L-Homocysteine thiolactone hydrochloride is an intramolecular thioester of homocysteine,It prevents translational incorporation of homocysteine into proteins.

Homocysteine thiolactone, a metabolite of homocysteine, exhibits cytotoxic properties and triggers apoptosis in HL-60 cells, as evidenced by increased phosphatidylserine exposure, hypoploid DNA content, internucleosomal DNA fragmentation, caspase-3 activation, and DNA fragmentation. Additionally, it significantly promotes IL-8 release. Conversion of homocysteine to homocysteine thiolactone by methionyl-tRNA synthetase happens across all cell types, from bacterial to human, including endothelial cells. Elevated homocysteine levels are recognized as an independent cardiovascular disease risk factor due to its conversion to the reactive thioester, homocysteine thiolactone, harmful to human cells.

Homocysteine thiolactone induces two types of seizures, the coexistence of convulsive and nonconvulsive epilepsy. The grade of seizures is dose dependent.?Homocysteine thiolactone is toxic, induces epileptic seizures in rodents, and has been implicated in Alzheimer's disease.