Novel Amide Derivatives as Potent Tyrosinase Inhibitors; In-vitro, In-vivo Antimelanogenic Activity and Computational Studies

Synthesis, Kinetics and Computational Explorations of 4-Phenylpiperazine Bearing N-(Aryl)-3-substituted-benzamides as Auspicious Tyrosinase Inhibitors

In the aimed research study, a new series of N-(aryl)-3-[(4-phenyl-1-piperazinyl)methyl]benzamides was synthesized, which was envisaged as tyrosinase inhibitor. The structures of these newly designed molecules were verified by IR, 1H-NMR, 13C-NMR, EI-MS and CHN analysis data. These molecules were screened against tyrosinase and their inhibitory activity explored that these 3-substituted-benzamides exhibit good to excellent potential, comparative to the standard. The Kinetics mechanism was investigated through Lineweaver-Burk plots which depicted that molecules inhibited this enzyme in a competitive mode. Moreover, molecular docking was also performed to determine the binding interaction of all synthesized molecules (ligands) with the active site of tyrosinase enzyme and the results showed that most of the ligands exhibited efficient binding energy values. Therefore, it is anticipated that these molecules might serve as auspicious therapeutic scaffolds for treatment of the tyrosinase associated skin disorders.

Cephalosporin as Potent Urease and Tyrosinase Inhibitor: Exploration through Enzyme Inhibition, Kinetic Mechanism, and Molecular Docking Studies

In present study, eleven cephalosporin drugs were selected to explore their new medically important enzyme targets with inherited safety advantage. To this end, selected drugs with active ingredient, cefpodoxime proxetil, ceftazidime, cefepime, ceftriaxone sodium, cefaclor, cefotaxime sodium, cefixime trihydrate, cephalexin, cefadroxil, cephradine, and cefuroxime, were evaluated and found to have significant activity against urease (IC50 = 0.06 ± 0.004 to 0.37 ± 0.046 mM) and tyrosinase (IC50 = 0.01 ± 0.0005 to 0.12 ± 0.017 mM) enzymes. Urease activity was lower than standard thiourea; however, tyrosinase activity of all drugs outperforms (ranging 6 to 18 times) the positive control: hydroquinone (IC50 = 0.18 ± 0.02 mM). Moreover, the kinetic analysis of the most active drugs, ceftriaxone sodium and cefotaxime sodium, revealed that they bind irreversibly with both the enzymes; however, their mode of action was competitive for urease and mixed-type, preferentially competitive for tyrosinase enzyme. Like in vitro activity, ceftriaxone sodium and cefotaxime sodium docking analysis showed their considerable binding affinity and significant interactions with both urease and tyrosinase enzymes sufficient for downstream signaling responsible for observed enzyme inhibition in vitro, purposing them as potent candidates to control enzyme-rooted obstructions in future.

Synthesis and Biological Activity Evaluation of 2-Cyanopyrrole Derivatives as Potential Tyrosinase Inhibitors

In order to find potential inhibitors of tyrosinase, two series of pyrrole derivatives A (1–17) and B (1–8) were synthesized and screened for their inhibitory activities on tyrosinase. Most of the 2-cyanopyrrole derivatives exhibited effective inhibitory activities. In particular, A12 exhibited the strongest inhibitory activities, with the IC₅₀ values of 0.97 μM, which is ∼30 times stronger than the reference inhibitor kojic acid (IC₅₀: 28.72 μM). The inhibitory mechanism analysis results revealed that A12 was a reversible and mixed-type inhibitor. Molecular docking experiments clarified the interaction between A12 with tyrosinase. Furthermore, A12 (100 μM) presented effective inhibitory effect on tyrosinase in B16 melanoma cells with inhibition of 33.48%, which was equivalent to that of Kojic acid (39.81%). Accordingly, compound A12 may serve as the lead structure for the further design of potent tyrosinase inhibitors. Molecular docking studies confirmed the interaction between the compound and tyrosinase.

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 (R ²) 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).

Natural and synthetic flavonoid derivatives as new potential tyrosinase inhibitors: a systematic review

Tyrosinase is a multifunctional glycosylated and copper-containing oxidase that is highly prevalent in plants and animals and plays a pivotal role in catalyzing the two key steps of melanogenesis: tyrosine's hydroxylation to dihydroxyphenylalanine (DOPA), and oxidation of the latter species to dopaquinone. Melanin guards against the destructive effects of ultraviolet radiation which is known to produce considerable pathological disorders such as skin cancer, among others. Moreover, the overproduction of melanin can create aesthetic problems along with serious disorders linked to hyperpigmented spots or patches on skin. Several skin-whitening products which reduce melanogenesis activity and alleviate hyperpigmentation are commercially available. A few of them, particularly those obtained from natural sources and that incorporate a phenolic scaffold, have been exploited in the cosmetic industry. In this context, synthetic tyrosinase inhibitors (TIs) with elevated efficacy and fewer side effects are direly needed in the pharmaceutical and cosmetic industries owing to their protective effect against pigmentation and dermatological disorders. Furthermore, the biological significance of the chromone skeleton and its associated medicinal and bioactive properties has drawn immense interest and inspired many researchers to design and develop novel anti-tyrosinase agents based on the flavonoid core (2-arylchromone). This review article is oriented to provide an insight and a deeper understanding of the tyrosinase inhibitory activity of an array of natural and bioinspired phenolic compounds with special emphasis on flavonoids to demonstrate how the position of ring substituents and their interaction with tyrosinase could be correlated with their effectiveness or lack thereof against inhibiting the enzyme.

Melanins as Sustainable Resources for Advanced Biotechnological Applications

Melanins are a class of biopolymers that are widespread in nature and have diverse origins, chemical compositions, and functions. Their chemical, electrical, optical, and paramagnetic properties offer opportunities for applications in materials science, particularly for medical and technical uses. This review focuses on the application of analytical techniques to study melanins in multidisciplinary contexts with a view to their use as sustainable resources for advanced biotechnological applications, and how these may facilitate the achievement of the United Nations Sustainable Development Goals.

Assessment of Agaricus Bisporus S-II Extract as a Bio-Controlling Agent against Human Pathogenic Bacterial Species

Agaricus bisporus mushrooms are well known for their nutritional and medicinal values. A. bisporus is a source of protein (about 40% on a dry basis), ergosterol, several minerals, carbohydrate, and fat. The present study was conducted to investigate the effect of A. bisporus S-II extracts on human pathogenic bacteria in-vitro condition. Totally, three human pathogenic bacterial strains (MTCC culture type) were procured from the Institute of Microbial Technology, India. Out of these three bacterial strains, one was Gram-negative (namely P. aeruginosa MTCC741), and the other two were Gram-positive (B. cereus MTCC9786 and S. aureus MTCC740). Microdilution assay was applied for the evaluation of the minimum inhibitory concentration (MIC). The highest antimicrobial activity was observed in methanol extract (26.5%) against S. aureus MTCC740, compared to ethanol extract (17%). Similar results were obtained for P. aeruginosa MTCC741 (21.8%) and B. cereus MTCC9786 (15%) in methanol extract. Least microbial growth inhibition observed for B. cereus MTCC9786 (13.82%) followed by P. aeruginosa MTCC741 (14%), compared to control in ethanol extract. The highest antimicrobial activity up to 17% with ethanolic extracts recorded against S. aureus MTCC740. The MIC results in microtitre plates showed the growth inhibition of P. aeruginosa MTCC741 and S. aureus MTCC740 at extract concentrations of 15 mg/ml and 20 mg/ml, respectively. However, no MIC detected for B. cereus MTCC9786 below 20 mg/ml extract concentration. Regarding minimum bactericidal concentration, the bactericidal value for P. aeruginosa MTCC741 and S. aureus MTCC740 was obtained at 10 mg/ml concentration. The present study indicated that the extracts of the A. bisporus S-II mushrooms had promising antimicrobial activities against the tested organisms.

Synthesis, molecular docking, dynamic simulations, kinetic mechanism, cytotoxicity evaluation of N-(substituted-phenyl)-4-{(4-[(E)-3-phenyl-2-propenyl]-1-piperazinyl} butanamides as tyrosinase and melanin inhibitors: In vitro, in vivo and in silico approaches

In the current research work, different N-(substituted-phenyl)-4-{(4-[(E)-3-phenyl-2-propenyl]-1-piperazinyl}butanamides have been synthesized according to the protocol described in scheme 1. The synthesis was initiated by reacting various substituted anilines (1a-e) with 4-chlorobutanoyl chloride (2) in aqueous basic medium to give various electrophiles, 4-chloro-N-(substituted-phenyl)butanamides (3a-e). These electrophiles were then coupled with 1-[(E)-3-phenyl-2-propenyl]piperazine (4) in polar aprotic medium to attain the targeted N-(substituted-phenyl)-4-{(4-[(E)-3-phenyl-2-propenyl]-1-piperazinyl}butanamides (5a-e). The structures of all derivatives were identified and characterized by proton-nuclear magnetic resonance (¹H NMR), carbon-nuclear magnetic resonance (¹³C NMR) and Infra-Red (IR) spectral data along with CHN analysis. The in vitro inhibitory potential of these butanamides was evaluated against Mushroom tyrosinase, whereby all compounds were found to be biologically active. Among them, 5b exhibited highest inhibitory potential with IC₅₀ value of 0.013 ± 0.001 µM. The same compound 5b was also assayed through in vivo approach, and it was explored that it significantly reduced the pigments in zebrafish. The in silico studies were also in agreement with aforesaid results. Moreover, these molecules were profiled for their cytotoxicity through hemolytic activity, and it was found that except 5e, all other compounds showed minimal toxicity. The compound 5a also exhibited comparable results. Hence, some of these compounds might be worthy candidates for the formulation and development of depigmentation drugs with minimum side effects.