Design of aminoethoxyvinylglycine functional analogues to delay postharvest ripening of tomato fruit

Ethylene is a key hormone in regulating fruit ripening, thus inhibiting ethylene production is an effective way to delay postharvest ripening of fruit. Aminoethoxyvinylglycine (AVG) is a competitively ethylene synthesis in-hibitor that can significantly delay the fruit softening at postharvest stage and prolong the fruit shelf life. However, the high production cost of AVG limits its widespread use. In this study, nine AVG analogues with simple structures were designed and synthesized based on the 1-aminocyclo-propane-1-carboxylic acid synthase (ACS) enzyme ACS2 (Protein Data Bank ID: 1AIY) of tomato. The molecular docking analysis of ACS2 with AVG analogues showed that the compounds 2i, 2k, and 2 n have higher predicted binding activity than the other analogues, which form hydrogen bonds with the key amino acids Ala54 and Arg412 of ACS2. Compounds 2i, 2k, and 2 n reduce ethylene production and delay the postharvest ripening of tomato fruit in varying degrees, and 2 n is the most effective AVG analogue, suggesting that the function of these analogues is basically associated with their predicted binding activity with ACS2. This study developed a new class of ethylene synthesis inhibitors with significant effects on the control of ethylene action and prolonging fruit shelf life. This work also has crucial implications for research on structure-activity relationship and development of more potential AVG functional analogues.