This invention provides an ADNF polypeptide comprising an active core site, the active core site comprising at least one D-amino acid. The invention also provides a pharmaceutical composition comprising an ADNF polypeptide comprising an active core site, the active core site comprising at least one D-amino acid. In particular, the pharmaceutical composition of the invention is orally active. The invention further provides methods for reducing neuronal cell death, methods for reducing oxidative stress, and methods for reducing a condition associated with fetal alcohol syndrome using the ADNF polypeptides and the pharmaceutical compositions of the invention.