Direct Delivery of ANA-TA9, a Peptide Capable of Aβ Hydrolysis, to the Brain by Intranasal Administration

Research Progress on the Strategies for Crossing the Blood-Brain Barrier

Recently, the incidence of brain diseases, such as central nervous system degenerative diseases, brain tumors, and cerebrovascular diseases, has increased. However, the blood-brain barrier (BBB) limits the effective delivery of drugs to brain disease areas. Therefore, the mainstream direction of new drug development for these diseases is to engineer drugs that can better cross the BBB to exert their effects in the brain. This paper reviews the research progress and application of the main trans-BBB drug delivery strategies (receptor/transporter-mediated BBB crossing, focused ultrasound to open the BBB, adenosine agonist reversible opening of the BBB, aromatic resuscitation, transnasal administration, cell-mediated trans-BBB crossing, and viral vector system-mediated brain drug delivery). Meanwhile, the potential applications, advantages, and disadvantages of these strategies for crossing the BBB are analyzed. Finally, the future development prospects of strategies for crossing the BBB are also discussed. These strategies have potential value for treating brain diseases.

An 11-mer Synthetic Peptide Suppressing Aggregation of Aβ25-35 and Resolving Its Aggregated Form Improves Test Performance in an Aβ25-35-Induced Alzheimer's Mouse Model

There is a high demand for the development of drugs against Alzheimer's disease (AD), which is related to the misfolding and aggregation of Amyloid-β (Aβ), due to the increasing number of patients with AD. In our present study, we aimed to assess the aggregation inhibitory effect of various synthetic YS-peptides on Aβ25-35 to identify an applicable peptide for clinical use for AD treatment and prevention. Suppression and aggregate resolution activities of YS-peptides against Aβ25-35 were evaluated using a Thioflavin T assay and scanning electron microscopy (SEM). Structure-activity relationship studies revealed that YS-RD11 (RETLVYLTHLD) and YS-RE16 (RETLVYLTHLDYDDTE) showed suppression and aggregate-resolution activities. The effect of YS-peptides on phagocytosis in microglial cells (BV-2 cells) demonstrated that YS-RD11 and YS-RE16 activated the phagocytic ability of microglia. In the Aβ25-35-induced AD mouse model, YS-RD11 prevented and improved the deficits in short-term memory. In conclusion, YS-RD11 is a suitable candidate therapeutic drug against AD and uses a strategy similar to that used for antibodies.

Left-Right Difference in Brain Pharmacokinetics Following Nasal Administration Via One-Site Nostrils

The olfactory and trigeminal pathways are direct delivery pathways between the nose and brain. To determine the effect of direct delivery on drug distribution in the brain, two model drugs with different physical properties, antipyrine (ANP), with high membrane permeability, and ranitidine (RNT), with low membrane permeability, were selected. For ANP, direct delivery from the nose to the brain was observed only in the olfactory bulb beside the nasal cavity, with a direct transport percentage (DTP) of approximately 45 %, whereas in the frontal and occipital brains, the contribution from the systemic circulation to the brain was observed as the primary route of brain distribution. No significant variations were observed in the pharmacokinetics of ANP in the left and right brain, whereas RNT was distributed in all brain regions with a DTP of > 95 %. The closer the brain region is to the nasal cavity, the higher the DTP. Furthermore, the left brain, the same nostril site (left nostril) of administration, had a larger level of drug delivery than the right brain. These findings imply that the influence of the administered nostril site differs based on the physicochemical properties and amount of the drug.

SKGQA, a Peptide Derived from the ANA/BTG3 Protein, Cleaves Amyloid-β with Proteolytic Activity

Despite the extensive research conducted on Alzheimer's disease (AD) over the years, no effective drug for AD treatment has been found. Therefore, the development of new drugs for the treatment of AD is of the utmost importance. We recently reported the proteolytic activities of JAL-TA9 (YKGSGFRMI) and ANA-TA9 (SKGQAYRMA), synthetic peptides of nine amino acids each, derived from the Box A region of Tob1 and ANA/BTG3 proteins, respectively. Furthermore, two components of ANA-TA9, ANA-YA4 (YRMI) at the C-terminus end and ANA-SA5 (SKGQA) at the N-terminus end of ANA-TA9, exhibited proteolytic activity against amyloid-β (Aβ) fragment peptides. In this study, we identified the active center of ANA-SA5 using AEBSF, a serine protease inhibitor, and a peptide in which the Ser residue of ANA-SA5 was replaced with Leu. In addition, we demonstrate the proteolytic activity of ANA-SA5 against the soluble form Aβ42 (a-Aβ42) and solid insoluble form s-Aβ42. Furthermore, ANA-SA5 was not cytotoxic to A549 cells. These results indicate that ANA-SA5 is a promising Catalytide and a potential candidate for the development of new peptide drugs targeting Aβ42 for AD treatment.

Small Peptides in the Detection of Mycotoxins and Their Potential Applications in Mycotoxin Removal

Mycotoxins pose significant risks to humans and livestock. In addition, contaminated food- and feedstuffs can only be discarded, leading to increased economic losses and potential ecological pollution. Mycotoxin removal and real-time toxin level monitoring are effective approaches to solve this problem. As a hot research hotspot, small peptides derived from phage display peptide libraries, combinatorial peptide libraries, and rational design approaches can act as coating antigens, competitive antigens, and anti-immune complexes in immunoassays for the detection of mycotoxins. Furthermore, as a potential approach to mycotoxin degradation, small peptides can mimic the natural enzyme catalytic site to construct artificial enzymes containing oxidoreductases, hydrolase, and lyase activities. In summary, with the advantages of mature synthesis protocols, diverse structures, and excellent biocompatibility, also sharing their chemical structure with natural proteins, small peptides are widely used for mycotoxin detection and artificial enzyme construction, which have promising applications in mycotoxin degradation. This paper mainly reviews the advances of small peptides in the detection of mycotoxins, the construction of peptide-based artificial enzymes, and their potential applications in mycotoxin control.