Review on bioactive compounds of medicinal plants with antiviral properties against Newcastle disease virus (NDV).

Newcastle disease virus (NDV) continues to cause major economic losses in poultry globally, especially in resource-limited settings. Although vaccination is the primary control strategy, its effectiveness is often compromised by viral mutations and short-lived immunity. This has prompted growing interest in medicinal plants as alternative or complementary antiviral sources. Several plants, including Pongamia pinnata (karanj), Withania somnifera (ashwagandha), Psidium guajava and Azadirachta indica (neem) have shown promising anti-NDV activity. Their bioactive compounds, such as karanjin, quercetin, withanine, eugenol and azadirachtin, can interfere with viral entry, replication, protein synthesis, or enhance host immune responses in in vitro, in ovo, and in silico models. This review consolidates current knowledge on active phytochemicals from various medicinal plants against NDV, highlighting their mechanistic insights and therapeutic potential. By bringing together existing evidence, it emphasizes the promise of plant-derived compounds as sustainable, cost-effective antivirals for poultry health management.