Du-ZhongorHardy rubber tree is a large deciduous tree that is native to the central region of China.
Its cortex has been used as a crude drug named Eucommiae. The bark has been used in natural medicine, with the Chinese name Du-Zhong. Recently, tea made from the leaf has been consumed as a health tonic in China, Korea and Japan. The pharmaceutical effects of Du-Zhong are closely related to protein metabolism, especially that of collagen. It is well known that during the aging process, collagen and non-collagenous protein metabolism is depressed. Du-Zhong is supposed that it might prevent the aging process by activating protein metabolism.