Polyuronide

Polyuronide is a polymeric substance which consists of uronic acid units that have glycosidic linkages which are commonly combined with monosaccharides. 
Sources.
Polyuronide widely occurs in soil and plants (such as gums and pectic substances).
Studies.
There are many scientific studies about polyuronide in plants. However, the most studied is the presence of polyuronide in avocado and tomato. There is also a study about its occurrence in barrel cacus.