Ligand fishing based on tubular microchannel modified with monoamine oxidase B for screening of the enzyme's inhibitors from Crocus sativus and Edgeworthia gardneri

Rapid Screening of Lipase Inhibitors From Chrysanthemum Based on Ionic Liquid/Chitosan Bifunctionalized Magnetic Multi-Walled Carbon Nanotubes Immobilized Lipase

In this study, a novel ionic liquid/chitosan bifunctionalized magnetic multi-walled carbon nanotubes composite material (m-MWCNTs@CS@IL) was utilized for the first time to immobilize lipase. The immobilized lipase exhibited exceptional stability and reusability, as evidenced by its characteristic properties. A ligand fishing approach utilizing the immobilized lipase was developed to enable rapid screening of lipase inhibitors from Chrysanthemum. Three ligands were successfully screened from Chrysanthemum and then identified as cynaroside, quercitrin, and linarin by ultra-high performance liquid chromatography-tandem mass spectrometry. The IC50 values of these three ligands were 76.77 ± 0.36, 83.01 ± 0.46, and 43.61 ± 0.77 µM, respectively. Furthermore, molecular docking analysis further confirmed the binding of three ligands to specific amino acid residues within the active site of lipase. This work presents a fast and efficient approach for screening lipase inhibitors from intricate natural sources, demonstrating promising prospects in discovering anti-obesity compounds.

Monoamine oxidase and neurodegeneration: Mechanisms, inhibitors and natural compounds for therapeutic intervention

Mammalian flavoenzyme Monoamine oxidase (MAO) resides on the outer mitochondrial membrane (OMM) and it is involved in the metabolism of different monoamine neurotransmitters in brain. During MAO mediated oxidative deamination of relevant substrates, H2O2 is released as a catalytic by-product, thus serving as a major source of reactive oxygen species (ROS). Under normal conditions, MAO mediated ROS is reported to propel the functioning of mitochondrial electron transport chain and phasic dopamine release. However, due to its localization onto mitochondria, sudden elevation in its enzymatic activity could directly impact the form and function of the organelle. For instance, in the case of Parkinson's disease (PD) patients who are on l-dopa therapy, the enzyme could be a concurrent source of extensive ROS production in the presence of uncontrolled substrate (dopamine) availability, thus further impacting the health of surviving neurons. It is worth mentioning that the expression of the enzyme in different brain compartments increases with age. Moreover, the involvement of MAO in the progression of neurological disorders such as PD, Alzheimer's disease and depression has been extensively studied in recent times. Although the usage of available synthetic MAO inhibitors has been instrumental in managing these conditions, the associated complications have raised significant concerns lately. Natural products have served as a major source of lead molecules in modern-day drug discovery; however, there is still no FDA-approved MAO inhibitor which is derived from natural sources. In this review, we have provided a comprehensive overview of MAO and how the enzyme system is involved in the pathogenesis of different age-associated neuropathologic conditions. We further discussed the applications and drawbacks of the long-term usage of presently available synthetic MAO inhibitors. Additionally, we have highlighted the prospect and worth of natural product derived molecules in addressing MAO associated complications.

Fast screening of α-glucosidase inhibitors from Ginkgo biloba leaf by using α-glucosidase immobilized on magnetic metal-organic framework

In this study, a ligand fishing method for the screening of α-glucosidase inhibitors from Ginkgo biloba leaf was established for the first time using α-glucosidase immobilized on the magnetic metal-organic framework. The immobilized α-glucosidase exhibited enhanced resistance to temperature and pH, as well as good thermal stability and reusability. Two ligands, namely quercitrin and quercetin, were screened from Ginkgo biloba leaf and identified by ultra-high performance liquid chromatography-tandem mass spectrometry. The half-maximal inhibitory concentration values for quercitrin and quercetin were determined to be 105.69 ± 0.39 and 83.49 ± 0.79 µM, respectively. Molecular docking further confirmed the strong inhibitory effect of these two ligands. The proposed approach in this study demonstrates exceptional efficiency in the screening of α-glucosidase inhibitors from complex natural medicinal plants, thus exhibiting significant potential for the discovery of antidiabetic compounds.