Topsentinols, 24-isopropyl steroids from the marine sponge Topsentia sp

Abstract

Three isopropyl steroids, topsentinols K, L, and K trisulfate (1-3), were isolated from an undescribed species of Topsentia. The structures of the new compounds were determined by extensive 1D and 2D NMR experiments and mass spectrometry measurements. Topsentinol K trisulfate (3) inhibited the aspartic protease BACE1, although in a detergent-dependent manner suggestive of nonspecific aggregation.

Figure 1

Key ROESY correlations used to establish the relative configuration of the ABCD rings of 1.

Figure 2

Detergent-dependent inhibition of chymotrypsin by 3 indicative of an aggregation mechanism.