Dicentrine

D. eximia (Ker) Torr. d-Corydine, cularine, d-dicentrine, eximidine,... 

D. formosa Walp. d-Corydine, corytuberine, eularine, dicentrine... 

Dicentrine, CgoHjjOjN. (Items 36, 37, 39, 40 list, pp. 172-3.) This alkaloid crystallises, from ether, alcohol, or ethyl acetate in prisms, m.p. 168-9° [a]i) + 62-1° (CHCI3), and yields well-crystallised salts. It contains two methoxyl groups and yields a monoacetyl derivative, colourless leaflets, m.p. 202°, which is not hydrolysed even by boiling alcoholic potash. 1 The methiodide, B. CH3I. HjO, has m.p. 224°, and according to Manske, yields a methine base, m.p. 158-9°, the methiodide of which with potassium hydroxide solution decomposes into trimethylamine and a crystalline substance, presumably a substituted phenanthrenyl-ethylene, which polymerises on recrystallisation. 

Taxonomically close to the Annonaceae, the Lauraceae family abounds with apor-phinoid alkaloids. A remarkable advance in the search for topoisomerase inhibitors from Lauraceae has been provided by Woo et al. (6). Using DNA-unwinding assay and structural modeling, they showed that dicentrine can attain a relatively planar conformation and molecular bulk which allow it to occupy the active site of topoisomerase II which becomes inactive. The requirement of a suboptimal conformation to achieve DNA binding appears to make dicentrine less potent against topoisomerase II than the... 

The cytotoxic activity of dicentrine is mediated via inhibition of topoisomerase II (6,7). Dicentrinone from Ocotea leucoxylon is closely related to dicentrine, and even more planar has shown potent topoisomerase I activity (9). 

Cassytha filiformis L., mentioned earlier, contains aporphine alkaloids such as actin odaphnine, cassythine, and dicentrine, which effectively bind to DNA and behave as typical intercalating agents and interfere with the catalytic activity of topoisomerases (3,10,11). 

In the Philippines, the sap expressed from the stem is drunk to alleviate headache. Using antiplatelet aggregation as a guide to fractionation, Chen et al. isolated a series of aporphines including actinodaphnine, N-methylactinodaphnine, launobine, dicentrine, O-methylbulbocapnine, hernovine, bulbocapnine, and oxoaporphines dicentrinone and liriodenine were isolated from the stems of I. luzonensis (13). 

Huang RL, Chen CC, Huang YL, et al. Anti-tumor effects of D-dicentrine from the root of Lindera megaphylla. Planta Med 1998 64 212-215. 

A careful investigation of the alkaloidal content of the Brazilian plant Ocotea minarum (Lauraceae) has led to five new aporphines, namely ocotominarine (3), ocominarine (4), norleucoxylonine (5), iso-oconovine (6), and 4-hydroxy-dicentrine (7).4... 

D-Dicentrine, A-methylnandigerine, A-methylovigerine, and the first natural occurrence of O-methylbulbocapnine (mp 129°-130° Md1 +248°). Some others were not identified dicentrinone was probably present (100). 

The effect of nitrogen quaternization on the chemical shifts of several aporphine alkaloids was studied by Marsaioli et al. (39). The conversion of dicentrine (59) to its methiodide salt (60) caused deshielding of C-5 and C-6a whereas C-3a, C-4, C-7, C-7a, and C-llc were all shielded. The shielding of the aromatic carbon atoms may be caused by the electric field effect similar to that observed in nitrogen protonation (8, 12). C-4 and C-7 were most likely experiencing the y steric effect of the new methyl group. 

Similar treatment of the neoproaporphine-borane complex (24) furnished pre-dicentrine (25), erybidine (26), and 2,9,10-trimethoxy-3-hydroxyaporphine (29). Furthermore, the neospirene-borane complex (30), when subjected to the same experimental conditions, supplied thaliporphine (28), the erybidine isomer (31), and 2-hydroxy-3,9,10-trimethoxyaporphine,1 which does not occur in Nature. 

Dicentrine Hordeum mlgare (barley) DNA (unwinds) (TOPII)... 

Dicentrine Hordeum vutgare (barley) [hypotensive] TOPII (formation of cleavable... 

Dicentrine and Dicentrinone. Dicentrine (283) was synthesized by photo-cyclization of the o-bromo- and chloroenamides 282a and b by Cava et al. (138) the former enamide (282a) was best suited for the synthesis of the alkaloids in view of yield and reaction time (Scheme 103). 

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