New amide alkaloids from Delphinium brunonianum

Abstract Five new amide alkaloids, named delamide A-E ( 1 – 5 ), along with five known ones, methyl-N-(3-carboxy-2-methylpropanoyl) anthranilate ( 6 ), benzoic acid, 2-[(1-oxodecyl) amino]-methylester ( 7 ), puberline ( 8 ), benzoic acid, 2-[(4-methoxy-2-methyl-1, 4-dioxobutyl) amino]-methylester ( 9 ) and benzoic acid, 2-[(4-methoxy-3-methyl-1, 4-dioxobutyl) amino]-methylester ( 10 ) were isolated from the extract of Delphinium brunonianum . Their structures were elucidated by extensive spectroscopic analyses (including 1D-, 2D-NMR, and HR-ESI-MS). 1 – 10 were also evaluated for their acetylcholinesterase (AChE) inhibiting activity by the Ellman's method. Delamide A (1) showed highly selective AChE inhibition activity. The kinetic analysis revealed that 1 was a mixed-type reversible inhibitor of AChE.