Evaluation of p-phenylene-bis and phenyl dithiocarbamate sodium salts as inhibitors of mushroom tyrosinase.

Abstract

Two structurally related compounds, phenyl dithiocarbamate sodium salt (I) and p-phenylene-bis (dithiocarbamate) sodium salt (II) were prepared by reaction of the parent aniline and p-phenylenediamine with CS₂ in the presence of sodium hydroxide. These water soluble compounds were characterized by spectroscopic techniques, IR, ¹H NMR and elemental analysis. The inhibitory effects of both compounds on both activities of mushroom tyrosinase (MT) from Agricus bisporus were studied at two temperatures, 27°C and 37°C. L-3, 4-dihydroxyphenylalanine (L-DOPA), and l-tyrosine were used as natural substrates for the catecholase and cresolase enzyme reactions, respectively. Kinetic analysis confirmed noncompetitive inhibition mode of I and mixed type of II on both activities of MT; I and II inhibit MT with inhibition constants (K(I)) of 300 µM and 4 µM, respectively. Analysis of thermodynamic parameters indicated predominant involvement of hydrophobic interactions in binding of I and electrostatic ones in binding of II to MT. It seems that II is a more potent MT inhibitor due to its two charged head groups able to chelate copper ions in the enzyme active site. Intrinsic fluorescence studies as a function of concentrations of both compounds showed unexpectedly quenching of emission intensity without any shift of emission maximum. Extrinsic ANS-fluorescence indicated that only binding of I induces limited changes in the tertiary structure of MT, in agreement with the postulated hydrophobic nature of the binding mechanism.

A comprehensive review on tyrosinase inhibitors

“…In addition to thiosemicarbazone derivatives, thiosemicarbazide and its derivatives 378–381 , 5-benzylidene(thio)barbiturate-beta- d -glycosides 382 , n -alkyl 383 , p -phenylene-bis, phenyl 384 , benzyl, p -xylidine-bis and p -pyridine dithiocarbamate sodium salts 385 , diethyldithiocarbamate, phenylthiourea 3 86 and other thiourea derivatives (Figure 12) such as methimazole, thiouracil, methylthiouracil, propylthiouracil, ambazone, and thioacetazone 387 have been identified as tyrosinase inhibitors.…”

Inhibitory effect of GB-2a (I3-naringenin-II8-eriodictyol) on melanogenesis

“…Tyrosinase is an enzyme with two copper ions, which are grouped antiferromagnetically in couples, where each copper is associated with three histidine residues (Amin et al, 2010). These coupled metal ions are responsible for the activity, and play a structural role (formation of the active site), function as Lewis acid and interact with the substrate (Weiner, 2007).…”

A calorimetric investigation for the bindings of mushroom tyrosinase to p-phenylene-bis dithiocarbamate and xanthates

“…Lineweaver-Burk plots showed different patterns of mixed inhibition for p-phenylene-bis(dithiocarbamate) and isopropyl xanthate and competitive inhibition for isobutyl and isopentyl xanthate. 4,9 In view of the increasing importance of controlling tyrosinase activities, we applied isothermal titration calorimetry (ITC) was applied in the present study to obtain thermodynamic parameters for the interaction between mushroom tyrosinase and inhibitors. EXPERIMENTAL MT was obtained from Sigma and the inhibitors were synthesized.…”