Oxirane is a three-membered ring compound consisting of one oxygen atom and two carbon atoms. Oxirane is present in natural products such as cryptocin, which has anticancer properties, and azidomycin, trienone, and epoxidomycin, which have shown activity against drug-resistant leukemias and AIDS-related lymphomas. Other oxirane containing bioactive molecules have anti-inflammatory, immunosuppressive, and antitumor activities. Oxiranes are a strained ring susceptible to various nucleophilic, ring-opening or rearrangement reactions, so they are considered to be one of the most important intermediates in organic synthesis.
Cyclanes are secondary metabolites that can be found in plants, and are also biochemicals that can be used in medicine. Cyclanes are found in pine trees, and are used in the making of plastics. Cyclenes are found in cinnamon, and have antifungal properties.