Phytochemicals from Moringa oleifera Exhibit Antiviral Activity against Bean Yellow Mosaic Virus in Vicia faba L.

Faba bean (Vicia faba L.) is a globally important legume and the most widely cultivated pulse crop in Egypt due to its high nutritional value. However, its productivity is severely constrained by Bean yellow mosaic virus (BYMV), a widespread and economically significant pathogen. This study aimed to isolate and characterize BYMV in Egypt and to evaluate the antiviral efficacy of Moringa oleifera leaf extract as a natural biocontrol agent. BYMV was biologically purified using Chenopodium amaranticolor and confirmed through DAS-ELISA and RT-PCR, which yielded an 832 bp amplicon. Sequencing of the Egyptian isolate (GenBank Accession No. OR242736.1) revealed 89-100% identity with global BYMV strains. Aqueous M. oleifera extract was applied via stem injection and foliar spray at concentrations of 25, 50, and 75 mg/mL, either 24 hours before or after virus inoculation. The post-infection foliar spray at 50 mg/mL (VM) resulted in the highest suppression of viral accumulation (88%) and significantly enhanced host defense responses, including total phenolic content (13.04 mg/g), peroxidase (12.14 U/mg/min), PAL (489.29 µg/mg), and catalase activity (32.94 U/mg/min). GC-MS profiling identified 27 phytochemicals dominated by terpenoids (34%), fatty acid derivatives (29%), sterols (17%), and hydrocarbons (15%). Major constituents-such as neophytadiene, linoleoyl chloride, and cholestanol derivatives-possess known antiviral and antioxidant properties. Neophytadiene, in particular, may contribute to viral inhibition by disrupting membrane integrity and replication processes. Overall, the findings highlight M. oleifera extract as a promising, eco-friendly antiviral agent that suppresses BYMV through a combination of direct virucidal activity and the activation of host defense pathways.