The invention relates to novel compositions of general formula (1) consisting of X1 Trp Gly Gln X2 or the pharmaceutically acceptable salts or esters or amides thereof, wherein X1 is absent or contains at least one type of aminoacid, X2 is absent or contains at least one type of aminoacid. The inventive compositions produce an antitumoral and antiviral effect by suppressing a tumoral cells proliferation, potentiating the action of other antitumoral preparations and by stimulating antitumoral and antiviral immunologic mechanisms.
