Anti-tyrosinase Agents Research Articles

Preparation and characterization of novel nanostructured lipid carriers (NLC) and solid lipid nanoparticles (SLN) containing coenzyme Q10 as potent antioxidants and antityrosinase agents

We developed novel and optimal Q10-NLC/SLN formulations as antioxidant and anti-tyrosinase agents. The formulations were analyzed for particle size, morphology, entrapment efficiency (EE %), and long-term stability. The in vitro drug release and in vivo skin penetration were evaluated using dialysis bag diffusion and Sprague Dawley (SD) rats, respectively. Cytotoxicity and protecting effects were assessed by AlamarBlue® assay, ROS level by DCFH-DA, and tyrosinase activity by l-DOPA assay, measuring the absorbance at 470 nm. The selected formulations had optimal surface characterizations, including Z-average size, PDI, and Zeta potential ranging from 125 to 207 nm, 0.09–0.22, and −7 to −24, respectively. They also exhibited physiochemical stability for up to 6 months and EE% above 80 %. The lipids ratio and co-Q10 amount as variable factors significantly affected particle size and zeta potential but were insignificant on PDI. The in vitro release diagram showed that Q10-NLC/SLN revealed a fast release during the first 8 h and prolonged release afterward. The in vivo skin permeation revealed a higher accumulative uptake of co-Q10 in the skin for Q10-NLC/SLN compared to Q10 emulsions. Both selected Q10-NLC and Q10-SLN could reduce intracellular ROS after exposure to H2O2. The Q10-NLC was found to be more potent for inhibiting the tyrosinase activity compared to O10-SLN. The results suggest that the new formulations are promising carriers for topical delivery of co-Q10 as an anti-aging and skin-whitening agent.

Phytochemical characterization and multifaceted bioactivity assessment of essential oil from Ptychotis verticillata Duby: Anti-diabetic, anti-tyrosinase, and anti-inflammatory activity

The aim of this study is to explore the pharmacological properties of the essential oil derived from Ptychotis verticillata Duby (PVEO), a medicinal plant native to Morocco, focusing on its antidiabetic, anti-tyrosinase, and anti-inflammatory effects. Additionally, the study aims to characterize the phytochemical composition of PVEO and evaluate its potential as a natural therapeutic alternative for various health conditions. To achieve this, phytochemical analysis was conducted using gas chromatography-mass spectrometry (GC-MS). Furthermore, in vitro assessments were conducted to investigate PVEO's antidiabetic activity by inhibiting α-amylase, xanthine oxidase, and α-glucosidase. Tests were also undertaken to evaluate the anti-inflammatory effect of PVEO on RAW 264.7 cells stimulated by lipopolysaccharide (LPS), as well as its efficacy as an anti-tyrosinase agent and its lipoxygenase inhibition activity. The results of the phytochemical analysis revealed that PVEO is rich in terpene compounds, with percentages of 40.35 % γ-terpinene, 22.40 % carvacrol, and 19.77 % β-cymene. Moreover, in vitro evaluations demonstrated that PVEO exhibits significant inhibitory activity against α-amylase, xanthine oxidase, and α-glucosidase, indicating promising antidiabetic, and anti-gout potential. Furthermore, PVEO showed significant anti-tyrosinase activity, with an IC50 of 27.39 ± 0.44 μg/mL, and remarkable lipoxygenase inhibition (87.33 ± 2.6 %), suggesting its candidacy for dermatoprotection. Additionally, PVEO displayed a dose-dependent capacity to attenuate the production of NO and PGE2, two inflammatory mediators implicated in various pathologies, without compromising cellular viability. The findings of this study provide a solid foundation for future research on natural therapies and the development of new drugs, highlighting the therapeutic potential of PVEO in the treatment of gout, diabetes, pigmentation disorders, and inflammation.

Design, synthesis, and molecular dynamics simulation studies of some novel kojic acid fused 2-amino-3-cyano-4H-pyran derivatives as tyrosinase inhibitors.

A novel series of kojic acid fused 2-amino-3-cyano-4H-pyran derivatives were synthesized via a multicomponent reaction involving kojic acid, benzyloxy benzaldehyde, and malonitrile as tyrosinase inhibitors. Subsequently, the structures of the compounds were characterized using FT-IR, 1H-, and 13C-NMR spectroscopic analyses. The designed compounds fall into three series: (1) 4-benzyloxy-phenyl kojopyran 6a-e, (2) 3-benzyloxy- phenyl kojopyran derivatives 6f-j, and (3) 4-benzyloxy-3-methoxy-phenyl kojopyran derivative 6k-o. The assessment of tyrosinase inhibition activity was conducted using L-Dopa as the substrate. Among synthesized compounds, 2-amino-4-(4-((4-fluorobenzyl)oxy)phenyl)-6-(hydroxymethyl)-8-oxo-4,8-dihydropyrano[3,2-b]pyran-3-carbonitrile (6b) demonstrated the highest antityrosinase activity with a competitive inhibition pattern (IC50 = 7.69 ± 1.99μM) as compared to the control agent kojic acid (IC50 = 23.64 ± 2.56µM). Since compound 6b was synthesized as a racemic mixture, in silico studies were performed for both R and S enantiomers. The R- enantiomer showed critical interactions compared with the S-enantiomer. Specifically, it established hydrogen bonds and hydrophobic interactions with crucial and highly conserved amino acids within the enzyme's binding site in the target protein. Moreover, the molecular dynamics simulations revealed that compound 6b demonstrated significant interactions with essential residues of the binding site, resulting in a stable complex throughout the entire simulation run. The drug-like and ADMET properties predictions showed an acceptable profile for compound 6b. Thus, it can serve as a drug candidate to develop more potent antityrosinase agents due to its low toxicity and its high inhibition activity.

Novel kojic acid-1,2,4-triazine hybrids as anti-tyrosinase agents: Synthesis, biological evaluation, mode of action, and anti-browning studies.

A class of new kojic acid hybrids (7a-7o) bearing a 1,2,4-triazine moiety were prepared, and their inhibitory activities and mechanism on tyrosinase were investigated. All derivatives showed good to excellent anti-tyrosinase activity with IC50 values ranging from 0.34±0.06μM to 8.44±0.73μM. In kinetic study, compound 7m was a mixed-type inhibitor with Ki and Kis of 0.73 and 1.27μM, respectively. The interaction mechanism toward tyrosinase of compound 7m was further elaborated in combination with molecular docking and various spectral techniques. The results showed that compound 7m could change the secondary structure of tyrosinase to reduce its catalytic activity. Anti-browning assays demonstrated that 7m inhibited the browning of bananas effectively during storage. What's more, 7m was found to have low cytotoxicity in vitro. In conclusion, compound 7m has the potential to be applied as an anti-browning agent.

Design, Synthesis, and Molecular Dynamics Simulation Studies of New Chalcone‐Based 2‐Arylidene‐1,3‐indandiones as Tyrosinase Inhibitors

AbstractIn this work, we synthesized a series of chalcone‐based 2‐arylidene‐1,3‐indandione and evaluated their inhibitory activities against the mushroom tyrosinase enzyme. Based on benzylidene moiety, derivatives were divided into 4‐benzyloxy‐benzylidene and 4‐benzyloxy‐3‐methoxy‐benzylidene derivatives. Among them, 2‐(3‐methoxy‐4‐((4‐methylbenzyl)oxy)benzylidene)‐1H‐indene‐1,3(2H)‐dione (6 l) was presented the superior activity with an IC50 value of 15.85±3.64 μM, which was lower than the standard kojic acid. The kinetic study of compound 6 l displayed an uncompetitive inhibition mode on the tyrosinase enzyme. Next, the docking study exhibited compound 6 l formed hydrogen bonds and hydrophobic interactions with critical highly conserved amino acids in the target protein. Furthermore, based on the molecular dynamics simulation, compound 6 l depicted noticeable interaction with the essential residues of the binding site and exhibited a stable complex during the simulation run. The methoxy group on the central ring was important in inducing the effective conformation for ligand‐enzyme interaction. The drug‐likeness and pharmacokinetic properties were calculated via in silico predictions and showed an acceptable profile for these agents. According to our results, it was proposed that compound 6 l can serve as a drug candidate to develop more potent antityrosinase agents.

In-Vitro Screenings for Biological and Antioxidant Activities of Aqueous Extract from Sacha Inchi (Plukenetia volubilis L.) Husks

Industrial processing of the Sacha inchi (Plukenetia volubilis L.) generated a large number of husks, which are one of the major by-products without sufficient utilization. Sacha inchi husk contains rich bioactive compounds unveiling its valorization potential. This study for the first time investigated the biological and antioxidant activities of the Sacha inchi husk extract recovered with distilled water at different temperatures (70, 80, 90 and 100 °C). The results showed that the aqueous extracts from Sacha inchi husks powder obtained at the extraction temperature of 80 °C showed the highest total phenolic content (7.90 mg GAE/g dry extract) and total flavonoid content (5.79 mg CE/g dry extract) and had the highest antioxidant activities (1,055.81, 53.60 and 1.59 µmol TE/g dry extract for DPPH, ABTS and FRAP assays, respectively, and 413.32 µmol EE/g dry extract for metal chelating assay). For antimicrobial activity, all extracts were effective against Gram-positive (Staphylococcus aureus and Listeria monocytogenes) and Gram-negative bacteria (Escherichia coli, Salmonella enteritidis, and Vibrio parahaemolyticus). In addition, Sacha inchi husks powder extraction at 80 °C exhibited the lowest MIC (≤ 0.625 mg/mL) and MBC (≤ 0.625 mg/mL) against all tested microorganisms. The extracts obtained at the extraction temperature of 80 °C also exhibited maximum inhibition of α-amylase (77.71 %) and α-glucosidase (76.40 %). The highest inhibition of tyrosinase activity was presented by the aqueous extract obtained at 80 °C with an IC50 value of 8.40 ± 1.40 mg/mL. Our findings suggested that the aqueous extract of Sacha inchi husks can be served as an economical source of antioxidant, antimicrobial, anti-diabetic and anti-tyrosinase agents. HIGHLIGHTS Sacha inchi husk has relatively high quantities of phenolic compounds The aqueous extracts of Sacha inchi husk showed high antioxidant activity, antimicrobial activity, anti-hypoglycemic activity and anti-tyrosinase activity Sacha inchi husk contains important medicinal values for human health applications GRAPHICAL ABSTRACT

Identification and molecular mechanism of novel 5-alkenyl-2-benzylaminothiazol-4(5H)-one analogs as anti-melanogenic and antioxidant agents

Mushroom tyrosinase is a tetramer, whereas mammalian tyrosinase is a monomeric glycoprotein. In addition, the amino acid sequence of mushroom tyrosinases differs from that of mammalian tyrosinases. MHY2081 exhibits potent inhibitory activity against both mushroom and mammalian tyrosinases. Accordingly, based on the MHY2081 structure, 5-alkenyl-2-benzylaminothiazol-4(5H)-one analogs were designed as a novel anti-tyrosinase agent and synthesized using 2-((3,4-dimethoxybenzyl)amino)thiazol-4(5H)-one (16), a key intermediate obtained via the rearrangement of a benzylamino group. Compounds 6 and 9 (IC50 = 1.5–4.6 µM) exhibited higher mushroom tyrosinase inhibitory activity than kojic acid (IC50 = 20–21 µM) in the presence of l-tyrosine and/or l-dopa. Based on kinetic analysis using Lineweaver-Burk plots, 6 was a mixed inhibitor, whereas 9 was a competitive inhibitor, and docking simulation results supported that these compounds could bind to the active site of mushroom tyrosinase. Using B16F10 mammalian cells, we demonstrated that these compounds inhibited melanogenesis more potently than kojic acid, and their anti-melanogenic effects could be attributed to tyrosinase inhibition. All synthesized compounds could scavenge reactive oxygen species (ROS), with five compounds exhibiting mild-to-strong ABTS+ and DPPH radical-scavenging abilities. Compounds 6 and 9 were potent tyrosinase inhibitors with strong antioxidant activities against ROS, ABTS+, and DPPH radicals. Moreover, the compounds significantly suppressed tyrosinase expression in a dose-dependent manner. Collectively, these results suggest that the novel 5-alkenyl-2-benzylaminothiazol-4(5H)-one analogs, especially 6 and 9, are potential anti-melanogenic agents with antioxidant activity.

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 Ki 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.

Anti-tyrosinase, anti-skin pathogenic bacterial, and antioxidant activities and phytochemical constituents of Dracaena cochinchinensis (Lour.) S.C. Chen extract

Dracaena cochinchinensis (Lour.) S.C. Chen (Chandaeng) is an important traditional medicinal plant used in ancient Thai household remedies. This research focused on investigating the biological properties, including the antibacterial, anti-tyrosinase, antioxidant activities, and phytochemical characteristics of crude Chandaeng extracts. Dried Chandaeng heartwood powder was extracted using ethanol, methanol, and deionized water. The antibacterial activities of the extracts were then tested against skin pathogens, including Cutibacterium acnes (DMST14916), Staphylococcus epidermidis (TISTR518), and Staphylococcus aureus (TISTR321). The ethanolic extract showed antibacterial activity. In a time-kill assay, all bacteria were completely killed after being exposed to it, while the cell membranes were found to have leaked when viewed under a scanning electron microscope. Antioxidant potential was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2¢-azino-bis -3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays. According to the findings, the crude ethanolic extract of Chandaeng showed the highest level of antioxidant activity. Furthermore, the potential of the extract to treat skin hyperpigmentation by inhibiting tyrosinase, an important melanin synthesis enzyme, was determined and the ethanolic extract was found to be an anti-tyrosinase agent. Finally, the crude ethanolic extract showed the highest total phenolic compound and flavonoid content. In conclusion, crude Chandaeng extract showed significant potential in activity against skin pathogenic bacteria, antioxidant activity, and tyrosinase inhibition. These properties of the extract could be applied to skincare cosmetics.

Hydroxylated Coumarin-Based Thiosemicarbazones as Dual Antityrosinase and Antioxidant Agents.

The design of novel antityrosinase agents appears extremely important in medical and industrial sectors because an irregular production of melanin is related to the insurgence of several skin-related disorders (e.g., melanoma) and the browning process of fruits and vegetables. Because melanogenesis also involves a nonenzymatic oxidative process, developing dual antioxidant and antityrosinase agents is advantageous. In this work, we evaluated the antioxidant and tyrosinase inhibition ability of two new bishydroxylated and two new monohydroxylated derivatives of (1E)-2-(1-(2-oxo-2H-chromen-3-yl)ethylidene)hydrazine-1-carbothioamide (T1) using different experimental and computational approaches. The study was also carried out on another monohydroxylated derivative of T1 for comparison. Interestingly, these molecules have more potent tyrosinase-inhibitory properties than the reference compound, kojic acid. Moreover, the antioxidant activity appears to be influenced according to the number and substitution pattern of the hydroxyl groups. The safety of the compounds without (T1), with one (T3), and with two (T6) hydroxyl groups, has also been assessed by studying their cytotoxicity on melanocytes. These results indicate that (1E)-2-(1-(2-oxo-2H-chromen-3-yl)ethylidene)hydrazine-1-carbothioamide and its hydroxylated derivatives are promising molecules for further drug development studies.

Tyrosinase Inhibitors Naturally Present in Plants and Synthetic Modifications of These Natural Products as Anti-Melanogenic Agents: A Review

Tyrosinase is a key enzyme target to design new chemical ligands against melanogenesis. In the current review, different chemical derivatives are explored which have been used as anti-melanogenic compounds. These are different chemical compounds naturally present in plants and semi-synthetic and synthetic compounds inspired by these natural products, such as kojic acid produced by several species of fungi; arbutin-a glycosylated hydroquinone extracted from the bearberry plant; vanillin-a phenolic aldehyde extracted from the vanilla bean, etc. After enzyme inhibition screening, various chemical compounds showed different therapeutic effects as tyrosinase inhibitors with different values of the inhibition constant and IC50. We show how appropriately designed scaffolds inspired by the structures of natural compounds are used to develop novel synthetic inhibitors. We review the results of numerous studies, which could lead to the development of effective anti-tyrosinase agents with increased efficiency and safety in the near future, with many applications in the food, pharmaceutical and cosmetics industries.

Inhibition of plant essential oils and their interaction in binary combinations against tyrosinase.

Essential oils (EOs), derived from aromatic plants, exhibit properties beneficial to health, such as anti-inflammatory, anti-oxidative, antidiabetic, and antiaging effects. However, the effect of EOs and their interaction in binary combinations against tyrosinase is not yet known. To evaluate the underlying mechanisms of EOs and their interaction in binary combinations against tyrosinas. We explored to investigate the inhibitory effect of 65 EOs and the interaction among cinnamon, bay, and magnolia officinalis in their binary combinations against tyrosinase. In addition, the main constituents of cinnamon, bay, and magnolia officinalis were analyzed by gas chromatography-mass spectrometry (GC-MS). The results showed that the most potent EOs against tyrosinase were cinnamon, bay, and magnolia officinalis with IC50 values of 25.7, 30.8, and 61.9 μg/mL, respectively. Moreover, the inhibitory mechanism and kinetics studies revealed that cinnamon and bay were reversible and competitive-type inhibitors, and magnolia officinalis was a reversible and mixed-type inhibitor. In addition, these results, assessed in mixtures of three binary combinations, indicated that the combination of cinnamon with bay at different dose and at dose ratio had a strong antagonistic effect against tyrosinase. Magnolia officinalis combined with cinnamon or bay experienced both antagonistic and synergistic effect in anti-tyrosinase activity. It is revealed that natural EOs would be promising to be effective anti-tyrosinase agents, and binary combinations of cinnamon, bay, and magnolia officinalis might not have synergistic effects on tyrosinase under certain condition.

Calixbenoquin: Calixarene-Based Cluster of Monobenzone as a New Anti-Tyrosinase Agent

Calixbenoquin: Calixarene-Based Cluster of Monobenzone as a New Anti-Tyrosinase Agent

Tyrosinase Inhibition Activity and Phytochemical Screening of Melaleuca leucadendron L. Leaves

Melaleuca leucadendron L. is a plant whose almost all parts (bark, leaves, twigs, and fruit) can be used as medicine, such as antioxidants, antifungals, sedative effects, and anti-hyaluronidase. This research was conducted to determine tyrosinase inhibition activity and compound content of M. leucadendron leaves. Maceration of M. leucadendron leaves was done in methanol, then carried out liquid-liquid fractionation with n-butanol, chloroform, and water. Methanol extract, butanol fraction, chloroform fraction, and water fraction were tested for phytochemical screening and tyrosinase inhibition using L-DOPA substrate with an ELISA plate well reader. The results of the tyrosinase inhibition activity test at concentrations of 100, 1000 and 10000 μg/mL respectively showed that methanol extract 29.532%, 55.227%, 89.583%; butanol fraction 29.313%, 59.174%, 94.737%, chloroform fraction 21.820%, 24.671%; 53.765%; water fraction 24,086%, 47.661%, 91.118%. Inhibition of the tyrosinase enzyme is shown through the IC50 value from methanol extract, butanol fraction and water fraction, and kojic acid as a positive control, respectively 645.438 μg/mL, 517.935 μg/mL, 669.403 μg/mL, 50.064 μg/mL. Phytochemical screening showed that the extract and fraction contained tannins, flavonoids, saponins, terpenes, and steroids. These results indicate that the butanol fraction is more potent as an anti-tyrosinase agent than the others.

New Alk(en)ylhydroxycyclohexanes with Tyrosinase Inhibition Potential from Harpephyllum caffrum Bernh. Gum Exudate.

This work presents the first report on the phytochemical investigation of Harpephyllum caffrum Bernh. gum exudate. A known cardanol, 3-heptadec-12′-Z-enyl phenol (1) and three new alk(en)ylhydroxycyclohexanes, namely, (1R,3R)-1,3-dihydroxy-3-[heptadec-12′(Z)-enyl]cyclohexane (2) (1S,2S,3S,4S,5R)-1,2,3,4,5-pentahydroxy-5-[octadec-13′(Z)-enyl]cyclohexane (3) and (1R,2S,4R)-1,2,4-trihydroxy-4-[heptadec-12′(Z)-enyl]cyclohexane (4) were isolated from the gum. The structures of the compounds were determined by extensive 1D and 2D NMR spectroscopy and HR-ESI-MS data. The ethanolic extract of the gum was found to be the most potent tyrosinase inhibitor with IC50 of 11.32 µg/mL while compounds 2 and 3, with IC50 values of 24.90 and 26.99 µg/mL, respectively, were found to be potential anti-tyrosinase candidates from the gum. Gum exudate may be a potential source for non-destructive harvesting of selective pharmacologically active compounds from plants. The results also provide evidence that H. caffrum gum may find application in cosmetics as a potential anti-tyrosinase agent.

Design, Synthesis, and Structural Characterization of Thioflavones and Thioflavonols as Potential Tyrosinase Inhibitors: In Vitro and In Silico Studies.

To find new potential tyrosinase inhibitors, a diverse range of 2-arylchromone-4-thione derivatives (2a–2p) were designed and synthesized by employing a multistep strategy, and the newly synthesized compounds, for the first time, were screened in vitro for their tyrosinase inhibitory activity. In this context, the newly synthesized compounds (2a–2p) were characterized using a combination of several spectroscopic techniques including Fourier transform infrared, UV–vis, 1H NMR, and 13C NMR spectroscopies and electron ionization–mass spectrometry. All the target compounds were potent against tyrosinase as compared to the standard inhibitor kojic acid (half-maximal inhibitory concentration (IC50) = 12.6 ± 0.6 μM). The compounds (2a–2p) produced IC50 values in the range from 1.12 ± 0.04 to 5.68 ± 0.13 μM. Among the synthesized 4-thioflavones and 4-thioflavonols, the compound 2n exhibited excellent tyrosinase inhibitory activity with the lowest IC50 of 1.12 ± 0.04 μM that could be recommended as potential lead candidates to cure tyrosinase-mediated hyperpigmentation in the future. A kinetic study of compound 2n revealed that compound 2n inhibited tyrosinase in a competitive mode. Furthermore, the nontoxic performance of the most beneficial compounds ranging from 1 to 25 g/mL was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test method for A375 human melanoma cells for the highly efficient target compounds (2m, 2n, 2o, and 2p). Moreover, a molecular modeling study was performed against tyrosinase enzyme (2Y9X) to check the binding interactions of the synthesized compounds (2a–2p) against the target protein. Furthermore, quantitative structure-activity relationship studies were conducted based on an antityrosinase assay. The value of the correlation coefficient (R2) 0.9997 shows that there was a good correlation between (2a–2p) structures and selected properties. The geometry optimization of all complexes was performed by using Gaussian 09. Additionally, a drug-likeness research was used to establish the potent analogues’ positive action as a new antityrosinase agent (2n, 2o, and 2p).

Synthesis and molecular modeling of new 2‐benzylidenethiobarbituric acid derivatives as potent tyrosinase inhibitors agents

AbstractNew 2‐benzylidenethiobarbituric acid‐(benzyloxyphenyl) derivatives were designed, synthesized, and evaluated as tyrosinase inhibitors. The products can be divided into two groups: 4‐hydroxybenzaldehyde derivatives and vanillin derivatives. Some of the 4‐hydroxybenzaldehyde derivatives showed significant inhibitory activity while all vanillin derivatives have no inhibitory activities. It seems that the presence of the methoxy group on the internal aromatic ring prevents the ligand–enzyme interaction. According to the tyrosinase inhibitory assay, 5‐(4‐([4‐Methylbenzyl]oxy)benzylidene)‐2‐thioxodihydropyrimidine‐4,6(1H,5H)‐dione (4g) is the most potent antityrosinase agents with an IC50 value of 23.90 ± 0.08 μM. It showed even better inhibitory activity than kojic acid. The results of kinetic and molecular docking studies demonstrated that compound 4g acts as a noncompetitive inhibitor and can bind to some amino acids such as His263 and Val283 of the active site through Pi–alkyl and Pi–Pi interactions and areas around the active site via the hydrogen bond. In‐silico adsorption, distribution, metabolism, excretion, and toxicity (ADMET) studies predicted that these products have good drug‐likeness. All findings indicate the 2‐benzylidenethiobarbituric acids with the benzyloxyphenyl tail have good potential for the treatment of melanogenesis compared to kojic acid.

Preparation and Characterization of Undecylenoyl Phenylalanine Loaded-Nanostructure Lipid Carriers (NLCs) as a New α-MSH Antagonist and Antityrosinase Agent.

Purpose: The aim of this study was to characterize the undecylenoyl phenylalanine (Sepiwhite (SEPI))-loaded nanostructured lipid carriers (NLCs) as a new antimelanogenesis compound. Methods: In this study, an optimized SEPI-NLC formulation was prepared and characterized for particle size, zeta potential, stability, and encapsulation efficiency. Then, in vitro drug loading capacity and the release profile of SEPI, and its cytotoxicity were investigated. The ex vivo skin permeation and the anti-tyrosinase activity of SEPI-NLCs were also evaluated. Results: The optimized SEPI-NLC formulation showed the size of 180.1±5.01 nm, a spherical morphology under TEM, entrapment efficiency of 90.81±3.75%, and stability for 9 months at room temperature. The differential scanning calorimetry (DSC) analysis exhibited an amorphous state of SEPI in NLCs. In addition, the release study demonstrated that SEPI-NLCs had a biphasic release outline with an initial burst release compared to SEPI-EMULSION. About 65% of SEPI was released from SEPI-NLC within 72 h, while in SEPI-EMULSION, this value was 23%. The ex vivo permeation profiles revealed that the higher SEPI accumulation in the skin following application of SEPI-NLC (up to 88.8%) compared to SEPI-EMULSION (65%) and SEPI-ETHANOL (74.8%) formulations (P<0.01). An inhibition rate of 72% and 65% was obtained for mushroom and cellular tyrosinase activity of SEPI, respectively. Moreover, results of in vitro cytotoxicity assay confirmed SEPI-NLCs to be non-toxic and safe for topical use. Conclusion: The results of this study demonstrate that NLC can efficiently deliver SEPI into the skin, which has a promise for topical treatment of hyperpigmentation.

Flavone-based hydrazones as new tyrosinase inhibitors: Synthetic imines with emerging biological potential, SAR, molecular docking and drug-likeness studies

Targeting tyrosinase (TYR), a key enzyme responsible for melanogenesis disorders, is a well-known approach utilized for the development of melanogenesis inhibitor. A variety of dermatological disorders and microbial skin infections can cause hyperpigmentation. Hence, exploring new scaffolds for the treatment of melanogenesis disease is an inspiring goal. In this context, a series of varyingly substituted flavone-based hydrazones have been designed, synthesized and characterized successfully. The present study describes the discovery of novel mushroom tyrosinase inhibitors (TIs) for treating hyperpigmentation. In due course, flavone scaffold has been incorporated into the novel chemotypes that exhibit in vitro inhibitory effects against mushroom tyrosinase for the purpose of discovering anti‐melanogenic agents. Biological investigations of prepared analogs herein demonstrated moderate to excellent activity against most of the fungal-bacterial strains and their activity is comparable to those of commercially available antibiotics i.e., Ciprofloxacin and Ketoconazole. Based on in vitro tyrosinase inhibitory assay, some compounds exhibited potent inhibition particularly, 3g (IC50 = 1.40 ± 0.16 µM), 3j (IC50 = 0.95 ± 0.07 µM), 3o (IC50 = 1.13 ± 0.11 µM), and 3q (IC50 = 1.01 ± 0.1 µM) showed best inhibition i.e., 0.7, 0.5, 0.6 and 0.5 folds, respectively, than kojic acid (IC50 = 1.79 ± 0.6 µM). Lineweaver-Burk plots demonstrated that the most potential derivative 3j tyrosinase inhibition proceeds via non-competitive pathway and the Michaelis-Menton constant (Km) value is 0.0265. Molecular modeling was performed for all tested analogs (3a–3q) using a model of mushroom tyrosinase to find crucial binding modes liable for inhibitory activity. The SARs were preliminarily examined, and the docking study revealed that analogs 3j, 3o and 3p had a strong binding association to tyrosinase (2Y9X). Furthermore, a drug-likeness study was employed and confirmed the favorable activity of the new analogs as a new anti-tyrosinase agent.

Phenolic Content and Biological Activities of Ethanol Extracts from Medicinal Plants in East Kalimantan, Indonesia

The Dayak tribe are the indigenous people of West Kutai, East Kalimantan, Indonesia, and they have experiences in using plants for traditional medicine and the commonly used plants include Baccaurea macrocarpa (Miq.) Müll.Arg., Entada phaseoloides (L.) Merr., Goniothalamus macrophyllus (Blume) Hook.f. &amp; Thomson, Gynura crepidioides Benth., Helicia robusta (Roxb.) R. Br var. robusta, Litsea elliptica, Pogostemon cablin (Blanco) Benth, and Rhodomyrtus tomentosa (Aiton) Hassk. Therefore, the present study aimed to analyze these plant species for their phenolic content, and antioxidant, antibacterial, anti-tyrosinase, and anticancer activities. The total phenolic content and total antioxidant capacity were analyzed using Folin-Ciocalteu reagent and the phosphomolybdenum method, respectively. The antioxidant activities were evaluated by DPPH and ABTS assays. The antibacterial activity was determined by agar well diffusion and microdilution methods against six bacterial strains. The anticancer activity of the plant extracts was assayed against MDA-MB-231 human breast cancer cells. Based on the ethanol extraction, the highest yield was obtained from L. elliptica (10.42%), while H. robusta extract contained the highest phenolic content, antioxidant capacity, and antioxidant activities. All the extracts exhibited antibacterial activities against all the tested strains of bacteria, with the highest activity found in R. tomentosa extract, which also showed the highest activity against the cancer cells. The ethanol extract from E. phaseoloides exhibited tyrosinase inhibition activity (IC50 = 543.83 ± 51.06 µg/mL). The results herein suggested that the ethanol extracts from some medicinal plants from East Kalimantan have potential as antioxidant, antibacterial, anticancer, and anti-tyrosinase agents.