Kinin

A kinin is any of various structurally related polypeptides, such as bradykinin and kallikrein. They are members of the autacoid family.

They act locally to induce vasodilation and contraction of smooth muscle.

It is a component of the kinin-kallikrein system.

Their precursors are kininogen.

In botany, it refers to plant hormones which delay aging.