The interaction of small molecules, such as drugs or metabolites, with proteins and biomembranes is of fundamental importance for their bioavailability. The systematic characterization of the binding affinity for structurally related ligands may provide rules that allow its prediction for any other relevant molecule. In this work we have studied a homologous series of fluorescent fatty amines with the fluorescent moiety 7-nitrobenz-2-oxa-1,3-diazol-4-yl covalently bound to the amine group (NBD-C(n); n = 4, 6, 8, 10, 12, 14, and 16) in aqueous solution and associated with BSA or lipid bilayers. We have found a linear dependence with the length of the alkyl chain, up to NBD-C(10), for the Gibb's free energy of partition between the aqueous solution and 1-palmitoyl-2-oleoyl phosphatidylcholine bilayers equal to ΔΔG = -2.5 ± 0.3 kJ/mol per methylene group. Additionally, the amphiphiles interacted efficiently with bovine serum albumin, and it was inhibited by fatty acids indicating that binding occurs to the fatty acids highest affinity binding site. The association of the amphiphiles with BSA and POPC bilayers was performed at different temperatures (15-35 °C) allowing for the calculation of the enthalpic and entropic contributions. A value of ΔH = -15 ± 4 kJ/mol was obtained for all amphiphiles and binding agents. The entropy contribution was always positive and increased with the length of the alkyl chain. The location of the ligand in the biological membrane is also of high relevance, namely because this will determine its effect on biomembrane properties at high ligand concentrations. With this goal, we have measured some photophysical properties of the amphiphiles inserted in POPC bilayers, and we found no significant variation along the series, indicating that the NBD group is located in a region with similar properties regardless of the length of the nonpolar group. An exception was noted for the case of NBD-C(14) whose parameters were somewhat different from the trend observed.

We present a complete characterization of the kinetics of interaction between the homologous series of fluorescent fatty amines with the fluorescent moiety 7-nitrobenz-2-oxa-1,3-diazol-4-yl covalently bound to the amine group, NBD-C n (n = 8–16), and a lipid bilayer in the liquid disordered phase. The insertion into and the desorption from the lipid bilayer, as well as the rate of translocation across the two bilayer leaflets, has been measured at different temperatures, allowing an estimation of the thermodynamic parameters in the formation of the transition state. This is the first report on the complete characterization of the kinetics of the interaction of a large series of structurally homologous amphiphiles. In a recent paper from this research group, the equilibrium interaction of NBD-C n (n = 4–10) with POPC bilayers and serum albumin was reported. This information allows the calculation of the equilibrium distribution of the amphiphiles among the aqueous phase, serum proteins, and biomembranes. The data presented in this manuscript complement its characterization with information on the kinetics of the interactions, making possible the quantitative evaluation of their pharmacokinetics. The rate of translocation is shown to decrease with increasing alkyl chain length up to n = 12, becoming relatively insensitive to further increases in n. The Gibbs free energy variation associated with the rate of desorption from the lipid bilayer increased linearly with n, with ΔΔG ‡o = 3.4 ± 0.5 kJ mol–1 per methylene group. It was also found that the process of insertion in the lipid bilayer is not diffusion-limited, although it is close to this limit for the smaller amphiphiles in the homologous series at high temperatures.

Quantification of 2 H and 13 C enrichment distributions in human urinary glucuronide following ingestion of 2 H 2 O and 13 C gluconeogenic tracers was achieved by NMR spectroscopy of the 1,2-O-isopropylidene-a-D-glucofuranurono-6,3-lactone and 5-O-acetyl-1,2-O-isopropylidene-a-D-glucofuranurono-6,3-lactone derivatives. The derivatization process is simple and can be applied to any glucuronide species. The derivatives are highly soluble in acetonitrile and generate well-resolved and narrow 2 H and 13 C NMR signals.The 1,2-O-isopropylidene-a-D-glucofuranurono-6,3-lactone derivative provided resolution of the six glucuronide 13 C signals and numerous 13 C isotopomer populations through one-and two-bond 13 C-13 C-coupling, while the 5-O-acetyl-1,2-Oisopropylidene-a-D-glucofuranurono-6,3-lactone derivative provided complete resolution of the 2 H NMR signals for the five glucuronide hydrogens. The isopropylidene methyl signals were also resolved and provided an internal 2 H enrichment standard following the acetonation of glucuronolactone with deuterated acetone.

Anthracyclines such as doxorubicin are used extensively in the treatment of cancers. Anthraquinone-related angucyclines also exhibit antiproliferative properties and have been proposed to operate via similar mechanisms, including direct genome targeting. Here, we report the chemical synthesis of marmycin A and the study of its cellular activity. The aromatic core was constructed by means of a one-pot multistep reaction comprising a regioselective Diels-Alder cycloaddition, and the complex sugar backbone was introduced through a copper-catalysed Ullmann cross-coupling, followed by a challenging Friedel-Crafts cyclization. Remarkably, fluorescence microscopy revealed that marmycin A does not target the nucleus but instead accumulates in lysosomes, thereby promoting cell death independently of genome targeting. Furthermore, a synthetic dimer of marmycin A and the lysosome-targeting agent artesunate exhibited a synergistic activity against the invasive MDA-MB-231 cancer cell line. These findings shed light on the elusive pathways through which anthraquinone derivatives act in cells, pointing towards unanticipated biological and therapeutic applications.

We developed a simple and convenient method to assemble biaryls exploiting a photoredox catalyst and visible light.

α‐Amino vinylphosphonates were prepared by chemo‐ and stereoselective reduction of α‐amino allenephosphonates. Our results showed that the substituents on the allene, phosphonate, and nitrogen moieties affected the stereoselectivity of the reduction. Z‐α‐Amino vinylphosphonates were prepared with good selectivities up to > 95:5.

α-Amino allenephosphonates were easily prepared in two steps from protected amines, propargyl alcohols, and chlorophosphites. First, ynamides were synthesized from unprotected 1-bromopropargyl alcohols using a copper(II) catalyzed coupling reaction. In the second step, the previously prepared ynamides were transformed directly to allenes through a [2,3]-sigmatropic rearrangement of propargyl phosphites. This efficient method led to the formation of a series of α-amino allenephosphonates with diverse substituents on the amine, the phosphonate, and the allene moieties.

Menthol glucuronide was isolated from the urine of a healthy 70-kg female subject following ingestion of 400 mg of peppermint oil and 6 g of 99% [U-13 C]glucose. Glucuronide 13 C-excess enrichment levels were 4 -6% and thus provided high signalto-noise ratios (SNRs) for confident assignment of 13 C-13 C spincoupled multiplet components within each 13 C resonance by 13