Capsofulvesins A–C, Cholinesterase Inhibitors from Capsosiphon fulvescens

Abstract

Activity-directed isolation of the n-hexane and dichloromethane fractions of Capsosiphon fulvescens resulted in the identification of four new glycolipids (1–3): (2S)-1-O-(6Z,9Z,12Z,15Z-octadecatetraenoyl)-2-O-(4Z,7Z,10Z,13Z-hexadecatetraenoyl)-3-O-β-D-galactopyranosyl glycerol (1, capsofulvesin A), (2S)-l-O-(9Z,12Z,15Z-octadecatrienoyl)-2-O-(10Z,13Z-hexadecadienoyl)-3-O-β-D-galactopyranosyl glycerol (2, capsofulvesin B), (2S)-1-O-(6Z,9Z,12Z,15Z-octadecatetraenoyl)-3-O-β-D-galacatopyranosyl glycerol (3, capsofulvesin C). Compounds 1–6 exhibited acetylcholinesterase (AChE) inhibitory activities with IC₅₀ values ranging from 50.90 to 82.83 µM, whereas 2–6 showed butyrylcholinesterase (BChE) inhibitory activities with IC₅₀ values of 114.75–185.55 µM. Although most of the compounds isolated lacked scavenging activity for 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and peroxynitrite (ONOO⁻), compound 8 showed ONOO⁻ scavenging activity with an IC₅₀ value of 26.23 µg/mL.