Tylophora crebriflora

Tylophora crebriflora S. T. Blake (T. floribunda Benth.) occurs in North Queensland. Extraction of the plant material with hot methanol afforded the crude mixture of alkaloids which was purified by chromatography on cellulose powder using propanol-2 N acetic acid as the eluent. Further purification by repeated chromatography yielded tylophorine (Bf 0.5 in butan-l-ol-acetic acid 97 3) and tylocrebrine (R 0.2 in the same solvent system) (mp 218°-220° [a] D — 45° + 2° (c 0.1, CHCI3). (+ )-Tylocrebrine isolated from Ficus septica Forst. f. was found (4) to have mp 220°-222° and [a] f + 20.5° + 2° (c 0.8, CHCI3). 

In addition to benzylisoquinolines, the family Lauraceae furnishes phenanthro-quinolizidine alkaloids such as the previously mentioned cryptopleurine (31) [77], a highly cytotoxic and vesicant substance first isolated from Cryptocarya pleurosperma [78]. These alkaloids are closely related structurally to the phenanthroindolizidines, a group of bases found in the families Asclepidaceae and Moraceae that are likewise vesicant. An example is tylocrebrine (56), which is elaborated by a Queensland plant from each family, Tylophora crebriflora [79] and Ficus septica [80], respectively. In the latter it occurs along with the seco analogue septicine (57), its presumed biosynthetic precursor. Apart from phenanthroindolizidines, certain Ficus spp. produce some simple pyrrolidine bases such as ficine (58) that are noteworthy because of their flavonoid substituents [81],... 

The constituents of Tylophora crebriflora S. T. Blake have also been reexamined and, in addition to tylocrebrine (32) and tylophorine, a total of six alkaloids has been isolated.14 Of these, Alkaloid F is septicine,15 and the remainder (Alkaloids A—E) are new. 

Systematic fractionation of an extract of Tylophora crebriflora has furnished six new alkaloids related to tylophorine (Ilia) which possess antitumour activity [37]. These alkaloids and several known phenanthroindolizidines have been tested against a number of experimental neoplasms [38]. Tylo-crebrine (Illb) is active against Ca 755, Murphy Sturm Lymphosarcoma, P-388 lymphocytic leukaemia and L 1210 tylophorine (Ilia) against... 

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