Sinistrin is a naturally occurring sugar polymer or

polysaccharide Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with wa ...

, also known as polyfructosane. It belongs to the fructan group, like inulin. As it is the case with similar substances, such as fructans or inulin, sinistrin acts as an energy storage molecule in plants.

Discovery, history, and manufacture

Already in 1879 Schmiedeberg managed to isolate this carbohydrate from the bulb of the red squill (''Urginea maritima'').''Biopolymers, Polysaccharides II'', Wiley-VCH, 2002, . He named the substance ’sinistrin’, from the Latin word 'sinister' for left, according to its

optical rotation Optical rotation, also known as polarization rotation or circular birefringence, is the rotation of the orientation of the plane of polarization about the optical axis of linearly polarized light as it travels through certain materials. Circul ...

activities. Sinistrin was also found in mucines of edible snails (''

Helix pomatia ''Helix pomatia'', common names the Roman snail, Burgundy snail, or escargot, is a species of large, edible, air-breathing land snail, a pulmonate gastropod terrestrial mollusc in the family Helicidae.MolluscaBase eds. (2021). MolluscaBase. ...

'') by Hammarsten in 1885.M. Geldmacher-Mallinckrodt und F. May:
Die Polysaccharide der Weinbergschnecke II. Die Mucin-Polysaccharide der Eiweißdrüse. 1. Mitteil.: Die Identität von Galaktogen und Sinistrin.
' Hoppe-Seyler's Zeitschrift für physiologische Chemie. Band 307, Heft 1-2, S. 191–201, ISSN (Online) 1437-4315, ISSN (Print) 0018-4888. . Today sinistrin is industrially manufactured out of the bulb of red squill by various extraction and purification steps.

Biochemistry

Sinistrin is an inulin-type β–D-fructan with branches on position 6. It belongs to the group of fructans and is partly counted among the

fructooligosaccharide Fructooligosaccharides (FOS) also sometimes called oligofructose or oligofructan, are oligosaccharide fructans, used as an alternative sweetener. FOS exhibits sweetness levels between 30 and 50 percent of sugar in commercially prepared syrups. It o ...

s (''FOS'').E. Nitsch, W. Iwanov und K. Lederer: ''Molecular characterization of Sinistrin''. Carbohydrate Research 72 (1979) 1-12. Sinistrin is composed out of

fructose Fructose, or fruit sugar, is a Ketose, ketonic monosaccharide, simple sugar found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is one of the three dietary monosaccharides, along with glucose and galacto ...

units (97%) and glucose units (3%, approximately), building a chain of fructose molecules with a terminal glucose unit. The degree of polymerisation (dp) of sinistrin is in average at 15, the molecular weight is at 3500 Da with a range from 2000 to 6000 Da.T. Spies, W. Praznik, A. Hofinger, F. Altmann, E. Nitsch, R. Wutka: ''Carbohydr. Res.'' 235 (1992) 221–230. The main differences between sinistrin and inulin are the higher alkali-resistance and the better water solubility (even in cold water) of sinistrin compared to inulin.

Uses

Medical

Like inulin the polymer sinistrin is not metabolized in human blood and passes the kidneys unchanged. Both, inulin and sinistrin, are therefore frequently used for the diagnosis of

kidney disorder Kidney disease, or renal disease, technically referred to as nephropathy, is damage to or disease of a kidney. Nephritis is an Inflammation, inflammatory kidney disease and has several types according to the location of the inflammation. Infla ...

s. An important measure of kidney function is the glomerular filtration rate (GFR). GFR is the volume of fluid filtered from the renal (kidney)

glomerular ''Glomerulus'' () is a common term used in anatomy to describe globular structures of entwined vessels, fibers, or neurons. ''Glomerulus'' is the diminutive of the Latin ''glomus'', meaning "ball of yarn". ''Glomerulus'' may refer to: * the filter ...

capillaries into the

Bowman's capsule Bowman's capsule (or the Bowman capsule, capsula glomeruli, or glomerular capsule) is a cup-like sac at the beginning of the tubular component of a nephron in the mammalian kidney that performs the first step in the filtration of blood to form ur ...

per time unit. To measure this parameter, a marker substance is injected into the blood stream, and its rate of excretion in urine is compared to the plasma concentration. Such a marker substance needs to be non-toxic, not

endogenous Endogenous substances and processes are those that originate from within a living system such as an organism, tissue, or cell. In contrast, exogenous substances and processes are those that originate from outside of an organism. For example, es ...

in the circulation, neither reabsorbed nor secreted in the kidney, and measurable. The measurement of the sinistrin- clearance is used to exactly determine the GFR in humans.B. Watschinger und I. Kobinger: ''Wiener Zeitschrift für Innere Medizin'' 45 (1964) 219-228.T. Buclin, A. Pechere-Bertschi, R. Sechaud et al.: ''Sinistrin clearance for determination of glomerular filtration rate: a reappraisal of various approaches using a new analytical method''. J Clin Pharmacol 1997;37:679–92. 204–211. The assays to determine sinistrin in urine or plasma are identical to that used for inulin. However, sinistrin is often preferred to the alternative, inulin, because it is highly soluble in water and easier to handle. For the application as a renal diagnostic an aqueous solution of sinistrin is approved under the trade name „Inutest“.''Inutest 25% Ampullen'' (PDF)
bei pharmazie.com, accessed on June 7th 2011.

Notes

References

* D.P. Mertz und H. Sarre: ''Polyfructosan-S: Eine neue inulinartige Substanz zur Bestimmung des Glomerulusfiltrates und des physiologisch aktiven extracellulären Flüssigkeitsvolumens beim Menschen''. Klin Wochenschrift 1963;41:868-72. {{Diagnostic agents Nephrology Polysaccharides