问 喜树碱用途是什么？

喜树碱抗癌药。用于胃癌、结肠癌、直肠癌、头颈部圆柱瘤型癌和膀胱癌。;用于治疗胃癌、肠癌、慢性粒细胞型和急性白血病等;不可逆转地的结合到DNA拓扑异构酶I复合物上，影响细胞周期进程;喜树碱最初是从喜树的茎材中分离出来的，表现出抗白血病/抗肿瘤活性。和DNA拓扑异构酶I复合体不可逆地结合，抑制拓扑异构酶I剪切后DNA重组，将酶和DNA以共价键形式锁住。Camptothecin was originally isolated from the stem wood of the Camptotheca acuminata tree and was shown to exhibit antileukemic/antitumor activity, and reversibly inhibit Mitochondrial Topo I (nuclear Topo I (topoisomerase I)) by binding to and stabilizing the topoisomerase-DNA covalent complex. Advancing replication forks are believed to interact with these complexes leading to double strand breaks, which is thought to be responsible for much of the cytotoxicity; other research has shown that some of the antitumor activity could be derived from the inhibition of NOS2 (iNOS or inducible nitric oxide synthase) which generates nitric oxide, an important regulator of angiogenesis and other biochemical pathways. The discovery of camptothecin spurred the development of many derivatives with superior activity and solubility, including irinotecan (sc-202186) and topotecan (sc-204919). Although most noted for its anticancer activity, camptothecin and derivatives have shown other pertinent biochemical actions, including: antiprotozoal, antimalarial, inhibition of HIV, upregulation of p53, and induction of apoptosis. This product also exhibits intense blue fluorescence when exposed to UV light, which could be useful in optical experiments.