Identification of (-)-Epicatechin 3-gallate from seeds of Platycarya strobilacea with dual-functions of direct antivirus and plant immune elicitation against TMV.

BACKGROUND

Global crop losses caused by plant viruses, particularly tobacco mosaic virus (TMV), amount to billions of dollars per year, necessitating the urgent development of potent and environmentally friendly antiviral agents.

RESULTS

Twelve natural products were identified from P. strobilacea seeds. Among them, (-)-Epicatechin 3-gallate (1) showed higher anti-TMV activity than ningnanmycin at 125-500 μg mL-1, with inhibition rates of 49.36-80.27%, 39.34-70.28%, 33.48-63.13%, and 32.18-65.17% in inactivation, protective, curative, and resistance-inducing assays, respectively. Compound 1 disrupted TMV particle integrity and reduced TMV-CP gene expression. Molecular docking further suggested a potential interaction between 1 and TMV-CP, with a predicted binding affinity of -7.5 kcal mol-1 through hydrogen-bonding interactions. In addition, 1 enhanced salicylic acid accumulation, increased H₂O₂ levels, activated defense enzymes including superoxide dismutase, peroxidase, and catalase, and upregulated defense-related genes including NPR1, PR1, PR2, PR5, and PAL. Lesion phenotype and relative electrical conductivity assays suggested that 1 induced a mild local HR-like response with limited membrane damage.

CONCLUSION

These results suggest that (-)-Epicatechin 3-gallate (1) is a promising lead compound for further development as both a direct-acting antiviral agent and a plant immune elicitor against TMV. © 2026 Society of Chemical Industry.