Search

A new N -oxide, Pseudolycorine N -oxide ( 1 ) was characterised along with eleven known alkaloids homolycorine ( 2 ), O -methylmaritidine ( 3 ), 8- O -demethylhomolycorine ( 4 ), homolycorine N -oxide ( 5 ), lycorine ( 6) , narciclasine ( 7 ), pseudolycorine ( 8 ), ungeremine ( 9 ), 8- O -demethylmaritidine ( 10 ), zefbetaine ( 11 ) and lycorine N -oxide ( 12 ), from Narcissus tazetta . Their structures were established on the basis of spectroscopic data analysis. The extract, fractions and isolated compounds were screened for in vitro cytotoxicity against two human cancer cell lines, human cervical cancer (SiHa) and human epidermoid carcinoma (KB) cells. The study demonstrated the cytotoxic potential of extract and its chloroform and n -butanol fractions. Further, the results revealed the bioactive potential of narciclasine, pseudolycorine and homolycorine alkaloids. However, new N -oxide ( 1 ) was not active against these cell lines.

This phytochemical study of stems and leaves of Erythrina stricta led to the isolation of twenty-three alkaloids, one of them previously unreported, 11 β -hydroxyerythratidine N -oxide. Their structures were elucidated on the basis of extensive 1D and 2D NMR spectroscopic analyses including HSQC, HMBC, 1 H- 1 H COSY, NOESY, as well as HRESIMS data in addition to comparison with reports in the literature.

Two new epimeric isopavine N-oxides, amuresinine N-oxide A (1) and B (2), were isolated from Meconopsis horridula var. racemosa. Their structures were elucidated by spectroscopic methods.

The preparation, characterization and chemistry of alkaloid N-oxides is reviewed. Because the literature on amine N-oxides is more extensive for animals than for plants, a brief resumé of the pharmacology, metabolism, and toxicity of N-oxides is given. Some 64 naturally occuring N-oxides representing pyrrolidine-piperidine-, pyrrolizidine-, quinolizidine-, tropane-, isoquinoline-, morphinane-, indole- and miscellaneous-type alkaloids are reviewed. These alkaloid N-oxides are additional to and, in the main, have been isolated since those described in a 1971 review. The earlier review dealt with some 56 naturally occurring N-oxides which represented mainly pyrrolizidine and indole types. The role of N-oxides in plants is discussed.