Ketides

Ketides are a class of naturally occurring organic compounds produced by a wide range of organisms, including bacteria, fungi, plants, and marine animals. They are characterized by the presence of a ketone functional group within their carbon backbone, alongside other functional groups such as hydroxyl, carboxyl, and ether moieties. The biosynthesis of ketides is a complex process involving polyketide synthases (PKS), which are large multimodular enzymes. These enzymes assemble carbon chains by repeatedly condensing acetyl-CoA and malonyl-CoA units, or their equivalents, in a process that resembles fatty acid synthesis but allows for greater structural diversity through variations in enzyme domains and substrate selection. The resulting molecular structures can be highly varied, ranging from simple acyclic chains to intricate polycyclic systems. Many ketides exhibit significant biological activity, which has led to their exploration and utilization in various fields. For instance, some ketides possess antimicrobial, antifungal, antiviral, or anticancer properties, making them valuable as pharmaceuticals. Examples include erythromycin, a widely used antibiotic, and rapamycin (sirolimus), an immunosuppressant. The structural diversity of ketides also makes them interesting targets for synthetic chemists, and their natural occurrence highlights the remarkable biosynthetic capabilities of living organisms. Research continues to uncover new ketide structures and explore their potential applications.