Uniquely identifiable characteristics
Distinguishing Feature :
No relation to : Rue or Goat's-Rue (Galega officinalis) nor Meadowsweet (Filipendula ulmaria) nor to Meadow-Foam (Limnanthes douglasii) [plants with similar names but which belong in differing families]. Nor is it related to Wall-rue (Asplenium ruta-muraria) which is a fern.
Somewhat surprisingly, both Common Meadow-Rue and Lesser Meadow-rue are members of the Buttercup Family.
Leaves reminiscent of those of Maidenhair Fern the garden plant. The plant is very variable and stands between 25cm to a metre tall, often zig-zagging on its thin and wiry stems. It grows on shingle or gravelly coastal shores and on coastal dunes, limestone rocks, mountain ledges and grassland. It is a garden plant that is widely naturalised, found here on MOD firing range land backing onto houses.
It is a very variable plant and some botanists have divided it into 9(!) different species, whilst others have divided it up into only 3 sub-species. But Clivbe Stace much more recently (2019) thinks it should be treated as just one species, albeit one that is very variable, with which a second botanist, Hilary Perry (who wrote a thesis on Lesser Meadow-rue in 1974) now agrees (in 2020) [at least those growing in the UK].
All parts of the plant are toxic and contains several alkaloids - Thalicmine , Thalicminine , Thalmidine , Thalmine , Thalictrimine , Thalicarpine , Thaliflavidine Magnoflorine, Glaucine, Berberine and Agrimoniin, a tannin.
Many of the above secondary metabolites (but not all) are IsoQuinoline or BisBenzylIsoQuinoline or aporphine or quaternary ProtoBerberines alkaloids - similar, but not identical, to those found in Common Meadow-Rue or many Poppies.
BENZYLISOQUINOLINE and BIS-BENZYLISOQUINOLINE ALKALOIDS
All parts of the plant are toxic and contain several toxic alkaloids - Thalicmine , Thalicminine , Thalmidine , Thalmine , Thalictrimine , Thalicarpine , Thaliflavidine (some of which which your Author cannot find on the internet, namely the latter), Magnoflorine, Glaucine, Berberine and Agrimoniin, a tannin (which is not an alkaloid).
Many of the above secondary metabolites (but not all) are BenzylIsoQuinoline or BisBenzylIsoQuinoline or Aporphines - being similar, but not identical, to those found in Common Meadow-Rue or in some Poppies.
Both Thalicmine and Thalicminine are Aporphine alkaloids.
Thalocarpine is the merger of an aporphine alkaloid (topmost moiety) with another aporphine moiety (albeit, one that has a broken central ring and is drawn the other way up).
Bisbenzylisoquinolines are two (hence the 'bis') conjoined Aporphines (aka BenzylIsoQuionoles ). They can be conjoined in numerous contorted ways which gives them more of a 3-D (non-planar) structure and thus more likely to interact (adversely) with biologically important molecules within mammals (or other forms of life) with normally dire consequences for the recipient. Thalmine and Thalmidine are two such examples found in Lesser Meadow-Rue. There are others, but your Author could not find chemical structural formulae for them; mostly because they seam to have chemical synonyms, and it is those beginning with 'thal' which are the much less well known synonyms - but your Author lacks a name-comparison table, so is unable to find them.
Thalictrimine is one such BisBenzylIsoQuinoline Alkaloids which has a synonym which is now known to your Author: α-AlloCryptopine. This example has a cross-bond missing and can be drawn in several differing ways because it has a 10-membered ring, which does not necessarily adopt this twin hexagonal configuration. It could adopt a large ring shape instead, or any other shape. Collectively, they are called Protopine BisBenzylIsoQuinolines, with or without the (missing here) cross-link. Thalictrimine , besides α-AlloCryptopine has a third alias: β-Homochelidonine.
Allo, in a chemistry context, refers to a geometrical isomer, such as occurs between Cryptopine and AlloCryptopine. The former has the =O moiety nearer to the two dangling CH3-O- bonds than the N-CH3 moiety, whereas in AlloCryptopine the =O moiety is closer to the other end of the molecule.
Another way of looking at it is that the two outer moieties have swapped places.
[As far as your author knows, Cryptopine does not occur in Lesser Meadow-Rue, but AlloCryptopine does].
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