Kinin, also called cytokinin or kinetic, is any of a group of plant hormones which affect growth and are used to slow down the aging process in plants, encourage seeds to germinate, and plants to flower, and are involved in plant responses to drought and waterlogging. They are used commercially to produce seedless grapes, to stimulate germination of barley in brewing, and to prolong the life of green-leaf vegetables. Kinins work in conjunction with auxins to promote swelling and division in the plant cells producing lateral buds.


In animals, kinins are peptides released by enzyme action which contraction of smooth muscle and elevate blood pressure, thus playing an important role in inflammation and shock.


Kinins, such as zeatin, are derived from adenine.