Substitution at the 1-position of the isohexyl side chain of 14b with a methyl group to give 46 resulted in a pan-potentiator with similar potency on GluN2A-D (EC50 values ranged from 25.0 to 39.4 M) to that of 14b (Tables 2 and ?and4,4, Figure 2). carboxylation using carbon monoxide gave ester 37 which was hydrolysed using base to afford acid 38 (Scheme 4). Sonogashira coupling between 10 and 4-pentyn-2-ol led to the synthesis of alcohol 39. Hydrogenation of the alkyne bond followed by oxidation of the alcohol using Dess-Martin periodinane (DMP) afforded ketone 40 in good yield (Scheme 4). The introduction of a carboxymethyl group was achieved by reacting ketone 40 with methyl diethylphosphonoacetate under Wittig reaction conditions. Hydrogenation of the resultant alkene gave ester (41) which was readily hydrolysed to di-acid 42 using base (Scheme 4). Open in a separate window Scheme 3a aReagents and conditions: (a) Alkene, P(oocytes. After Rabbit Polyclonal to HSL (phospho-Ser855/554) 2 to 5 days, NMDAR currents were induced by L-glutamate (Glu) (10 M) and glycine (Gly) (10 M) and after a steady-state response was obtained, the test compounds were co-applied with agonist. Data from these studies are shown in Tables 1C3 and ?and5.5. Full concentration-response curves (Figures U-93631 2 and ?and3)3) and EC50 or IC50 values across GluN2A-D were then generated for compounds with significant NMDAR potentiating or inhibitory activity identified in the initial screen (Tables 4 and ?and6).6). All compounds were soluble and showed no visible signs of precipitation at the concentrations tested in these assays. The originally described compounds (e.g. 1 and 7, Figure 1) did not display glutamate-site or glycine-site NMDAR agonist activity nor were they active in the absence of agonists [7,13]. In this study, compounds with the greatest PAM activity (14b and 46, Tables 1, ?,22 and ?and4)4) were similarly evaluated and found to have no NMDAR agonist activity or effect on the holding current (Saptoka et al., 2017). Open in a separate window Figure 2 Potentiation of NMDAR responses by 2-naphthoic acid derivatives. Select PAMs identified in Table 1 were tested for activity at various concentrations to determine potency U-93631 and efficacy. Compounds were tested on NMDA receptors containing GluN1a and the indicated GluN2 subunit expressed in oocytes. After obtaining a steady state NMDAR response evoked by 10 M L-glutamate and 10 M glycine, test compounds were co-applied with agonists at various concentrations. Values (mean s.e.m.) represent the % potentiation of the response above the agonist-alone response. Open in a separate window Figure 3 Inhibition of NMDAR U-93631 responses by 2-naphthoic acid derivatives. A. 7, B. 79h, C. 79i, D. 79j. NAMs described in Table 6 were tested for activity at various concentrations to determine inhibitory potency and the percentage of maximum inhibition. Compounds were tested on NMDA receptors containing GluN1a and the indicated GluN2 subunit expressed in oocytes. After obtaining a steady state NMDAR response evoked by 10 M L-glutamate and 10 M glycine, test compounds were co-applied with agonists at various concentrations. Values (mean s.e.m.) represent the % response in the presence of the test compound compared to response in the presence of agonists alone. Table 1. SAR studies on naphthalene derivatives and comparsion to corresponding phenanthrene deriavtives. Values are percentage response for agonist (10 M L-glutamate/10 M glycine) in presence of test compound (100 M) compared to agonist alone. oocytes. After obtaining a steady state NMDAR response evoked by 10 M L-glutamate and 10 M glycine, test compounds (100 M) were co-applied with agonists. Values (mean s.e.m.) represent the % response in the presence of the test compound compared to response in the presence of agonists alone. Values 100 represent potentiation and those 100 represent inhibition of the agonist response. Table 2. SAR studies to probe the effect of substitution of the alkyl chain at the 6-position of the naphthalene ring. Values are percentage response for agonist (10 M L-glutamate/10 M glycine) in presence of test compound (100 M) compared to agonist alone. double bond gave 12b, which displayed an increase in potentiation of agonist response on GluN2C and GluN2D compared to 14b (Table 1). However, a similar conformational restriction of the double bond into the side chain of 14b can be used to increase selectivity for GluN2C/GluN2D versus GluN2A/GluN2B. Adding a 4-phenylbut-1-yl substituent to the 6-position of the naphthalene ring (Figure 2, Table 1) to give 27a reduced potentiation.