Hypoxanthine, fish

Hu et al. [84] Hypoxanthine Fish Xanthine oxidase/within a polyaniline film on the electrode surface by electropolymerisation Sodium montmorillonite-methyl viologen carbon paste modified electrode/-0.72V vs. Ag/ AgCl Methyl viologen... 

Basu et al. [85] Hypoxanthine Fish Meat Xanthine oxidase (XO)/ cross-linked with glutaraldehyde in the presence of BSA. Covered with gelatine and a membrane of cellulose acetate ... 

Ghosh et al. [14] hypoxanthine, respectively Hypoxanthine Fish Catla- Xanthine oxidase, Conducting polypyrrole Ferrocene carboxylic acid... 

Guanine (Pearl Essence). Guanine (Cl Natural White 1, Cl No. 75170), is the crystalline material obtained from fish scales and consists principally of the two putines, guanine [73-40-5] (42) and hypoxanthine [68-94-0] (43). The guanine content of the colorant varies from 75% to 97%, whereas the hypoxanthine content ranges from 3% to 25%, depending on the particular fish and tissue from which the crystals ate derived. 

FIGURE 2.1 Hypoxanthine oxide, a fish alarm pheromone. 

A method similar to K value is the Kj value index that is used for freshness evaluation of fish that accumulate more inosine than hypoxanthine during spoilage (24). The K value is illustrated in Figure 3 (18,19,20,24). K is used with salmon, halibut, yellowtail, and numerous other tropical fish, while K value is reliable for catfish, white flounder, ocean perch, English sole, and various other species (24). The Kj value can be utilized for species specified for K value but not vice versa due to sensitivity of Kj value to the build up of hypoxanthine and not the total sum of degradation products as needed with K value (24). 

Natural pearl essence (Essence d Oriente, Fish Silver) is a pigment suspension derived from fish scales, skin, or bladder. It is the oldest commercial pearl luster pigment, consisting mainly of a mixture of the purines guanine [73-40-5] (75-97%) and hypoxanthine [68-94-0] (25-3%). 

In addition to analyzing compounds, enzyme sensor has been used to determine the freshness of meats. Xanthine oxidase has been used to determine the levels of xanthine and hypoxanthine that are accumulated from purine degradation during muscle aging so as to monitor fish freshness for a long time. Traditional methods including the automated colorimetric method (54) were time consuming. Jahn et al (55) developed a dipstick test by... 

G. Cayuela, N. Pena, A.J. Reviejo and J.M. Pingarron, Development of a bienzymic graphite-Teflon composite electrode for the determination of hypoxanthine in fish, Analyst, 123(2) (1998) 371-377. 

A.K. Basu, P. Chattopadhyay, U.R. Choudhury and R. Chakraborty, Development of an amperometric hypoxanthine biosensor for determination of hypoxanthine in fish and meat tissue, Indian J. Exp. Biol., 43(7) (2005) 646-653. 

This concept has been enployed (11) to measure hypoxanthine extracted from fish with a xanthine oxidase-peroxidase nylon mesh electrode ... 

Table V. dialysis of Hypoxanthine in Fish Meats Using Bi-enzyme Electrode and AMC Spectrophotometr ic Methods...

Natural pearl essence is isolated as a silky lustrous suspension from fish scales. The organic pigment particles in the suspension are platelet-shaped with a very high aspect ratio (0.05 pm x 1-10 pm x 20-50 pm), and consist of 75-97% guanine and 3-25% hypoxanthine (natural fish silver) [5.122, 5.123, 5.128, 5.130]. 

Enz5une sensors or assays exist for the determination of adenosine triphosphate (ATP) and its degradation products inosine 5 -monophosphate (IMP), inosine (HxR), hypoxanthine (Hx) and xanthine (X) as ATP is used as an indicator of the presence of microorganisms and the concentrations of its degradation products are used as indicators for fish and meat freshness in food industry [118]. 

Hypoxanthine ratio determination in fish extract using CE and immobilized enzymes IMP, HxR and Hx from cod, salmon and trout fillets Fish sample homogenized with 10% TCA, supernatant centrifuged, neutralized, diluted and filtered... 

Xanthine oxidase cross-linked with glutaraldehyde into cellulose triacetate membranes and attached to a Teflon membrane on an oxygen electrode Hypoxanthine as an indicator of fish freshness [35]... 

Luong and Male (1992) developed a biosensor system to measure the hypoxanthine concentration ratio as an indicator of fish freshness. Hy-poxanthine is the autodegradation product formed from adenosine 5 -triphosphate in fish tissue and is responsible for the bitter off-taste characteristic of fish which has lost its freshness. 

Luong, J. H. T., and Male, K. B. (1992). Development of a new biosensor system for the determination of the hypoxanthine ratio, an indicator of fish freshness. Enzyme Microbiol Technol 14, 125-130. 

Brown, G. E., Adrian, J. C., Jr., and Shih, M. L., 2001a, Behavioural respoiees of fathead minnows Pimephales promelas) to hypoxanthine-3-Af-oxide at varying concentrations, J. Fish Biol. 58 1465-1470. 

Trap experiments have also been used to determine the chemical composition of Ostariophysan alarm cues. In a study by Brown et al. (2000), traps labeled with fathead minnow extract, hypoxanthine-3-N-oxide or pyridine-N-oxide caught significantly fewer fishes (including dace and minnow) than those labeled with distilled water. These field results validate the outcome of laboratory studies in which significant increases in antipredator behavior in both fathead minnows and finescale dace were observed when they... 

Purine analysis can be achieved with this system, specifically inosine (the co-substrate, with phosphate. Scheme 5.5) can be determined quantitatively using similar methodology. The hypoxanthine ratio ([hypoxanthine]/ [hypoxanthine] + [inosine] + [inosine-monophosphate]) is key measure of fish freshness as hypoxanthine is a product of nucleotide degradation and a sign of spoilage. As mentioned previously, hypoxanthine or xanthine... 

Classification Natural purine Definition Crystalline material obtained from fish scales, consisting of 75-97% guanine and 3-25% hypoxanthine (CAS 68-94-0)... 

In this degradation process, ATP, ADP, and AMP are rapidly degraded, resulting in accumulations of inosine and hypoxanthine. The percentages of inosine and hypoxanthine in the total nucleic acid-related compounds are highly correlated to the stage of freshness in fish [10]. Thus, to indicate fish freshness, a K value is defined as Equation 28.4. 

The first pearl pigment was derived from fish scales as platy crystals of guanine and hypoxanthine. This remained imrivaled in luster for approximately 300 years, until the refinement of crystallization processes for... 

Hypoxanthine, CgH4N40, has been obtained chiefly from nucleotides. It is present in extracts of glandular and muscle tissue, in fish sperm and bone marrow, and, in traces, in milk and urine. Urinary hypoxanthine is greatly increased in leukaemia. It occurs in microcrystals of low solubility in water and organic solvents, but dissolves in acids or alkalies to form salts. On oxidation, it is converted into xanthine. 

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