Background: Polyphenol Oxidase (PPO) belongs to the oxidoreductase enzyme family. Methods: Here, PPO was purified from potato using Sepharose 4B-L-tyrosine-p-aminobenzoic acid affinity chromatography. It determined the interactions between some phenolic acids and the enzyme. Results: The enzyme was obtained with a specific activity of 15333.33 EU/mg protein and 7.87- fold purification. It was found that phenolic acids exhibited inhibitory properties for PPO. The IC50 values of the phenolic acids were found in the range of 0.36-2.12 mM, and their Ki values were found in the range of 0.28± 0.07-1.72±0.32 mM. It was determined that all studied compounds displayed a competitive inhibition effect. Among these compounds, 3-hydroxybenzoic acid was found to be the most effective PPO inhibitor (Ki: 0.28±0.07 mM). Conclusion: Investigating the inhibition kinetics of the enzyme will simplify the testing of PPO inhibitor candidates.

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Fresh-cut vegetables and fruits have gained attention among consumers because of their fresh appearance, lack of pollution, nutrition, and convenience. However, in fresh-cut foods, enzymatic browning is the main problem. Polyphenol oxidase (PPO) is a vital enzyme involved in the process of enzymatic browning. In this study, PPO was purified from potato using Sepharose 4B-l-tyrosinep-aminobenzoic acid affinity chromatography and the effect of some indazoles on the enzyme was determined. The enzyme was purified with a specific activity of 52,857.14 EU/mg protein and 21.26-purification fold. Indazoles exhibited inhibitor properties for PPO with IC 50 values in the range of 0.11-1.12 mM and K i values in the range of 0.15 ± 0.04-3.55 ± 0.88 mM. Among these compounds, 7-chloro-1H-indazole was shown as the most potent PPO inhibitor (K i : 0.15 ± 0.04 mM). Determination of the enzyme's inhibition kinetics will simplify the testing of candidate PPO inhibitors.

Heterocyclic pyrazole compounds have cytotoxic, anticancer, antimicrobial, anti‐inflammatory properties, as well as their derivatives containing sulfonamide moiety, show superior effects on inhibiting various enzymes. Pre‐synthesized celecoxib‐derived compounds were studied for their inhibitory effects on human carbonic anhydrase (hCA I and hCA II) isoforms and acetylcholinesterase (AChE). The compound containing 2,3 dimethoxyphenyl functional groups from the celecoxib derivative containing this sulfonamide moiety showed a strong inhibitory effect with Ki values at 21.70±2.50 nM, 4.70±2.20 nM, and 4.58±0.80 nM for hCA I, hCA II, and AChE, respectively. In addition, these compounds were evaluated against acetazolamide (AZA) and tacrine (TAC), which are used as standard inhibitors for the studied enzymes. The compound obtained as a result of the reaction of pyrazole compounds with propionic anhydride and showing the best inhibition effect had higher inhibitory activity than the standard inhibitors we used. In addition, molecular docking analyses to the strongest inhibitor were performed to identify possible binding mechanisms with the active sites of all three enzymes. Based on both in vitro and molecular docking analysis results, this compound was determined as a potential inhibitor of AChE, hCA I, and hCA II isoenzymes.