Polyphenol oxidase properties, anti-urease, and anti-acetylcholinesterase activity of Diospyros lotus L. (Plum Persimmon)

Abstract

Diospyros lotus fruit polyphenol oxidase was purified using affinity chromatography, resulting in a 15-fold enrichment in specific activity. The purified enzyme, having 16.5 kDa molecular weight on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, exhibited the highest activity toward 4-methylcatechol. Maximum diphenolase activity was reached at pH 7.0 and 60°C in the presence of 4-methylcatechol. Km and Vmax values were calculated as 3.8 mM and 1250 U/mg protein, respectively. Ascorbic acid was a promising inhibitor with an IC50 value of 0.121 µM. The activity of the purified enzyme was stimulated by Fe2+, Sr2+, Zn2+, and K+ and deeply inhibited by Hg2+, at 1 mM final concentration. Aqueous extract of Diospyros lotus L. fruit showed strong substantial urease and acetylcholinesterase inhibition, with IC50 values of 1.55 ± 0.05 and 16.75 ± 0.11 mg/mL, respectively.