Synthesis and evaluation of enantiomers of hydroxychloroquine against SARS-CoV-2 in vitro

New methods for resolution of hydroxychloroquine by forming diastereomeric salt and adding chiral mobile phase agent on RP-HPLC

Hydroxychloroquine (HCQ), 2-([4-([7-Chloro-4-quinolyl]amino)pentyl]ethylamino)ethanol, exhibited significant biological activity, while its side effects cannot be overlooked. The RP-HPLC enantio-separation was investigated for cost-effective and convenient optical purity analysis of HCQ. The thermodynamic resolution of Rac-HCQ, driven by enthalpy and entropy, was achieved on the C18 column using Carboxymethyl-β-cyclodextrin (CM-β-CD) as the chiral mobile phase agent (CMPA). The effects of CCM-β-CD, pH, and triethylamine (TEA) V% on the enantio-separation process were explored. Under the optimum conditions at 24°C, the retention times for the two enantiomers weret R 1 = 29.39 min $$ {t}_{R1}=29.39\ \min $$ andt R 2 = 32.42 min $$ {t}_{R2}=32.42\ \min $$ , resulting inR s = 1.87 $$ {R}_s=1.87 $$ . The resolution via diastereomeric salt formation of Rac-HCQ was developed to obtain the active pharmaceutical ingredient of single enantiomer S-HCQ. Di-p-Anisoyl-L-Tartaric Acid (L-DATA) was proved effective as the resolution agent for Rac-HCQ. Surprisingly, it was found that refluxing time was a key fact affecting the resolution efficiency, which meant the kinetic dominate during the process of the resolution. Four factors-solvent volume, refluxing time, filtration temperature, and molar ratio-were optimized using the single-factor method and the response surface method. Two cubic models were established, and the reliability was subsequently verified. Under the optimal conditions, the less soluble salt of 2L-DATA:S-HCQ was obtained with a yield of 96.9% and optical purity of 63.0%. The optical purity of this less soluble salt increases to 99.0% with a yield of 74.2% after three rounds recrystallization.

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.

Discovery of quinazolin-4-one-based non-covalent inhibitors targeting the severe acute respiratory syndrome coronavirus 2 main protease (SARS-CoV-2 Mpro)

The COVID-19 pandemic caused by SARS-CoV-2 continues to pose a great threat to public health while various vaccines are available worldwide. Main protease (M^pro) has been validated as an effective anti-COVID-19 drug target. Using medicinal chemistry and rational drug design strategies, we identified a quinazolin-4-one series of nonpeptidic, noncovalent SARS-CoV-2 M^pro inhibitors based on baicalein, 5,6,7-trihydroxy-2-phenyl-4H-chromen-4-one. In particular, compound C7 exhibits superior inhibitory activity against SARS-CoV-2 M^pro relative to baicalein (IC₅₀ = 0.085 ± 0.006 and 0.966 ± 0.065 μM, respectively), as well as improved physicochemical and drug metabolism and pharmacokinetics (DMPK) properties. In addition, C7 inhibits viral replication in SARS-CoV-2-infected Vero E6 cells more effectively than baicalein (EC₅₀ = 1.10 ± 0.12 and 5.15 ± 1.64 μM, respectively) with low cytotoxicity (CC₅₀ ＞ 50 μM). An X-ray co-crystal structure reveals a non-covalent mechanism of action, and a noncanonical binding mode not observed by baicalein. These results suggest that C7 represents a promising lead for development of more effective SARS-CoV-2 M^pro inhibitors and anti-COVID-19 drugs.

COVID-19 in early 2023: Structure, replication mechanism, variants of SARS-CoV-2, diagnostic tests, and vaccine & drug development studies

Coronavirus Disease-19 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome-coronaviruses-2 (SARS-CoV-2), a highly pathogenic and transmissible coronavirus. Most cases of COVID-19 have mild to moderate symptoms, including cough, fever, myalgias, and headache. On the other hand, this coronavirus can lead to severe complications and death in some cases. Therefore, vaccination is the most effective tool to prevent and eradicate COVID-19 disease. Also, rapid and effective diagnostic tests are critical in identifying cases of COVID-19. The COVID-19 pandemic has a dynamic structure on the agenda and contains up-to-date developments. This article has comprehensively discussed the most up-to-date pandemic situation since it first appeared. For the first time, not only the structure, replication mechanism, and variants of SARS-CoV-2 (Alpha, Beta, Gamma, Omicron, Delta, Epsilon, Kappa, Mu, Eta, Zeta, Theta, lota, Lambda) but also all the details of the pandemic, such as how it came out, how it spread, current cases, what precautions should be taken, prevention strategies, the vaccines produced, the tests developed, and the drugs used are reviewed in every aspect. Herein, the comparison of diagnostic tests for SARS-CoV-2 in terms of procedure, accuracy, cost, and time has been presented. The mechanism, safety, efficacy, and effectiveness of COVID-19 vaccines against SARS-CoV-2 variants have been evaluated. Drug studies, therapeutic targets, various immunomodulators, and antiviral molecules applied to patients with COVID-19 have been reviewed.

Multi-target activity of copper complexes: Antibacterial, DNA binding, and molecular docking with SARS-CoV-2 receptor

A series of pendant-armed mixed-ligand copper(II) complexes of the type [CuL^1-3(diimine)] (1-6) have been synthesized by the reaction of pendant-armed ligands N,N-bis(2-(((E)-2-hydroxy-5-methylbenzylidene)amino)ethyl)benzamide (H₂L¹), N,N-bis(2-(((E)-2-hydroxy-5-methylbenzylidene)amino)ethyl)-4-nitrobenzamide (H₂L²) and N,N-bis(2-(((E)-2-hydroxy-5-methylbenzylidene)amino)ethyl)-3,5-dinitrobenzamide (H₂L³) with diimine = 2,2'-bipyridyl (bpy) or 1,10-phenanthroline (phen) in the presence of copper(II) chloride and analyzed using various spectroscopic methods. All the spectroscopic results support that the complexes adopt a pentagonal-bipyramidal shape around the copper ion. Gram-positive and Gram-negative bacteria were used to test all the complexes for antibacterial activity and all the complexes had greater potency against gram-negative pathogens. DNA-binding experiments of complexes with calf thymus DNA revealed a major-groove binding pattern, further supported by molecular docking studies. Complexes have significantly interacted with SARS-CoV-2 receptor via π-π, π-σ, π-alkyl, π-anion, π-cation, alkyl, hydrogen bond, van der Waals, and electrostatic interactions. The estimated binding energy and inhibition constant of these complexes are higher than standard drugs, chloroquine, and molnupiravir.

Structural growth of zinc oxide nanograins on carbon cloth as flexible electrochemical platform for hydroxychloroquine detection

Pharmaceutical pollution that imposes a health threat worldwide is making accurate and rapid detection crucial to prevent adverse effects. Herein, binder-free zinc oxide nanograins on carbon cloth (ZnO NGs@CC) have been synthesized hydrothermally and employed to fabricate a flexible electrochemical sensor for the quantification of hydroxychloroquine (HCQ) that is typical pharmaceutical pollution. The characteristics of ZnO NGs@CC were investigated by various in-depth electron microscopic, spectroscopic and electroanalytical approaches. Compared with the pristine CC platform, the ZnO NGs@CC platform exhibits superior electrochemical performance in detecting HCQ with a large oxidation current at a low over-potential of +0.92 V with respect to the Ag/AgCl (Sat. KCl) reference electrode. With the support of desirable characteristics, the fabricated ZnO NGs@CC-based electrochemical sensor for HCQ detection displays good performances in terms of wide sensing range (0.5-116 μM), low detection limit (0.09 μM), high sensitivity (0.279 μA μM^-1 cm^-2), and strong selectivity. By the resulting 3D hierarchical nanoarchitecture, ZnO NGs@CC has progressive structural advantages that led to its excellent electrochemical performance in sensing applications. Furthermore, the electrochemical sensor is employed to detect HCQ in biological and environmental samples and also achieves good recovery rates. Thus, the designed ZnO NGs@CC demonstrates admirable electrochemical activity toward HCQ real-time monitoring and would be an excellent electrochemical platform for HCQ sensing.

Neutrophil Immunomodulatory Activity of (−)-Borneol, a Major Component of Essential Oils Extracted from Grindelia squarrosa

Grindelia squarrosa (Pursh) Dunal is used in traditional medicine for treating various diseases; however, little is known about the immunomodulatory activity of essential oils from this plant. Thus, we isolated essential oils from the flowers (GEO_Fl) and leaves (GEO_Lv) of G. squarrosa and evaluated the chemical composition and innate immunomodulatory activity of these essential oils. Compositional analysis of these essential oils revealed that the main components were α-pinene (24.7 and 23.2% in GEO_Fl and GEO_Lv, respectively), limonene (10.0 and 14.7%), borneol (23.4 and 16.6%), p-cymen-8-ol (6.1 and 5.8%), β-pinene (4.0 and 3.8%), bornyl acetate (3.0 and 5.1%), trans-pinocarveol (4.2 and 3.7%), spathulenol (3.0 and 2.0%), myrtenol (2.5 and 1.7%), and terpinolene (1.7 and 2.0%). Enantiomer analysis showed that α-pinene, β-pinene, and borneol were present primarily as (−)-enantiomers (100% enantiomeric excess (ee) for (−)-α-pinene and (−)-borneol in both GEO_Fl and GEO_Lv; 82 and 78% ee for (−)-β-pinene in GEO_Fl and GEO_Lv), while limonene was present primarily as the (+)-enantiomer (94 and 96 ee in GEO_Fl and GEO_Lv). Grindelia essential oils activated human neutrophils, resulting in increased [Ca²⁺]_i (EC₅₀ = 22.3 µg/mL for GEO_Fl and 19.4 µg/mL for GEO_Lv). In addition, one of the major enantiomeric components, (−)-borneol, activated human neutrophil [Ca²⁺]_i (EC₅₀ = 28.7 ± 2.6), whereas (+)-borneol was inactive. Since these treatments activated neutrophils, we also evaluated if they were able to down-regulate neutrophil responses to subsequent agonist activation and found that treatment with Grindelia essential oils inhibited activation of these cells by the N-formyl peptide receptor 1 (FPR1) agonist fMLF and the FPR2 agonist WKYMVM. Likewise, (−)-borneol inhibited FPR-agonist-induced Ca²⁺ influx in neutrophils. Grindelia leaf and flower essential oils, as well as (−)-borneol, also inhibited fMLF-induced chemotaxis of human neutrophils (IC₅₀ = 4.1 ± 0.8 µg/mL, 5.0 ± 1.6 µg/mL, and 5.8 ± 1.4 µM, respectively). Thus, we identified (−)-borneol as a novel modulator of human neutrophil function.