Alkaloids are structurally diverse nitrogen-containing secondary metabolites produced by many plant species and are widely recognized for their significant biological activities. They exhibit a broad spectrum of bioactive properties, including insecticidal, fungicidal, antibacterial, antiviral, and herbicidal effects, making them promising candidates for sustainable agricultural applications. This review summarizes the origin, structural diversity, and ecological roles of plant-derived alkaloids, with particular emphasis on their mechanisms of action and effectiveness against major agricultural pests and plant pathogens. Representative compounds such as boldine, camptothecin, anabasine, lycorine, antidesmone, and chenoalbicin illustrate the structural complexity and functional versatility of this class of natural products. Key plant families, including Fabaceae, Amaryllidaceae, and Papaveraceae, are highlighted as major sources of bioactive alkaloids, particularly quinolizidine, Amaryllidaceae-type, and isoquinoline alkaloids. The review also discusses ecological and molecular factors that influence alkaloid activity, such as environmental conditions, soil composition, and interactions with other phytochemicals. In addition, recent advances in extraction and production strategies, including supercritical fluid extraction, deep eutectic solvents, microwave-assisted, and ultrasound-assisted methods, are discussed alongside biotechnological and synthetic strategies such as genetic transformation, CRISPR-mediated editing, and asymmetric synthesis to enhance sustainable production. Emphasizing underexplored botanical sources, process optimization, and integrated plant- and laboratory-based approaches, this work underscores the pivotal role of alkaloids in advancing agricultural bioprotection and pharmaceutical innovation.
Kaur et al. (Fri,) studied this question.