2.2.1 Arbutin
Synonyms Ursin; Arbutoside; Uvasol; Uvaursi; Bearberry leaves; Busserole.
Biological source It occurs in the dried leaves of Bergenia crassifolia (L.) Fritsch, belonging to the family Saxifragaceae.
It is also obtained from the dried leaves Uva-Ursi or Bearberry Arctostaphylos uva-ursi (Linné) Sprengel, belonging to family (Ericaceae) and other related plants e.g., coactylis or adenotricha Fernald and McBride (family Ericaceae). Besides, it is extracted from the leaves of blueberry, cranberry and pear trees (Pyrus communis L., family; Rosaceae).
Geographical Source Bearberry is mostly grown in various parts of North and Central Europe, North America, Canada and Scotland.
Description Arbutin occurs in white needles that are promptly soluble in water and ethanol. It is very hygroscopic in nature.
Chemical Constituents The structure of arbutin is given below:
It has a β-D-glucopyranoside function attached to the para position of a phenol.
It yields upon hydrolysis, either by dilute acids or by emulsin, one mole each of D-glucose and hydroquinone.
Besides, the leaves also contain methyl arbutin, quercetin, gallic acid, ursolic acid and tannin. However, arbutin forms a complex with hexamethylenetetramine that may be used as a means to separate it from methylarbutin.
Chemical Tests
1. Arbutin yields a blue colouration with ferric chloride solution.
2. Its presence in crude drug may be detected by frist moistening the powdered tissues with dilute HCl, warming cautiously over a watch glass on a low flame and carefully collecting the sublimate as crystals of hydroquinone that forms on another watch glass.
Important Features The presence of gallotannin usually helps in preventing certain specific enzyme, for instance: b-glucosidase from splitting arbutin that justifiably explains why the crude plant extracts are more effective therapentically, as compared to pure arbutin.
Uses
1. It is used as a diuretic.
2. It finds its application as an antiseptic agent on the urinary tract.
3. It also exerts astringent actions.
