Sheu S Y, Lin C Y, Wu J D, Chiang H C
School of Pharmacy, Taipei Medical College, Taiwan, ROC.
Anticancer Res. 1999 Jan-Feb;19(1A):119-23.
Fourteen synthetic benzothiazinone analogues were tested for their inhibitory effects on xanthine oxidase. The enzyme, xanthine oxidase (XO) catalyses the oxidation of hypoxanthine to xanthine and of xanthine to uric acid, which has a lambda max of 295 nm, forming the basis for a spectrophotometric assay for the activity of xanthine oxidase. The results showed that 2-amino-4H-1,3-benzothiazine-4-one (1), 2-guanidino-4H-1,3-benzothiazin-4-one (2) and rhodanine (3) display inhibitory effects on xanthine oxidase with an order of activity of IC50 = 5.54, 5.60 and 121.40 microM respectively. The apparent inhibition constants (Ki) were 5.12, 19.47 and 206.23 microM, and induced non-competitive, mixed type (non-competitive-uncompetitive) and mixed type (non-competitive-uncompetitive) inhibitions respectively with respect to the substrate xanthine.
测试了十四种合成苯并噻嗪酮类似物对黄嘌呤氧化酶的抑制作用。黄嘌呤氧化酶（XO）催化次黄嘌呤氧化为黄嘌呤以及黄嘌呤氧化为尿酸，尿酸在295nm处有最大吸收波长，这构成了黄嘌呤氧化酶活性分光光度测定法的基础。结果表明，2-氨基-4H-1,3-苯并噻嗪-4-酮（1）、2-胍基-4H-1,3-苯并噻嗪-4-酮（2）和若丹宁（3）对黄嘌呤氧化酶有抑制作用，活性顺序为IC50分别为5.54、5.60和121.40微摩尔。表观抑制常数（Ki）分别为5.12、19.47和206.23微摩尔，并且相对于底物黄嘌呤分别诱导非竞争性、混合型（非竞争性-非竞争性）和混合型（非竞争性-非竞争性）抑制。
