A further analysis of the effects of the steroidal alkaloid batrachotoxin (BTX) on sodium channels in frog node of Ranvier has been carried out under voltage-clamp conditions. The main properties of modified channels as compared with those of normal ones are as follows: The rate of channel closing is drastically decreased, whereas that of opening is changed slightly if at all; The steady-state ...

The furanobisindole alkaloid, phalarine, possesses a unique structural framework within the alkaloid family of natural products. Our laboratory recently disclosed the racemic total synthesis of phalarine, featuring an efficient azaspiroindolenine rearrangement; this achievement is revisited in detail. Upon completion of the first-generation total synthesis, we explored some interesting mechanis...

We have developed a nickel-catalyzed method for the asymmetric cross-coupling of secondary electrophiles with secondary nucleophiles, specifically, stereoconvergent Negishi reactions of racemic benzylic bromides with achiral cycloalkylzinc reagents. In contrast to most previous studies of enantioselective Negishi cross-couplings, tridentate pybox ligands are ineffective in this process; however...

A dihydropyridone alkaloid, cenocladamide, and a derivative of piplartine, 4'-desmethylpiplartine were isolated along with piplartine from the leaves of Piper cenocladum. The structures of the new compounds were determined by spectroscopic methods and by comparison to piplartine. Concentrations of these amides in plants with and without ant mutualists, are compared.

Mass-directed isolation of the CH(2)Cl(2)/CH(3)OH extract from a marine sponge of the genus Pseudoceratina resulted in the purification of a new antimalarial bromotyrosine alkaloid, psammaplysin H (1), along with the previously isolated analogs psammaplysins G (2) and F (3). The structure of 1 was elucidated following 1D and 2D NMR, and MS data analysis. All compounds were tested in vitro again...

The novel quinoline alkaloid scolopendrine was isolated from the centipede, Scolopendra subspinipes mutilans L. Koch. The structure was determined to be 2-hydroxy-7-[(4-hydroxy-3-methoxyphenyl)methyl]-3-methoxy-8-quinolyl sulfate on the basis of high-resolution electron-spray ionization mass spectroscopy and two-dimensional NMR spectral data. Unlike quinoline alkaloids so far reported, scolopen...

Berberine azide, berberine thiocyanate, and 8-cyano-8H-berberine were prepared from berberine chloride, a quaternary protoberberine alkaloid. The molecular and crystal structures of all compounds are reported and discussed.

A new diketopiperazine alkaloid named spirotryprostatin K (1), and five known alkaloids, spiro[5H,10H-dipyrrolo[1,2-a:1',2'-d]pyrazine-2(3H),2'-[2H]-indole]-3',5,10(1'H) trione (2), 6-methoxyspirotryprostatin B (3), pseurotin A (4), N-β-acetyltryptamine (5), and lumichrome (6) were isolated from the endophytic fungus Aspergillus fumigatus. The structure and the absolute configuration of spirotr...

THE TITLE COMPOUND [SYSTEMATIC NAME: (1S,4S,5R,7S,8S,9R,10R,11S,13S,14S,16S,17R)-N-methyl-8,14-dihy-droxy-1,16-tri-meth-oxy-4-(meth-oxy-methyl-ene)aconitane], C(24)H(39)NO(5), was isolated from the roots of Aconitum carmichaelii Debx., which is known as 'Chuanwu' in Chinese traditional herbal medicine. The mol-ecule has an aconitane carbon skeleton with four six-membered rings and two five-memb...

The asymmetric formal synthesis of schulzeines A and C is described. Key features of the synthesis include the efficient and stereoselective construction of the benzoquinolizidine skeleton via the aza-Claisen rearrangement-induced ring expansion of the 1-vinyl-N-glycyl-isoquinoline, which was prepared by the highly enantioselective asymmetric allylation of the 8-benzyloxy-substituted dihydroiso...