Brazilian alcohol: Food versus fuel?

The creation of the ProAlcool (National Alcohol Programme) late in 1975 for the production of fuel alcohol has raised varied criticisms as to the possible consequences for food production in Brazil. This food ‘problem’ in Brazil is embedded in its socio-economic and political system. Agricultural production has kept ahead of population growth, but the main beneficiaries have been commodity export crops; the issue can be identified as ‘commodity export crop production versus crop production for the domestic market’ rather than ‘food versus fuel’. The possible effects of the ProAlcool on food production have been exaggerated and the real implications largely overlooked. The sugar and alcohol sector is today among Brazil's largest industries and, with all its faults, the ProAlcool remains the world's most successful biomass energy programme and as such its importance extends beyond Brazil's national boundaries. Biomass has been demonstrated by a Third World country to be a viable alternative or complement to oil on a national scale. Despite the current (1986) low oil prices an interministerial commission has recently recommended that the ProAlcool programme should be maintained.     

χ alcohol dehydrogenase isozymes of horse liver

Horse liver contains previously unrecognized isozymes of alcohol dehydrogenase. In contrast to the molecular forms identified up to now, under the conditions employed these variants migrate toward the anode on starch gel electrophoresis and were separated from the cathodic isozymes by DEAE-cellulose chromatography. They were then purified on agarose-hexane-AMP. Their physicochemical and compositional characteristics are similar to those x alcohol dehydrogenases from human liver. Like these and similar ones from simian liver, they retain most of their activity in the presence of10 mm 4-methylpyrazole, oxidize short-chain primary alcohols very poorly, and appear to prefer longer chain primary alcohols and ω-hydroxy fatty acids as substrates.     

Mammalian alcohol dehydrogenase — Functional and structural implications

Mammalian alcohol dehydrogenase (ADH) constitutes a complex system with different forms and extensive multiplicity (ADH1–ADH6) that catalyze the oxidation and reduction of a wide variety of alcohols and aldehydes. The ADH1 enzymes, the classical liver forms, are involved in several metabolic pathways beside the oxidation of ethanol, e.g. norepinephrine, dopamine, serotonin and bile acid metabolism. This class is also able to further oxidize aldehydes into the corresponding carboxylic acids, i.e. dismutation. ADH2, can be divided into two subgroups, one group consisting of the human enzyme together with a rabbit form and another consisting of the rodent forms. The rodent enzymes almost lack ethanol-oxidizing capacity in contrast to the human form, indicating that rodents are poor model systems for human ethanol metabolism. ADH3 (identical to glutathione-dependent formaldehyde dehydrogenase) is clearly the ancestral ADH form and S-hydroxymethylglutathione is the main physiological substrate, but the enzyme can still oxidize ethanol at high concentrations. ADH4 is solely extrahepatically expressed and is probably involved in first pass metabolism of ethanol beside its role in retinol metabolism. The higher classes, ADH5 and ADH6, have been poorly investigated and their substrate repertoire is unknown. The entire ADH system can be seen as a general detoxifying system for alcohols and aldehydes without generating toxic radicals in contrast to the cytochrome P450 system.     

Dihydroconiferyl alcohol — A cell division factor from Acer species

A compound that stimulated growth of soybean callus was isolated from spring sap of sycamore (Acer pseudoplatanus L.). Insufficient compound was isolated to permit it to be characterised. A compound with identical properties was isolated from commercial maple syrup, the concentrated spring sap of Acer saccharum L. The compound was identified as 3-(3-methoxy-4-hydroxyphenyl)-propan-1-ol (dihydroconiferyl alcohol, DCA). DCA was also active in the tobacco callus and radish leaf senescence assays, but was inactive in four other tests for cytokinin activity. DCA acted synergistically with kinetin to promote soybean callus growth. It is concluded that DCA has properties distinct from those of purine cytokinins.Abbreviation DCA dihydroconiferyl acohol - GC gas chromatography - IAA indole-3-acetic acid - iP isopentenyladenine - [9R]iP isopentenyladenosine - LC liquid chromatography - MS mass spectrometry - NAA 1-napthylacetic acid - TLC thinlayer chromatography - TMSi trimethylsilyl     

Can alcohol consumption be an alternative treatment for fibromyalgia?

Treatment of chronic pain conditions such as fibromyalgia is challenging due to limitations of drug therapies. An initial exploration into the relationships between self-reported alcohol consumption, symptom severity, and quality of life for individuals with fibromyalgia sheds new light on plausible hypotheses and potential mechanisms of action for future research. Evidence suggests that alcohol consumption may improve social and psychological factors because of activity in the ascending and descending pain pathways in modulating gamma-aminobutyric acid neurotransmission. Further methodologically rigorous studies in this field to improve well-being of individuals with fibromyalgia are warranted.In a previous issue of Arthritis Research & Therapy, Kim and colleagues [1] reported the first study to examine the association between alcohol consumption, symptom severity, and quality of life of individuals with fibromyalgia (FM). Treatment of chronic pain conditions such as FM is challenging because the drug therapies currently available are expensive and associated with numerous limitations such as undesirable side effects and addiction or tolerance issues. Despite undergoing drug treatment, patients are often left with unrelieved pain, restricted mobility, and reduced physical function. Lifestyle interventions, including dietary modifications such as alcohol consumption, have gained popularity as explorations in symptom management.Several observational studies have examined the association between alcohol consumption and chronic pain conditions. In a prospective study, Bergman and colleagues [2] found that regular weekly or daily alcohol consumption is a significant protective factor for the development of chronic pain. Two case–control studies have also shown that moderate alcohol consumption correlates with a reduced risk of rheumatoid arthritis [3,4]. However, a systematic review of nine epidemiological studies has concluded that alcohol consumption is not associated with low back pain [5]. Kim and colleagues are the first to examine the association between alcohol consumption and FM symptom severity and quality of life. Among the 946 adult FM patients (94 % women, mean age of 49 years old) reporting low or moderate alcohol consumption (≤3 or >3 to 7 drinks per week), there was lower FM symptom severity and better quality-of-life scores compared with those who reported no alcohol consumption (non-drinkers). However, these associations were not observed in patients who were heavy drinkers (>7 drinks per week) compared with non-drinkers. Drinkers had higher education, less unemployment, lower body mass index, and lower frequency of opioid use than non-drinkers. Thus, their analyses were adjusted for these potential confounders.Because alcohol consumption consists of complex behaviors that intersect with many social, economic, psychological, and demographic factors, disentangling this complex web of relationships is a challenge. Interestingly, after exploring possible mechanisms for their findings, Kim and colleagues speculated that alcohol consumption may attenuate FM symptoms and improve quality of life by mediating psychological benefits and stress relief or by promoting factors associated with social integration. Another possible mechanism proposed is central nervous mediation via the modulating gamma-aminobutyric acid (GABA) system. Several neurotransmitters (including GABA) in the ascending and descending pain pathways have been implicated in FM [6]. Thus, behavioral and pharmacological therapies that modulate or mimic the effects of GABA production can be promising for FM treatment.This initial exploration into the relationships between alcohol consumption, symptom severity, and quality of life for FM has posed a number of questions that need to be answered by future studies with stronger study designs. Kim and colleagues discussed limitations associated with cross-sectional study design, and we would like to underscore additional concerns relating to the potential for non-random misclassifications of alcohol consumption among FM patients with different levels of symptom severity or quality of life. Such information bias is not uncommon in cross-sectional studies providing data on both exposure and outcome variables from questionnaires. Because the questionnaires are administered at the same time in a cross-sectional study and relied on respondent recall, the measurement errors of exposure (that is, alcohol consumption) may be dependent on the measurement errors of the outcomes (that is, quality of life or FM symptoms). If such dependent bias occurs, the observed association between exposure and outcome is likely to be inflated [7]. Owing to lack of prior data demonstrating that such bias exists in cross-sectional studies of alcohol consumption and FM symptom severity, we provide a possible scenario to examine the potential impacts of dependent bias on this relationship. FM patients who on one occasion had more severe symptoms may in fact have consumed more alcohol to ameliorate symptoms and thus may have felt better (fewer symptoms) at the time of the survey, or FM patients with more severe symptoms at the time of the survey may have stopped drinking alcohol (thus no symptom relief) because of their symptoms. The impact of such dependent bias would result in an inflation of the ‘true’ association. Owing to cross-sectional design, this potential bias cannot be evaluated. In addition to the potential for dependent bias, patients with FM may be too embarrassed to reveal their ‘true’ alcohol intake level because of social desirability biases [8]. Such reporting bias [9], however, is likely to be random and independent of symptom severity. There is still great uncertainty in the study results; therefore, we agree with Kim and colleagues that these preliminary results should not be used as grounds for advising patients to drink alcohol.In sum, the study by Kim and colleagues sheds new light on plausible hypotheses and mechanisms to consider in future methodologically rigorous studies to improve the well-being of individuals with FM. Because it may not be feasible to randomize alcohol consumption in human subject research, methodologically rigorous prospective longitudinal studies are needed. Measuring alcohol consumption at different time points is essential in order to minimize dependent biases from patient-reported exposure and outcome measures.     

Determination of Β-isomerized aspartic acid as the corresponding alcohol

The age-related formation of succinimides in proteins, through spontaneous deamidation of asparagine, and through cyclization of aspartic acid, is thought to be followed by the hydrolysis of the succinimide ring, yielding a mixture of normal aspartic acid sites and-isomerized aspartic acid sites (isoaspartic acid). The chemical reduction of an isoaspartyl site to the corresponding amino acid alcohol, isohomoserine, has now been investigated as a general approach to measuring the accumulation of isomerized residues in aging proteins. The methods employed were based on conditions previously found to be successful in reducing protein aspartic acid to homoserine. Borane was employed as the reducing agent, and was found to produce the expected amino acid alcohols in reactions with model peptides. In addition, amino acid analysis revealed a complex pattern of unknown products of these reduction reactions, some of which were also evident when a much stronger reducing agent, lithium aluminum hydride, was used. The correlation of some of these side-products with the isomerization of the peptide suggests, unexpectedly, that the reactivity of reducing agents toward aspartyl residues and perhaps other sites in the peptide may be influenced by steric factors related to aspartyl isomerization. The borane reduction method was also applied to proteins. No detectable isohomoserine was formed either in ovalbumin, a model aged protein, or in human lens proteins of advanced age, with conditions that fully reduced normal aspartyl residues to homoserine. These tests thus indicate that the percentage of aspartic acid in the isomerized form in these proteins is below the limit of detectability (below 5%). These results complement previous experimental results that have indicated a low bulk isoaspartyl content in most natural proteins.     

A novel substrate for yeast alcohol dehydrogenase – p-nitroso-N,N-dimethylaniline

Yeast alcohol dehydrogenase (EC 1.1.1.1) catalyzes the novel reduction of p-nitro-so-N,N-dimethylaniline with NADH as a cofactor. Apparent kinetic constants for this enzymatic reaction are: V ₂=2.1 s^–1, K _Q=456 M, K _iQ=119 M, and K _P=1.47 mM, at pH 8.9, 25 °C. This reaction is especially useful for the quantitative determination of NAD⁺ and NADH by enzymatic cycling.     

Comments on the “Maintenance coefficient” changes during alcohol fermentation

Summary The concept of maintenance is discussed in terms of the biological meaning and the applicability of the maintenance coefficient, m, in bioengineering for optimization of yields in fermentation. A method of calculation is proposed for the evaluation of m in the course of fermentation in the case of a metabolite (e.g, ethanol). During alcoholic fermentation m is not constant and decreases with the growth rate.The phenomena involved in maintenance are numerous and complex and there is a semantic problem in its definition which can be generalized by the apparently non-finalized substrate consumption.Nomenclature a specific maintenance rate (defined by eq. (9)) - m maintenance coefficient - X cell mass concentration (as a dry weight) - S substrate concentration - P product concentration - r rate of reaction - r_x,r_s,r_p rate of reaction related to biomass, substrate and product - r_sm,r_sg,r_spi rate of reaction related only to the consumption by maintenance, growth and the synthesis of the ith product - r_xe maintenance rate defined by eq. (10) - q_s,q_Pi specific rate of substrate consumption and i^th product production - Y yield coefficient - Y^o, Y^o apparent yield coefficient related to the cell and i^th product - Y _xs ^xs , Y _Pis ^Pis maximum theoretical yield coefficient related to the cell and i^th - specific growth rate produce 420     

Molecular simulation of β-cyclodextrin inclusion complex with 2-phenylethyl alcohol

The structures of β-cyclodextrin inclusion complexes with 2-phenylethyl alcohol in vacuum and aqueous solution have been investigated by using molecular dynamics simulation. The inclusion structures and the physicochemical stability of the complexes were also analysed, discussed and validated by ultraviolet spectrums and thermodynamic properties. The results of molecular dynamics simulation indicate that the A-type β-cyclodextrin inclusion complex with 2-phenylethyl alcohol in both vacuum and aqueous solution have better physical stability, and its chemical stability also has obvious promotion than that of free one. Therefore, the β-cyclodextrin can be used to control and regulate the release of the 2-phenylethyl in food.     

Induction of isoenzymes of alcohol dehydrogenase in “flor” yeast

Summary Two isoenzymes of alcohol dehydrogenase (adh I and adh II) from Saccharomyces cheresiensis have been differentiated by thermal treatment of the crude extracts. The effect of pH on the stability and the K _m for ethanol are different for the two isoenzymes.The proportions in which they are present depend on the carbon source used by the yeast: adh I is the major component in cells grown on glucose, and adh II in those grown on ethanol. Cells grown on glucose plus ethanol show high levels of both isoenzymes, indicating that the synthesis of adh I is subjected to nutritional induction by glucose, and that of adh II by ethanol.The physiological roles of the two isoenzymes are discussed in relation with the nutritional characteristics of S. cheresiensis.     

Class II alcohol dehydrogenase (ADH2) — adding the structure

Class II alcohol dehydrogenase (ADH2) represents a highly divergent class of alcohol dehydrogenases predominantly found in liver. Several species variants of ADH2 have been described, and the rodent enzymes form a functionally distinct subgroup with interesting catalytic properties. First, as compared with other ADHs, the catalytic efficiency is low for this subgroup. Second, the substrate repertoire is unique, e.g. rodent ADH2s are not saturated with ethanol as substrate, and while ω-hydroxy fatty acids are common substrates for the human ADH1–ADH4 isoenzymes, including ADH2, these compounds function as inhibitors rather than substrates. The recently determined structure of mouse ADH2 reveals a novel substrate-pocket topography that accounts for the observed substrate specificity and may, therefore, be important for the exploration of orphan substrates of ADH2. It is possible to improve the catalytic efficiency of mouse ADH2 by an array of mutations at position 47. Residue Pro47 of the wild type ADH2 enzyme seems to strain the binding of coenzyme, which prevents a close approach between the coenzyme and substrate for efficient hydrogen transfer. Based on crystallographic and mechanistic investigations, the effects of residue replacements at position 47 are multiple, affecting the distance for hydride transfer, the pK_a of the bound alcohol substrate as well as the affinity for coenzyme.     

Design, synthesis and cytotoxic activities of novel β-amino alcohol derivatives

Three series of novel β-amino alcohols possessing an N-anthranyl group have been obtained using tryptophan as the major starting material. These compounds were screened for cytotoxic activity against five human cancer cell lines in vitro by MTT assay, and some of them exhibited potential ability to be anticancer agents. Structure-activity relationship was carefully investigated. Only the compounds possessing small substituents (H or CH₃) at C-6 position showed the same activity as cisplatin (DDP) did.     

Characterization of α-tocopherol as interacting agent in polyvinyl alcohol–starch blends

In this study, the interactions of α-tocopherol (α-TOH) in PVOH–starch blends were investigated. α-TOH is an interacting agent possesses a unique molecule of polar chroman “head” and non-polar phytyl “tail” which can improve surface interaction of PVOH and starch. It showed favorable results when blending PVOH–starch with α-TOH, where the highest tensile strengths were achieved at 60 wt.% PVOH–starch blend for 1 phr α-TOH and 50 wt.% for 3 phr α-TOH, respectively. This due to the formation of miscible PVOH–starch as resulted by the compatibilizing effect of α-TOH. Moreover, the enthalpy of melting (ΔH_m) of 60 wt.% PVOH–starch and 50 wt.% PVOH–starch added with 1 and 3 phr α-TOH respectively were higher than ΔH_m of the neat PVOH–starch blends. The thermogravimetry analysis also showed that α-TOH can be used as thermal stabilizer to reduce weight losses at elevated temperature. The surface morphologies of the compatible blends formed large portion of continuous phase where the starch granules interacted well with α-TOH by acting as compatilizer to reduce surface energy of starch for embedment into PVOH matrix.