Role of secondary metabolites of medicinal plants againstAscaridia galli

SUMMARYIn recent years, the roundworm Ascaridia galli has been found to be the most common poultry parasite, with 64.8% prevalence in flocks globally. It causes a 60–84% decrease in egg and meat production. Profitability is reduced without proper control of A. galli, and a wide range of chemically synthetic anthelmintics are commonly used. Emergence of drug resistance in nematodes has made scientists search for effective replacements. Among the alternatives to anthelmintics, natural products can be used which are more environment, consumer and host friendly, due to lower or no toxic effects. Certain plants exhibit anthelmintic effects through secondary metabolites (SMBs), such as terpenes (glycosides and saponins), phenolic compounds (flavonoids and tannins) and nitrogen-containing compounds (alkaloids, cyanogenic glycosides and non-protein amino acids). Generally, SMBs exhibit control of nematodes by causing starvation, damaging the external membrane, impairing fertility and growth rate and damaging musculature. In this review paper, the studies related to the screening of plants and their SMBs' activities (both in vivo and in vitro) are discussed. Some plants have efficacy more than 75% and comprehensive information about their taxonomy and dosage has been documented. Plants that have been found with intense efficacy against A. galli include Acanthus ilicifolius (100%), Cleome viscosa (100%), Osmium sanctum (100%), Murraya koenigii (100%), Sesbania grandiflora (90%), Citrus limon (87.5%), Polygonum hydropiper (83.3%), Swietenia macrophylla (76.6%) and Momordica charantia (75%). Important secondary metabolites include terpenoids (51.72%) followed by phenolic compounds (27.58%) and nitrogen-containing compounds (20.68%). Such plant-derived alternatives are almost 50% more cost-effective than synthetic drugs.