Natural Antifungal Alkaloids for Crop Protection: An Overview of the Latest Synthetic Approaches

Alkaloids are nitrogen-containing compounds naturally occurring in plants, microorganisms, and marine organisms. Potent biological activities have been reported to date, ranging from neuroprotective to antioxidant and anticancer effects. Alkaloids have recently gained attention as potential antifungal agents for crop protection due to their broad spectrum of activity, eco-friendly nature, and ability to overcome some of the issues associated with synthetic fungicides, such as resistance development and environmental contamination. Several efforts have been made to obtain natural and nature-derived alkaloids endowed with significant activity against numerous pathogenic fungal strains. In this review, we collect synthetic strategies developed over the past decade to produce alkaloid fungicides for crop protection. Special emphasis is given to recent advancements in obtaining pure natural compounds and more potent analogs endowed with tailored and optimized properties.