Synthesis of New Poly(N-Vinyl Pyrrolidone-Co-Maleic Acid) Peptide Hormone Conjugates with Anticancer Activity

Gonadotropin releasing hormone (GnRH) is a decapeptide regulating the gonadotropin release in organisms. Its analogues inhibit breast, endometrium and prostatic tumor cell proliferation in vitro. Some analogues were conjugated via the lysine side chain to poly( N-vinyl pyrrolidone- co-maleic acid) using biodegradable and non-biodegradable oligopeptide spacers. The conjugates were prepared by acylation of oligopeptide nitrophenyl esters with the polymeric precursor, poly( N-vinyl pyrrolidone- co-maleic anhydride), by reacting the GnRH analogues with the polymeric active ester. In vitro tests of these products exhibited increased effects on MCF-7 and MDA MB-231 breast, Ishikawa endometrium and PC3 prostatic human tumor cells compared with the parent decapeptides.