Exudate Gums of Families in the Orders Rutales, Parietales, and Malvales

5 Exudate Gums of Families in the Orders Rutales, Parietales, and Malvales 

Trees of the genus Boswellia (Burseraceae) exude gum frankincense, a mixture of a resin and an acidic polysaccharide. The acidic polysaccharides of the exudates of Boswellia papyrifera and B, carteri are indicated to be substituted, branched galactans (see 159, 162, 174). The polysaccharide obtained from gum myrrh, which exudes from the damaged bark of Commiphora myrrha (Burseraceae) (159, 174), is difficult to isolate because of its association with protein (162). 

The most extensively studied citrus (Rutaceae) gum is that exuded from Citrus limon (lemon) (159, 162, 174). The indications are that it has a branch-on-branch galactan framework (see 162). Citrus maxima (grapefruit) and C. sinensis (orange) trees produce less exudate, and their exudate gums have been less extensively studied (159, 162, 174). The polypeptide portion of bhirra gum from Chloroxylan spp. (Rutaceae) has been examined (9). 

The exudate gum of Khaya senegalensis (African mahogany) (Meliaceae) contains two polysaccharides. The major component is an acetylated branched polymer of complex structure that has some of the structural features of Sterculia 

Ketha gum, which exudes from the bark of Feronia elephantum (Rutaceae, Rutales) is reported to have properties similar to those of the Acacia gums (159). The polypeptide portion of a gum from trees of Azadirachta spp. (Meliaceae) has been examined (9). Neem gum Azadirachta indica) (159) contains 35% protein (13). 

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