Bothrops Jaracara, or the Brazilian Pit Viper, is a poisonous snake that lives in this region. Along with anticoagulants, in the 1960s it was discovered that its venom contains “bradykinin potentiating peptides” that inhibit the angiotensin converting enzyme. In this salt-deprived environment, a bite from this snake would rapidly lead to hypotension and syncope. Captopril, the first commercially available ACE inhibitor, was derived from these peptides in the 1970s. Thus, something which provided a competitive advantage to a viper in the Amazon has become a mainstay in the treatment of hypertension and renal disease today. Similar peptides have been found in the venom of another snake, Agkistrodon Halys Blomhoffii, which is native to Japan and China.
Thank you to commenter Trevedy who pointed me in the direction of an article on the origin of ACE inhibitors.