Novel codeinone derivatives via Michael addition of barbituric acids

Novel benzimidazole-linked (thio)barbiturates as non-hydroxamate HDAC6 inhibitors targeting leukemia: Design, synthesis, and structure-activity relationship

Based on the well-established pharmacophoric features required for histone deacetylase (HDAC) inhibition, novel easy-to-prepare benzimidazole-linked (thio)barbiturate derivatives were designed and synthesized as HDAC6 inhibitors. The proposed structures of the title compounds were confirmed based on their spectral data and elemental analyses. The newly synthesized compounds were screened in vitro against HDAC6. All tested compounds showed potent HDAC6 inhibition at the nanomolar level. Several compounds displayed a remarkable HDAC6 inhibitory activity (IC₅₀  = 48.85-75.62 nM), superior to that of the reference drug suberoylanilide hydroxamic acid (SAHA; IC₅₀  = 91.73 nM). The most potent derivatives were further assessed for their in vitro anticancer activity against two human leukemia cell lines. Thiobarbiturate 3e was two times more potent than SAHA against the tested cells. The detailed structure-activity relationship was also described. Furthermore, molecular docking simulation revealed the ability of the title compounds to chelate the catalytic Zn⁺² ion located within the binding pocket of HDAC6. In silico evaluation of physicochemical properties indicated that the target compounds are promising candidates in terms of pharmacokinetic aspects.

Supramolecular assembly and spectroscopic characterization of indolenine–barbituric acid zwitterions

The intermolecular hydrogen bonding of barbiturates assists in the supramolecular aggregation and a hypsochromic shift is shown in protic solvents.

Enantioselective organocatalytic Michael additions of N,N'-dialkylbarbituric acids to enones

N,N'-Dialkylbarbituric acids as cyclic malonamide donors were successfully used in the enantioselective Michael addition reaction of enones. Using cinchona alkaloid-based bifunctional squaramide as an organocatalyst, this Michael reaction of N,N'-di-tert-butylbarbituric acid with various enones features a highly enantioselective (91-99% ee) production of the corresponding optically active 5-substituted barbituric acid derivatives. The transformations of the Michael product for the barbituric acid structural unit were realized in two ways, deprotection to remove the N-tert-butyl group and alkylation to produce 5,5-disubstituted barbituric acid derivatives.

Design and synthesis of new barbituric- and thiobarbituric acid derivatives as potent urease inhibitors: Structure activity relationship and molecular modeling studies

In this study 36 new compounds were synthesized by condensing barbituric acid or thiobarbituric acid and respective anilines (bearing different substituents) in the presence of triethyl orthoformate in good yields. In vitro urease inhibition studies against jack bean urease revealed that barbituric acid derived compounds (1-9 and 19-27) were found to exhibit low to moderate activity however thiobarbituric acid derived compounds (10-18 and 28-36) showed significant inhibition activity at low micro-molar concentrations. Among the synthesized compounds, compounds (15), (12), (10), (36), (16) and (35) showed excellent urease inhibition with IC50 values 8.53 ± 0.027, 8.93 ± 0.027, 12.96 ± 0.13, 15 ± 0.098, 18.9 ± 0.027 and 19.7 ± 0.63 μM, respectively, even better than the reference compound thiourea (IC50 = 21 ± 0.011). The compound (11) exhibited comparable activity to the standard with IC50 value 21.83 ± 0.19 μM. In silico molecular docking studies for most active compounds (10), (12), (15), (16), (35) and (36) and two inactive compounds (3) and (6) were performed to predict the binding patterns.

Reduced antinociception of opioids in rats and mice by vaccination with immunogens containing oxycodone and hydrocodone haptens

Prescription opioids abuse and associated deaths are an emerging concern in the USA. Vaccination against prescription opioids may provide an alternative to pharmacotherapy. An oxycodone hapten containing a tetraglycine linker at the C6 position (6OXY(Gly)(4)OH) conjugated to keyhole limpet hemocyanin (KLH) has shown early proof-of-efficacy in rodents as a candidate immunogen (6OXY(Gly)(4)-KLH) for the treatment of oxycodone abuse. In this study, oxycodone-based and hydrocodone-based haptens were conjugated to KLH to generate immunogens that would recognize both oxycodone and hydrocodone. Vaccination with 6OXY(Gly)(4)-KLH increased drug binding in serum, reduced drug distribution to brain, and blunted analgesia for both oxycodone and hydrocodone. An analogous C6-linked hydrocodone vaccine blocked hydrocodone effects but less so than 6OXY(Gly)(4)-KLH. C8-Linked hydrocodone immunogens had only limited efficacy. Amide conjugation showed higher haptenation ratios and greater efficacy than thioether conjugation to maleimide activated KLH (mKLH). The 6OXY(Gly)(4)-KLH vaccine may be used for treatment of prescription opioid abuse.