A biomolecular archaeological approach to ‘Nordic grog’

The combined archaeological, biomolecular, and archaeobotanical evidence from four sites in Denmark (Nandrup, Kostræde, and Juellinge) and Sweden (Havor on the island of Gotland) provide key reference points for reconstructing ‘Nordic grog’ from ca. 1500 BC to the first century AD. In general, Nordic peoples preferred a hybrid beverage or ‘grog,’ in which many ingredients were fermented together, including locally available honey, local fruit (e.g., bog cranberry, and lingonberry) and cereals (wheat, rye, and/or barley), and sometimes grape wine imported from farther south in Europe. Local herbs/spices, such as bog myrtle, yarrow and juniper, and birch tree resin rounded out the concoction and provide the earliest chemical attestations for their use in Nordic fermented beverages. The aggregate ingredients probably served medicinal purposes, as well as contributing special flavors and aromas. They continued to be important ingredients for many kinds of beverages throughout medieval times and up to the present. The importation of grape wine from southern or central Europe as early as ca. 1100 BC, again chemically attested here for the first time, is of considerable cultural significance. It demonstrates the social and ceremonial prestige attached to wine, especially when it was served up as ‘Nordic grog’ in special wine-sets imported from the south. It also points to an active trading network across Europe as early as the Bronze Age in which amber might have been the principle good exchanged for wine. The presence of pine resin in the beverages likely derives from the imported wine, added as a preservative for its long journey northward

Beginning of Viniculture in France

Chemical analyses of ancient organic compounds absorbed into the pottery fabrics of imported Etruscan amphoras (ca. 500-475 B.C.) and into a limestone pressing platform (ca. 425-400 B.C.) at the ancient coastal port site of Lattara in southern France provide the earliest biomolecular archaeological evidence for grape wine and viniculture from this country, which is crucial to the later history of wine in Europe and the rest of the world. The data support the hypothesis that export of wine by ship from Etruria in central Italy to southern Mediterranean France fueled an ever-growing market and interest in wine there, which, in turn, as evidenced by the winepress, led to transplantation of the Eurasian grapevine and the beginning of a Celtic industry in France. Herbal and pine resin additives to the Etruscan wine point to the medicinal role of wine in antiquity, as well as a means of preserving it during marine transport

Solvent effects and redox control on host-guest binding phenomena

In the first chapter the binding constant between the cyclophane host cyclobis(paraquat-p-phenylene) and the guests indole and catechol was found to exhibit strong solvent dependence. With both guests, the measured free energy of complexation correlated linearly with the solvent Z- and E\sb{\rm T}(30) values, which were proven to be more suitable measurements of solvent polarity. The results obtained were consistent with the concept of enthalpically-driven hydrophobic effect for inclusion type complexation by cyclophane receptors, which is a result of (i) strong cohesive interactions between polar solvent molecules, and (ii) less favorable solvent-solute interactions between highly polarizable apolar hydrocarbon surfaces and the less polarizable molecules of the polar solvent. Charge-transfer interactions between the $\pi$-electron rich guest and the $\pi$-electron deficient cavity of the cyclophane were found to play a minor role in the stabilization of the complex, while solvophobic interactions were shown to act as the governing binding force.The complexation properties of the hydrophilic viologens 4,4\sp\prime-bipyridinium-N,N\sp\prime- di-(2-(2-(2-ethoxy)ethoxy)ethanol), 4,4\sp\prime-bipyridinium-N,N\sp\prime-di-(carboxyhexane), 4,4\sp\prime-bipyridinium-N,N\sp\prime-di-(propylsulfonate) with the hosts $\beta$-cyclodextrin ($\beta$-CD) and heptakis-(2,6-O-dimethyl)-$\beta$-cyclodextrin (DM-$\beta$-CD) were investigated in the chapter II using electrochemical and digital simulation techniques. The hydrophilic substituents of these viologens allowed their full electrochemical characterization without problems associated with the precipitation of reduced viologen species. Detailed analysis of the voltammetric results using digital simulation techniques revealed that the oxidized forms of the guests did not interact appreciably with either CD host, the 2-electron reduced guests formed extremely stable inclusion complexes, with association constants in the range \rm10\sp3{-}10\sp4\ M\sp{-1}, while the cation radical forms exhibited intermediate binding affinities \rm({\sim}10\sp2\ M\sp{-1}). In all cases, DM-$\beta$-CD was found to form more stable complexes than unmodified $\beta$-CD.The synthesis and characterization of water soluble electroactive 4,4\sp\prime-bipyridinium derivatives was described in chapter III. The complexation properties of these compounds in aqueous solution were studied electrochemically. All four $\beta$-CD derivatives were found to exhibit a novel phenomenon of concentration dependent and electrochemically driven intermolecular self-complexation, where their reduced species of form head-to-head type intermolecular dimer complexes in aqueous solution. These complexes are destabilized in the presence of a competing water soluble guest (1-adamantane carboxylic acid or 1-adamantane tetramethylammonium chloride) or a host (DM-$\beta$-CD)

Modulation of neuronal nicotinic acetylcholine receptors by mercury

Mercuric chloride exerted a biphasic modulatory effect on rat neuronal nicotinic acetylcholine receptors (nAChRs) expressed in Xenopus laevis oocytes as heteromers of the alpha3 or alpha4 and beta2 or beta4 subunits. The degree of modulation was subunit-dependent, with beta4-containing receptors displaying greater potentiation and alpha4-containing receptors displaying greater inhibition. Thus, alpha4beta4 receptors displayed both robust potentiation and robust inhibition. During prolonged coapplication of HgCl(2), first potentiation then inhibition of the acetylcholine (ACh) response was observed. Upon coapplication of 1 microM HgCl(2), a 2-fold increase in ACh-induced current was achieved in 55 +/- 1 s. With continued HgCl(2) application, the ACh response was slowly inhibited until, after 5 min, less than 10% of the initial response remained. By measuring potentiation at its peak and inhibition 5 min after the start of HgCl(2) coapplication, we obtained EC(50) and IC(50) values of 262 +/- 75 and 430 +/- 72 nM, respectively. HgCl(2) potentiation was voltage-dependent, increasing at more positive holding potentials. Upon washout of mercury chloride, potentiation reversed with a t(1/2) of 4.6 min. Inhibition reversed more slowly, with less than half the initial response recovered after 15 min of wash. Although free cysteine residues are common targets for mercury, elimination of all free cysteines located in the extracellular domains of the alpha4 and beta4 subunits did not alter the effects of mercuric chloride. Potentiation and inhibition of neuronal nAChRs may occur through action at a transmembrane or cytoplasmic location after passive diffusion of mercuric chloride across the plasma membrane

Electrochemically controlled self-complexation of cyclodextrin-viologen conjugates

Self-complexation of cyclodextrin-viologen conjugates can be controlled electrochemically through changes in the oxidation states of the viologen subunits as well as chemically when competing water-soluble hosts or guests are added to solutions of the conjugates

Reactive Pseudorotaxanes: Inclusion Complexation of Reduced Viologens by the Hosts β‐Cyclodextrin and Heptakis(2,6‐di‐o‐Methyl)‐β‐Cyclodextrin

The complexation of three guests containing 4,4′‐bipyridinium redoxactive residues by β‐cyclodextrin (β‐CD) and its heptakis‐(2,6‐O‐dimethyl) analogue (DM‐β‐CD) was investigated by means of voltammetric techniques. The three 4,4′‐bipyridinium (viologen) derivatives used as guests were designed to be water‐soluble in all three accessible oxidation states. The N‐substituents chosen to enhance aqueous solubility were: 2‐(2‐(2‐ethoxy)ethoxy)ethanol (guest 12+), 6‐hexanoate (guest 2), and 3‐propanesulfonate (guest 3). Detailed analysis of the voltammetric results by digital simulation techniques revealed that the oxidized forms of the guests did not interact appreciably with either CD host; the two‐electron reduced guests formed extremely stable inclusion complexes, with association constants in the range 103–104M−1, while the cation radical forms exhibited intermediate binding affinities (≈︁102M−1). In all cases, DM‐β‐CD was found to form more stable complexes than unmodified β‐CD. Redox switchable and highly stable inclusion complexes are formed between β‐cyclodextrin or its heptakis(2,6‐di‐O‐methyl) analogue and the two‐electron reduced forms of a series of viologen guests functionalized to increase their aqueous solubility in all three oxidation states (see Scheme). These complexes exhibit a pseudorotaxane structure and the unusual feature that the cyclodextrin includes an electrochemically generated subunit, which, therefore, is highly reactive

2002. Modulation of neuronal nicotinic acetylcholine receptors by mercury

ABSTRACT Mercuric chloride exerted a biphasic modulatory effect on rat neuronal nicotinic acetylcholine receptors (nAChRs) expressed in Xenopus laevis oocytes as heteromers of the ␣3 or ␣4 and ␤2 or ␤4 subunits. The degree of modulation was subunit-dependent, with ␤4-containing receptors displaying greater potentiation and ␣4-containing receptors displaying greater inhibition. Thus, ␣4␤4 receptors displayed both robust potentiation and robust inhibition. During prolonged coapplication of HgCl 2 , first potentiation then inhibition of the acetylcholine (ACh) response was observed. Upon coapplication of 1 M HgCl 2 , a 2-fold increase in ACh-induced current was achieved in 55 Ϯ 1 s. With continued HgCl 2 application, the ACh response was slowly inhibited until, after 5 min, less than 10% of the initial response remained. By measuring potentiation at its peak and inhibition 5 min after the start of HgCl 2 coapplication, we obtained EC 50 and IC 50 values of 262 Ϯ 75 and 430 Ϯ 72 nM, respectively. HgCl 2 potentiation was voltage-dependent, increasing at more positive holding potentials. Upon washout of mercury chloride, potentiation reversed with a t 1/2 of 4.6 min. Inhibition reversed more slowly, with less than half the initial response recovered after 15 min of wash. Although free cysteine residues are common targets for mercury, elimination of all free cysteines located in the extracellular domains of the ␣4 and ␤4 subunits did not alter the effects of mercuric chloride. Potentiation and inhibition of neuronal nAChRs may occur through action at a transmembrane or cytoplasmic location after passive diffusion of mercuric chloride across the plasma membrane

Solvent effects on the binding equilibria between the guests indole and catechol and the host cyclobis

Academi

Identification of residues that confer alpha-conotoxin-PnIA sensitivity on the alpha 3 subunit of neuronal nicotinic acetylcholine receptors

Neuronal nicotinic receptors composed of the alpha3 and beta2 subunits are at least 1000-fold more sensitive to blockade by alpha-conotoxin-PnIA than are alpha2beta2 receptors. A series of chimeric subunits, formed from portions of alpha2 and alpha3, were coexpressed with beta2 in Xenopus oocytes and tested for toxin sensitivity. We found determinants of toxin sensitivity to be widely distributed in the extracellular domain of alpha3. Analysis of receptors formed by a series of mutant alpha3 subunits, in which residues that differ between alpha3 and alpha2 were changed from what occurs in alpha3 to what occurs in alpha2, allowed identification of three determinants of alpha-conotoxin-PnIA sensitivity: proline 182, isoleucine 188, and glutamine 198. Comparison with determinants of alpha-conotoxin-MII and kappa-bungarotoxin sensitivity on the alpha3 subunit revealed overlapping, but distinct, arrays of determinants for each of these three toxins. When tested against an EC50 concentration of acetylcholine, the IC50 for alpha-conotoxin-PnIA blockade was 25 +/- 4 nM for alpha3beta2, 84 +/- 7 nM for alpha3P182Tbeta2, 700 +/- 92 nM for alpha3I188Kbeta2, and 870 +/- 61 nM for alpha3Q198Pbeta2. To examine the location of these residues within the receptor structure, we generated a homology model of the alpha3beta2 receptor extracellular domain using the structure of the acetylcholine binding protein as a template. All three residues are located on the C-loop of the alpha3 subunit, with isoleucine 188 nearest the acetylcholine-binding pocket