Insight into the inhibitory effect of five plants essential oils on catechol oxidase from prestigious Algerian date fruit ( <i>Phoenix dactylifera</i> L.): <i>in vitro</i> and <i>in silico</i> study

The enzyme activity of catechol oxidase (CO) give rise to enzymatic browning, leading to undesirable changes in fruits and vegetables. The aim of this work is to investigate the inhibitory effect of five essential oils (EOs) on CO from date fruits (<i>Phoenix dactylifera</i>). Catechol oxidase has been purified from date fruit through three-phase partitioning (TPP). Essential oils were extracts from <i>Artemisia herba-alba</i>, <i>Artemisia campestris</i>, <i>Thymus vulgaris</i>, <i>Origanum vulgare</i>, and <i>Salvia Rosmarinus</i>, and were tested against CO. The composition of these five essential oils was then identified using GC-MS. Major constituents identified were camphor (20.91%) and davanone D (19%) for <i>A. herba alba</i>, capillene (47.79%) for <i>A. compestris</i>, thymol (33.75%) and linalool (30.44%) for <i>T. vulgaris</i>, carvacrol (68.60%) for <i>O. vulgare</i>, and camphor (33.89%) for <i>S. Rosmarinus.</i> The EO from <i>A. campestris</i> was the most potent inhibitor of enzyme (IC₅₀ = 3.44±0.09 mg/mL) while the weakest effect was observed for EO of <i>O. vulgare</i> (IC₅₀ = 10.24±0.29 mg/mL). Different mechanism of inhibition was obtained. Hence, a competitive inhibition for both EOs of <i>A. herba-alba</i> and <i>T. vulgaris</i>, uncompetitive behavior for <i>A. campestris</i>, noncompetitive mechanism for <i>S. rosmarinus</i> and <i>O. vulgare</i> were observed. The docking molecular of those major constituents was investigated using crystal structure of CO from <i>Ipomoea batatas</i> (1BT1). The best-docked compound was davanone D (-5.55 kcal/mol) while camphor show weaker docking scores (3.79 kcal/mol). Thus, the results from our work could be important and offer an approach of control enzymatic browning using essential oils.