Abstract
Aging is becoming one of a big problem in advanced countries, thus development of medicine treating or preventing dementia is carried out since incidence of the disease is raised higher along with aging. We tried to find the components inducing neuronal differentiation from 57 kinds of traditional medicinal plants in Myanmar. From the results of evaluation of cytotoxicity and induction of phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) in PC12 cells by 171 extracts from 57 species of traditional medicinal plants in Myanmar, only three kinds of Croton tiglium L. extracts and ethyl acetate extract of Oroxylum indicum (L.) Benth. ex kurz, showed both of low-cytotoxicity and phosphorylation of ERK1/2. It was deduced that neuronal differentiation was induced by C. tiglium methanol extract, because it up-regulated both neurite outgrowth and expression of neurofilament-M (NFM). On the other hand, from the results using three mitogen-activated protein kinase (MAPK) inhibitors, it was considered that phosphorylation of five kinases (ERK1/2, p38MAPK, c-jun N-terminal kinas (JNK), ERK5, and Akt) and three kinases (ERK1/2, p38MAPK, and JNK) were necessary for neuronal differentiation by NGF and C. tiglium methanol extract, respectively. Water soluble polymer such as proteins is not contained in C. tiglium methanol extract, though the neuronal differentiation induction was shown by it. Therefore, there is a possibility that the taken active components from C. tiglium are carried by blood flow followed by transportation to the brain.
