Xanthine oxidase

Laminaran, extracted from seaweed Eisenia bicyclis, was purchased from Tokyo Chemical Industry (CAS No.: 9008-22-4, Tokyo, Japan). Ind was purchased from Wako Pure Chemical Industries (Osaka, Japan) and dissolved in dimethyl sulfoxide (DMSO) at a concentration of 100 mM and prepared for each experiment. Dab was purchased from Cayman Chemical Co. (Ann Arbor, MI, USA) and dissolved in DMSO at a concentration of 10 mM and stored at −20 °C until use. Acid red and 1-oxyl-2,2,6,6-tetramethyl-4-hydroxypiperidine (TEMPOL) were purchased from Tokyo Chemical Industry (Tokyo, Japan). Hydrogen peroxide (H₂O₂) and xanthine were purchased from Wako Pure Chemical Industries. 5-(2,2-dimethyl-1,3-propoxycyclophosphoryl)-5-methyl-1-pyrroline N-oxide (CYPMPO) was purchased from Radical Research Inc. (Tokyo, Japan). xanthine oxidase was purchased from Nacalai Tesque (Kyoto, Japan).

Noncommercial salacca vinegars made from Pondoh, Gula Pasir, Madura, Madu, and Swaru salacca fruits were prepared according to the method of [12 ]. Chemical composition of salacca vinegar made from selected local salacca types can be seen in Table 1.
White female Wistar rats Rattus norvegicus (age 2.5–3.0 months; body weight 150–200 g) were obtained from laboratory of Pharmacology, Faculty of Health and Biomedicine, Brawijaya University, Malang. Comfeed PARS feed (PT. JapfaComfeed Indonesia Tbk.), miliQ water, Streptozotocin (STZ) (Nacalai Tesque, Kyoto, Japan), ether, Buffer Neutral Formalin (BNF) 10%, HCL 1 N, TCA, Na-Thiobarbiturate, PBS, xanthine, xanthine oxidase, NBT, hematoxylin eosin (HE), and paraffin were all obtained from Laboratory of Pharmacology and Laboratory of Pathology Anatomy, Faculty of Health and Biomedicine, Brawijaya University, Malang.

Urine samples were collected from 20 patients with diabetes from the University of Toyama Hospital and stored at −20 °C. Before usage, the urine samples were centrifuged at 17,800× g for 5 min to remove insoluble components.
The proteins (1 mg/mL) shown in Figure 1 consisted of papain (Wako), trypsin (Nacalai), RNaseA (Roche), transferrin (Nacalai), xanthine oxidase (Nacalai), collagenase (Worthington Biochemical), dispase (Thermo Fisher), proteinase K (Roche), human serum albumin (Nacalai), and bovine serum albumin (Sigma). IgG, shown in Figure 1, was raised in our laboratory [36 (link)].