The present study was carried out to isolate, purify and elucidate the structure of low molecular weight bioactive compounds from sea anemone, Gyrostoma helianthus of the Red Sea environment. The obtained results indicated that the ethanolic crude extract of the sea anemone, G. helianthus showed inhibition activity against acetylcholinesterase (AchE). The 0.5 kD fraction inhibited the activity of the AchE that indicated the presence of low M.W active compound(s) of less than 0.5 kD. Two active fractions were obtained after BioGel P2 fractionation of the 0.5 kD of the G. helianthus. The first active fraction inhibited the activity of the acetylcholinesterase, while the other fraction did not. High-performance liquid chromatography (HPLC) technique aided by semipreparative columns was used to isolate the target compounds in a pure form for the structure elucidation, one dimensional nuclear magnetic resonance (NMR) analysis (1H and 13C-NMR) and DEPT were carried out to elucidate the structure of the isolated compound which was tentatively identified as N,N'-bis-(1-methyl-pyridin-2-yl)-hydrazine.
Key words: Sea anemone, Gyrostoma helianthus, Red Sea, structure elucidation, acetylcholinesterase (AchE) inhibitor.