This thesis is divided into two parts. Part A describes the isolation and structural studies on the alkaloids from Rhazya stricta, Alstonia macrophylla and Neisosperma oppositifolia.
Phytochemical investigations on the alkaloidal contents of Rhazya stricta have resulted in the isolation of a new alkaloid along with two known bases, one of which is reported for the first time from this species:
N-Methylleuconolam (92) Heterocycles, (submitted for publication) 20 (R)-19,20-Dihydrocondylocarpine (101) Heterocycles, (submitted for publication). Rhazidigenine (102)
Work on the alkaloidal extracts of leaves of Alstonia macrophylla have led to the isolation of a new oxindole alkaloid along with five known alkaloids, two of which are reported for the first time from this species:
i.16-Hydroxy-Nb-demethylalstopylline oxindole (103) Heterocycles, 27(3), 725 (1988). N-Methyl-1,2-dihydrostrictamine (107) Heterocycles, 27(3), 725 (1988). iii.Alstonisine (106 Fitoterapia, 1, 91 (1990). Quebrachidine (109) Fitoterapia, 1,91 (1990) Nb-Demethlalstophylline oxindole (110) Vincorine (111)
Alkaloidal extracts of Neisosperma oppositifolia upon investigation have produced a new oxindole alkaloid along with an oxindole previously known from other sources. Three other known compounds were also isolated:
Neisosposinine (112) Heterocycles, 28(2), 999 (1989). Isocarapanaubine (117) Heterocycles, 28(2), 999 (1989). Isoreserplline (118) Heterocycles, 28(2), 999(1989). Reserpiline (119) Heterocycles, 28(2), 999(1989). Ochroposinine (120) Heterocycles, 28(2), 999(1989).
Part B of this thesis deals with the chemical constituents isolated from Rhazya stricta, Swertia cordata and Primula species:
Lupeol (121) Lupeol-3-O-acetate (122) Β-Sitosterol glucoside (123)
The following two new xanthones have been isolated from Swertia cordiata along with two previously known xanthones:
1-Hydroxy-3,5,7,8-tetramethoxyxanthone (124) J. Nat. Prod. (accepted for publication). ii.1,7-Dihydroxy-3,5,8-trimethoxyxanthone (125() J. Nat. Prod. (accepted for publication). iii.1,5,8-Trihdroxy-3 methoxyxanthone (126) 1,5-Dihydroxy-3-methoxy-8-O-glcosylxanthone (127)
Phytochemical investigation on Primula denticulate have resulted in the isolation of the new flavone:
5,6-Dihydroxyflavone (128) J. Nat. Prod. (accepted for publication).
Extensive spectroscopic techniques such as EIMS, FDMS, FABMS, HRMS, UV, IR, FTIR, 1H and 13C-NMR (BB, DEPT, COSY-45°, J-resolved, NOE difference, hetero-COSY, HMBC and HMQC) were employed to elucidate the structures of the above compounds.