text: The most common thiolactone, homocysteine thiolactone is produced biochemically from homocysteine and it may play a role in protein damage. The thiolactone functional group is also present in some pharmaceutical drugs such as citiolone and erdosteine. Thiolactone rings can also be found in peptides synthesized by bacteria such as Staphylococcus aureus in order to regulate their quorum-sensing system.