Hydroxy-3-Phenylcoumarins as Multitarget Compounds for Skin Aging Diseases: Synthesis, Molecular Docking and Tyrosinase, Elastase, Collagenase and Hyaluronidase Inhibition, and Sun Protection Factor

Abstract

Skin aging is a progressive biological process of the human body, and it is not only time-dependent. Differently substituted 3-phenylcoumarins proved to efficiently inhibit tyrosinase. In the current work, new substitution patterns have been explored, and the biological studies were extended to other important enzymes involved in the processes of skin aging, as elastase, collagenase and hyaluronidase. From the studied series, five compounds presented inhibitory activity against tyrosinase, one compound against elastase, eight compounds against collagenase and two compounds against hyaluronidase, being five compounds dual inhibitors. The 3-(4'-Bromophenyl)-5,7-dihydroxycoumarin (1) and 3-(3'-bromophenyl)-5,7-dihydroxycoumarin (2) presented the best profiles against tyrosinase (IC₅₀ = 1.05 µM and 7.03 µM) and collagenase (IC₅₀ = 123.4 µM and 110.4 µM); the 3-(4'-bromophenyl)-6,7-dihydroxycoumarin (4) presented a good inhibition against tyrosinase and hyaluronidase; the 3-(3'-bromophenyl)-6,7-dihydroxycoumarin (5) showed an effective tyrosinase and elastase inhibition; and 6,7-dihydroxy-3-(3'-hydroxyphenyl)coumarin (11) presented a dual profile inhibition against collagenase and hyaluronidase. Furthermore, considering the overall activities tested, compounds 1 and 2 proved to be the most promising anti-aging compounds. These compounds also showed to have a photo-protective effect, without being cytotoxic to human skin keratinocyte cells. To predict the binding site with the target enzymes, computational studies were also carried out.

Keywords: collagenase; elastase; hyaluronidase; hydroxy-3-phenylcoumarins; molecular docking; skin aging; sun protection factor; tyrosinase.

Figure 1

Examples of tyrosine inhibitors already described by our research group. The 3-(4′-Bromophenyl)-5,7-dihydroxycoumarin (1) has been the inspiration for the current work, exploring the activity against other enzymes involved in skin-aging and related diseases.

Scheme 1

Synthetic methodologies and reaction conditions: (a) CH₃CO₂K, Ac₂O, reflux, 16 h; (b) HCl, MeOH, reflux, 3 h.

Figure 2

Effect of compounds 1 and 2 on HaCaT cell viability. Cells were treated with compounds at different concentrations (10–200 μM) and their viability was measured by MTT assay. Data represent mean ± SD of triplicate experiments.

Figure 3

Protein–ligand interactions with active site residues of collagenase enzyme. (A) compound 1; (B) compound 2; and (C) compound 13. The ligand in orange–licorice representation, hydrogen bond (H-bond) interactions in blue, hydrophobic (H-phobic) interactions in grey dash lines, pi-stacking in green dash lines, halogen bond interactions in cyan, and salt-bridge interactions in yellow dashed line. Single letter code is used for naming the amino acids.

Figure 4

Protein–ligand interactions with active site residues of tyrosinase enzyme. (A) compound 1; (B) compound 2; and (C) compound 5. The ligand in orange–licorice representation, hydrogen bond (H-bond) interactions in blue, hydrophobic (H-phobic) interactions in grey dash lines, pi-stacking in green dash lines, halogen bond interactions in cyan, and salt-bridge interactions in yellow dashed line. Single letter code is used for naming the amino acids.