High-throughput screening for amyloid-β binding natural small-molecules based on the combinational use of biolayer interferometry and UHPLC−DAD-Q/TOF-MS/MS

Discovery of drugs rapidly and effectively is an important aspect for Alzheimer's disease(AD).In this study,a novel high-throughput screening(HTS)method aims at screening the small-molecules with amyloid-β(Aβ)binding affinity from natural medicines,based on the combinational use of biolayer interferometry(BLI)and ultra-high-performance liquid chromatography coupled with diode-array detector and quadrupole/time-of-flight tandem mass spectrometry(UHPLC−DAD-Q/TOF-MS/MS)has been firstly developed.Briefly,the components in natural medicines disassociated from biotinylated Aβwere collected to analyze their potential Aβbinding affinity by UHPLC−DAD-Q/TOF-MS/MS.Here,baicalein was confirmed to exhibit the highest binding affinity with Aβin Scutellaria baicalensis.Moreover,polyporenic acid C(PPAC),dehydrotumulosic acid(DTA),and tumulosic acid(TA)in Kai-Xin-San(KXS)were also identified as potent Aβinhibitors.Further bioactivity validations indicated that these compounds could inhibit Aβfibrillation,improve the viability in Aβ-induced PC-12 cells,and decrease the Aβcontent and improve the behavioral ability in Caenorhabditis elegans.The molecular docking results confirmed that PPAC,DTA,and TA possessed good binding properties with Aβ.Collectively,the present study has provided a novel and effective HTS method for the identification of natural inhibitors on Aβfibrillation,which may accelerate the process on anti-AD drugs discovery and development.

Exploring the taste presentation and receptor perception mechanism of salty peptides from Stropharia rugosoannulata based on molecular dynamics and thermodynamics simulation

The taste presentation and receptor perception mechanism of the salty peptide of Stropharia rugosoannulata were predicted and verified using peptide omics and molecular interaction techniques.The combination of aspartic acid(D)and glutamic acid(E),or peptide fragments composed of arginine(R),constitute the characteristic taste structural basis of salty peptides of S.rugosoannulata.The taste intensity of the salty peptide positively correlates with its concentration within a specific concentration range(0.25–1.0 mg/mL).The receptor more easily recognizes the first amino acid residue at the N-terminal of salty peptides and the aspartic acid residue in the peptides.GLU513,ASP707,and VAL508 are the critical amino acid residues for the receptor to recognize salty peptides.TRPV1 is specifically the receptor for recognizing salty peptides.Hydrogen bonds and electrostatic interactions are the main driving forces for the interactions between salty peptides and TRPV1 receptors.KSWDDFFTR has the most potent binding capacity with the receptor and has tremendous potential for application in sodium salt substitution.This study confirmed the taste receptor that specifically recognizes salty peptides,analyzed the receptor-peptide binding interaction,and provided a new idea for understanding the taste receptor perception of salty peptides.

Development of a Label-Free Colorimetric Aptasensor with Rationally Utilized Aptamer for Rapid Detection of Okadaic Acid

Okadaic acid(OA)is a typical marine toxin with strong toxicity causing diarrheic shellfish poisoning(DSP).Aptamers show great advantages in toxin detection and attract increasing attentions in the field of food analysis.In this study,a label-free col-orimetric aptasensor was constructed for visual and rapid detection of OA in shellfish.To exploit the binding capability of the anti-OA aptamer,the inherent molecular recognition mechanism of aptamer and OA was studied,based on molecular docking,fluorescent assay,and biolayer interferometry.Consistent results showed that the stem-loop near the 3’terminal of the aptamer exhibit dominate binding capacity.Based on the revealed recognition information,the aptamer was thus rationally utilized and combined with AuNPs and cationic polymer polydiallyl dimethyl ammonium chloride(PDDA)for the development of the label-free colorimetric aptasensor,in which the 3’terminal was thoroughly exposed to OA.The aptasensor provided robust performance with a linear detection range of 100-1200 nmol L-1,a limit of detection of 41.30 nmol L-1,recovery rates of 91.6%-106.2%,as well as a high selectivity towards OA in shellfish samples.The whole detection process can be completed within 1 h.To our best knowledge,this is the first time that the anti-OA aptamer was thoroughly studied,and a label-free colorimetric aptasensor was rationally designed in this way.This study not only provides a rapid detection method for highly sensitive and specific detection of OA,but also serves as a reference for the design of efficient aptasensors in the future.