Under microscopic observation, degeneration or/and necrosis in vascular endoththelial cells and structure change of vessel wall were observed in the injection site (cauda vein) of a few animals in each treatment group while there were no changes in the vessels of other organs. The diseases in caudal vein were in remission after recovery period. The result indicates that the honokiol microemulsion has irritation to the vascular of the injection site, which should be paid attention to in clinical medication. As a widely studied natural component of the genus Magnolia, Honokiol has been investigated mostly for

its chemotherapeutic properties for many years. However, recent studies indicate that it has potential to be an effective neuroprotective agent. Pre-clinical investigations Selleckchem NVP-BKM120 have been conducted in rodent models, administration

of honokiol intravenously either pre-ischemia or post-ischemia can significantly reduced the total volume of infarction ( PLX4032 manufacturer Liou et al., 2003a and Liou et al., 2003b), and honokiol can also ameliorate the neurotoxic impairments in the model of seizure disorder ( Chang-Mu et al, 2010). Mechanisms of its neuroprotection effects have been investigated, and there are several putative pathways, including inhibition of the immune system and oxidative stress pathways ( Chen et al., 2007 and Harada et al., 2012). However, honokiol may exert its neuroprotective activities through a variety of mechanisms. Besides, because of its good liposolubility, honokiol can

easily cross the blood-brain barrier and accumulate in the brain to exert neuroprotective effects. In order to further investigate the neuroprotective properties of honokiol, honokiol microemulsion has been prepared and its influence Cyclic nucleotide phosphodiesterase on global ischemia in mice has been investigated in our previous study (Yang et al, 2012). The results showed that injection of honokiol microemulsion at a dosage range of 7∼70μg/kg body weight can significantly increase the breath time of mice and decrease lactic acid contents and augment ATP level in brain homogenate in this global ischemia model. The mechanism of its effect may be correlated with its alleviating ischemia status, inhibiting energy consumption, reducing MPTP opening and inhibiting PARP-1 over action, thus protects neural cells. Honokiol (2.5∼10μmol/L) concentration dependently inhibited PARP-1 activation and the IC50 was 76.82μmol/L. In conclusion, the estimated median lethal dosage (LD50) was 50.5mg/kg body weight in mice.