Phytochemistry of Tinospora cordifolia by Brijesh Kumar Vikas Bajpai and Nikhil Kumar

Author:Brijesh Kumar, Vikas Bajpai and Nikhil Kumar
Language: eng
Format: epub
Publisher: CRC Press
Published: 2020-07-15T00:00:00+00:00

2.18 Benzylisoquinoline Alkaloids

In TCS, three compounds (at peaks 7, 10 and 12) showed characteristic fragments of benzylisoquinolines. Peak 7 at m/z 272.1271 produced fragment ion at m/z 255.0926 due to loss of methylamine and the most prominent benzylic cleavage fragment ion at m/z 107.0503 and isoquinoline fragment ion at m/z 164.0678. On the basis of the previous reports and recorded MS/MS pattern, peak 7 was identified as the norcoclaurine which is the prototype of the benzylisoquinoline group of alkaloids. Peak 10 was identified as reticuline at m/z 330 (C19H23NO4). Loss of CH3NH2 (m/z 299.1273) followed by CH3OH (m/z 267.1002), the isoquinoline fragment (m/z 192.1019) and the benzylic cleavage fragment (m/z 137.057) supported the identification (Sarma et al., 1998).

The exact mass and molecular formula (m/z 314.1752, C19H24NO3+) of peak 12 corresponded to that of oblongine. Its MS/MS spectrum showed a prominent ion at m/z 58.0663 by RDA fragmentation having a formula [C3H8N]+ due to [(CH3)2N=CH2]+, thereby showing the presence of two methyl groups on the nitrogen. Elimination of (CH3)2NH from [M]+ resulted in the fragment at m/z 269.1176, which further loses CH3OH to yield the fragment at m/z 237.0906. Minor fragment ions at m/z 175.0763, m/z 143.0496, and 145.0620 were supported by available literature (Nair et al., 2006; Peer and Sharma, 1989).

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