Etymology of Echinocandins
Echinocandins are named after their structural origin from the fungal metabolite echinocandin B, which was first isolated from Aspergillus nidulans var. echinulatus, with "echino-" referring to the spiny or rough appearance of the fungal colony and "-candin" denoting the candida-active properties of these compounds. 1
Chemical Structure and Nomenclature
The echinocandins represent a class of semisynthetic amphiphilic lipopeptides composed of a cyclic hexapeptide core linked to a variably configured N-acyl side chain 1. This distinctive chemical structure forms the basis for the class name, as all three currently available agents (caspofungin, micafungin, and anidulafungin) share this fundamental molecular architecture 2, 3.
Historical Development
The original natural product echinocandin B was discovered as a fermentation product from fungal sources, and subsequent medicinal chemistry efforts led to the development of the three semisynthetic derivatives now used clinically 3, 4. The name reflects both:
- The source organism's morphological characteristics (the spiny or "echino-" appearance of the fungal colony from which the parent compound was isolated) 3
- The antifungal activity against Candida species (the "-candin" suffix highlighting the primary therapeutic target) 4, 5
Mechanism and Class Identity
The echinocandins act by noncompetitive inhibition of β-(1,3)-D-glucan synthase, an enzyme involved in the biosynthesis of β-(1,3)-D-glucan, which is a component specific to the cell wall of many fungi 1, 3. This unique mechanism of action, targeting fungal cell wall synthesis rather than membrane integrity like polyenes or ergosterol synthesis like azoles, further distinguishes this class and justifies its separate nomenclature 1.
The class name effectively communicates both the natural product origin and the primary clinical application against candidal infections, though these agents also demonstrate fungistatic activity against Aspergillus species 3, 4, 5.