Strychnos 1990 - 2004 - Crops for the Future

More documents

Recommendations

Info

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.
Author Title Year Source title Reference Bonjoch, J., J. Catena and N. Valls Total synthesis of (+/-)-deethylibophyllidine: Studies of a fischer indolization rout 1996 Journal of Organic Chemistry 61(20): 7106-7115 Abstract The total synthesis of (+/-)-deethylibophyllidine is described, proceeding in eight steps from 4- (methoxyphenyl)ethylamine in 5% overall yield (Scheme 6). In terms of sequential annulation, the strategy involves the following operations: E --> DE --> ABDE --> ABCDE (Scheme 1). The key steps in the synthesis are the stereoselective formation of octahydroindol-6-ones by acid treatment of dihydroanisole derivatives, the regioselective Fischer indolization to obtain octahydropyrrolo-[3,2- c]carbazoles, and the tandem process consisting of Pummerer rearrangement upon a beta-amino sulfoxide and thionium ion cyclization upon a beta-indole position of a 2,3-disubstituted indole to generate the quaternary spiro center. Attempts to effect the construction of the pentacyclic framework by means of Fischer indolization of the octahydropyrrolo[3,2,1-hi]indol-6-one resulted in f a i l u r e ( S c h e m e 2 ) . Author Title Year Source title Reference Abstract Bosch, J., J. Bonjoch and M. Amat The Strychnos alkaloids 1996 Alkaloids 48: 75-189 - Author Title Year Source title Reference Abstract Bosch, J., M. L. Bennasar and M. Amat A general method for the synthesis of bridged indole alkaloids 1996 Pure and Applied Chemistry 68(3): 557-560 -
Page 1 and 2:
Strychnos 1990 - 2004 Author Title
Page 3 and 4:
Author Title Year Source title Refe
Page 5 and 6:
Page 7 and 8:
Page 9 and 10:
Page 11 and 12:
Page 13 and 14:
Page 15 and 16: Author Title Year Source title Refe
Page 65: Author Title Year Source title Refe
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
show all

Strychnos 1990 - 2004 - Crops for the Future

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?