Corrigendum: Zilucoplan, a macrocyclic peptide inhibitor of human complement component 5, uses a dual mode of action to prevent terminal complement pathway activation.

[This corrects the article DOI: 10.3389/fimmu.2023.1213920.].

Zilucoplan, a macrocyclic peptide inhibitor of human complement component 5, uses a dual mode of action to prevent terminal complement pathway activation.

Introduction: The complement system is a key component of the innate immune system, and its aberrant activation underlies the pathophysiology of various diseases. Zilucoplan is a macrocyclic peptide that binds and inhibits the cleavage/activation of human complement component 5 (C5). We present in vitro and ex vivo data on the mechanism of action of zilucoplan for the inhibition of C5 activation, including two clinically relevant C5 polymorphisms at R885. Methods: The interaction of zilucoplan with C5, including for clinical C5 R885 variants, was investigated using surface plasmon resonance (SPR), hemolysis assays, and ELISA. The interference of C5b6 formation by zilucoplan was investigated by native gel analysis and hemolysis assay. The permeability of zilucoplan in a reconstituted basement membrane was assessed by the partition of zilucoplan on Matrigel-coated transwell chambers. Results: Zilucoplan specifically bound human complement C5 with high affinity, competitively inhibited the binding of C5 to C3b, and blocked C5 cleavage by C5 convertases and the assembly of the cytolytic membrane attack complex (MAC, or C5b9). Zilucoplan fully prevented the in vitro activation of C5 clinical variants at R885 that have been previously reported to respond poorly to eculizumab treatment. Zilucoplan was further demonstrated to interfere with the formation of C5b6 and inhibit red blood cell (RBC) hemolysis induced by plasmin-mediated non-canonical C5 activation. Zilucoplan demonstrated greater permeability than a monoclonal C5 antibody in a reconstituted basement membrane model, providing a rationale for the rapid onset of action of zilucoplan observed in clinical studies. Conclusion: Our findings demonstrate that zilucoplan uses a dual mode of action to potently inhibit the activation of C5 and terminal complement pathway including wild-type and clinical R885 variants that do not respond to eculizumab treatment. These data may be relevant to the clinically demonstrated benefits of zilucoplan.

In Vitro and In Vivo Interaction Studies Between Lesinurad, a Selective Urate Reabsorption Inhibitor, and Major Liver or Kidney Transporters.

BACKGROUND AND OBJECTIVES: Lesinurad is a selective uric acid reabsorption inhibitor (SURI) under investigation for the treatment of gout. This study elucidated the interaction of lesinurad with major liver and kidney transporters in vitro and evaluated the drug-drug interactions (DDIs) of lesinurad and atorvastatin, metformin, and furosemide in clinical studies. METHODS: Lesinurad interaction with membrane transporters was evaluated in validated transporter-expressing cell systems and analyzed by liquid scintillation counting. Healthy male subjects (ages 18-65 years; body mass index 18-32 kg/m(2)) received atorvastatin (40 mg; n = 28) with or without lesinurad 200 or 400 mg, or received metformin (850 mg; n = 12) or furosemide (40 mg; n = 11) with or without lesinurad 400 mg. Plasma concentrations of each concomitant drug were determined by validated liquid chromatography with tandem mass spectrometry methods. RESULTS: Lesinurad interacted in vitro with OATP1B1, OCT1, and OAT1/3 transporters. Co-administration of lesinurad 200 mg did not significantly alter plasma exposure (maximum concentration [C max] and area under the concentration-time curve [AUC]) of total atorvastatin (atorvastatin + hydroxyl-metabolites) or atorvastatin, while co-administration of lesinurad 400 mg increased the C max of total atorvastatin and atorvastatin by 17-26 %, but had no effect on AUC. Co-administration of lesinurad 400 mg had no effect on the plasma exposure of metformin. Furosemide plasma AUC was reduced by 31 % in the presence of lesinurad 400 mg, but furosemide renal clearance and diuretic activity were unchanged. CONCLUSIONS: No clinically relevant DDIs were observed between lesinurad and substrates of major liver or kidney transporters.

Absorption, metabolism, and excretion of [14C]viramidine in humans.

Absorption, metabolism, and excretion of [14C]viramidine, a prodrug of ribavirin, were studied in humans following a single oral dose (600 mg). Viramidine was rapidly absorbed, with a time to maximum concentration of the drug in plasma of 1.5 h. Viramidine and ribavirin accounted for only 4.3% and 42% of plasma area under the concentration-time curve (AUC) for radioactivity, respectively, indicating extensive conversion of viramidine to ribavirin, followed by further metabolism of ribavirin. The drug was largely trapped in red blood cells (RBC), with an RBC-to-plasma radioactivity AUC0-infinity ratio of 108. Excretion of total radioactivity in urine and feces accounted for 50.8% and 26.1% of the dose, respectively. The metabolic profile in urine (0 to 24 h) indicated that viramidine was excreted primarily as triazole carboxamide (TCONH2), triazole carboxylic acid nucleoside (TCOOH), and ribavirin with a small amount of unchanged viramidine, which each accounted for 64.1%, 17.0%, 15.7%, and 3.2% of urinary radioactivity, respectively. The amounts of unchanged viramidine (3.4% of dose) and ribavirin (10% of dose) in urine were small after oral administration of viramidine.

Sesquiterpene lactones from Inula britannica and their cytotoxic and apoptotic effects on human cancer cell lines.

Three new sesquiterpenes (1-3), together with four known sesquiterpene lactones, were isolated from the flowers of Inula britannica var. chinensis. Structures were established on the basis of high-field 1D and 2D NMR methods supported by HRMS. All sesquiterpene lactones were tested for cytotoxicity as well as apoptotic ratio in human COLO 205, HT 29, HL-60, and AGS cancer cells. Compounds 3 and 4, two alpha-methylene gamma-lactone-bearing sesquiterpenes, were modestly active in these assays.

Single-dose pharmacokinetics and metabolism of [14C]remofovir in rats and cynomolgus monkeys.

Single-dose pharmacokinetics and metabolism of [(14)C]remofovir was studied in rats and monkeys following intravenous (i.v.) and oral administration (30 mg/kg of body weight). Oral absorption and bioavailability were 29.7 and 5.42% in rats and 65.6 and 19.4% in monkeys, respectively. Following i.v. administration, the elimination half-life for remofovir was 0.7 h in both rats and monkeys. Total body clearance was 5.85 liters/h/kg in rats and 2.60 liters/h/kg in monkeys; apparent volume of distribution was 5.99 liters/kg in rats and 2.70 liters/kg in monkeys. Following oral administration, remofovir was extensively converted to 9-(2-phosphonylmethoxyethyl)adenine (PMEA) and other metabolites in both species. In rats, excretion of total radioactivity in urine accounted for 61.8% of the i.v. dose and 12.9% of the oral dose, while in monkeys it accounted for 43.3% of the i.v. dose and 34.9% of the oral dose. Following i.v. dosing of [(14)C]remofovir, fecal excretion of radioactivity accounted for 37.5% of the dose in rats and 17.4% of the dose in monkeys, indicating significant biliary excretion of the drug in animals. PMEA and metabolite A were the major urinary metabolites in both species after i.v. and oral administration of remofovir.

New unusual iridoids from the leaves of noni (Morinda citrifolia L.) show inhibitory effect on ultraviolet B-induced transcriptional activator protein-1 (AP-1) activity.

A novel iridoid dimer in whose structure the two iridoid units are connected by a rare ether group, together with two new unusual iridoids showing significant inhibition of UVB-induced Activator Protein-1 (AP-1) activity in cell cultures, have been isolated from the leaves of noni (Morinda citrifolia L.). Their structures were determined on the basis of detailed high-field 1D and 2D spectral analysis. Their inhibitory effect on UVB-induced transcriptional Activator Protein-1 (AP-1) activity are also discussed.

Identification and characterization of methylated and ring-fission metabolites of tea catechins formed in humans, mice, and rats.

(-)-Epigallocatechin gallate (EGCG), the most abundant tea catechin, has been proposed to be beneficial to human health based on its strong antioxidative and other biological activities in vitro. Inadequate knowledge regarding the bioavailability and biotransformation of EGCG in humans, however, has limited our understanding of its possible beneficial health effects. In this study, 4',4' '-di-O-methyl-EGCG (4',4' '-DiMeEGCG) was detected in human plasma and urine by LC/MS/MS following green tea ingestion. Both 4',4' '-DiMeEGCG and EGCG reached peak plasma values (20.5 +/- 7.7 and 145.4 +/- 31.6 nM, respectively, in 4 subjects) at 2 h after the dose. The half-lives of 4',4' '-DiMeEGCG and EGCG were 4.1 +/- 0.8 and 2.7 +/- 0.9 h, respectively. The cumulative urinary excretion of 4',4' '-DiMeEGCG during a 24 h period was 140.3 +/- 48.6 microg, about 5-fold higher than that of EGCG, but the excreted 4',4' '-DiMeEGCG and EGCG in urine only accounted for about 0.1% of ingested EGCG. (-)-5-(3',4',5'-Trihydroxyphenyl)-gamma-valerolactone (M4) and (-)-5-(3',4'-dihydroxyphenyl)-gamma-valerolactone (M6), along with another possible ring-fission metabolite, (-)-5-(3',5'-dihydroxyphenyl)-gamma-valerolactone (M6'), were detected in human urine after green tea ingestion. The cumulative excretion of M4, M6', and M6 during a 24 h period ranged from 75 microg to 1.2 mg, 0.6 to 6 mg, and 0.6 to 10 mg, respectively. The combined excretion of all three ring-fission metabolites accounted for 1.5-16% of ingested catechins. M4, M6', and M6 were all observed after the ingestion of pure EGCG or EGC by human subjects, whereas only M6 was produced after EC ingestion. These metabolites as well as monomethylated EGCG were detected in mice and rats after tea or EGCG administration, and the tissue levels reflected the rather low bioavailability of EGCG in rats. The presently characterized methylated EGCG metabolites and ring-fission products exist in substantial quantities and may contribute to the biological activities of tea.

Characterization of 2-methyl-4-amino-5-(2-methyl-3-furylthiomethyl)pyrimidine from thermal degradation of thiamin.

Thiamin hydrochloride was thermally degraded in phosphate buffer (pH 6.5) at 110 degrees C for 2 h. A major decomposition product was isolated by column chromatography and structurally identified by spectrometric techniques ((1)H NMR, (13)C NMR, 2D NMR, and MS) as 2-methyl-4-amino-5-(2-methyl-3-furylthiomethyl)pyrimidine (MAMP). The possible formation pathway of MAMP was studied using two model systems. It is proposed that MAMP is formed by nucleophilic attack of 2-methyl-3-furanthiol on the thiamin.

Triterpene saponins from debittered quinoa (Chenopodium quinoa) seeds.

Twelve triterpene saponins have been isolated from the debittered seeds of quinoa (Chenopodium quinoa), and their structures were characterized on the basis of hydrolysis and spectral data, especially NMR evidence. Among them, three compounds, including 3-O-beta-D-glucuropyranosyl oleanolic acid (1), 3-O-beta-D-glucopyranosyl-(1-->3)-alpha-L-arabinopyranosyl hederagenin (2), and the new compound 3-O-beta-D-glucopyranosyl-(1-->3)-alpha-L-arabinopyranosyl-30-O-methyl spergulagenate 28-O-beta-D-glucopyranosyl ester (3), are identified for the first time from quinoa seeds. The other isolated saponins have been previously reported in quinoa.