Rhazya orientalis

The enzyme responsible for the stereospecific condensation of trypt-amine and secologanin 34) was called strictosidine synthase, and its presence was demonstrated by Treimer and Zenk 194) in a number of indole alkaloid-producing plants, including Amsonia salicifolia, Catharanthus roseus, Ochrosia elliptica, Rauwolfia vomitoria, Rhazya orientalis, Stem-madenia tomentosa. Vinca minor, and Voacanga africana. Enzyme activity as high as 1698 pkat/mg protein was observed for O. elliptica. No... 

Rhamnosyl(l 6)[rhamnosyl(l — 2)(3"- -p-coumaroylgalactoside)]-7-rhamnoside 3-Rhamnosyl(l 6)[rhamnosyl(l — 2)(4"- -p-coumaroylgalactoside)]-7-rhamnoside Rhazya orientalis aerial parts Apocynaceae 359... 

Rhamnosyl(l 6)[rhamnosyl(l 2) Rhazya orientalis aerial parts Apocynaceae 359... 

Isolation of the stereospecific strictosidine s)mthase (STS) and formation of strictosidine with the 3a-(S) configuration proved conclusively that this was the natural precursor of the terpenoid indole alkaloids. Strictosidine occurs naturally in Rhazya stricta and the synthase has been isolated from a number of other species Amsonia salicifolia, A. tabemaemontam, Catharanthus pusillus, C. roseus, Rauvolfia verticillata, R. vomitoria, R. serpentina, Rhazya orientalis and Voacanga africana. The enzyme has been purified to homogeneity from R. serpentina (Hampp and Zenk, 1988). A comparison of the activity of STS from C. roseus roots, the only portion of the plant to contain ajmalicine, with that present in plant cell cultures producing the same alkaloid demonstrated that the plant cell cultures are far more metabolically active (Ziegler and Facchini, 2008). 

L-Tryptophan was shown to be incorporated with high efficiency into 5a-carboxystrictosidine (33a) in Rhazya orientalis, from where it was originally isolated. It joins the small group of indole alkaloids which retain the carboxyl of precursor tryptophan. The di-acid (33c) and the acid (33b), corresponding to strictosidine, were also isolated in this study. 

Strictosidine (104) is produced by the plant Rhazya stricta. A crude enzyme preparation from the plant was used to produce labelled strictosidine this, when incubated with Catharanthus enzyme, again gave the three alkaloids (105), (106), and (107). ° Cell-free preparations of cell-suspension cultures of Amsonia tabernaemontana, Rhazya orientalis, and Vinca minor were also observed to convert (102) plus (103) into strictosidine (104) with fair efficiency the formation of vincoside (109) was never observed. ... 

Even closer to the postulated biogenetic intermediate are the structures of a group of alkaloids isolated from Rhazya stricta and/or R. orientalis. These are four monomers,derivatives of secodine (SD) (125a), and two dimeric groups, one based on presecamine (126) and the other on secamine " (127). ... 

Three new Rhazya alkaloids possessing the general structure of a hypothetical intermediate which could bridge the major types of Indole alkaloids have been obtained from R. stricta and R. orientalis tetrahydro-(4) and dihydrosecodine (5) from the first species, and tetrahydrosecodine (by dilution analysis)and tetrahydrosecodin-17-ol (6) from the second. 

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