Effect of chrysin omega‐3 and 6 fatty acid esters on mushroom tyrosinase activity, stability, and structure

Abstract

The estreification of chrysin with α‐Linolenic acid (complex I) and linoleic acid (complex II) poly unsaturated fatty acids resulted to design of new mushroom tyrosinase (MT) inhibitors. Thermodynamic parameters of enzymes, including the melting point (Tm) and ∆G values, were obtained from thermal and chemical denaturation curves. Complexes I and II showed a competitive inhibitory effect on MT with Ki values of 0.45 and 0.29 mM, respectively. The Tm values were calculated as 328.6, 322.4, and 318 K and the ∆G values as 62.8, 52.9, and 47.1 KJ mol−1 for the enzyme alone and its interaction with complexes I and II, respectively. Intrinsic and extrinsic fluorescence techniques showed structural instability of the enzyme in concomitance with a decrease in the regular secondary structure acquired using CD spectrometry. This data clearly prove that the new derivatives show a stronger inhibitory effect than the separate compounds. Molecular docking analysis showed that the best possible interaction condition was achieved for chrysin with n‐6. Practical applications MT is a suitable model in medicine for the investigation of melanogenesis, skin disorders, and hyperpigmentation because of its accessibility and close structural similarity to mammalian tyrosinase. In recent years, the designing of tyrosinase inhibitors from natural substances for prevention of hyperpigmentation in medicine, skin cosmetics, and undesired browning in agriculture and food industry has risen sharply. Many of the pharmaceutical products based on the use of flavonoids and poly unsaturated acids as natural compounds or on their semi‐synthetic derivatives have been interested for investigations because of their usefulness in many pathological conditions such as inflammation, cancer, and skin disorders. The limitation of the flavonoids applications are low bioavailability, permeability, and solubility for the cells. In this study, conjugation of chrysin with n‐3 and n‐6 fatty acids resulted in a stronger inhibitors of MT with a synergic inhibitory effect on its activity.

Exploring the Potential of ω3 Derivatives as Tyrosinase Inhibitors: A Comprehensive Study Combining Experimental, Computational, and Biological Approaches

“…For ω3‐NA, Glu322, His855, and Asn286 were involved in a hydrogen bond with a length of 3.04, 2.89, and 2.86 Å and 6 residues (Asn260, His 263, Phe 264, Gly281, Val283, Pro 284) were involved in the hydrophobic interaction (Figures 7). In a previous study on chrysin‐ω3 and chrysin‐ω6 complexes, based on residues and hydrophobic interactions, the existence of alpha‐helixes around the active site was detected [18] . The presence of alpha helixes in picolinic and nicotinic complexes with ω3 is also confirmed [39] …”

“…Kinetic assessment of the enzyme activity in the presence of ω3‐NA and ω3‐PA induced a competitive manner of inhibition, with the inhibitory constant (Ki) of 5.2 and 5.1 mM, the order of ω3‐NA and ω3‐PA, respectively. In previous studies, complexes Chyrsin‐ω3 and Chyrsin‐ω6 showed a competitive inhibitory effect on MT with Ki values of 0.45 and 0.29 mM and the diphenols, nicotinic acid, and picolinic acid activity with K i of 2.4 and 2.93 mM, respectively [18,31] . The inhibition of tyrosinase activity might depend on the hydroxyl groups on the phenolic compounds of the flavonoids, which may form hydrogen bonds with the enzyme active site, inducing a competitive manner of inhibition, leading to lower enzymatic activity [32,33] .…”

“…It was entered into Auto Dock Tools, and after selecting the active site residues, a grid box of (XYZ) (−10.758, −27.141, −45.39 Å) was used. Autodock can determine the lowest binding energy of tyrosinase/ω3‐PA and tyrosinase/ω3‐NA for docking confirmation that was assumed as early conformations for MD simulation [18,48,49] …”

“…[16,17] Nowadays, the use of combined inhibitors and the study of their mechanism of action is essential in drug design and development. Jamali [18] has addressed this importance in several studies; for example, the study of the effect of chrysin ω3 and ω6 fatty acid esters on mushroom tyrosinase (MT) using spectroscopic examination and molecular dynamics reported better inhibition of combination drug. In this study, due to the inhibitory properties of nicotinic acid and picolinic acid, we decided to investigate the two aforementioned compounds' effect in combination with ω3 fatty acids on the enzyme tyrosinase.…”

Structural and inhibitory effects of fulvic and humic acids against tyrosinase

“…The docking results revealed that HA and FA can bind to the active site of tyrosinase with the lowest binding energies of −4.2 and −6.4 kcal/mol, respectively. It must be mentioned that as a general rule, the lowest binding free energy of the enzyme–inhibitor binding was utilized as models for MD simulation (Farasat et al, 2020; Jamali et al, 2019). The 2D illustrations of tyrosinase–inhibitor complexes of MD simulation are displayed in Figure 5.…”