Tylophora alkaloids

The phenanthroindolizidine alkaloid (-)-tylocrebrine has been shown to have the S configuration, like (-)-tylophorine, from a study of the o.r.d. and c.d. spectra of these two alkaloids and of the phenanthroquinolizidine alkaloid cryptopleurine.  

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Tylophorine (1) and its analogs, the phenanthroindolizidine alkaloids also referred to as tylophora alkaloids, have been isolated primarily from plants of the family Asclepiadaceae [13-16], Fig. (1), including members of the genus Tylophora, Vincetoxicum, Pergularia, Cynanchum, but also from Hypoestes verticillaris (Acanthaceae) [17], Cryptocarya phyllostemmon (Lauraceae) [18], Ficus hispida and F. septica (Moraceae) [2, 19]. TTie isolations of these alkaloids are summarized in Table 1. The most significant phenanthroindolizidine alkaloids are tylophorine (1), tylocrebrine (2), antofine (3), and tylophorinine (4), Fig. (2). 

Reagents anef Conditions i BuLi, nil Vyg C, ii a Cl jCOOll, CH2CI2 b NaBH, MeOII iii (CH20)n, HCl, EtOH Scheme (7), Lebrun et al. approach to total Rynthesis of racemic tylophora alkaloids... 

Ganguly et al. [93] demonstrated that (unspecified) tylophora alkaloids could induce apoptosis in a human erythroleukemic cell line (K562) on the basis of nuclear condensation, apoptotic body formation, flipping of membrane phosphatidylserine, activation of caspase 3 and release of mitochondrial cytochrome c. These findings suggest that tylophora alkaloids, in addition to their antiproliferative activity, can also induce apoptosis in certain types of tumor cells. 

Tylophora Alkaloids.—Administration of [2- C]tyrosine to Tylophora asthma-tica was followed by the isolation of radioactive tylophorine (51) and tylo-phorinine (52). Degradation of the former indicated an exclusive incorporation of the label at in (51). It is perhaps surprising that one rather than two tyrosine units is apparently involved in the biosynthesis of tylophorine, but on the other hand the tracer experiments on these alkaloids have only just begun. 

Pinidine and Coniine Nicotiana Alkaloids yV-Methylpelletierine Lycopodium Alkaloids Lyduraceae Alkaloids Pyrrolizidine Group Tropane and Pyrrolidine Alkaloids Quinoline and Acridme Alkaloids Benzodiazepine Alkaloids Tylophora Alkaloids Cactus Alkaloids Ephedrine... 

ISOLATION OF TYLOPHORA ALKALOIDS FROM MEDICINAL PLANTS... 

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