Biosynthesis of the tropine moiety of hyoscyamine from δ-N-methylornithine

Ahmad, Afzal; Leete, Edward

doi:10.1016/s0031-9422(00)85738-6

Cited by 28 publications

(6 citation statements)

References 14 publications

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“…The increase in total alkaloid contents under salinity is parallel to the accumulation of proline. This could be due to the fact that ornithine, the precursor of alkaloids, and proline have the same precursor namely, glutamic acid (Ahmed and Leete, 1970). Therefore, salinity could inhibit the transamination reactions and hence the glutamic acid is accumulated and transformed to other nitrogenous compounds such as proline and ornithine.…”

Section: Discussionmentioning

confidence: 99%

Seed Priming with Extracts of two Seaweeds Alleviates the Physiological and Molecular Impacts of Salinity Stress on Radish (Raphanus sativus)

Kasim¹,

Saad‐Allah²,

Hamouda³

2016

IJAB

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To cite this paper: Kasim, W.A., K.M. Saad-Allah and M. Hamouda, 2016. Seed priming with extracts of two seaweeds alleviates the physiological and molecular impacts of salinity stress on radish (Raphanus sativus AbstractSeeds of radish were primed with the extract of either Codium taylorii or Pterocladia capillacea for 2 h, then sown in claysandy soil and left to grow under the effect of either 150 or 200 mM NaCl, however the control treatment was irrigated only with tap water, for 35 days. The results indicated that salinity decreased water content, shoot length, photosynthetic pigments and total lipids, while it increased total soluble proteins, proline, phenolic compounds and alkaloid contents. Priming with C. taylorii or P. capillacea alleviated the adverse effects of salinity on radish seedlings. Under 150 and 200 mM NaCl treatments, 5 bands with molecular weights 40, 70, 80, 100 and 171 kDa were newly synthesized as stress proteins, while that of the salt stressed seedlings primed with seaweed extracts showed appearance of four new bands with molecular weights 4, 15, 21 and 44 kDa with C. taylorii and 5, 6, 23 and 149 kDa with P. capillacea. The data of the ISSR analysis produced by five different primers reflected the appearance of seven new bands with the treatment 150 and 200 mM NaCl, and there was a disappearance of eight other bands. Priming of radish seeds with seaweed extract and treated with 150 and 200 mM NaCl resulted in the disappearance of five other bands. It might be concluded that the priming in seaweed extracts could represent a useful and powerful tool in alleviating salinity stress.

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Section: Discussionmentioning

confidence: 99%

Seed Priming with Extracts of two Seaweeds Alleviates the Physiological and Molecular Impacts of Salinity Stress on Radish (Raphanus sativus)

Kasim¹,

Saad‐Allah²,

Hamouda³

2016

IJAB

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“…Oddly the hyoscyamine and scopolamine isolated from these A. belladonna plants, which were fed the '4C-or 3H-ornithines, were unlabeled. [2-14C, N-methyl-14C]-a-N-Methylornithine (25) did not serve as a precursor ofhyoscyamine when fed to Datura stramonium plants (27). When this same compound was fed to tobacco plants (28), the resultant nicotine was labeled at C-2' and C-5' (equal labeling) and on its Nmethyl group.…”

Section: Nh2mentioning

confidence: 97%

“…However the status of this methylated amino acid as an authentic natural product is in doubt. It was found that the administration of [2-14C, N-methyl-14C]-ô-N-methylornithine to Datura stramonium plants (by hydroponics) afforded radioactive hyoscyamine which was labeled at its C-1 and N-methyl positions (the ratio of activity at these two positions was the same as the ratio of the analogous positions in the 5-N-methylornithine (27).…”

Section: Nh2mentioning

confidence: 99%

Recent Developments in the Biosynthesis of the Tropane Alkaloids¹

Leete¹

1990

Planta Med

Self Cite

112

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All the experimental evidence is consistent with the 1-methyl-A 1-pyrrolinium salt (30) being a precursor of the tropane nucleus. The various biosynthetic routes which have been established for its formation are summarized in Fig. 4. Initially it was thought that the double bond in the iminium salt could isomerize between its C-2 and C-5 positions, which would result in the scrambling of any isotopic label (e.g. 14C

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“…The majority of these studies used in vivo feeding of radiolabeled precursors (4)(5)(6) to elucidate the outlines of a general tropane alkaloid biosynthetic pathway (7,8). Biosynthesis is initiated from the polyamine putrescine, which is derived from the amino acids ornithine or arginine (Fig.…”

mentioning

confidence: 99%

Plant tropane alkaloid biosynthesis evolved independently in the Solanaceae and Erythroxylaceae

Jirschitzka

Schmidt

Reichelt

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

101

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The pharmacologically important tropane alkaloids have a scattered distribution among angiosperm families, like many other groups of secondary metabolites. To determine whether tropane alkaloids have evolved repeatedly in different lineages or arise from an ancestral pathway that has been lost in most lines, we investigated the tropinone-reduction step of their biosynthesis. In species of the Solanaceae, which produce compounds such as atropine and scopolamine, this reaction is known to be catalyzed by enzymes of the short-chain dehydrogenase/reductase family. However, in Erythroxylum coca (Erythroxylaceae), which accumulates cocaine and other tropane alkaloids, no proteins of the shortchain dehydrogenase/reductase family were found that could catalyze this reaction. Instead, purification of E. coca tropinonereduction activity and cloning of the corresponding gene revealed that a protein of the aldo-keto reductase family carries out this reaction in E. coca. This protein, designated methylecgonone reductase, converts methylecgonone to methylecgonine, the penultimate step in cocaine biosynthesis. The protein has highest sequence similarity to other aldo-keto reductases, such as chalcone reductase, an enzyme of flavonoid biosynthesis, and codeinone reductase, an enzyme of morphine alkaloid biosynthesis. Methylecgonone reductase reduces methylecgonone (2-carbomethoxy-3-tropinone) stereospecifically to 2-carbomethoxy-3β-tropine (methylecgonine), and has its highest activity, protein level, and gene transcript level in young, expanding leaves of E. coca. This enzyme is not found at all in root tissues, which are the site of tropane alkaloid biosynthesis in the Solanaceae. This evidence supports the theory that the ability to produce tropane alkaloids has arisen more than once during the evolution of the angiosperms.

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Biosynthesis of the tropine moiety of hyoscyamine from δ-N-methylornithine

Cited by 28 publications

References 14 publications

Seed Priming with Extracts of two Seaweeds Alleviates the Physiological and Molecular Impacts of Salinity Stress on Radish (Raphanus sativus)

Seed Priming with Extracts of two Seaweeds Alleviates the Physiological and Molecular Impacts of Salinity Stress on Radish (Raphanus sativus)

Recent Developments in the Biosynthesis of the Tropane Alkaloids¹

Plant tropane alkaloid biosynthesis evolved independently in the Solanaceae and Erythroxylaceae

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Biosynthesis of the tropine moiety of hyoscyamine from δ-N-methylornithine

Cited by 28 publications

References 14 publications

Seed Priming with Extracts of two Seaweeds Alleviates the Physiological and Molecular Impacts of Salinity Stress on Radish (Raphanus sativus)

Seed Priming with Extracts of two Seaweeds Alleviates the Physiological and Molecular Impacts of Salinity Stress on Radish (Raphanus sativus)

Recent Developments in the Biosynthesis of the Tropane Alkaloids1

Plant tropane alkaloid biosynthesis evolved independently in the Solanaceae and Erythroxylaceae

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Recent Developments in the Biosynthesis of the Tropane Alkaloids¹