Not to be semantically confused with :
Liquorice (Glycyrrhiza glabra) [a plant belonging to a differing genus within the same Pea family having a similar common name]
Some similarities to : another Milk-vetch with whitish-cream (to yellow) flowers
Lesser Milk Vetch (Astragalus odoratus), but that is much shorter, to 30cm, with many more leaflets in a leaf (between 19-29).
Slight resemblance to : Tree Lupin (Lupinus arboreus) but that is woody, usually taller, and has a longer spike of flowers which are more yellow. Also to
Yellow Oxytropis (Astragalus campestris) but that is rarer, much shorter, and has much narrower leaflets which number about 21.
The leaves smell aromatic and sweetish when crushed. The roots are said to be a substitute for liquorice, but not by way of taste! Wild Liquorice is not the liquorice that is grown around Pontefract to make 'Pontefract cakes' which are 10p sized thick discs of black, pliable liquorice, for that is Glycyrrhiza glabra.
POLYHYDROZYLATED INDOLIZIDINE ALKALOIDS
A new class of toxins has recently been identified as occurring in several plants primarily those belonging to the Pea Family (Fabaceae), namely polyhydroxylated indolizidine alkaloids (such as
Swainsonine), which escaped detection by the normal means of identifying alkaloids, such as reacting the extracts with reagents such as
iodoplatinate. The sugar-like character of these substances enabled them to evade such tests. These polyhydroxylated alkaloids join a growing number of other recently discovered classes of polyhydroxylated alkaloids found in nature. These now include the Calystegines (found in Bindweeds and some members of the Solanum genus such as Potato and also in some Cochlearia such as Danish Scurvygrass) and the polyhydroxylated pyrrolidines and pyrrolizidines (found in Bluebell and other members of the Scilla and Muscari genera).
Being like a sugar with a few hydroxyl groups scattered about it might be expected that it interferes with sugar metabolism, and indeed it does - it inhibits glycoside hydrolases. It was first found in plants of the genus Swainsona from Australia, which do not occur naturally in the UK. It also occurs in so-called
Locoweed, a set of poisonous plants belonging to the Astragalus and Oxytropis genera which grow in North America. Consumption of Locoweed gives rise to a disease called Swainsonine disease when eaten (usually by cattle and other livestock). The poisonous principal of Locoweed is
Swainsonine. The 'loco' part of the name Locoweed refers to the effect of turning any who eat it crazy, or loco. The Spanish word 'loco' means insane. No doubt the early locomotive manufacturers called their steam-powered railway contraptions 'Locomotive' because of its insane motion (or perhaps it was the populace at large who so called them?).
Swainsonine also occurs in other Astragalus species, but most of the 2000 species occurring worldwide do not synthesize it. Swainsonine has anti-cancer properties and is used pharmaceutically for as an adjuvant with other anti-cancer drugs for treating glioma and gastric carcinoma. Swainsonine also reduces the toxicity of another anti-cancer drug,
Doxorubicin, which is a synthetic antracycline antibiotic similar to the naturally occurring antibiotic called Daunomycin, found in Streptomyces peucetius.
Many similar spiro-steroidal compounds have toxic effects on the heart, although Cycloastragenol may not be one of them? It has a cyclo-propane unit, shown in red.
Cycloastragenol is found in some Astragalus species including Wild Liquorice, and is said to lengthen the telomeres on those genes that have short telomeres. Shortening of telomeres occurs as a natural ageing process in cells of the human body. When the telomere is of such a short length, the cell finds itself unable to divide properly and apportion two equal genes to each dividing cell. The cell then dies, a natural ageing process in the human body when it is getting old. It is claimed that Cycloastragenol lengthens short telomeres, the implication being that this will extend lifespan. However, it has never been proven that lengthening the telomeres results in extending human life. But that does not stop many sellers of Cycloastragenol selling it on the assumption or implication that it does. It may have other beneficial effects such as improved joint mobility and reduction in joint pain, according to patient-reported surveys by the manufacturers. There are no peer-reviewed papers by reputable journals of its efficacy.
A large number of volatiles have been found in Wild Liquorice, some may be responsible for its sweet aromatic smell when the leaves are crushed.
Those present at the leaf development phase follow:
The alcohols with the highest concentration are
2-methoxy-4-vinyl Phenol (1.3%) and Benzyl Alcohol (0.7%).
Tetradecanoic Acid is the volatile acid with the highest concentration (0.6%). 3-Hexen-1-ol Acetate the ester with the highest concentration (1.1%). Nonacosane (3.3%) the long-chain hydrocarbon with highest concentration, although
Octacosane follow very closely behind at between 2% - 3% each.
When flowering Geranial, at 2.7% is the main terpene followed by
HexaHydroFarnesyl Acetate at 0.5% coming second. A diester,
Hexanedioic Acid Ethyl Ester weighs in at 3.7%.
At the fruiting stage several chlorinated compounds are present amongst them
Hexachloroethane at a staggering 30% of total volatiles, followed by Pentachloroethane at only 3.9%.
Some members of the Astragalus genus are also Hyperaccumulators of the poisonous element
Selenium, when it is present in the soil. Although Selenium is poisonous in excess it is an essential mineral but is only required in tiny amounts by the human body.