New tyrosinase inhibitors by effect directed synthesis

ESCALANTE, ANDREA M.; RIERA, MICAELA; SALAZAR MARIO O.; FURLAN RICARDO L. E.

Rosario

Congreso; 7ma edición de la Reunión Internacional de Ciencias Farmacéuticas; 2023

Enzymes play a crucial role in biology, serving as nature's catalysts that can facilitate almost any chemical transformation. Because of their importance, many diseases are directly linked to specific enzyme-catalyzed processes. Tyrosinase is an essential copper-containing oxidation enzyme that is responsible for melanin production. This enzyme is widely distributed in microorganisms, animals, and plants and plays a key role in undesirable processes such as antibiotic resistance, skin pigment formation, sclerotization of the cuticle, neurodegeneration, and more. As a consequence, tyrosinase has been acknowledged as a valuable therapeutic target for developing antibacterial agents, skin-whitening agents, insecticides, and various other therapeutic molecules, useful for cosmetic and pharmaceutical, food and agricultural industries.ii Typically, the identification of bioactive molecules involves synthesis, purification, characterization and biological evaluation of each compound, in a milligram scale. Lead generation is generally driven by iterative cycles in which series of molecules are designed, synthetized, purified and tested, consuming high inversion of time and pounds. Recently, we introduced the combination of library preparation and TLC assays for the rapid detection of dithioacetals that showed tyrosinase inhibitor activity. In brief, two mixture-libraries were prepared using 21 aldehydes, 3 monothiols and 3 dithiols as building blocks. These building blocks were selected in order to produce dithioacetals that include aromatic, aliphatic, and heterocyclic moieties (with N, O or S) having phenol, methoxyl, carboxyl and alcohol substituents as potential recognition groups. Both libraries were prepared in dichloromethane, in the presence of TFA at room temperature. Tyrosinase inhibition by both libraries was evaluated by TLC-bioautography using dichloromethane:methanol (95:5) and formic acid (0.050) as mobile phase. Mixtures of all building blocks were also spotted, separately, as controls. Clear composition differences between the two libraries were observed by TLC analysis and reflected in the biological properties of two spots, corresponding to only two dithioacetal libraries members, 1 and 2. These dithioacetals were studied in order to confirm the identity and further study tyrosinase inhibition and pharmaceutical properties. Compound 1 was prepared in 36 % yield and 2 was prepared in 40 % yield. 1 showed an IC50 value of 0.060 +- 0.0005 µM, more than 518 times lower than the IC50 of kojic acid (33.19 +-0.26 µM) determined using the same conditions. Studies in silico (SwissADME) show for 1 a lipophilicity in the range for skin permeation (Log Po/w1-3, while 2 is out of this range), and acceptable Lipinsky’s rules for 1 both pharmaceutical properties useful for potential applications.