Rapid and efficient isolation of the nicotinic receptor antagonist methyllycaconitine from delphinium: Assignment of the methylsuccinimide absolute stereochemistry as S

Conversion of the sodium channel activator aconitine into a potent α7‐selective nicotinic ligand

“…2 and K~ values are given in Table 1. MLA, isolated and purified in this laboratory as the free base [14], inhibited [125I]~Bgt binding to rat brain membranes with a K, of 4 nM, and was at least 3 orders of magnitude less potent at [3H]nicotine binding sites or muscle nAChR. These data are in good agreement with our previous evaluations of MLA [2,3].…”

“…(Amersham, Bucks., UK). Aconitine was purchased from Aldrich Chemical Co. MLA was purified from a Garden Hybrid Delphinium strain as previously described [14]. Potential ligands were dissolved in ethanol to a stock concentration of 10-3M and stored at 4°C.…”

Diterpenoid Alkaloids from Delphinium yunnanense

“…Similarly, correlations between H a ÀC(6), and CH 2 (19), HÀC (16), and H a ÀC(12) suggested the a-orientation of HÀC(6) and HÀC (16). The configuration of C(2'') could be deduced as (S) based on comparison of the 13 C-NMR data of methylsuccinimide moiety of 1 with those of methyllycaconitine [19]. Thus, the structure of yunnanensine A (1) was determined as (1a,6b,14a,16b)-20-ethyl-1,6,14,16-tetramethoxy-7-oxo-8,17-cyclo-7,17-secoaconitan-18-yl 2-(2b-2-methylsuccinimide)benzoate.…”

“…In the NOESY spectrum, correlations between H b ÀC(1) and H b ÀC(10), and H b ÀC (14) and H b ÀC(10) indicated the b-orientation of HÀC(1) and HÀC (14). Similarly, correlations between H a ÀC(6), and CH 2 (19), HÀC (16), and H a ÀC(12) suggested the a-orientation of HÀC(6) and HÀC (16). The configuration of C(2'') could be deduced as (S) based on comparison of the 13 C-NMR data of methylsuccinimide moiety of 1 with those of methyllycaconitine [19].…”

“…To the best of our knowledge, no previous study has been reported concerning the phytochemistry of this plant. As part of an ongoing research program to investigate the chemistry and biological activities of diterpenoid alkaloids from Aconitum and Delphinium plants, we have investigated whole plants of D. yunnanense and isolated a new rearranged-type C 19 diterpenoid alkaloid, yunnanenseine A (1), and two hetisine-type C 20 -diterpenoid alkaloids, yunnanenseines B and C (2 and 3, resp.). The present investigation also led to the isolation of the following 15 known compounds: methyllycaconitine [6], 14-deacetylnudicauline [7], anhweidelphinine [8], postanisine F [9], delelatine [10], delbonine [11], delsemine A [12], delsemine B [12], 14-dehydrodecosine [13], deltaline [14], delcosine [15], blacknine [16], browniine [17], 14-dehydrobrowniine [12], and lycoctonine [12].…”