13C NMR (DMSO-1.6 Hz, H-2), 7.03 (1H, dd, 1.6 Hz, 8.0 Hz, H-6), 6.94 (1H, d, 8.0 Hz, H-5), 6.88 (1H, s, H-8), 6.02 (2H, s, O-CH2-O). we were unable to relate the GLIDE score of these inhibitors to their inhibitory potency, most likely due to their small size relative to the 15-hLO-1 active site and Nav1.7-IN-2 the poor estimation of the metal-catechol bond by the docking program. Open in a separate window Physique 1 Representative poses of compound docking simulations for 15-hLO-1 with the closest phenolic distance to the iron, for inner sphere reduction, indicated with a dashed collection. 25b, 3.2 ? (A), 25e, 3.2 ? Nav1.7-IN-2 (B), 29, 4.2 ? (C) and 30, 3.1 ? (D). The first coordination sphere ligands that surround the active site iron are also shown, with Thr# labeled. In summary, the data offered here outlines a number of important discoveries. First, the aromaticity and oxidation state of ring C in our flavonoid compounds appears to be important for both the inhibitory potency and selectivity against hLO, with isoflavones and isoflavanones preferentially inhibiting 12-hLO and isoflavanes preferentially inhibiting 15-hLO-1. Second, modification of the basic flavonoid structure has produced a number of selective inhibitors of both 12-hLO (25c, 26b and 25j) and 15-hLO-1 (26c, 27a and 27d), indicating that the flavonoid skeleton is a viable scaffold for selective inhibitor development. Third, a variety of binding modes are possible for flavonoids in lipoxygenases as seen by the fact that compounds 25b, 25e, 29 and 30 all are potent, reductive inhibitors but their relative positioning of ring B to their catechol moiety is different. Finally, it appears that the structural requirements for 15-hLO-2 inhibition are dramatically different from those of 15-hLO-1 and 12-hLO, which indicates that if 15-hLO-2 has a beneficial role in malignancy prevention, inhibitors can be developed that do not target its activity. Experimental Section Chemical synthesis Melting points were determined on an Electrothermal apparatus and were not corrected. UV spectra were recorded on a Spectronic Genesys 5 instrument. 1H and 13C NMR spectra were recorded at 300 MHz or 400 MHz (1H) and 75 or 100 MHz (13C), respectively (Bruker AMX 300 and Bruker AMX 400 spectrometers) with (CH3)4Si as internal standard. Chemical Nav1.7-IN-2 shifts are reported in parts per million, using tetramethylsilane as an internal research. High-resolution mass spectra were recorded with an EI MS-50 AEI instrument at Bonn University or college, Germany and with a MAT 95XP, Thermo-Finnigan spectrometer at the University or college of Chile, Santiago. All starting materials were commercially available, 98% purity, and used without further purification. Quercetin, baicalein, fisetin, 3-hydroxyflavone, 6-hydroxyflavone, 7-hydroxyflavone, 3,5-dihydroxyflavone, 3,6-dihydroxyflavone and 3,7-dihydroxyflavone were purchased from Aldrich. The HPLC analyses of the compounds were performed using a Merck-Hitachi Intelligent L-6200A Pump, an L-4250 UV-Vis Detector and a D-7000 HSM System Manager Statement, a C18 reverse phase column (Hypersil ODS-5, 250 mm 4 mm) and a circulation rate of 1 1 mL/min. Compounds 7a to 14 were detected at 260 Rabbit Polyclonal to EIF2B3 nm, 21a to 21f at 319 nm, 25a to 25j, 26a, 26b, 27b, 27f and 27g at 255 nm, and 27a and 27c to 27e at 295 nm. Two different solvent systems were used: system 1: (A) acetonitrile and (B) 1% acetic acid and system 2: (A) acetonitrile and (B) a 1:1 mixture of 1% acetonitrile/methanol. A gradient of 30 minutes of duration was used in both cases, beginning with 30% of (A), reaching 99% at 30 minutes, and.