Research Mechanism and Progress of the Natural Compound Curcumin in Treating Alzheimer´s Disease.

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases. AD patients usually present symptoms, such as cognitive dysfunction, progressive memory loss, and other manifestations. With the increasing number of AD cases worldwide, there is an urgent need to develop effective drug treatments. Currently, drugs targeting AD symptoms may not change or prevent the progression of the disease. Curcumin, a polyphenol extracted from the turmeric herb, has been used for the treatment of AD. In this review, we summarized both cellular and animal studies and described the mechanism of action of curcumin in altering the pathological features of AD. Curcumin attenuates the formation of amyloid-ß plaques and promotes its decomposition, reduces the phosphorylation of tau, improves its clearance rate, and binds with copper to reduce cholesterol. It changes the activity of microglia, suppresses acetylcholinesterase, regulates insulin signal transduction, and exhibits antioxidant properties. Studies have found that curcumin can promote nerve repair and has a significant effect on AD. However, the low bioavailability of curcumin may hinder its use as a therapeutic agent. If this limitation can be overcome, curcumin may emerge as a promising drug for the treatment of AD.

A strategy to improve the solubility and bioavailability of the insoluble drug piperlongumine through albumin nanoparticles.

Piperlongumine (PL) is a biologically active alkaloid derived from peppers, has significant cytotoxic effects on cancer with no cytotoxicity. This study used NabTM technology to prepare PL albumin nanoparticles (PL-BSA-NPs) to improve water solubility and bioavailability. We carried out a pharmacological evaluation of the PL-BSA-NPs. The morphological profile of the PL-BSA-NPs was relatively uniform, with an average particle size of approximately 210 nm, with drug load of 2.1% and encapsulation rate of 87.6%. PL-BSA-NPs were stable for 4 weeks when stored at 4°C. In vitro release behavior of the PL-BSA-NPs showed a sustained release, with a cumulative release of 67.24% in approximately 24 hours. The pharmacokinetic properties of PL-BSA-NPs were shown that PL-BSA-NPs could maintain a certain level of blood drug concentration for a long time, thus demonstrating the sustained release and increased bioavailability of PL. Finally, we investigated the in vitro antitumor activity of the PL-BSA-NPs and found that PL can significantly inhibit HepG2 cell proliferation, and that PL-BSA-NPs enhanced the inhibitory effect of PL on this proliferative effect. Thus, we concluded that PL can destroy liver cancer cells by increasing ROS levels. These results suggested that PL-BSA-NPs show promising potential as a targeted anti-tumor drug.

Synthesis and evaluation of curcumin-based near-infrared fluorescent probes for detection of amyloid ß peptide in Alzheimer mouse models.

The abnormal accumulation of amyloid ß protein (Aß) is one of the most important causes of Alzheimer's disease (AD) and is usually a detecting biomarker. Curcumin and its derivatives have potential Aß aggregate targeting ability; we synthesized a series of curcumin-based near-infrared fluorescence probes in this study. By characterizing the excitation wavelength and emission wavelength, the imaging characteristics of the investigation in the near-infrared light region were determined; with an increase in the concentration of the probe compounds, the fluorescence intensity showed an upward trend, demonstrating ideal optical characteristics. In vivo, imaging results showed that the synthesized probe compounds could penetrate the blood-brain barrier (BBB) and specifically bind to Aß in the brain of APP/PS1 mice. Especially for compound 3b, the maximum emission wavelength was around 667 nm, and the fluorescence signal intensity in the brain of the APP/PS1 mice model was more than twice that of the wild control group at 120 min after administration, which could display Aß pathological changes. The fluorescent probes designed in this study can become an effective tool for early AD diagnosis and visual detection.