Isolation and Characterization of Natural Nanoparticles in Naoluo Xintong Decoction and Their Brain Protection Research

Currently, researchers use modern analytical techniques in a unique perspective of physical pharmacy to analyze the phase composition of traditional Chinese medicine (TCM) and have discovered that natural nanoparticles commonly exist in decoctions. This study aims to isolate and characterize the structure and composition of nanoparticles in Naoluo Xintong (NLXT) and investigate whether the brain protection effect of NLXT is closely related to NLXT-Nanoparticles (NLXT-NPs). Firstly, the dialysis-centrifugation method was used to separate the nanoparticles and then their size distribution, potential, and morphology were characterized. In addition, infrared spectroscopy and ultra-high performance liquid chromatography-quadrupole-time of flight-mass spectrometer (UPLC-Q-TOF-MS) technology were used to analyze the composition of nanoparticles. As for the pharmacodynamic experiment, Sprague Dawley (SD) rats were randomly divided into sham, Middle cerebral artery occlusion (MCAO) model, NLXT, NLXT with nanoparticles removing (NLXT-RN), NLXT-RN+Nanoparticles (NLXT-RN+NPs), and NLXT-NPs groups. After administration, the neurological function, histopathological changes, oxidative stress, and apoptosis level were measured. Our research showed that NLXT-NPs are mainly composed of polysaccharides, proteins, and saponins, with typical characteristics of two hundred-nanometer size and negatively loaded. NLXT can improve nerve function, reduce oxidative stress, and inhibit cell apoptosis. However, removing nanoparticles can significantly reduce the brain-protective effect of NLXT, which indicates that NLXT-NPs play an essential role in the efficacy of NLXT.