Pyrus communis Arbutin

The simplest phenolic n-glucoside is arbutin (p-hydroxyphenyl /3-d-glucopyranoside), which occurs in a number of plant species, including the pear Pyrus communis. Arbutin is usually accompanied in plant tissues by methylarbutin (p-methoxyphenyl S-D-glucopyranoside)Salix and Populus spp. contain the D-glucoside salicin, o-(hydroxymethyl)-phenyl /S-D-glucopyranoside, and certain species of poplar contain also a... 

Arbutin (= Hydroquinone-P-D-glucopyranoside) (phenol glucoside) Rhodiola sacra (Crassulaceae), Origanum majorana (Lamiaceae), Pyrus communis (Rosaceae) PEP (391 pM) [115]... 

Arbutin occurs in leaves of the pear tree Pyrus communis) and Arctostaphylos uva-ursi, and is a urinary tract antiseptic and diuretic. Arbutin is hydrolysed to hydroquinone in alkaline urine, this effect being strictly localised in the urinary tract. It is indicated for urinary tract infections, in particular cystitis, urethritis and prostatitis. 

Examples of simple phenols (Ce) include catechol and phloroglucinol. Although most of the more complex plant polyphenols contain these two simple phenols as a parts of their stracmres, catechol and phloroglucinol are uncommon in plant tissues. Catechol has been found in leaves of Gaultheria species, while phloroglucinol has been found as glucoside in the peel of various Citrus fruits. Arbutin (III) is found in leaves of various Vaccinium spp., such as bluebeny, cranberry, cowberry, and pear trees (Pyrus communis L., Rosaceae) [41-43]. 

Pears (Pyrus communis) were cultivated by the Phoenicians and later by the Romans. There are now in excess of 500 named varieties worldwide. The total phenolic content of some cultivars of pears has been shown to be between 1235 and 2500 mg/kg in the peel and 28-81 mg/kg in the flesh (Galvis-Sdnchez etal. 2003). The phenolic composition of pears is very similar to that of apples containing 5-0-caffeoylquinic acid, 4-O-p-coumaroylquinic acid, procyanidins and quercetin glycosides. The main difference in the phenolic content of apples and pears is the presence of hydroquinone glucoside (arbutin) (Figure 7.24) in pears and the hydroxychalcones in apples (Spanos and Wrolstad 1992). The average... 

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