Since their discovery, essential oils are known as a hugely valuable resource to treat a variety of infections due to their multiple biological functions, especially their antimicrobial, and antioxidant activities. Unfortunately, these volatile compounds have also certain limits such as the processes for extracting of these oils, the purification of their bioactive molecules and their minimal amount. For that reason several scientists have been oriented their research towards synthetic molecules as a new tool to overcome the progression of many chronic diseases (cancer, fibrosis, cirrhosis, arthritis). The prime focus of this work was the synthesis and characterization of four α-aminophosphonate derivatives 4(a-d). Then we evaluated their antioxidant activity against oxidative and nitrosative stress. The in vivo experiments are conducted using Tetrahymena protozoan treated with IC50 of hydrogen peroxide (H2O2) or sodium nitroprusside (SNP); finally we checked their antioxidant behavior in vitro through DPPH and DC assay. The results of this paper confirmed that under the both conditions: in vivo and in vitro, two derivatives among the four synthesized possess an antioxidant activity; it is the 4a and 4c products. This project is an attempt to obtain new organic compounds that have the potential to be developed as new therapeutic agents.