Studies on the Alkaloids of Rhazya stricta

Journal of Natural Products
1986.0

Abstract

Continuing our investigations (1-7) on Rhazya stricta Decsne. (Apocynaceae) (8), we describe here the isolation from the roots and identification of a dimeric indole alkaloid, didemethoxycarbonyltetrahydrosecamine (DDCTHS). Condylocarpine was also isolated from the leaves. DDCTHS was obtained as a colorless, amorphous material that gave a light yellow color with CeSO4 solution. The UV spectrum was characteristic for the indole chromophore, and its IR spectrum did not show any peak in the carbonyl region. Accurate mass measurements afforded the exact mass to be 564.4141, corresponding to the molecular formula C38H52N4. The 1H-NMR spectrum was identical to that reported for DDCTHS (9-12). The alkaloid probably arises in the plant by hydrolysis and decarboxylation of tetrahydrosecamine (THS), and it has been previously prepared synthetically from THS and demethoxycarbonyltetrahydrosecamine (DCTHS) by this procedure (9-11). Condylocarpine was isolated as an amorphous material which gave a blue color with CeSO4 solution. The UV spectrum was characteristic for the anilinoacrylate chromophore. Its spectrum showed the presence of an α,β-unsaturated ester. The molecular formula was established by HRMS to be C20H22N2O2 (calcd. 322.1681; obsd. 322.1671). On the basis of comparison of NMR and other spectral data with the earlier reported values (13,14), the alkaloid isolated was identified as condylocarpine. Condylocarpine has been reported earlier from Diplorhynchus condylocarpon (15) but has not been isolated from R. stricta. In a program (1) to screen high altitude (above 3200 m) plants of Himalayan glacier areas for active medicinal compounds and to investigate such plants chemically, Heracleum brunonis Benth. (Umbelliferae) was collected and found to be rich in furanocoumarins. Four known furanocoumarins have been isolated and identified.

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