Enhanced production of novel bioactive metabolites in mung bean (Vigna radiata (L.) R. Wilczek) plants induced by signal molecule ethylene in a vertical farm

In the biofunctional material industry, enhancing bioactive metabolites in plants using signal stimulants is an emerging strategy. This study investigated the changes in bioactive metabolite content in different organs of mung bean plants treated with ethylene (ETL) in a closed chamber. In addition, we also examined its biomass, novel compounds, biological activities, and DNA protection. Through this approach, a practical method for producing mung bean plants with enhanced bioactive metabolites was proposed. ETL treatments led to a notable reduction in biomass, particularly in the leaves and roots, without affecting plant height. ETL treated leaves exhibited significant increases in the total phenolic, flavonoid, isoflavone, and flavone contents. Four compounds were identified in the mung bean organs following ETL treatment: 2′-hydroxydaidzein-4′,7-O-diglucoside, daidzein-4′,7-O-diglucoside, 2′-hydroxydaidzin, and 2′-hydroxydaidzein. Among these isoflavones, 2′-hydroxydaidzin and daidzin showed the highest significant accumulation levels in ETL treated leaves. In particular, the contents of 2′-hydroxydaidzin, daidzin, and genistin in the ETL treated leaves was increased by 77.4-fold (273.24–21,159.88 μg/g), 74.2-fold (429.67–31,845.13 μg/g), and 12.0-fold (268.35–3209.12 μg/g) respectively, compared with their contents in untreated leaves. Furthermore, the total phenolic and flavonoid contents increased from 13.87–24.59 and from 9.89 to 12.87 mg/g, respectively. These enhanced active metabolites in ETL treated mung bean organs significantly improved the antioxidant capacity, including radical scavenging, digestive enzyme-inhibition, and DNA protection activities. These findings underscore the potential of ETL as an effective elicitor and enhancer of bioactive metabolite production, supporting its application in high value functional bioresources.