１３．Physiological role
That has not been fully elucidated.
It is well-known that 1,5-AG and its precursor ,1,5-anhydrofructose (1,5-AF), affect appetite center. The chemical derivative of 1,5-AG was found on the Japanese patent applications as a anti-obesity drug. Blood 1,5-AG level is high in patients with anorexia nervosa despite feeding poor, while often low level in bulimia nervosa. 1,5-AF increase glucagon-like peptide (GLP)-1.
There is a metabolic pathway from glycogen to 1,5-AG via 1,5-AF in the liver. The pathway is small scale and its physiological significance is unknown.
1,5-AG stimulated insulin release in several kinds of β-cell lines and experimental animals. Uptake of 1,5-AG was markedly inhibited by glucose in β-cells. 1,5-AG can be phosphorylated by glucokinase (GK).
1,5-AF has strong anti-inflammatory action, but not in 1,5-AG. 1,5-AG can promote adiponectin production.
Polygala, a famous good quality grass, contains much Onji substance including rich 1,5-AG.
1,5-AG increases at the time of germination. The reason for these phenomenon is not known.
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