Arbutin

Yellow needle-shaped crystals with bitter taste

Fixed

199.5 ° C

561.6 ° C

Practically 0 at 25 ° C

Moderately in water (50 g · l -1)

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Arbutin ( hydroquinone - β -D-glucopyranoside ) is a chemical compound selected from the group of aryl - β - glucoside and hydroquinones.

Occurrence

Arbutin comes in Damiana, cranberry, blueberry, raspberry, wheat germ, rosemary, Round-leaved wintergreen, bearberry (minimum requirement according to the European Pharmacopoeia 7% ), coffee, tea, red wine and pears and pear leaves ( with more or less content) before. It is converted by bacteria in the intestine to glucose and hydroquinone.

Biosynthesis

Arbutin is the precursor of the coumaric acid formed via the shikimate pathway. Through a β - oxidation of the propylene side chain produced p- hydroxybenzoic acid, from which finally the benzohydroquinone is formed by oxidative decarboxylation. The latter will now be O- glycosylated to arbutin.

Pharmacology

Arbutin is Hydrochinonglukosid as a prodrug dar. It is in its original form not readily absorbed and can not get to its site of action in this form. Therefore, before absorption, it has to be hydrolyzed only in the stomach and upper small intestine to the well- absorbable hydroquinones. The " detoxification " is performed in the liver, conjugated with glucuronic acid by hydroquinone or sulfuric acid, thus improving the water solubility and transport in the blood. About this route reach within 6 hours from 70% to 75 % of the amount taken, the kidneys, where they are excreted in the urine. Bacteria in the bladder can the hydroquinone complex split again and so hydroquinone release. Hydroquinone has an antibacterial effect. Arbutin - containing drugs (eg bearberry leaves) and their extracts are therefore applied medication for bacterial infections of the urinary tract.

Limitations on use

The resulting arbutin from hydroquinone has at higher doses a hepatotoxic effect and is suspected to have mutagenic or possibly even carcinogenic effects. This gives rise to the restrictions in the application:

• Not more than 5 times a year and only for 1 week
• Do not use during pregnancy or lactation
• Not in children

Due to the high tannin content of arbutin -containing drugs nausea and vomiting is possible with preparation of tea. Therefore, it should be prepared as a cold maceration, since so little tannins are extracted from the plant material.