Enzymatic Browning Of Vegetables Research Articles

Evaluation of inhibitory effects of some novel phenolic derivatives on the mushroom tyrosinase activity: Insights from spectroscopic analyses, molecular docking and in vitro assays

Tyrosinase plays determinant role in enzymatic browning of vegetables and fresh-cut fruits. Development of new tyrosinase inhibitors is of great concern in food and agriculture. To discover new inhibitors, novel phenolic derivatives were synthesized and their inhibitory effects were investigated on activity of mushroom tyrosinase. All compounds showed potent inhibitory activities in their low concentrations and compound 4-(4-hydroxyphenyl)butan-2-one (1b) was found to be the most potent inhibitor (73.75% inhibition, IC50 value 5.6 μmol L−1). This ligand inhibited enzyme activity in a mixed pattern and kinetic parameters were also determined. In vitro assays revealed that this compound has not cytotoxicity/hemolytic effects and can be considered as safe for further investigations. Analysis of fluorescence spectra showed that all ligands quenched enzyme intrinsic fluorescence. The quenching mode and important binding parameters were also calculated. Enzyme-ligands interactions were also theoretically analyzed by molecular docking and results showed that the ligands interact with structurally/functionally critical residues.

Benzylidene-6-hydroxy-3,4-dihydronaphthalenone chalconoids as potent tyrosinase inhibitors.

Background and purpose:Tyrosinase enzyme has a key role in melanin biosynthesis by converting tyrosine into dopaquinone. It also participates in the enzymatic browning of vegetables by polyphenol oxidation. Therefore, tyrosinase inhibitors are useful in the fields of medicine, cosmetics, and agriculture. Many tyrosinase inhibitors having drawbacks have been reported to date; so, finding new inhibitors is a great need.Experimental approach:A variety of 6-hydroxy-3,4-dihydronaphthalenone chalcone-like analogs (C1-C10) have been synthesized by aldol condensation of 6-hydroxy tetralone and differently substituted benzaldehydes. The compounds were evaluated for their inhibitory effect on mushroom tyrosinase by a spectrophotometric method. Moreover, the inhibition manner of the most active compound was determined by Lineweaver-Burk plots. Docking study was done using AutoDock 4.2. The drug-likeness scores and ADME features of the active derivatives were also predicted.Results/Findings:Most of the compounds showed remarkable inhibitory activity against the tyrosinase enzyme. 6-Hydroxy-2-(3,4,5-trimethoxybenzylidene)-3,4-dihydronaphthalen-1(2H)-one (C2) was the most potent derivative amongst the series with an IC50 value of 8.8 μM which was slightly more favorable to that of the reference kojic acid (IC50 = 9.7 μM). Inhibitory kinetic studies revealed that C2 behaves as a competitive inhibitor. According to the docking results, compound C2 formed the most stable enzyme-inhibitor complex, mainly via establishing interactions with the two copper ions in the active site. In silico drug-likeness and pharmacokinetics predictions for the proposed tyrosinase inhibitors revealed that most of the compounds including C2 have proper drug-likeness scores and pharmacokinetic properties.Conclusion and implications:Therefore, C2 could be suggested as a promising tyrosinase inhibitor that might be a good lead compound in medicine, cosmetics, and the food industry, and further drug development of this compound might be of great interest.

A Series of Benzylidenes Linked to Hydrazine-1-carbothioamide as Tyrosinase Inhibitors: Synthesis, Biological Evaluation and Structure-Activity Relationship.

Tyrosinase is a type 3 copper enzyme responsible for skin pigmentation disorders, skin cancer, and enzymatic browning of vegetables and fruits. In the present article, 12 small molecules of 2-benzylidenehydrazine-1-carbothioamide were designed, synthesized and evaluated for their anti-tyrosinase activities followed by molecular docking and pharmacophore-based screening. Among synthesized thiosemicarbazone derivatives, one compound, (2E)-2-[(4-nitrophenyl)methylidene]hydrazine-1-carbothioamide, is the strongest inhibitor of mushroom tyrosinase with IC50 of 0.05 μM which demonstrated a 128-fold increase in potency compared to the positive control. Kinetic studies also revealed mix type inhibition by this compound. Docking studies confirmed the complete fitting of the synthesized compounds into the tyrosinase active site. The results underline the potential of 2-benzylidenehydrazine-1-carbothioamides as potent pharmacophore to extend the tyrosinase inhibition in drug discovery.

Synthesis, molecular docking and kinetic studies of novel quinolinyl based acyl thioureas as mushroom tyrosinase inhibitors and free radical scavengers

The enzyme tyrosinase plays a vital role in melanin biosynthesis and enzymatic browning of vegetables and fruits. A series of novel quinolinyl thiourea analogues (11a-j) were synthesized by reaction of 3-aminoquinoline and corresponding isothiocyanates, in moderate to excellent yields with different substitutions and their inhibitory effect on mushroom tyrosinase and free radical scavenging activity were evaluated. The compound N-(quinolin-3-ylcarbamothioyl)hexanamide (11c) exhibited the maximum tyrosinase inhibitory effect (IC50 = 0.0070 ± 0.0098 µM) compared to other derivatives and the reference Kojic acid (IC50 = 16.8320 ± 0.0621 µM). The docking studies were carried out and the compound (11c) showed most negative estimated free energy of −7.2 kcal/mol in mushroom tyrosinase active site. The kinetic analysis revealed that the compound (11c) inhibits the enzyme tyrosinase non-competitively to form the complex of enzyme and inhibitor. The results revealed that 11c could be identified as putative lead compound for the design of efficient tyrosinase inhibitors.

Liposome-entrapped essential oils onin vitroandin vivoantioxidant activity in leafy vegetables

Enzymatic browning in vegetables can cause undesirable quality changes during handling, processing and storage. Because of antioxidant properties of essential oils, effects of rosemary (Rosmarinus officinalis L.) and lemon (Citrus limonum L.), and their liposomal derivatives, were evaluated on reduction of peroxides and polyphenoloxidase activities, enzymes that promotes enzymatic browning and nutritional damage in plant tissues, in spinach (Spinacia oleracea L., cv. Inner), lettuce (Lactuca sativa L., cv. Dark green cos) and red cabbage (Brassica oleracea L. capitata, cv. Danish bull head). Multillamelar liposomes were prepared using a thin film hydration method. Antioxidant activity of the essential oils was compared with liposomal oils. Antioxidant activity of oils were maintained in the liposomal derivatives, and enhanced at low oils concentration. The highest percentage of antioxidant activity reduction was achieved in vitro and in vivo using a 0.1 mg/ml concentration of liposomal rosemary oil in all vegetables. Since essential oil is a natural compound in aromatic plants and residues have been successfully encapsulated in liposomes, the liposomal of essential oil hold potential of becoming a safe and effective method to prolong shelf-life of vegetables.