The work embodied in the present thesis consists of two parts. Part A describes the phytochemical studies in the chemical constituents of plumeria otusa and part B deals with the structure and activity relationship studies in the harmine series of alkaloids.
PART A The neutral and the acidic fractions obtained on work-up (scheme i) of the methanolic extract of fresh,underied and uncrushed leaves of plumeria obtuse (Apocynacease) were subjected to chemical investigations . The neutral fraction was divided into petrol soluble (N-1), petrol EtOAc (7.3) soluble (N-2) petrol. EtOAo(1:1) soluble(N.3) and petrol EtOAc(1:1) insoluble (N-4) fractions (Scheme I and ii) Work on the neutral fraction N-2 led to the isolation of a newlupane triterpenoid (1) along with the five known (2.6)compounds noted below, which are reported for the first time from this source.
Obtusalin (1) Betutinic acid (2) Oleanolic acid (3) Ursolic acid (4) Kaneroside (5) Oleandrin(6)
The neutral fraction N-3 afforded ten new compounds (11-13,15-19,22,23) besides eight known compounds (7-10,14,20,21,24) isolated for the first time from this species :
a-Amyrin (7) Neriucoumaric acid (8) isoneriucoumaric acid (9) Alphitolic acid (10) Obtusin (11) Oytusinin(12) Obtusllin (13) 3b.23-Dihydroxyurs 12-en.28 oic acid (14) Obtusidin (15) Obtusidin (16) Obtusidin (17) Obtusidin (18) Obtusidin (19) 27.p-Z.Coumaroytoxyursolic acid (20) 27.p-E.Coumaroytoxyursolic acid (21) Coumarobtusanoic acid (22) Coumarobtusane (23) Oleanonic acid (24)
The investigation of the neutral fraction N-4 resulted in the isolation of a new compound (27) in addition to five known compounds (4,25,26,28,29) reported for the first time from this species. It may be noted that compound 4 was also obtained from fraction N-2, however its yield was greater in fraction N-4 (vide Experimental).
iUrsolic acid (4) iiPlumierde (25) iiiMethyl.p-E-coumarate (26) ivObtusilic acid (27) vPlumieride p.Z-coumarates (28) viPlumieride p.E-coumarates (29)
Phytochemical investigation on the acidic fraction (Scheme ii) of the methanoltic extract of the leaves led to the isolation of two new indoids (31,32) and a known coumarin (30)
Scopoletin (30) 6-0.Acetylptumieride p.E coumrate (31) 6-0.Acetylptumieride p-Z-coumarate (22) PART B
This part of the thesis deals with the structure and activity relationship studies in the harmine series of bases leading to the synthesis of thirteen new B-carboline derivatives (4-7,16-19,21-24,26) and four new tryptamine derivatives (10-13) alongwith several known compounds.The antibacterial activity (Table 6, Table 11 and Table 12) of these compounds and effect on CNS was also determined.
4-Acetyl-11. methoxy 3 methyiene-12 nitro 3,4,5,6 tetrahydro B-carboline (4) 4-Benzyle-11-methoyxoy 3-methylene-12 nitro 3,4,5,6 tetrahydro B-carboline (5) 4-Cinnamoyl-11 methoxy-3-methylene-12 nitro 3,4,5,6-tetrahydro B-carboline (6) 4-Benzenesulfonyl-11 methoxy 3-methylene 12-nitro-3,4,5,6 tetrahydro B-carboline (7) 3-(2-Acetamidoethyl) 2-acetyl-7-methoxy-8-nitroindole (10) 2-Acetyle 3-(2-benzamidoethyl)7 methoxy 8 nitroindole (11) 2-Acetyl-3(2-cinnamidoethyl)7-methoxy-8 nitroindole (12) 2-Acetyl-3(2-benzenesulfonamidoethyl)7-methoxy-8-nitroindole (13) 4-Amyl-11 methoxy 3 methyl-12-nitro-3,4,5,6-tetrahydro-B-carboline (16) 4=Butyl-11-methoxy 3-methyl-12-nitro-3,4,5,6-tetrahydro-B-carboline (17) 11-Methoxy-3 methyl-12 nitro-4 propyl-3,4,5,6-tetrahydro-B-carboline(18) 4-Ethyl-11-methoxy-3-methyl-12-nitro-3,4,5,6-tetrahydro-B-carboline (19) 4-Allyl-11-methoxy-3-methyl-12-nitro-3,4,5,6-tetrahydro-B-carboline (21) 4-Benzyl-11-methoxy-3-methyl-12-nitro-3,4,5,6-tetrahydro-B-carboline (22) 11-methoxy-3-methyl-12-nitro-4(p-nitrobenzyl)3,4,5,6-tetrahydro-B-carboline (24) 1-Methoxy-3-methyl-12-nitro,3,4,5,6.tetrahydro-4(3,4,5-Trimethoxybenzoyl)B-carboline (26) Extensive spectroscopic techniques such as EIMS,FDMS,FABMS,HRMS UV,IR,1H,and 13C-NMR (BB.DEPT)2D-NMR(COSY-45 NOESY,HeteroCOSY J-resolved) and chemical reactions were employed to elucidate the structures of the compounds noted in Part Aand B.
The introduction of part A and B provides a review of the earlier contribution made in the chemistry and pharmacoloby of the genus plumeria and the plant peganum harmala respectively. The biosynthesis of terpenoids with particular reference to monoterpenoids (iridoids) and pentacyclic triterpenoids has also been described.
The work emobided in the present thesis has resulted in ten research papers as listed in the list of publications.