Investigating interactions between chloroquine/hydroxychloroquine and their single enantiomers and angiotensin-converting enzyme 2 by a cell membrane chromatography method

Chiral distinction between hydroxychloroquine enantiomers in binding to angiotensin-converting enzyme 2, the forward receptor of SARS-CoV-2

Soon after the outset of the Coronavirus Disease 2019 (COVID-19) pandemic (March-April 2020), formulations of the old antimalarial racemic drug hydroxychloroquine (HCQ) sulfate were authorized by the U.S. Food and Drug Administration (FDA) for emergency treatment of hospitalized patients with COVID-19. A call for the chiral switch of HCQ to the single enantiomer (S)-(+)-HCQ for treating the disease followed. The above authorizations were later withdrawn. Angiotensin-converting enzyme 2 (ACE2) has been recognized to be the forward receptor of SARS-CoV-2, the virus responsible for COVID-19. The objective of the present study was to evaluate the chiral distinction in the potential preferential binding of the HCQ enantiomers to ACE2, as a basis for its future drug repurposing, using high-field solution Nuclear Magnetic Resonance (NMR) spectroscopy. Proton selective spin-lattice relaxation rates were measured for selected diagnostic nuclei; in particular, protons belonging to the quinoline ring proved to be the most affected by the presence of the protein, for both (S)-(+)-HCQ and (R)-(-)-HCQ enantiomers. An increase in mono-selective relaxation rates was observed for both enantiomers. A significant difference in the magnitude of the increase was detected for all protons investigated, up to a 5-fold and an 8-fold increase in the case of (R)-(-)-HCQ and (S)-(+)-HCQ, respectively. Furthermore, comparison between the normalized mono-selective relaxation rates of the two HCQ enantiomers in their binary mixtures with ACE2 pointed out a certain preference for the (S)-(+)-HCQ enantiomer over (R)-(-)-HCQ in the interaction with ACE2. The findings form the basis for a future application of the drug repurposing/chiral-switch combination strategy to racemic HCQ in previously reported indications for hydroxychloroquine treatment and in the search for new indications in which ACE2 receptors are involved.

Plant-Derived Natural Compounds as an Emerging Antiviral in Combating COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a human virus that burst at Wuhan in China and spread quickly over the world, leading to millions of deaths globally. The journey of this deadly virus to different mutant strains is still ongoing. The plethora of drugs and vaccines have been tested to cope up this pandemic. The herbal plants and different spices have received great attention during pandemic, because of their anti-inflammatory, and immunomodulatory properties in treating viruses and their symptoms. Also, it has been shown that nano-formulation of phytochemicals has potential therapeutic effect against COVID-19. Furthermore, the plant derived compound nano-formulation specifically increases its antiviral property by enhancing its bioavailability, solubility, and target-specific delivery system. This review highlights the potentiality of herbal plants and their phytochemical against SARS-CoV-2 utilizing different mechanisms such as blocking the ACE-2 receptors, inhibiting the main proteases, binding spike proteins and reducing the cytokine storms.

Dissimilar effects of stereoisomers and racemic hydroxychloroquine on Ca2+ oscillations in human induced pluripotent stem cell-derived cardiomyocytes

All currently employed pharmaceutical formulations of hydroxychloroquine (HCQ) sulfate are a racemate, consisting of equal parts mixture of two stereoisomers: R(-)HCQ and S(+)HCQ sulfates. The aims of the current study were first, to obtain and characterize pure HCQ enantiomers. The separation and purification of free base HCQ enantiomers from the racemate form were performed using semi-preparative chiral high-performance liquid chromatography. Second, we compared the pharmacological properties of both optical isomers and racemic mixture on the intracellular Ca2+ oscillations employing an in vitro model of human cardiomyocytes derived from induced pluripotent stem cells (iPSCs). The results of the pharmacological investigations indicate that the racemic and pure stereoisomer forms of HCQ sulfate exhibited a dose-dependent inhibition of spontaneous Ca2+ oscillations (as measured from their frequency and Ca2+ peak widths) in cardiomyocytes 5-45 min following exposure. In addition, the concentration-response relationships for all three compounds indicated that the rank order of potency (IC50 ) was R(-)HCQ >racemic HCQ >S(+)HCQ for the frequency of the Ca2+ oscillations and width of Ca2+ peaks for all time points examined. These studies indicate that both R(-) and S(+) stereoisomers exhibit differing pharmacological actions on hiPSC cardiomyocytes, with the former effecting a greater potency on cell Ca2+ handling.

Establishment of angiotensin-converting enzyme 2 and cluster of differentiation 147 dual target cell membrane chromatography based on SNAP-tag technology for screening anti severe acute respiratory syndrome coronavirus 2 active components

Patients have different responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and these may be life-threatening for critically ill patients. Screening components that act on host cell receptors, especially multi-receptor components, is challenging. The in-line combination of dual-targeted cell membrane chromatography and a liquid chromatography-mass spectroscopy (LC-MS) system for analyzing angiotensin-converting enzyme 2 (ACE2) and cluster of differentiation 147 (CD147) receptors based on SNAP-tag technology provides a comprehensive solution for screening multiple components in complex samples acting on the two receptors. The selectivity and applicability of the system were validated with encouraging results. Under the optimized conditions, this method was used to screen for antiviral components in Citrus aurantium extracts. The results showed that 25 µmol /L of the active ingredient could inhibit virus entry into cells. Hesperidin, neohesperidin, nobiletin, and tangeretin were identified as antiviral components. In vitro pseudovirus assays and macromolecular cell membrane chromatography further verified the interaction of these four components with host-virus receptors, showing good effects on some or all of the pseudoviruses and host receptors. In conclusion, the in-line dual-targeted cell membrane chromatography LC-MS system developed in this study can be used for the comprehensive screening of antiviral components in complex samples. It also provides new insight into small-molecule drug-receptor and macromolecular-protein-receptor interactions.

Enhanced stability designs of cell membrane chromatography for screening drug leads

Cell membrane chromatography is an effective method for screening bioactive components acting on specific receptors in complex systems, which maintains the biological activity of the membrane receptors and improves screening efficiency. However, traditional cell membrane chromatography suffers from poor stability, resulting in a limited life span and low reproducibility, greatly limiting the application of this method. To address this problem, cyanuric chloride-decorated silica gel was used for the covalent immobilization of the cell membranes. Cyanuric chloride reacts with amino groups on the cell membranes and membrane receptors to form covalent bonds. In this way, the cell membranes are not easy to fall off. The column life of the cyanuric chloride-decorated epidermal growth factor receptor/cell membrane chromatography column was extended to more than 8 days, whereas the column life of the normal cell membrane chromatography column dropped sharply in the first 3 days. A cyanuric chloride-decorated epidermal growth factor receptor/cell membrane chromatography online HPLC-IT-TOF-MSn system was applied for screening drug leads from Trifolium pratense L.. One potential drug lead, formononetin, which acts on the epidermal growth factor receptor, was screened. Our strategy of covalently immobilizing cell membrane receptors also improved the stability of cell membrane chromatography. This article is protected by copyright. All rights reserved.

Natural Products and Nanotechnology Against Coronavirus Disease 2019

Coronavirus disease 2019 (COVID-19) is a new and severe infectious disease and new global disaster and is spreading rapidly worldwide. Natural products have a long history and have been widely used to treat various acute, chronic, and even life-threatening diseases worldwide. However, the natural products have reduced bioavailability and availability as they have poor kinetic properties, such as large molecular weight, inability to cross lipid membranes, and weak absorption ability. With the rapid development of nanotechnology, using novel nanotechnology in conjunction with natural products can effectively eliminate the molecular restriction of the entry of nanoproducts into the body and can be used to diagnose and treat various diseases, including COVID-19, bringing new strategies and directions for medicine. This article reviews the role and implementation of natural products against COVID-19 based on nanotechnology.