Systematic investigation of the amino acid profiles that are correlated with xanthine oxidase inhibitory activity: Effects, mechanism and applications in protein source screening

In this study, a polydopamine (PDA)-modified hollow fiber-immobilized xanthine oxidase (XOD) was prepared for screening potential XOD inhibitors from flavonoids. Several parameters for the preparation of PDA-modified hollow fiber-immobilized XOD, including the dopamine concentration, modification time, XOD concentration and immobilization time, were optimized. The results show that the optimal conditions for immobilized XOD activity were a dopamine concentration of 2.0 mg/mL in 10.0 mM Tris-HCl buffer (pH 8.5), a modification time of 3.0 h, an XOD concentration of 1000 μg/mL in 10.0 mM phosphate buffer (pH 7.5) and an immobilization time of 3.0 h. Subsequently, the enzymatic reaction conditions such as the pH value and temperature were investigated, and the enzyme kinetics and inhibition parameters were determined. The results indicate that the optimal pH value (7.5) and temperature (37 °C) of the PDA-modified hollow fiber-immobilized XOD were consistent with the free enzyme. Moreover, the PDA-modified hollow fiber-immobilized XOD could still maintain above 50% of its initial immobilized enzyme activity after seven consecutive cycles. The Michaelis–Menten constant (Km) and the half-maximal inhibitory concentration (IC50) of allopurinol on the immobilized XOD were determined as 0.25 mM and 23.2 μM, respectively. Furthermore, the PDA-modified hollow fiber-immobilized XOD was successfully applied to evaluate the inhibitory activity of eight flavonoids. Quercetin, apigenin, puerarin and epigallocatechin showed a good inhibition effect, and their percentages of inhibition were (79.86 ± 3.50)%, (80.98 ± 0.64)%, (61.15 ± 6.26)% and (54.92 ± 0.41)%, respectively. Finally, molecular docking analysis further verified that these four active compounds could bind to the amino acid residues in the XOD active site. In summary, the PDA-modified hollow fiber-immobilized XOD is an efficient method for the primary screening of XOD inhibitors from natural products.

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Changes in Amino Acid Profiles and Bioactive Compounds of Thai Silk Cocoons as Affected by Water Extraction

Molecules ◽

10.3390/molecules26072033 ◽

2021 ◽

Vol 26 (7) ◽

pp. 2033

Author(s):

Chuleeporn Bungthong ◽

Sirithon Siriamornpun

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Biological Activities ◽

Radical Scavenging Activity ◽

Radical Scavenging ◽

Silk Protein ◽

Extraction Time ◽

Antioxidant Power ◽

Silk Cocoon ◽

Amino Acid Profiles

Silk proteins have many advantageous components including proteins and pigments. The proteins—sericin and fibroin—have been widely studied for medical applications due to their good physiochemical properties and biological activities. Various strains of cocoon display different compositions such as amino-acid profiles and levels of antioxidant activity. Therefore, the objectives of this study were to find a suitable silk protein extraction method to obtain products with chemical and biological properties suitable as functional foods in two strains of Bombyx mori silk cocoon (Nangsew strains; yellow cocoon) and Samia ricini silk cocoon (Eri strains; white cocoon) extracted by water at 100 °C for 2, 4, 6 and 8 h. The results showed that Nangsew strains extracted for 6 h contained the highest amounts of protein, amino acids, total phenolics (TPC) and total flavonoids (TFC), plus DPPH radical-scavenging activity, ABTS radical scavenging capacity, and ferric reducing antioxidant power (FRAP), anti-glycation, α-amylase and α-glucosidase inhibition. The longer extraction time produced higher concentrations of amino acids, contributing to sweet and umami tastes in both silk strains. It seemed that the bitterness decreased as the extraction time increased, resulting in improvements in the sweetness and umami of silk-protein extracts.

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Alteration of serum amino acid profiles by dietary adenine supplementation inhibits fatty liver development in rats

Scientific Reports ◽

10.1038/s41598-020-79234-w ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Hiroki Nishi ◽

Daisuke Yamanaka ◽

Masato Masuda ◽

Yuki Goda ◽

Koichi Ito ◽

...

Keyword(s):

Amino Acid ◽

Fatty Liver ◽

Causative Factor ◽

Amino Acid Profile ◽

Liver Development ◽

Concentration Data ◽

Amino Acid Profiles ◽

Arginine Deficiency ◽

Branched Chain ◽

Tag Accumulation

AbstractStudies on animal models have demonstrated that feeding a low-arginine diet inhibits triacylglycerol (TAG) secretion from the liver, resulting in marked fatty liver development in rats. Here, we first showed that culturing hepatocytes in the medium mimicking the serum amino acid profile of low-arginine diet-fed rats induced TAG accumulation in the cells, indicating that the specific amino acid profile caused TAG accumulation in hepatocytes. Dietary adenine supplementation completely recovered hepatic TAG secretion and abolished hepatic TAG accumulation in rats. A comprehensive non-linear analysis revealed that inhibition of hepatic TAG accumulation by dietary adenine supplementation could be predicted using only serum amino acid concentration data. Comparison of serum amino acid concentrations indicated that histidine, methionine, and branched-chain amino acid (BCAA) concentrations were altered by adenine supplementation. Furthermore, when the serum amino acid profiles of low-arginine diet-fed rats were altered by modifying methionine or BCAA concentrations in their diets, their hepatic TAG accumulation was abolished. Altogether, these results suggest that an increase in methionine and BCAA levels in the serum in response to dietary arginine deficiency is a key causative factor for hepatic TAG accumulation, and dietary adenine supplementation could disrupt this phenomenon by altering serum amino acid profiles.

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Antioxidant activity, xanthine oxidase inhibitory activity, and compounds determination of Cipadessa baccifera leaf extract

10.1063/5.0053207 ◽

2021 ◽

Author(s):

Syarifah Ramadhani Lubis ◽

Subandi Subandi ◽

Muntholib Muntholib ◽

Jamilah Abbas ◽

Tjandrawati Mozef

Keyword(s):

Antioxidant Activity ◽

Xanthine Oxidase ◽

Inhibitory Activity ◽

Leaf Extract

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Inhibitory Activity of Asana, Heartwood of Pterocarpus marsupium, Against Xanthine Oxidase

Natural Product Communications ◽

10.1177/1934578x19887891 ◽

2019 ◽

Vol 14 (12) ◽

pp. 1934578X1988789

Author(s):

Takahiro Deguchi ◽

Yusuke Hata ◽

Atsushi Tamai ◽

Moe Yamamoto ◽

Takanori Fujita ◽

...

Keyword(s):

Liquid Chromatography ◽

Xanthine Oxidase ◽

Inhibitory Activity ◽

Soluble Fraction ◽

Ethanolic Extract ◽

Modern Medicine ◽

Noncommunicable Disease ◽

Promising Candidate ◽

Pterocarpus Marsupium ◽

Novel Agent

The heartwood of Pterocarpus marsupium is called as “Asana” in Ayurveda. Its aquatic infusion was used for treating “prameha,” which indicates a polyuria disease in modern medicine. In our research program to investigate a novel agent to improve hyperuricemia, we focused on the extract of Asana as a xanthine oxidase (XOD) inhibitor. Asana extract (50% ethanolic extract, PM-ext) showed 11%, 35%, and 38% inhibition at 50, 200, and 500 µg/mL, respectively. Subsequently, PM-ext was partitioned with ethyl acetate (AcOEt), butanol, and water. Among them, AcOEt-soluble fraction indicated the most potent XOD inhibitory activity and was consecutively fractionated using various liquid chromatography to obtain liquiritigenin (1), isoliquiritigenin (2), and marsupsin (3) as active principles. Compound 1 showed 16% inhibition at 200 µM while 2 showed 20%, 32%, and 46% inhibition at 50, 100, and 200 µM, respectively. Compound 3 showed 15% inhibition at 500 µM. This is the first report on the XOD inhibitory activity of 3. From these results, PM-ext is a promising candidate material for improvement of hyperuricemia. Here, Asana was recognized as an effective material against noncommunicable disease and is expected to be developed as a functional ingredient.

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