Myrtillin is an anthocyanin

Anthocyanin

Anthocyanins are water-soluble vacuolar pigments that may appear red, purple, or blue according to pH...

. It is the 3-glucoside

Glucoside

A glucoside is a glycoside that is derived from glucose. Glucosides are common in plants, but rare in animals. Glucose is produced when a glucoside is hydrolysed by purely chemical means, or decomposed by fermentation or enzymes....

 of delphinidin

Delphinidin

Delphinidin is an anthocyanidin, a primary plant pigment, and also an antioxidant. Delphinidin gives blue hues to flowers like violas and delphiniums...

. It can be found in all green plants, most abundantly in blackcurrant

Blackcurrant

Blackcurrant, Ribes nigrum, is a species of Ribes berry native to central and northern Europe and northern Asia, and is a perennial....

, in blueberry

Blueberry

Blueberries are flowering plants of the genus Vaccinium with dark-blue berries and are perennial...

 or huckleberry

Huckleberry

Huckleberry is a common name used in North America for several species of plants in two closely related genera in the family Ericaceae:* Vaccinium* GaylussaciaHuckleberry may also refer to:-Plants:...

 leaves and various myrtles, in the roselle plant

Roselle (plant)

The roselle is a species of Hibiscus native to the Old World tropics, used for the production of bast fibre and as an infusion. It is an annual or perennial herb or woody-based subshrub, growing to tall...

, in the Centella asiatica

Centella asiatica

Centella asiatica is a small herbaceous annual plant of the family Mackinlayaceae or subfamily Mackinlayoideae of family Apiaceae, and is native to India, Sri Lanka, northern Australia, Indonesia, Iran, Malaysia, Melanesia, Papua New Guinea, and other parts of Asia...

plant (Hydrocotyle asiatica) and in the bilberry

Bilberry

Bilberry is any of several species of low-growing shrubs in the genus Vaccinium , bearing edible berries. The species most often referred to is Vaccinium myrtillus L., but there are several other closely related species....

 leaf. It is also present in yeast

Yeast

Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...

 and oatmeal

Oatmeal

Oatmeal is ground oat groats , or a porridge made from oats . Oatmeal can also be ground oat, steel-cut oats, crushed oats, or rolled oats....

. The sumac

Sumac

Sumac is any one of approximately 250 species of flowering plants in the genus Rhus and related genera, in the family Anacardiaceae. Sumacs grow in subtropical and temperate regions throughout the world, especially in Africa and North America....

fruits pericarp owes its dark red colour to anthocyanin pigments, of which chrysanthemin, myrtillin and delphinidin have yet been identified.

Myrtillin tends to stabilize the blood sugar, which otherwise fluctuates widely, and that it spares insulin.