Determination of purine contents of alcoholic beverages using high performance liquid chromatography

Correlation between the bacterial community succession and purine compound changes during Huangjiu fermentation

Purine is mainly culprit of hyperuricemia (HUA) and gout, which is widely present in Huangjiu in the form of free bases. Bacterial succession plays an important role in quality control in Huangjiu. The correlation between the purine compound content and the bacterial communities during the fermentation process has not yet been evaluated. In this study, high-throughput sequencing (HTS) technology was used to monitor the bacterial community composition of Huangjiu at different fermentation stages. The correlation between the bacterial community and the contents of physicochemical properties and purine compounds were evaluated using the Spearman analysis method. The key enzymes of purine metabolism pathway in the microbial community were analyzed by bioinformatics using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt). The results showed that the purine content in Huangjiu increased gradually in 0∼9d of fermentation (21.05-65.71 mg/L), and stabilized gradually in 12∼18d (65.63-69.55 mg/L), while the abundance of lactic acid bacteria (LAB) of bacterial microbial flora were increased (0∼9d) and then stabilized (12∼18d). Moreover, Lactobacillus acetotolerans and Lactobacillus helveticus were highly correlated positively with purine contents, while Limosilactobacillus fermentum and Lactiplantibacillus plantarum were correlated negatively. In addition, the dominant strains of bacteria were involved in the metabolism of purine, and the key enzymes for purine compound synthesis were more abundant than that for purine degradation. This study is helpful to scientifically understand the formation mechanism of purines, providing a basis for screening functional strains of purine degrading to accurately regulate purine level in Huangjiu.

Screening and application of purine degrading Limosilactobacillus fermentum LF-1 from Huangjiu fermentation broth

BACKGROUND

As the important building blocks of nucleic acids, purines are alkaloids and responsible for hyperuricemia and gout. The purine content in Huangjiu is higher, and mainly exists in the form of free bases, which is easier to be absorbed by human body. However, the currently available reports on purine in Huangjiu mainly focus on detection methods and content survey. No studies on the regulation of the purine content in Huangjiu have been reported.

RESULTS

Eighty-four strains, with the degradation capacity of purine, were screened from the fermentation broth of Huangjiu. In detail, the isolated lactic acid bacteria (LAB) strain 75 # showed the strongest degradation ability of guanosine, inosine and four purines, which reduce their levels by 83.4% (guanosine), 97.4% (inosine), 95.1% (adenine), 95.0% (guanine), 94.9% (hypoxanthine) and 65.9% (xanthine), respectively. Subsequently, the LAB strain 75# was identified to be Limosilactobacillus fermentum by 16S rRNA gene sequencing, which was named as Limosilactobacillus fermentum LF-1 and applied to the fermentation of Huangjiu in the laboratory. Compared with the fermentation broth of Huangjiu without adding L. fermentum LF-1, the content of purine compounds in the fermentation broth inoculated with L. fermentum LF-1 was reduced by 64.7%. In addition, the fermented Huangjiu had richer flavor compounds, and the physicochemical indices were in accordance with the national standard of Chinese Huangjiu.

CONCLUSION

The screened strain L. fermentum LF-1 may be a promising probiotic for the development of a novel that can efficiently degrade purine in Huangjiu. © 2023 Society of Chemical Industry.

Efficient removal of purine compounds from solutions via biomass carbons derived from pomelo peel

The high purine diet could result in the increase of the level of blood uric acid, causing serious health problems such as hyperuricemia, gout, nephropathy and cardiovascular diseases. To find out a safe, cheap and super adsorption material for removing purines in stomach or pretreating high-purine beverages, we used different tissues of pomelo peel to prepare biomass carbon by drying, chemical modification and carbonization and then applied it to remove purine compounds in strong acidic solution, beer and soybean milk. The characteristic analysis of pomelo-peel-derived carbons (PPCs) indicated that the preparation methods significantly affected the structures and adsorption capacities of PPCs. Compared with the biomass carbon derived from bamboo, PPCs exhibited higher adsorption capabilities for purine compounds in strong acidic solution (adsorption rates > 99% in 15 min) and soybean milk (adsorption rates > 56% in 30 min) but slightly lower adsorption capabilities in beer (adsorption rates > 52% in 30 min). In addition, the adsorption capabilities of PPCs for purine compounds in beer and soybean milk were not obviously affected by temperatures. Therefore, PPCs are promising absorbents for applications in removing purine compounds from beverages to produce low-purine, healthier products for treating hyperuricemia. The strong adsorption capabilities of PPCs on purine compounds in strong acidic environment also provides a possibility of using the PPCs as food additives for removing purines in stomach for healthcare applications such as gout prevention after confirming their biosafety.

Assessment of nucleic acid content, amino acid profile, carcass, and meat quality of Thai native chicken

Functional foods are innovative products that hold health-enhancing potential. They are contributing to changing trends in both consumer behavior and the market. This study was conducted to investigate the effects of breed on the nucleic acid content, amino acid profile, carcass, and meat quality of different breeds of chickens. The outcomes of which could lead to the production of functional chicken meat. In this experiment, 4 genotypes of chicken, namely commercial broilers (CBR), Thai native chickens (Mae Hong Son; MHS), Thai native chickens (Pradu Hang Dam; PHD), and male layer chickens (MLC), were fed commercial feed and reared under identical conditions. All chickens were slaughtered at the market age, whereas the breasts and thighs were separated from the carcasses to determine chemical composition and meat quality. The results indicated that carcass and meat quality traits were significantly different (P < 0.05) among chicken breeds and meat parts. Notably, commercial breeds (CBR and MLC) were superior in performance and carcass quality when compared with the Thai native chickens (MHS and PHD). CBR had the highest growth performance and carcass quality traits (P < 0.01), whereas MHS exhibited the lowest weight gain (P < 0.05). However, Thai native chickens were lower in fat, cholesterol, triglycerides, purine, and uric acid (P < 0.05) contents than the commercial breeds. Interestingly, MHS contained the lowest purine and malondialdehyde levels when compared with the other breeds (P < 0.01). Moreover, MHS contained the highest amounts of glutamic acid in both the breasts and thighs (P < 0.05). Therefore, the meat of MHS may be classified as a functional chicken meat, as it was found to have a pleasant meaty taste and hold nutritional value, which positively influences consumers' health.

Determination of purines in prepackaged food using optimum acid hydrolysis followed by high performance liquid chromatography

A high performance liquid chromatography was established to determine purine content of prepackaged food. Chromatographic separation was performed on Agilent5 TC-C18 column. Ammonium formate (10 mmol/L, pH = 3.385) and methanol (99:1) were used as mobile phase. Purine concentration and peak area showed good linear relationships in the range from 1 to 40 mg/L (guanine, hypoxanthine, adenine) and xanthine exhibited a good linear relationship ranged from 0.1 to 4.0 mg/L. Recoveries of four purines ranged from 93.03% to 107.42%. Purine content in prepackaged food was following: animal derived prepackaged food: 16.13-90.18 mg/100 g; beans and bean products: 66.36-157.11 mg/100 g; fruits and fruit products: 5.64-21.79 mg/100 g; instant rice and flour products: 5.68-30.83 mg/100 g; fungi, algae, fungi and algae products: 32.57-70.59 mg/100 g. This proposed method had good precision and accuracy with a wide linear range for detection of purine. Animal derived prepackaged food was purine-rich food, purine content of plant derived prepackaged food varied greatly.

[2022 Update of the Austrian Society for Rheumatology and Rehabilitation nutrition and lifestyle recommendations for patients with gout and hyperuricemia]

BACKGROUND

Gout is the most frequent inflammatory joint disease in the western world and has a proven genetic background. Additionally, lifestyle factors, such as increasing life expectation and standard of living, sufficient or excess nutrition and a growing prevalence of obesity in the population as well as e.g. alcohol consumption, contribute to the rising incidence of hyperuricemia and gout. Apart from an adequate medication, medical consultation on nutrition and lifestyle is an essential part of the management of gout patients, who have a high risk of internal comorbidities.

OBJECTIVE

In 2015 the Austrian Society for Rheumatology and Rehabilitation (ÖGR) working group for osteoarthritis and crystal arthropathies published nutrition and lifestyle recommendations for patients with gout and hyperuricemia. Since then, a multitude of studies have been published addressing this topic, which necessitated an update.

METHODS

First, the authors performed a hierarchical literature search to screen for the literature published since 2015. Considering references given in the first publication, the relevant literature was selected and the recommendations from 2015 were either kept as published, reformulated or recreated. Finally, the evidence level and the level of agreement for each recommendation were added by the authors.

RESULTS

Based on this process, 10 recommendations were generated instead of the initial 9. As in the original publication, a graphical presentation with symbols was constructed to complement the written text.

CONCLUSION

The ÖGR recommendations on nutrition and lifestyle for patients with gout and hyperuricemia were updated in accordance with the most recent relevant literature. These are supposed to serve as information and education material for patients and updated information for physicians.

Environmental Triggers of Hyperuricemia and Gout

Gout is the most prevalent type of inflammatory arthritis worldwide and environmental factors contribute to hyperuricemia and risk for gout flare. Causes of hyperuricemia include increased purine consumption from meat, alcohol, and high fructose corn syrup as well as medications such as cyclosporine, low-dose aspirin, or diuretics. Triggers for gout flares include increased purine consumption and medication use such as urate lowering therapy and diuretics. Environmental exposures including lead exposure, particulate matter exposure, temperature fluctuations, and physiologic stress have been found to trigger flares. In the right clinical scenario, these factors should be considered when treating gout patients.

2022 update of the Austrian Society of Rheumatology and Rehabilitation nutrition and lifestyle recommendations for patients with gout and hyperuricemia

Background

Gout is the most frequent inflammatory joint disease in the western world and has a proven genetic background. Additionally, lifestyle factors like increasing life span and wealth, sufficient to excess nutritional status and a growing prevalence of obesity in the population, as well as e.g. alcohol consumption contribute to the rising incidence of hyperuricemia and gout. Apart from an adequate medication, medical advice on nutrition and lifestyle is an essential part of the management of gout patients, being at high risk of internal comorbidities.

Objective

In 2015, the ÖGR (Österreichische Gesellschaft für Rheumatologie und Rehabilitation) working group for osteoarthritis and crystal arthropathies already published nutrition and lifestyle recommendations for patients with gout and hyperuricemia. Since then, a multitude of literature has been published addressing this topic, what required an update.

Methods

First, the authors performed a hierarchical literature search to screen the meanwhile published literature. Also considering references of the first publication, the relevant literature was selected, and the 2015 recommendations were either kept as published, reformulated or newly produced. Finally, the evidence level and the level of agreement with each recommendation were added.

Results

Following this process, ten recommendations were generated instead of the initial nine. Like in the original publication, a colored icon presentation was provided to complement the written text.

Conclusion

The Austrian nutrition and lifestyle recommendations for patients with gout and hyperuricemia were updated incorporating the most recent relevant literature, serving as education material for patients and updated information for physicians.

Simultaneous Determination of Purines and Uric Acid in Chinese Chicken Broth Using TFA/FA Hydrolysis Coupled with HPLC-VWD

Chinese chicken broth is well known for its outstanding nutritional value and flavor, widely consumed in China. This study was designed to develop a sensitive and accurate high-performance liquid chromatography-variable wavelength detector (HPLC-VWD) method to simultaneously determine purines and uric acid in Chinese chicken broth for gout and hyperuricemia dietary management. Chromatographic separation was performed on an Agilent TC-C18 (2) column (4.6 mm × 250 mm, 5.0 µm), using 0.02 M KH₂PO₄ (pH 4.0) as a mobile phase. Sample pretreatment was optimized to enable the extraction of all analytes from Chinese chicken broth. The optimal pretreatment conditions were chicken broth-60% trifluoroacetic acid (TFA)/20% formic acid (FA) (1:1, v/v) in a volume ratio of 1:3 and hydrolysis for 40 min at 85 °C in a water bath. The limits of detection (LODs) and limits of quantification (LOQs) of the purines and uric acid were 0.58–1.71 µg/L and 1.92–5.70 µg/L, respectively. The recoveries were 91–101%, with the relative standard deviations (RSDs) lower than 3%. The complete method has been successfully applied to determine purines and uric acid in various Chinese chicken soups obtained from different provinces in China.

Surface-enhanced Raman scattering of DNA bases using frozen silver nanoparticle dispersion as a platform

Raman spectroscopy is a powerful method to characterize molecules in various media. Although surface-enhanced Raman scattering (SERS) is often employed to compensate for the intrinsically poor sensitivity of Raman spectroscopy, there remain serious tasks, such as simple preparations of SERS substrates, sensitivity control, and reproducible measurements. Here, we propose freezing as an efficient way to overcome these problems in SERS measurements using DNA bases as model targets. Solutes are expelled from ice crystals and concentrated in the liquid phase upon freezing. Silver nanoparticles (AgNPs) are also concentrated in the liquid phase to aggregate with Raman target analytes. The SERS signal intensity is maximized when the AgNP concentration exceeds the critical aggregation value. Freezing allows up to 5000 times enhancements of the SERS signal. Thus, an efficient SERS platform is prepared by simple freezing. The simultaneous detection of four DNA bases effectively eliminates variations of signal intensities and allows the reliable determination of concentration ratios.

Towards the Use of Adsorption Methods for the Removal of Purines from Beer

Beer corresponds to a fermented alcoholic beverage composed of several components, including purine compounds. These molecules, when ingested by humans, can be catabolized into uric acid, contributing to uric acid’s level increase in serum, which may lead to hyperuricemia and gout. To assure a proper management of this disease, physicians recommend restrictive dietary measures, particularly by avoiding the consumption of beer. Therefore, it is of relevance to develop efficient methods to remove purine compounds from alcoholic beverages such as beer. In this review, we provide an introduction on fermented alcoholic beverages, with emphasis on beer, as well as its purine compounds and their role in uric acid metabolism in the human body in relation to hyperuricemia and gout development. The several reported enzymatic, biological and adsorption methods envisaging purine compounds’ removal are then reviewed. Some enzymatic and biological methods present drawbacks, which can be overcome by adsorption methods. Within adsorption methods, adsorbent materials, such as activated carbon or charcoal, have been reported and applied to beer or wort samples, showing an excellent capacity for adsorbing and removing purine compounds. Although the main topic of this review is on the removal of purine compounds from beer, other studies involving other matrices rather than beer or wort that are rich in purines are included, since they provide relevant clues on designing efficient removal processes. By ensuring the selective removal of purine compounds from this beverage, beer can be taken by hyperuricemic and gouty patients, avoiding restrictive dietary measures, while decreasing the related healthcare economic burden.

Gicht – auch eine Frage des Lebensstiles

Mit steigenden Harnsäurewerten steigt das Risiko einer Gicht. Da die Harnsäure-Homöostase von zahlreichen Lebensstilfaktoren beeinflusst wird, ist das Auftreten einer Gicht fast immer auch mit der Lebensweise assoziiert. Lange schon ist bekannt, dass die Zufuhr purinreicher Lebensmittel (z. B. Fleisch, Meeresfrüchte) über vermehrte Harnsäurebildung aus exogen zugeführten Purinen zu Gichtanfällen führen kann. Auch Fruktose-haltige Getränke haben über einen vermehrten Abbau von ATP bei der Verstoffwechslung von Fruktose eine Hyperurikämie zur Folge, wogegen bei vermehrter Alkoholzufuhr und Adipositas eine verminderte renale Harnsäureausscheidung für die Hyperurikämie ursächlich ist. Einige Lebensmittel (z. B. Milch, Kaffee) scheinen einen harnsäuresenkenden Effekt zu haben und können Patienten explizit empfohlen werden. Mit Blick auf den Lebensstil spielen jedoch nicht nur Ernährungsfaktoren (Lebensmittel) eine wichtige Rolle. So kommt es beim aktuell sehr populären Heilfasten durch die entstehende Ketose und häufig gleichzeitig zu geringer Flüssigkeitszufuhr zu einer verminderten Harnsäureausscheidung über die Niere und konsekutiv Harnsäureanstieg. Auch Extremsport wie Marathon stellt aufgrund der katabolen Stoffwechsellage (Ketose) und hohen mechanischen Belastung (Mikrotraumata) bereits arthrotisch vorgeschädigter Gelenke einen Risikofaktor für das gehäufte Auftreten von Gichtanfällen dar. Patienten mit einer Hyperurikämie sollten als Basismaßnahme immer über eine mögliche Ernährungsumstellung beraten werden, zumal die Hyperurikämie eng mit dem metabolischen Syndrom assoziiert ist, häufigen Stoffwechselkrankheiten wie Diabetes mellitus, Hyperlipidämien und Adipositas, die ebenfalls durch eine Lebensstilmodifikation günstig zu beeinflussen sind. Eine manifeste (langjährige) Gicht kann allerdings durch eine alleinige Ernährungsumstellung nur selten erfolgreich behandelt werden. Der Zusammenhang zwischen Lebensstil und Gicht ist seit Jahrhunderten bekannt. Leider beschränken sich die wenigen Studien zu diesem Thema meist auf epidemiologische Erhebungen, über die in dieser Arbeit eine Übersicht gegeben werden soll.

Determination of total purine and purine base content of 80 food products to aid nutritional therapy for gout and hyperuricemia

The aim of this work is to facilitate the nutritional therapy of gout and hyperuricemia. In Japan, patients with gout or hyperuricemia are recommended to consume less than 400 mg of dietary purines per day. When receiving nutritional therapy for gout or hyperuricemia, purine-rich foods (>200 mg/100 g) should be eaten in even lower quantities. The purine content of foods reported in this study are as follows: noodles, 0.6-12.1 mg/100 g; bread, 4.4 mg/100 g; peas or seeds, 19.6-67.1 mg/100 g; dairy, 0.0-1.4 mg/100 g; Japanese vegetables, 0.9-47.1 mg/100 g; seasonings, 0.7-847.1 mg/100 g; meat or fish, 19.0-385.4 mg/100 g; fish milt, 375.4-559.8 mg/100 g; and supplements, 81.9-516.0 mg/100 g. Foods containing very large amounts of purine (>300 mg/100 g) included anchovy, cutlassfish (hairtail), cod milt, globefish milt, dried Chinese soup stock, dried yeast, a Euglena supplement, and a Lactobacillus supplement. When eating these high-purine food or supplements, the quantity taken at one meal should be limited, especially milt because they typically consumed amount of 20-30 g is equivalent to 75-168 mg total purines. This is 20%-40% of the recommended daily amount (400 mg/day) for patients with gout or hyperuricemia. Thus, these patients should restrict the amount of purine-rich foods they consume. Good dietary habits with a good balance of nutrients are recommended.

Simultaneous quantification by HPLC of purines in umami soup stock and evaluation of their effects on extracellular and intracellular purine metabolism

Ribonucleotide flavor enhancers such as inosine monophosphate (IMP) and guanosine monophosphate (GMP) provide umami taste, similarly to glutamine. Japanese cuisine frequently uses soup stocks containing these nucleotides to enhance umami. We quantified 18 types of purines (nucleotides, nucleosides, and purine bases) in three soup stocks (chicken, consommé, and dried bonito soup). IMP was the most abundant purine in all umami soup stocks, followed by hypoxanthine, inosine, and GMP. The IMP content of dried bonito soup was the highest of the three soup stocks. We also evaluated the effects of these purines on extracellular and intracellular purine metabolism in HepG2 cells after adding each umami soup stock to the cells. An increase in inosine and hypoxanthine was evident 1 h and 4 h after soup stock addition, and a low amount of xanthine and guanosine was observed in the extracellular medium. The addition of chicken soup stock resulted in increased intracellular and extracellular levels of uric acid and guanosine. Purine metabolism may be affected by ingredients present in soups.

A technique based on droplet evaporation to recognize alcoholic drinks

Chromatography is, at present, the most used technique to determine the purity of alcoholic drinks. This involves a careful separation of the components of the liquid elements. However, since this technique requires sophisticated instrumentation, there are alternative techniques such as conductivity measurements and UV-Vis and infrared spectrometries. We report here a method based on salt-induced crystallization patterns formed during the evaporation of alcoholic drops. We found that droplets of different samples form different structures upon drying, which we characterize by their radial density profiles. We prove that using the dried deposit of a spirit as a control sample, our method allows us to differentiate between pure and adulterated drinks. As a proof of concept, we study tequila.

Urinary excretion of uric acid, allantoin, and 8-OH-Deoxyguanosine in uricase-knockout mice

Although uricase-knockout (Uox KO) mice are reported to develop uric acid (UA) nephropathy, those that mature without severe nephropathy could be useful for research into purine metabolism in humans. In this study, we measured the urinary excretion of creatinine, UA, allantoin, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) collected from Uox KO mice housed in metabolic cages. UA and allantoin were determined using liquid chromatography-mass spectrometry and creatinine and 8-OHdG were measured with a commercial kit. Uox KO mice excreted significantly higher levels of UA than wild-type mice (C57BL/6), while the excretion of allantoin was significantly lower. Urinary allantoin was detected in Uox KO mice despite a lack of uricase, which is the same as in humans. In contrast to the elevated levels of UA, the daily excretion of 8-OHdG, an oxidative stress marker, was lower in Uox KO mice. UA is thought to act as an anti-oxidizing agent in humans; thus, these results show that Uox KO mice are potential animal models for research into human purine metabolism.

Determination of four different purines and their content change in seafood by high-performance liquid chromatography

BACKGROUND

Seafood is regarded as a high-purine food that may induce gout, which has attracted extensive attention concerning its safety. Therefore, the aim of this study was to develop a simple and reliable method to determine the purine content in seafood and its change during storage to offer consumers healthy diet information.

RESULTS

Chromatographic separation was carried out using Waters Atlantis dC₁₈ column, and potassium phosphate monobasic solution (0.02 mol L^-1 , pH 3.6) as a mobile phase. The average recovery yields of four purines were 91.5-105.0%, and relative standard deviation values were around 1.8-6.5%. Shrimp and snail contained higher amounts of purine than fish and bivalves; the livers and skins of fish contained higher amounts of purine than muscles; and the main purine varied depending on the type of seafood. Also, purine content of seafood changed during storage.

CONCLUSION

The purine content of seafood differed depending on species, body part and degree of freshness, which could recommend consumers a healthy diet, especially for people with hyperuricemia and gout. © 2016 Society of Chemical Industry.

Analysis of Intra- and Extracellular Levels of Purine Bases, Nucleosides, and Nucleotides in HepG2 Cells by High-performance Liquid Chromatography

To evaluate cellular uptake and purine transport, we developed a high-performance liquid chromatography method for intra- and extracellular purine quantification. Our aim was to develop an effective method for simultaneously quantifying the substrate and metabolites with high sensitivity. C18 columns from different manufacturers were tested for simultaneous quantification of 22 different purine bases, nucleosides, and nucleotides. We used a YMC-Triart C18 column. The analysis conditions, including extraction solutions for the cells and cell culture medium, were optimized to achieve good quantification. Linearity, accuracy, determination limits, and recovery were assessed and showed good performance. The developed HPLC method was successfully applied to the qualitative analysis of 22 different intra- and extracellular purines, demonstrating that it is useful for studying the overall pattern of purine metabolism. This method could also be useful for evaluating metabolic dynamics of purines under a variety of stimulatory conditions of culture cells.

Electrochemical sensing of guanine, adenine and 8-hydroxy-2′-deoxyguanosine at glassy carbon modified with single-walled carbon nanotubes covalently functionalized with lysine

Synthesis and characterization of l-lysine covalently functionalized SWCNT and analytical application for the highly sensitive quantification of guanine, adenine and 8-hydroxy-2′-deoxyguanosine.

Development and Validation of LC-MS/MS Method for Quantitative Determination of Adenosine, Guanosine, Xanthine and Uric Acid in Widely Consumed Vegetables in Thailand

In this study, a triple quadrupole LC-MS/MS electrospray ionization method was developed and validated for quantitative determination of adenosine, guanosine, xanthine and uric acid in fifteen widely consumed Thai vegetables. The method was successively developed by using caffeine as internal standard. The lower limit of quantitation (LLOQ) was 0.2 μg/g for adenosine and guanosine, and 1.0 μg/g for uric acid and xanthine. The method was fully validated according to USFDA guidelines and all performance characteristics were found acceptable. Subsequently, the developed and validated LC-MS/MS method was applied to determine the four interest substances in fifteen widely consumed vegetables in Thailand. The results showed that all vegetables included in the study could be classified as low adenosine, guanosine, xanthine and uric acid containing foods since the concentrations of these substances were less than 50 mg per 100 g. This finding was enormously valuable information for hyperuricemia and gouty patients.

Determination and profiling of purines in foods by using HPLC and LC-MS

Purines in food are known to raise serum uric acid levels. We determined the purine content of sweet potato and beef by high-performance liquid chromatography and liquid chromatography-mass spectrometry. The purine content of the samples was 118-1,034 μmol/100 g. The total purine content was also divided into purine bases, nucleosides, nucleotides, and nucleic acids. Our results suggest that differences in total purine content and in the ratio of purine types between vegetables and beef cause a difference in elevation of serum uric acid levels.

Characterizing substrate properties of purine-related compounds with purine metabolism enzymes for enzymatic peak-shift HPLC method

We have extended peak-shift method for measuring purine bases to make it suitable for other purine-related compounds. We optimized the reactions of the purine metabolism enzymes 5'-nucleotidase (EC 3.1.3.5), purine nucleoside phosphorylase (PNP) (EC 2.4.2.1), xanthine oxidase (XO) (EC 1.17.3.2), urate hydroxylase (EC 1.7.3.3), adenosine deaminase (ADA) (EC 3.5.4.4), and guanine deaminase (EC 3.5.4.3) by determining their substrate specificity and reaction kinetics. These enzymes eliminate the five purine base peaks (adenine, guanine, hypoxanthine, xanthine, and uric acid) and four nucleosides (adenosine, guanosine, inosine, and xanthosine). The bases and nucleosides can be identified and accurately quantified by comparing the chromatograms before and after treatment with the enzymes. Elimination of the individual purine compound peaks was complete in a few minutes. However, when there were multiple substrates, such as for XO, and when the metabolites were purine compounds, such as for PNP and ADA, it took longer to eliminate the peaks. The optimum reaction conditions for the peak-shift assay methods were an assay mixture containing the substrate (10 μL, 0.1 mg/mL), the combined enzyme solution (10 μL each, optimum concentration), and 50 mM sodium phosphate (up to 120 μL, pH 7.4). The mixture was incubated for 60 minutes at 37°C. This method should be suitable for determining the purine content of a variety of samples, without interference from impurities.

Determination of purine contents in different parts of pork and beef by high performance liquid chromatography

Determination of adenine, hypoxanthine, guanine and xanthine in different parts of pork and beef using high performance liquid chromatography was described. Chromatographic separation was carried out on Waters Atlantis T3 column (4.6 mm × 250 mm × 5 μm) with column temperature at 30 °C. The mobile phase contained 99% 10.0 mmol/L ammonium formate solution at pH 3.6 and 1.0% methanol. Chromatography was achieved at a flow rate of 1.0 mL/min and detection wavelength at 254 nm. The results indicated that total purine amounts in pork rump and beef sirloin were higher than those in other parts (P<0.05). The principal purine bases were hypoxanthine and adenine, and hypoxanthine content was the most highest in all samples (P<0.05). As pork rump and beef sirloin contain considerable amounts of total purine and uricogenic purine base, we suggest that excess consumption of them be avoid, whereas pork loin chop and beef rib eye are more suitable for a low-purine diet.

Alcohol intake and the risk of hyperuricaemia: a 6-year prospective study in Japanese men

BACKGROUND AND AIMS

Since there is little information derived from prospective studies on the amount of alcohol drinking required to induce hyperuricaemia, we attempted to address this issue in a Japanese population.

METHODS AND RESULTS

A total of 3310 Japanese men aged 20-54 years that were free of hyperuricaemia were classified according to their alcohol intake per week at baseline. Incident hyperuricaemia, defined as >7.0 mg/dl and/or taking medication for hyperuricaemia, was assessed through annual heath examinations for 6 years after the baseline examination. During follow-up, 529 incident cases of hyperuricaemia occurred. There was a positive, dose-response relationship between alcohol intake and the risk of incident hyperuricaemia. The hazard ratio (95% confidence interval) for hyperuricaemia in drinkers compared with non-drinkers was 1.10 (0.85-1.42) for <10.0 drinks/week, 1.40 (1.07-1.84) for 10.0-19.9 drinks/week, 1.64 (1.23-2.21) for 20.0-29.9 drinks/week and 1.98 (1.40-2.80) for ≥30.0 drinks/week (one drink contained 11.5 g of ethanol) after adjusting for age, baseline serum uric acid, body mass index, smoking habits, exercise habits, serum creatinine, blood pressure, serum cholesterol and blood glucose. The fraction of hyperuricaemia in the population attributable to alcohol intake was 21.6%. A clear dose-response pattern was observed for both beer and sake, when the consumption of these two beverages was analysed separately.

CONCLUSION

Habitual alcohol intake significantly contributed to the development of hyperuricaemia in Japanese men, regardless of type of alcoholic beverage consumed. Therefore, it is essential to reduce excessive alcohol intake to prevent and manage hyperuricaemia.

Analysis of purine in purine-rich cauliflower

Purine is a general term for purine nucleotides, nucleosides, bases, and nucleic acid. The amount of purine nucleotides, nucleosides, and bases in purine-rich cauliflower was determined with the use of LC-MS and HPLC, and the ratio of these molecules were compared with in raw and in heated condition. Total purine content of raw and heated cauliflower was 42.6 and 43.2 mg/100 g, respectively. Nucleotide content was increased from 0.02 to 50.8 micromol/100 g, and nucleoside content was decreased from 12.4 to 7.7 micromol/100 g, by heating.