Biostimulatory Effect of 3-Acetonyl-3-Hydroxyoxindole on the Growth and Secondary Metabolites of Khaya senegalensis: UPLC–MS/MS Profiling and Molecular Docking Insights

Abstract

Developing sustainable agricultural biostimulants that simultaneously optimize vegetative growth and specialized metabolic pathways is critical for maximizing plant growth, photosynthetic efficiency, and metabolome reprogramming. In this study, for the first time, the effects of the biostimulant 3-acetonyl-3-hydroxyoxindole (AHO) on plant growth, photosynthetic efficiency and metabolomics reprogramming were evaluated. The multifaceted effects of AHO (0, 1, 5, 10, and 20 µg/mL) applied via foliar application were evaluated via comprehensive morpho- physiological, UPLC–MS/MS metabolomic and computational docking approaches. AHO positively affects plant growth performance in a concentration-dependent manner. Foliar application at 20 µg/mL produced the maximum vegetative vigor and biomass accumulation, as well as the highest levels of chlorophyll a, chlorophyll b, carotenoids, total flavonoids, and indole contents, while the maximum value of total phenolics was 1 µg/mL. Substantial metabolic flux modulation was confirmed by UPLC–MS/MS profiling, which revealed that 10 µg/mL selectively accumulated chlorogenic acid and rutin, whereas 5 µg/mL preferentially enriched quercetin, quercitrin, limonin and catechin. These empirical metabolic responses are supported by computational docking models, which predict favorable structural interactions between AHO and key biosynthetic enzymes. Insights gained from these integrated morphological, physiological, metabolomic, and computational analyses indicate that AHO applications can effectively improve plant growth and biomass, increase the concentration of bioactive compounds, and enhance the accumulation of bioactive secondary metabolites within the plant.