Hori Y, Abe Y, Nishimura M, Goto T, Okuhara M, Kohsaka M
Exploratory Research Laboratories, Fujisawa Pharmaceutical Co., Ltd., Ibaraki, Japan.
J Antibiot (Tokyo). 1993 Jul;46(7):1069-75. doi: 10.7164/antibiotics.46.1069.
R1128 B (1,3,6-trihydroxy-8-n-butylanthraquinone), a new antibiotic produced by Streptomyces sp. No. 1128, inhibited estrogen binding to its receptor. The IC50 value of R1128 B for partially purified rat uterine cytosol receptor was 1.2 x 10(-7) M. However, the IC50 value of R1128 B against androgen-receptor binding was about 50-fold greater than that against estrogen-receptor binding. R1128 B was a competitive inhibitor against estrogen-receptor binding. R1128 B inhibited the growth of estrogen-responsive human mammary adenocarcinoma MCF-7 cells in soft agar. This inhibition, however, was reversed when estradiol was added to the culture medium. R1128 B showed antitumor activities against MCF-7 both xenografted to nude mice and implanted in subrenal capsule of mice (SRC assay). The potency of R1128 B was about 8-fold lower than that of tamoxifen both in vitro and in vivo.
R1128 B（1,3,6 - 三羟基 - 8 - 正丁基蒽醌）是链霉菌属1128号菌株产生的一种新型抗生素，它能抑制雌激素与其受体的结合。R1128 B对部分纯化的大鼠子宫胞质溶胶受体的IC50值为1.2×10⁻⁷ M。然而，R1128 B对雄激素受体结合的IC50值比对雌激素受体结合的IC50值大约高50倍。R1128 B是雌激素受体结合的竞争性抑制剂。R1128 B在软琼脂中抑制雌激素反应性人乳腺腺癌MCF - 7细胞的生长。然而，当向培养基中添加雌二醇时，这种抑制作用会被逆转。R1128 B对移植到裸鼠体内和植入小鼠肾包膜下（SRC试验）的MCF - 7均显示出抗肿瘤活性。R1128 B在体外和体内的效力比他莫昔芬低约8倍。
