New pregnane-type steroidal alkaloids from Sarcococca saligna and their cholinesterase inhibitory activity

Abstract

Five new steroidal alkaloids, 5,14-dehydro-N a-demethylsaracodine [3β-N a-methyl-20S-N b-acetyl-N b- methylamino-pregn-5,14-diene] (1), 14-dehydro-N a-demethylsaracodine [3β-N a-methyl-20S-N b-acetyl-N b- methylamino-5α-pregn-14-ene] (2), 16-dehydrosarcorine [(20S)-20-(N,N- dimethylamino)-3β-(N a-acetylamido)-5α-pregn-16-ene] (3), 2,3-dehydrosarsalignone [(20S)-20-(N,N-dimethylamino)-3β-(tigloylamino)- pregn-2,5-diene-4-one] (4), and 14,15-dehydrosarcovagine-D [(20S)-20-(N,N- dimethylamino)-3β-(tigloylamino)-5α-pregn-2,14-diene-4-one] (5), were isolated from the ethanolic extract of Sarcococca saligna, along with two known bases, sarcovagenine-C (6) and salignarine-C (7). Their structures were elucidated on the basis of spectroscopic methods. All seven compounds were found to possess cholinesterase inhibitory potential in a concentration-dependent manner with the IC 50 values ranging from 12.5 to 200 μM against acetylcholinesterase and from 1.25 to 32.2 μM against butyrylcholinesterase. © 2004 Elsevier Inc. All rights reserved.