A novel botanical drug (DA-9801) for the treatment of diabetic neuropathy

Diabetic neuropathy is one of the most common causes of chronic neuropathic pain. In our search for bioactive constituents from plant sources, we found a diabetic neuropathy agent, DA-9801. Ethanol extract of two herbal mixture (the rhizome of Dioscorea japonica Thunberg and Dioscorea nipponica Makino. DA-9801 induces increases in endogenous Nerve growth factor (NGF) levels, and thereby has a protective effect against diabetic neuropathy. NGF plays an important role in the survival and maintenance of neurons in the nervous system and in nerve injury repair. The rhizome of D. japonica has been used in traditional medicine and as food in East Asia to strengthen stomach functions and to dilute sputum in TCM. The rhizome of D. nipponica has been used in traditional medicine in East Asia for treatment of rheumatoid arthritis and diabetes. After phytochemical investigation we found 2 new furostanol saponins besides 13 known compounds in DA-9801. We evaluated the anti-diabetic neuropathic effect of DA-9801 in a streptozotocin (STZ)-induced animal model. After treatment with DA-9801, NGF levels increased significantly in STZ-induced diabetic rats. Results from a nociceptive test (thermal & mechanical hyperalgesia) showed an increased latency time in groups treated with DA-9801 when compared with control and reference drug groups. The results suggest that DA-9801 may improve the damage produced by diabetic neuropathy via increasing the level of NGF in target tissue, shows improvement on nerve conduction velocity (NCV) and recovery from nerve degeneration. Therefore DA-9801 might have a potential therapeutic effect in patients with diabetic neuropathy.

Acknowledgement: This study was supported by grant from the Korea Healthcare Technology R&D Project, Ministry for Health, Welfare & Fammily Affairs, Republic of Korea (2011-A111082)