Heparin antiproliferative activity on bovine pulmonary artery smooth muscle cells requires both N-acetylation and N-sulfonation

Abstract

The antiproliferative activity of Heparin (HP) on bovine pulmonary artery smooth muscle cells (BPASMC) in vitro requires both N-acetylation and N-sulfonation. This was demonstrated by quantifying the relative N-acetylation of three commercial heparins of known antiproliferative activities, using their Fourier-transform infrared (FTIR) band areas at 1381–1378 and 1320–1317 cm −1, which combined resulted in 1.0, 1.0 and 1.3 cm 2 for Choay, Elkins–Sinn and Upjohn HP, respectively. These results show that Upjohn HP, which is at least 44% more antiproliferative than the other two, is 30% more N-acetylated. Upjohn HP was also N-desulfonated chemically, and its antiproliferative activity was determined. Its total sulfonate (SO 3 −) content ( O- and N-sulfonate) was quantified using the FTIR band area at 1260–1200 cm −1 for the SO stretching; a drop in sulfonate content from 21.87% (w/w) before N-desulfonation to 16.51% (w/w) after N-desulfonation, resulted in a 67% decrease in its inhibitory potency. In addition to the requirement that ∼24% of the sulfonate content be bonded to N, the data show a direct correlation between the extent of Upjohn HP N-acetylation and its antiproliferative activity on BPASMC.