Bacterial neuraminidase inhibitory chalcones from flowers of Coreopsis lanceolata, their kinetic characterization and antibiofilm effect.

BACKGROUND: Bacteria within biofilms are thousand times more resistant to antibiotics. Neuraminidase is a crucial enzyme for bacterial adhesion and biofilm formation, it hydrolyzes glycosidic residue of glycoproteins, glycolipids, and oligosaccharides. Coreopsis lanceolata L. flowers may have a significant potential of bacterial neuraminidase (BNA) inhibition because of high natural abundance of chalcones. PURPOSE: The investigation of bacterial biofilm inhibitors has emerged as a novel therapeutic strategy against antibiotic resistance. Therefore, individual chalcones were isolated from C. lanceolata and their capacity to inhibit BNA and formation of Escherichia coli biofilm were evaluated. METHODS: Different chromatographic techniques were used to isolate the compounds (1-12). Enzyme inhibition and detailed kinetic behavior of compounds was determined by estimation of kinetic parameters (Michaelis-Menten constants (Km), maximum velocity (Vmax), dissociation constant for binding with the free enzyme (KI) and enzyme-substate complex (KIS)). Binding affinities (KSV) and binding modes of inhibitors were elucidated by fluorescence quenching and molecular docking, respectively. The natural abundance of chalcones was established through UPLC-Q-TOF/MS. The most potent inhibitor (1) was tested for its ability to inhibit the formation of E. coli biofilm, which was examined by crystal violet assay, scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM). RESULTS: A series of eight chalcones (1-8) and four chalcone glucosides (9-12), inhibited BNA in a dose-dependent manner with IC50 of 8.3 ∼ 77.0 µM. The most potent chalcones were butein (1, IC50 = 8.3 µM) and its glucoside 9 (IC50 = 13.8 µM). The aglycones (1-8) showed non-competitive inhibition, while chalcone glucosides (9-12) displayed a mixed type I (KI < KIS). Inhibitory behaviors were doubly confirmed by KSV and matched with tendency of IC50. The functional group responsible for BNA inhibition were disclosed as 4'-hydroxyl group on B-ring by structure activity relationship (SAR) and molecular docking experiments. Butein (1) suppressed E. coli biofilm formation by > 50 % at 100 µM according to crystal violet assay, which was confirmed by SEM and CLSM imaging. CONCLUSION: The results showed that chalcones (1-8) and chalcone glucosides (9-12), metabolites isolated from the flowers of C. lanceolata, had BNA inhibitory and antibiofilm formation effect on E. coli.

New Class of Tyrosinase Inhibitors, Rotenoids, from Amorpha fruticosa.

A series of rotenoids including a new one from the seeds of Amorpha fruticosa were found to have significant potential as tyrosinase inhibitors. All of the isolated rotenoids (1-6) displayed inhibitory activity against tyrosinase, both as a monophenolase for the oxidation of l-tyrosine and as a diphenolase for the oxidation of l-DOPA. The three most active compounds (1, 5, and 6) showed significant monophenolase inhibition with IC50 values of 2.1, 1.7, and 1.2 µM, respectively. They also inhibited diphenolase function with IC50 values in the range of 9.5-21.5 µM. The inhibition kinetics established all compounds to be competitive inhibitors of both oxidation processes. All rotenoids formed the Emet·I complex effectively around their IC50 values with long lag times. Tyrosinase inhibition of the new rotenoid 6 was additionally demonstrated using high-performance liquid chromatography (HPLC) analysis with N-acetyl-l-tyrosine. Molecular docking disclosed that the sugar moiety of 5 interacted with the bottom of the catalytic gorge.

Clinical relevance and prognostic implications of contrast quantitative flow ratio in patients with coronary artery disease.

BACKGROUND: We sought to evaluate the diagnostic performance of contrast quantitative flow ratio (cQFR) in all-comer patients with coronary artery disease, and to compare the vessel-oriented composite outcomes (VOCO) according to cQFR values. METHOD: 599 vessels with 452 patients who underwent clinically indicated fractional flow reserve (FFR) and cQFR measurement were evaluated. The cQFR, derived from 3-dimensional quantitative coronary angiography combined with TIMI frame-counts was compared with FFR as a reference standard. The risk of VOCO at 2 years, a composite of cardiac death, target-vessel myocardial infarction, and ischemia-driven target lesion revascularization, was compared according to cQFR and FFR value. RESULTS: cQFR strongly correlated with FFR (r=0.860, p<0.001) and showed diagnostic accuracy of 91.2% to predict FFR≤0.80. cQFR showed significantly higher c-index to predict FFR≤0.80 (0.953, 95%CI 0.937-0.969) than %DS, percent area stenosis, resting distal coronary pressure/aortic pressure, and fixed QFR (p<0.001). Diagnostic accuracy of cQFR was not different according to various subgroups including non-culprit vessel of acute coronary syndrome and diabetes mellitus. Vessels with low cQFR (≤0.80) showed a significantly higher risk of VOCO at 2-year compared to those with high cQFR (>0.80) (HR 4.650, 95%CI 1.254-17.240, p=0.022). Discriminatory ability of cQFR for VOCO was similar with that of FFR (0.672 vs. 0.643, p=0.147). CONCLUSION: cQFR showed excellent correlation and diagnostic accuracy with FFR in diverse clinical presentations or patient characteristics. Low cQFR was significantly associated with a higher risk of VOCO at 2 years compared with high cQFR and cQFR showed similar discriminatory ability for VOCO with FFR.

Residual functional SYNTAX score by quantitative flow ratio and improvement of exercise capacity after revascularization.

OBJECTIVES: This study aimed to evaluate the association between improvement in exercise capacity and functional completeness of revascularization, determined by residual functional SYNTAX score (rFSS), which is the sum of residual SYNTAX score of the vessels with post- percutaneous coronary intervention (PCI) quantitative flow ratio (QFR) ≤0.80. BACKGROUND: In patients with stable ischemic heart disease (SIHD), the efficacy of PCI in improving exercise capacity has been under debate and the differential effect of PCI for exercise capacity, according to functional completeness of revascularization, has not been evaluated. METHODS: Among patients enrolled in the QFR multicenter registry, 110 patients who underwent routine exercise treadmill tests before and after PCI were analyzed. Patients were classified into functional complete revascularization (CR) group (rFSS = 0) and functional incomplete revascularization (IR) group (rFSS ≥ 1). Increase of exercise time after PCI was compared between the two groups. Improvement of exercise capacity was defined as ≥10% increase of exercise time after PCI. RESULTS: Functional CR was achieved in 79 patients (71.8%), otherwise classified as functional IR in 31 patients (28.2%) without differences in baseline characteristics including medication profiles. Increase of exercise time was significantly associated with increase of 3-vessel QFR (sum of QFRs in all three vessels; r = .198, p = .038) and rFSS (r = -.312, p < .001), but not with decrease of SYNTAX score (r = .097, p = .313). The rFSS showed significantly higher c-index to predict the improvement of exercise capacity after PCI than increase of 3-vessel QFR or decrease of SYNTAX score (0.722 vs. 0.627 vs. 0.492, respectively, p < 0.001). Patients with functional CR, defined by rFSS, showed significantly higher absolute and relative increase in exercise time than those with functional IR (97.7 s vs. 12.5 s, p < .001; 25.4% vs. 3.6%, p = .001). Functional CR was an independent predictor for improvement of exercise capacity after PCI (adjusted OR 4.656, 95% CI 1.678-12.920, p = .002). CONCLUSIONS: Integrated anatomic and functional scoring system (rFSS) was significantly associated with improvement of exercise capacity after PCI. SIHD patients with functional CR, defined by rFSS, showed significantly higher exercise capacity after PCI than those with functional IR.