Effect of Thai medicinal plants Acanthus ebracteatus Vahl. Carthamus tinctorius L. and Streblus asper Lour. on neurite outgrowth activity in Neuro-2A cells

Background: Neurite outgrowth is an important process in neural reorganization and repair after neuronal injury. Neurite outgrowth is one of the important mechanisms to maintain normal physiological neuronal function. Neurite stimulation may help to prevent or rehabilitate brain regions in neurodegenerative disease. Objectives: The aim of this study was to screen selected ethnopharmacological herbs for stimulatory effects on neurite outgrowth and to test for any cytotoxicity and phytochemical properties. Materials and methods: The herbal extracts derived from Acanthus ebracteatus Vahl. leaves, Carthamus tinctorius L. flower, and Streblus asper Lour. bark was tested for neurite outgrowth stimulation/potentiation and cytotoxic and phytochemical properties. Results: The extract of Carthamus tinctorius L. flowers at concentrations of 50 and 500 µg/mL could significantly stimulate potentiation of neurite outgrowth in Neuro-2a cells whereas other extracts could not. We found that treatment of the cells with a concentration up to 500 µg/mL of the Carthamus tinctorius L. extract showed no cytotoxicity. Conclusion: The neurite potentiation effect might be due to other chemical constituents rather than phytochemical properties, especially total flavonoid, and phenolic contents, and antioxidant activity of the Carthamus tinctorius L. extract. The result showed that Carthamus tinctorius L. flowers extract could be a good candidate for use as a drug protecting against neuronal damage and neurodegenerative disease since it provides low cytotoxicity and neurogenic enhancement.