Trehalose, also known as mycose or tremalose, is a natural alpha-linked
disaccharide formed by an α,α-1,1-glucoside bond between two
α-glucose units. In 1832, H.A.L. Wiggers discovered trehalose in an ergot of rye,
and in 1859 Marcellin Berthelot isolated it from trehala manna, a substance made
by weevils, and named it trehalose. It can be synthesised by bacteria, fungi,
plants, and invertebrate animals. It is implicated in anhydrobiosis — the
ability of plants and animals to withstand prolonged periods of
desiccation. It has high water retention capabilities, and is used in food and
cosmetics. The sugar is thought to form a gel phase as cells dehydrate, which
prevents disruption of internal cell organelles, by effectively splinting
them in position. Rehydration then allows normal cellular activity to be
resumed without the major, lethal damage that would normally follow a
dehydration/rehydration cycle. Trehalose has the added advantage of being an
antioxidant. Extracting trehalose was once a
difficult and costly process, but circa the year 2000, the Hayashibara company
confirmed an inexpensive extraction technology from starch for mass
production. Trehalose is currently being used for a
broad spectrum of applications. Structure
Trehalose is a disaccharide formed by a 1,1-glucoside bond between two α-glucose
units. Because trehalose is formed by the bonding of two reducing aldehyde
groups, it has no capacity to participate in the Maillard reaction.
There is an industrial process where trehalose is derived from corn starch.
There are at least 3 biological pathways for trehalose biosynthesis.
Chemical properties Trehalose is a nonreducing sugar formed
from two glucose units joined by a 1-1 alpha bond, giving it the name of
lucopyranosyl-(1→1)-α-D-glucopyranoside. The bonding makes trehalose very
resistant to acid hydrolysis, and therefore is stable in solution at high
temperatures, even under acidic conditions. The bonding also keeps
nonreducing sugars in closed-ring form, such that the aldehyde or ketone end
groups do not bind to the lysine or arginine residues of proteins. Trehalose
is less soluble than sucrose, except at high temperatures. Trehalose forms a
rhomboid crystal as the dihydrate, and has 90% of the calorific content of
sucrose in that form. Anhydrous forms of trehalose readily regain moisture to
form the dihydrate. Anhydrous forms of trehalose can show interesting physical
properties when heat-treated. Trehalose aqueous solutions show a
concentration dependent clustering tendency. Owing to their ability to form
hydrogen bonds between one another, they self-associate in water to form clusters
of various sizes. All-atom molecular dynamics simulations have shown that
when reaching a concentration of 1.5-2.2 molar, the trehalose molecular clusters
percolate and form large, continuous aggregates within the system.
Trehalose directly interacts with nucleic acids, facilitates melting of
double stranded DNA and stabilizes single-stranded nucleic acids.
Nutritional and dietary properties Trehalose is nutritionally equivalent to
glucose, because it is rapidly broken down into glucose by the enzyme
trehalase, which is present in the brush border of the intestinal mucosa of
omnivores and herbivores.p. 135 Trehalase deficiency is unusual in
humans, except in the Greenlandic Inuit, where it occurs in 10%-15% of the
population.p. 197 Trehalose has about 45% the sweetness of sucrose at
concentrations above 22%, but when the concentration is reduced, its sweetness
decreases more quickly than that of sucrose, so that a 2.3% solution tastes
6.5 times less sweet as the equivalent sugar solution.p. 444
Biological properties In nature, trehalose can be found in
animals, plants, and microorganisms. In animals, trehalose is prevalent in
shrimp, and also in insects, including grasshoppers, locusts, butterflies, and
bees, in which blood-sugar is trehalose. The trehalose is then broken down into
glucose by the catabolic enzyme trehalase for use. Trehalose is also
present in the nutrition exchange liquid of hornets and their larvae.
Trehalose is the major carbohydrate energy storage molecule used by insects
for flight. One possible reason for this is that the glycosidic linkage of
trehalose, when acted upon by an insect trehalase, releases two molecules of
glucose, which is required for the rapid energy requirements of flight. This is
double the efficiency of glucose release from the storage polymer starch, for
which cleavage of one glycosidic linkage releases only one glucose molecule.
In plants, the presence of trehalose is seen in sunflower seeds, moonwort,
Selaginella plants, and sea algae. Within the fungi, it is prevalent in
some mushrooms, such as shiitake, maitake, nameko, and Judas's ear, which
can contain 1% to 17% percent of trehalose in dry weight form. Trehalose
can also be found in such microorganisms as baker's yeast and wine yeast, and it
is metabolized by a number of bacteria, including Streptococcus mutans, the
common oral bacterium responsible for dental plaque.
When tardigrades dry out, the glucose in their bodies changes to trehalose when
they enter a state called cryptobiosis — a state wherein they appear dead.
However, when they receive water, they revive and return to their metabolic
state. It is also thought that the reason the larvae of sleeping chironomid
and artemia are able to withstand dehydration is because they store
trehalose within their cells. Even within the plant kingdom,
Selaginella, which grows in desert and mountainous areas, may be cracked and
dried out, but will turn green again and revive after a rain because of the
function of trehalose. It is also said that the reason dried shiitake mushrooms
spring back into shape so well in water is because they contain trehalose.
The two prevalent theories as to how trehalose works within the organism in
the state of cryptobiosis are the vitrification theory, a state that
prevents ice formation, or the water displacement theory, whereby water is
replaced by trehalose, although it is possible that a combination of the two
mechanisms is at work. Use to treat amyloidosis
Trehalose induces autophagy via an mTOR independent pathway. It may have use for
treatments of Huntington's disease, Parkinson disease or tauopathies, as it
may correct defects in autophagy seen in these diseases and improve removal of
these aggregated proteins. Other possible benefits
Oral trehalose shows antidepressant properties in the mouse model of
depression, possibly through reducing p62/Beclin-1 ratio and increasing
autophagy in the frontal cortex. See also
Biostasis Cryptobiosis
Freeze drying Cryoprotectant
References External links
Cryopreservation with Sugars Novel functions and applications of
trehalose Tremalose