Strychnos 1990 - 2004 - Crops for the Future

Author
Title
Year
Source title
Reference
Bennasar, M. L., E. Zulaica, A. Ramirez and J. Bosch
Synthetic efforts toward akuammiline alkaloids from tetracyclic 6,7-seco derivativ
1996
Journal of Organic Chemistry
61(4): 1239-1251
Abstract
The addition of enolates derived from indole-3-acetic esters 1-3 to pyridinium salts 4, 23, and 24,
followed by acid cyclization of the resulting 1,4-dihydropyridines, leads to tetrahydro-1,5-
methanoazocino[3,4-b]indoles 5-7, 25-27, which have been subsequently elaborated into 4Eethylidene(or
4 alpha-ethyl)-hexahydro-1,5-methanoazocino[3,4-b]indoles. Closure of the sixmembered
C ring of akuammiline alkaloids by formation of C-6/C-7 bond from appropriately N-(b)-
substituted derivatives of these tetracyclic ABDE substructures has been extensively investigated. In
the N-unsubstituted indole series, both cyclization of thionium ions generated either by Pummerer
reaction from sulfoxide 16 or by DMTSF treatment of dithioacetal 36 and photocyclization of
chloroacetamide 47 occur upon the indole nitrogen to give pentacycles 18, 38, and 49, respectively.
When the indole nitrogen is blocked by a substituent, the thionium ions derived from sulfoxides 17
and 43 and dithioacetals 37 and 44 do not cyclize and lead to different products depending on the
reaction conditions, whereas chloroacetamides 48 and 51 undergo a reductive photodehalogenation.
Attempted radical cyclization of seleno derivatives 53, 55, and 56 under a variety of conditions gives
the corresponding reduced products. Finally, attempted photoisomerization of 1-acylindole 62 leads
t o t h e N - ( b ) - m e t h y l t e t r a c y c l e 6 3 .
Author
Title
Year
Source title
Reference
Bonjean, K. A. P. M., M. C. A. J. dePauwGillet, J. QuetinLeclercq, L. Angenot an
In vitro cytotoxic activity of two potential anticancer drugs isolated from Strychno
1996
Anticancer Research
16(3A): 1129-1137
Abstract
The cytotoxicity and the selective antiprotozoal activity of some Strychnos alkaloids, namely
strychnopentamine (SP) and usambarensine (US) (7) led us to analyze and compare their effects with
emetine (EM) by using mouse B16 melanoma cells cultivated in vitro. We observed by cytological
analysis and proliferation rate studies that these substances induce analogous cytotoxic effects in
B16 cells, but at different concentrations i.e. formation of lamellar bodies in the cytoplasm, the
which contain pre-melanosomes in the case of SP and US, vacuoles and blebs. At concentrations
near their respective IC50, SP and US, but not EM, decreased colony formation. We showed by
incorporation of labelled precursors that SP and US first inhibit RNA synthesis while EM initially
acts on protein synthesis. These alkaloids increased melanin synthesis. Furthermore, only EM and
SP caused hemolysis of sheep red blood corpuscles. This could explain why the rate of
antiplasmodial activity is higher for SP and EM.