Strychnos 1990 - 2004 - Crops for the Future

Author
Title
Year
Source title
Reference
Wins, P., I. Margineanu, J. Penelle, L. Angenot, T. Grisar and L. Bettendorff
Bisindole alkaloids from Strychnos guianensis are effective antagonists of nicotini
2003
Naunyn-Schmiedebergs Archives of Pharmacology
367(3): 253-259
Abstract
Several mono- and bisindole quaternary alkaloids isolated from the stem bark of Strychnos
guianensis have recently been shown to be effective blockers of neuromuscular transmission in mice.
In this study, we used a human clonal cell line (TE671) expressing muscle-type nicotinic
acetylcholine receptors. The agonist carbamylcholine activated a receptor-mediated Rb-86(+) efflux
and this activation was antagonized by the indole alkaloids, the most active being bisindole
bisquaternary compounds. The most effective antagonist, guiachrysine, had an IC50 around 0.43
muM in the presence of 0.5 mM carbamylcholine, compared to 0.16 muM for d-tubocurarine, the
most potent curarizing alkaloid. Guiaflavine and 5',6'-dehydroguiaflavine were slightly less effective.
Monoindole compounds were 10 to 100 times less potent than bisindole alkaloids. Kinetic analysis
showed that the inhibition of the carbamylcholine-dependent Rb-86(+) efflux by guiaflavine was of
mixed competitive and uncompetitive type. The competitive component (K-I = 0.21 muM) is
presumably due to binding at the acetylcholine site, while the uncompetitive component (K'(I) = 0.92
m u M ) m a y b e d u e t o o p e n c h a n n e l b l o c k .
Author
Title
Year
Source title
Reference
Zlotos, D. P.
Iso-caracurine v, a novel unexpected decomposition product of caracurine v
2003
Journal of Natural Products
66(1): 119-120
Abstract
The structure of iso-caracurine V (3), an unexpected decomposition product of the Strychnos
alkaloid caracurine V (1), was determined by NMR spectroscopy. Compound 3, which was probably
previously regarded as bisnortoxiferine I (2), is a one-sided ring closed product of 2.