evaluation of 2,3-Dihydro-1,5-benzothiazepine Derivatives as Potential Tyrosinase Inhibitors: In Vitro and In Silico Studies

Benzothiazepines are pharmacologically active compounds, frequently utilized as a precursor for acquiring versatile molecules with several bioactivities including anti-inflammatory, anti-human immunodeficiency virus (anti-HIV), analgesic, antitumor, antimicrobial, and antitubercular. In this study, the 2,4-diphenyl-2,3-dihydro-1,5-benzothiazepine scaffold was selected for their in vitro, docking, and druglikeness studies to evaluate their inhibitory potential against mushroom tyrosinase. All synthesized analogues, 1-14, exhibited moderate to good IC₅₀ values ranging from 1.21 to 70.65 μM. The synthesized benzothiazepine derivatives were potent tyrosinase inhibitors, which outperformed the reference kojic acid (IC₅₀ = 16.69 μM). The kinetic analysis revealed that compound 2 (2-(3,4-dimethoxyphenyl)-4-(p-tolyl)-2,3-dihydrobenzo[b][1,4]thiazepine) was a mixed-type tyrosinase inhibitor with a K_i value of 1.01 μM. Molecular modeling studies against tyrosinase protein (PDB ID: 2Y9X) were conducted to recognize the binding modes of these analogues. The utilization of molecular dynamic (MD) simulations enabled the assessment of the protein-ligand complex's dynamic behavior, stability, and binding affinity for the compounds. These simulations ultimately led to the identification of compound 2 as a potential inhibitor of tyrosinase. Additionally, a druglikeness study was conducted, which supported the promising potential of the new analogues as novel antityrosinase agents. The in silico studies were consistent with the in vitro results, showing that these ligands had good binding scores against tyrosinase and interacted with the core residues of the target protein. Gaussian 09 was used for the geometry optimization of all complexes.

Molecular Characterization of Prunus lusitanica L. Fruit Extracts and Their Health-Promoting Potential in Inflammation, Diabetes, and Neurodegenerative Diseases

Prunus lusitanica L. is a shrub belonging to the genus Prunus L. (Rosaceae family) that produces small fruits with none known application. Thus, the aim of this study was to determine the phenolic profile and some health-promoting activities of hydroethanolic (HE) extracts obtained from P. lusitanica fruits, harvested from three different locations. Qualitative and quantitative analysis of extracts was performed using HPLC/DAD-ESI-MS and antioxidant activity was assessed by in vitro methods. Antiproliferative/cytotoxic activity was determined on Caco-2, HepG2, and RAW 264.7 cells, anti-inflammatory activity was assessed using lipopolysaccharide (LPS)-stimulated RAW 264.7 cells, and the antidiabetic, antiaging, and neurobiological action of extracts was determined in vitro by assessing their inhibitory effect against the activity of α-amylase, α-glucosidase, elastase, tyrosinase, and acetylcholinesterase (AChE). Results showed that P. lusitanica fruit HE extracts from the three different locations showed identical phytochemical profile and bioactivities, although small differences were observed regarding the quantities of some compounds. Extracts of P. lusitanica fruits contain high levels in total phenolic compounds, namely, hydroxycinnamic acids, as well as flavan-3-ols and anthocyanins, primarily cyanidin-3-(6-trans-p-coumaroyl)glucoside. P. lusitanica fruit extracts have a low cytotoxic/antiproliferative effect, with the lowest IC50 value obtained in HepG2 cells (352.6 ± 10.0 μg/mL, at 48 h exposure), but high anti-inflammatory activity (50-60% NO release inhibition, at 100 μg/mL extract) and neuroprotective potential (35-39% AChE inhibition, at 1 mg/mL), and moderate antiaging (9-15% tyrosinase inhibition, at 1 mg/mL) and antidiabetic (9-15% α-glucosidase inhibition, at 1 mg/mL) effects. The bioactive molecules present in the fruits of P. lusitanica deserve to be further explored for the development of new drugs of interest to the pharmaceutical and cosmetic industry.