Abuta alkaloids from

Cometa MF, Fortuna S, Palazzino G, Volpe MT, Salgado ER, Nicoletti M, et al. New cholinesterase inhibiting bisbenzyhsoquinoline alkaloids from Abuta grandifoha. Fitoterapia 2012 83(3) 476-80. 

Swaffar DS, Holley CJ, Fitch RW, EUdn KR, Zhang C, Sturgill JP, et al. Phytochem-iocal investigation and in vitro cytotoxic evaluation of alkaloids from Abuta rufes-cens. Planta Med 2012 78(3) 230-2. 

Skiles JW, Saa JM, Cava MP 1979 Splendidine, a new oxoaporphine alkaloid from Abuta rufescens Aublet. Can J Chem 57 1642-1646... 

Abd El Kawi M (1983) Isolation and structure elucidation of alkaloids from Indian and Sri Lankan Pachygone ovata Miers (Menispermaceae). Ph D Dissertation, Univ Pittsburgh, 288 pp Ahmad R, Cava MP (1977) Grisabine and grisabutine, new bisbenzylisoquinoline alkaloids from Abuta grisebachil J OrgChem42 2271-2273... 

Full understanding is hampered by current deficiencies in our knowledge of the chemical composition of the plants concerned—for tubocurarine has so far only been found in Chondrodendron tomentosum—yet, as demonstrated by the curare formulas given in Section 1.2.3.1, there are curares from regions 2 and 3 that do not have this species as an ingredient, so that their muscle-relaxant activity must be due to alkaloids from other plants, e.g. Abuta (cf. Section 1.4.6.4) or Cur area species. 

Chloroform adducts 190a and 190b of berberine (15) and palmatine (64) are well known. Column chromatography of palmatine-chloroform 190b on silica gel with chloroform-methanol gave saulatine (192) (Scheme 34). This alkaloid and its analog puntarenine (191) had been isolated from Abuta bullata (108) and B. actinacantha (109), respectively, but have now been shown to be artifacts (107). 

Two related alkaloids, grisabine (53 R = Me) and grisabutine (53 R = H), have been isolated from Abuta grisebachii Triana et Planchon. Their structures were determined by splitting the diphenyl ether linkage with sodium-liquid ammonia ... 

A new oxoaporphine alkaloid is oxostephanine (38) from Stephania japonica. Imerubrine, found together with a variety of oxoaporphines and azafiuoranthenes in the South American vines Abuta imene and A. rufescens has been tentatively... 

Saulatine (35) is the only alkaloid of the isohomoprotoberberine type found in one South American Menispermaceae, Abuta bullata, collected from Guyana [23]. Homologation of protoberberine is thought to be the biogenetic pathway for the formation of this compound. 

There are only three alkaloids in this small subgroup, and all are derivatives of the monophenolic [C(12)], monosecondary [N(2)] alkaloid peinamine (71a) which has only been isolated from Abuta grisebachii (Menispermaceae). The other two alkaloids are 7-0-demethylpeinamine (60a) and N-methyl-7-O-demethylpeinamime (66b), both being metabolites of the same plant as above. In addition, the latter has been isolated from Pachygone dasycarpa (Menispermaceae). 

The unusual alkaloids imeluteine (99) and rufescine (100), found in Abuta imene and A. rufescens, probably originate biogenetically from decarbonylation of oxo-aporphine precursors. Such an in vivo pathway is supported by the observation that Abuta imene also produces the oxoaporphine homomoschatoline (1,2,3-trimethoxyoxoaporphine). It is unlikely, on the other hand, that azafluoranthenes... 

Azafluoranthenes.—Two alkaloids of a novel type are imeluteine (234) and rufescine (235), isolated from the Amazonian vines Abuta imene and A. rufescens (Menispermaceae). The structures of both alkaloids were confirmed by synthesis using the Bischler-Napieralski and Pschorr sequences. 

This type of alkaloid has so far been found only in the family Menispermaceae. It is a good chemical marker for the mily, but so far, alkaloids of this type have been isolated only from the genera Abuta and Cissampelos. 

The first TROPOL was imerubrine, isolated by Cava et al. from Abuta imene (38). In that paper, the chemical structure was erroneously assigned as an oxoaporphine. Later when the same authors isolated a second TROPOL (grandirubrine) from Abuta grandiflora (39), this new type of alkaloid was established. 

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