Cyclopropane derivatives and their diverse biological activities

Natural and synthetic cyclopropanes bearing simple functionalities are endo wed with a large spectrum of biological properties ranging from enzyme inhi bitions to insecticidal, antifungal, herbicidal, antimicrobial, antibiotic, antibacterial, antitumor and antiviral activities. The simple 2-substituted 1-aminocyclopropanecarboxylic acids (ACCs) are cur rently attracting special attention because of their potential use in confo rmationally restricted peptides, providing biosynthetic and mechanistic pro bes. As the immediate biosynthetic precursor of ethylene, the phytohormone that initiates and regulates many aspects of plant growth (germination, inh ibition, senescence, fruit ripening, etc.), the parent ACC, structurally re lated to glycine, is a potent and selective ligand of the glycine modulatio n site coupled to the N-methyl-D-aspartate (NMDA) receptor, one of the four different receptors that mediate the action of the excitatory amino acids (EAA) in the brain transmitter systems; thus, such amino acids have also be en proven to be useful in neurochemical studies. The mechanisms responsible for the diverse specific biological activities of compounds containing thr ee-membered carbocyclic moieties are also being discussed.