Esculeoside A is a spirosolane-type glycoside with the molecular formula C58H95NO29.
Extraction
This
natural product can be obtained using column chromatographies of high-porous
polystyrene gels and reversed
from a
extract of many varieties of
.
It will appear as colorless needles when synthesized using this method.
Biosynthesis
Evidence suggests that α-
tomatine is a precursor of esculeoside A.
In order for α-tomatine to be converted to esculeoside A,
isomerization of the
F-ring is required. The mechanism for this reaction is unclear at this time but research from Iijima and colleagues in 2009 suggest a
glycosylation step in the putative pathway from α-tomatine to esculeoside A depends on the
plant hormone ethylene.
When humans domesticated , they selected for less bitter fruits. This corresponded to the increased activity of a 2-oxoglutarate-dependent dioxygenases called 23DOX (synonym GAME31) during fruit ripening, which converts the bitter and slightly toxic α-tomatine into hydroxytomatine, which is eventually converted into the non-bitter and non-toxic esculeoside A.
Occurrence
,
eggplant, and tomatoes are all
solanaceous plants that contain unique
.
In the case of tomatoes, one of those unique glycoalkaloids is esculeoside A.
A tomato
saponin, esculeoside A, is found in quantities four times that of
lycopene in ripe tomatoes.
Potential health benefits
Studies have shown esculeoside A may be metabolized into derivatives that perform various beneficial activities in the human body including anti-
osteoporosis, anti-
Menopause and
anti-tumor activities.
Recent studies in mice have shown a potential link between esculeoside A and
cholesterol levels. In one study, esculeoside A administered to mice reduced serum levels of
LDL cholesterol and
by 25-45% without impacting the rates of
HDL cholesterol.
The potential health benefits of esculeoside A appear to change with factors such as the age of the tomato fruit, the heat used in processing tomatoes, and the pH used in processing.
The highest amounts of esculeoside A were found in the outer skin and wall (
pericarp wall) of the tomato fruit. Mature tomatoes tended to show higher amounts of esculeoside A than extracts taken from immature tomatoes. Extracts of esculeoside A in the Katsumata study were shown to be stable when heated until the point of 225 °C. This same study found esculeoside A extracts in water at pH 7-11 were stable throughout the heat sterilization process but unstable under acidic conditions.
Research has also shown esculeoside A amounts increase when tomatoes are treated with the phytohormone, ethylene.
Collectively, research suggests daily intake of esculeoside A from tomatoes could have many benefits.
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