Thymosin α1 (Thymosin Alpha 1)

Thymosin α1 is a peptide fragment derived from prothymosin alpha, a protein that in humans is encoded by the PTMA gene.[3]

It was the first of the peptides from Thymosin Fraction 5 to be completely sequenced and synthesized. Unlike β thymosins, to which it is genetically and chemically unrelated, thymosin α1 is produced as a 28-amino acid fragment, from a longer, 113-amino acid precursor, prothymosin α.[4]


Thymosin α1 is believed to be a major component of Thymosin Fraction 5 responsible for the activity of that preparation in restoring immune function in animals lacking thymus glands. It has been found to enhance cell-mediated immunity in humans as well as experimental animals.[5]

Therapeutic application

As of 2009 Thymosin α1 is approved in 35 under-developed or developing countries for the treatment of Hepatitis B and C, and it is also used to boost the immune response in the treatment of other diseases.[6][7]

Clinical studies

Clinical trials suggest it may be useful in cystic fibrosis, septic shockacute respiratory distress syndromeperitonitisacute cytomegalovirus infectionTBsevere acute respiratory syndrome, and lung infections in critically ill patients.,[7] and for chronic hepatitis B.[8]

It has been studied for possible use in treating cancer (e.g. with chemotherapy).[9]