Thioquinoline derivatives conjugated to thiosemicarbazide as potent tyrosinase inhibitors with anti-melanogenesis properties

Structure-based development of 3,5-dihydroxybenzoyl-hydrazineylidene as tyrosinase inhibitor; in vitro and in silico study

A series of new analogs of 3,5-dihydroxybenzoyl-hydrazineylidene conjugated to different methoxyphenyl triazole (11a-n) synthesized using click reaction. The structures of all synthesized compounds were characterized by FTIR, 1H, 13C-NMR spectroscopy, and CHO analysis. The tyrosinase inhibitory potential of the synthesized compounds was studied. The newly synthesized scaffolds were found to illustrate the variable degree of the inhibitory profile, and the most potent analog of this series was that one bearing 4-methoxyphenyl moiety, and exhibited an IC50 value of 55.39 ± 4.93 µM. The kinetic study of the most potent derivative reveals a competitive mode of inhibition. Next, molecular docking studies were performed to understand the potent inhibitor's binding mode within the enzyme's binding site. Molecular dynamics simulations were accomplished to further investigate the orientation and binding interaction over time and the stability of the 11m-tyrosinase complex.

Synthesis, in vitro potency of inhibition, enzyme kinetics and in silico studies of quinoline-based α-glucosidase inhibitors

Diabetes mellitus is a multifactorial global health disorder that is rising at an alarming rate. One effective therapeutic approach for controlling hyperglycemia associated with type-2 diabetes is to target α-glucosidase, which catalyzes starch hydrolysis in the intestine. In an attempt to find potential α-glucosidase inhibitors, a series of twenty new quinoline linked benzothiazole hybrids (8a-t) were synthesized in good yields from suitable reaction procedures and their chemical structures were analyzed by 1HNMR, 13CNMR, IR, and ESI-MS analysis. The synthesized derivatives further screened for their activity against α-glucosidase. Among them, compounds 8b, 8h, 8n and 8o exhibited remarkable α-glucosidase inhibitory activity with IC50 values ranging from 38.2 ± 0.3 to 79.9 ± 1.2 µM compared with standard drug acarbose (IC50 = 750.0 ± 2.0 µM). Enzyme kinetic studies of the most active compound (8h) indicated a non-competitive inhibition with Ki value of 38.2 µM. Moreover, the homology modeling, molecular docking and molecular dynamics simulation studies were conducted to reveal key interactions between the most active compound 8h and the targeted enzyme. These results are complementary to the experimental observations. In order to predict the druggability of the novel derivatives, the pharmacokinetic properties were also applied. These findings could be useful for the design and development of new α-glucosidase inhibitors.

Tetrahedral framework nucleic acid loaded with glabridin: A transdermal delivery system applicated to anti-hyperpigmentation

Topical application of tyrosinase inhibitors, such as hydroquinone and arbutin, is the most common clinical treatment for hyperpigmentation. Glabridin (Gla) is a natural isoflavone that inhibits tyrosinase activity, free radical scavenging, and antioxidation. However, its water solubility is poor, and it cannot pass through the human skin barrier alone. Tetrahedral framework nucleic acid (tFNA), a new type of DNA biomaterial, can penetrate cells and tissues and can be used as carriers to deliver small-molecule drugs, polypeptides, and oligonucleotides. This study aimed to develop a compound drug system using tFNA as the carrier to transport Gla and deliver it through the skin to treat pigmentation. Furthermore, we aimed to explore whether tFNA-Gla can effectively alleviate the hyperpigmentation caused by increased melanin production and determine whether tFNA-Gla exerts substantial synergistic effects during treatment. Our results showed that the developed system successfully treated pigmentation by inhibiting regulatory proteins related to melanin production. Furthermore, our findings showed that the system was effective in treating epidermal and superficial dermal diseases. The tFNA-based transdermal drug delivery system can thus develop into novel, effective options for non-invasive drug delivery through the skin barrier.

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.

Design, synthesis, in vitro, and in silico evaluations of kojic acid derivatives linked to amino pyridine moiety as potent tyrosinase inhibitors

In the present study, novel series of kojic acid derivatives conjugated to amino pyridine moiety were designed and synthesized to explore their inhibitory activity against tyrosinase. To this end, the structure of all derivatives was characterized by 1H NMR, 13C NMR, FT-IR, and elemental analysis. Next, all derivatives were evaluated against tyrosinase compared to the kojic acid as positive control and exhibited different inhibitory potencies. Furthermore, the antioxidant potential of all derivatives was determined. The kinetic analysis of the most active agent revealed that 3-hydroxy-6-(hydroxymethyl)-2-((3-nitrophenyl)(pyridin-2-ylamino)methyl)-4H-pyran-4-one (4h) binds to the enzyme in the uncompetitive mode of action. The docking analysis and molecular dynamic simulations showed considerable binding affinity and significant interactions with tyrosinase enzyme to target the melanogenesis pathway, proposing them as potent candidates to control hyperpigmentation in the future.

Heterocyclic Compounds as Synthetic Tyrosinase Inhibitors: Recent Advances

Tyrosinase is a copper-containing enzyme which is widely distributed in nature (e.g., bacteria, mammals, fungi) and involved in two consecutive steps of melanin biosynthesis. In humans, an excessive production of melanin can determine hyperpigmentation disorders as well as neurodegenerative processes in Parkinson's disease. The development of molecules able to inhibit the high activity of the enzyme remain a current topic in medicinal chemistry, because the inhibitors reported so far present several side effects. Heterocycle-bearing molecules are largely diffuse in this sense. Due to their importance as biologically active compounds, we decided to report a comprehensive review of synthetic tyrosinase inhibitors possessing heterocyclic moieties reported within the last five years. For the reader's convenience, we classified them as inhibitors of mushroom tyrosinase (Agaricus bisporus) and human tyrosinase.

Synthesis, in vitro α-glucosidase inhibitory activities, and molecular dynamic simulations of novel 4-hydroxyquinolinone-hydrazones as potential antidiabetic agents

In the present study, new structural variants of 4-hydroxyquinolinone-hydrazones were designed and synthesized. The structure elucidation of the synthetic derivatives 6a-o was carried out using different spectroscopic techniques including FTIR, ¹H-NMR, ¹³C-NMR, and elemental analysis, and their α-glucosidase inhibitory activity was also determined. The synthetic molecules 6a-o exhibited good α-glucosidase inhibition with IC₅₀ values ranging between 93.5 ± 0.6 to 575.6 ± 0.4 µM as compared to the standard acarbose (IC₅₀ = 752.0 ± 2.0 µM). Structure-activity relationships of this series were established which is mainly based on the position and nature of the substituent on the benzylidene ring. A kinetic study of the active compounds 6l and 6m as the most potent derivatives were also carried out to confirm the mode of inhibition. The binding interactions of the most active compounds within the active site of the enzyme were determined by molecular docking and molecular dynamic simulations.