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.