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Isothebaine, biosynthesis

In contrast to the formation of isothebaine by a route involving a dienone, an alternative process is implicated in the biosynthesis of another aporphine alkaloid. Bulbocapnine (78) has been shown to be derived from reticuline (75). The methylation pattern of reticuline implies a direct ortho-ortho phenol coupling in which corytuberine (77) is the first alkaloid to be formed. Further experiments have been directed towards distinguishing this mode of coupling from an alternative pathway which involves hydroxylation of reticuline at C-6 and formation of bulbocapnine via a biologically unknown dienone type (76, Scheme... [Pg.21]

The biosynthesis of aporphine alkaloids takes the course—laudanoso-line, norlaudanosoline, reticuline, or orientaline—by means of phenolic oxidation via the cyclohexadienone proaporphine (27, 28, 39, 40, 47, 49, 65, 66, 68, 69,147,148,150, 229, 231, 240, 250, 275, 349, 445, 451, 512) after dienone-phenol or dienol-benzene rearrangement, as described in more detail in the preceding section. The foregoing results, considered as a whole (39,49), provide good evidence that isothebaine is biosynthesized in P. orientale along the following pathway ... [Pg.362]

Two sets of P. orierUale plants were fed separately, one with doubly labeled orientaline and the other with 3A C-reticuline. The former batch of plants afforded radioactive isothebaine (1.6% incorporation) and negligibly active thebaine (<5xl0 % incorporation) whereas the latter batch gave a reverse result. From these, the thebaine was active (0.2% incorporation) and the isothebaine was virtually inactive (<7x 10" % incorporation). Clearly both alkaloids are being biosynthesized at the time of these experiments and the results show that no significant conversion of isothebaine into thebaine occurs. These experiments also demonstrate that biosynthesis in the oriental poppy is directed to different final skeletons at least in part by O-methylation (39). [Pg.366]

No doubt exists as far as the pathway A in Scheme 12 is concerned, though cyclohexadienone could not be demonstrated as an intermediary product (pathway B) of this biosynthesis. Experiments with labeled compounds have also shown that, during the biosynthesis of isothebaine (25b), the plant utilizes in the first place orientaline (7s) and only then the two isomers of orientalinone 258, 456). Blaschke s results 467, 468) are confirmed by... [Pg.420]

Aporphine Alkaloids.—Isothebaine (65) derives from orientaline (62) along a pathway which involves thedienone(63)and the dienol(64). The biosynthesis of the aporphine alkaloids of Dicentra eximia is quite different but dienone intermediates are also implicated. By comparison the biosynthesis of bulbocapnine (66) is simple, for the alkaloid arises directly from reticuline (67), in Corydalis cava, by ortho-ortho phenol oxidative coupling. [Pg.15]

Mecambrine exhibits antihistaminic and hypertensive properties, is toxic with an LD50 (mouse p.o.) of 4.1 mg/kg. Pronuciferine shows potent local anesthetic activity. Orientalinone is an intermediate in the biosynthesis of isothebaine. [Pg.514]

The importance of 0-methylation pattern in deciding the course of coupling is well illustrated by results of a study on the biosynthesis of thebaine 6.151) and isothebaine 6.135) which are both natural constituents oiPapaver orientale. Whereas reticuline 6.127) is modified to give thebaine 6.151) (Section 6.3.4) orientaline 6.132) differing from reticuline in the location of one methyl group, has a quite different fate in isothebaine 6.135). In other cases a precursor, with the wrong methylation pattern, fails to yield alkaloid. [Pg.117]

Because the benzylisoquinoline skeleton derives from tyrosine 6.94) which has a phenolic hydroxy-group at C-4, the aporphines should have hydroxy-groups at equivalent positions. Isothebaine 6.135) lacks such a group at one expected site, C-10. It follows that a hydroxy-group is lost from this site in the course of biosynthesis, plausibly via dienol-benzene rearrangement in 6.134) (see Section 1.3.1). This suggests the route shown in Scheme 6.26, which experiments have shown is correct [92]. Orientaline 6.132), and the key... [Pg.117]

The importance of a particular 0-methylation pattern in deciding the product of coupling is illustrated in an excellent way by the results of a study on the biosynthesis of thebaine (35) and isothebaine (39) in Papaver orientale. Thebaine (35) is formed via reticuline (25) but not via orientaline (36), whereas the reverse is true for isothebaine (39) it is derived exclusively via orientaline (36) (Battersby et al. 1965) (Fig. 7). [Pg.218]

Battersby AR, Brown RT, Qements JH, Iverach GG (1965) On the biosynthesis of isothebaine. J Chem Soc Chem Commun 230-232... [Pg.227]

Battersby AR, Brocksom TJ, Ramage R (1969) Further studies on the synthesis and biosynthesis of isothebaine. J Chem Soc Chem Commun 464-465 Battersby AR, McHugh JL, Staunton J, Todd M (1971) Biosynthesis of the apparently directly coupled aporphine alkaloids. J Chem Soc Chem Commun 985-986 Battersby AR, Herbert RB, Pijewska L, Santavy F, Sedmera P (1972a) Alkaloid biosynthesis, part XVII. The structure and chemistry of androcymbine. J Chem Soc Perkin Trans 1 1736-1740... [Pg.227]


See other pages where Isothebaine, biosynthesis is mentioned: [Pg.218]    [Pg.218]    [Pg.167]    [Pg.366]    [Pg.3]    [Pg.87]    [Pg.420]    [Pg.11]   
See also in sourсe #XX -- [ Pg.218 ]




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