To reduce the pervasive toxicity of natural shikonin, alkannin, and their synthetic analogues and to enhance the selectivity of these chemotherapeutics toward cancer cells, a novel 5,8-dimethyl alkannin oxime derivative (DMAKO-20) was designed, synthesized, and evaluated for its strong antitumor activity both in vitro and in vivo. It showed potent growth inhibitory effects against HCT-15, HCT-116, and K562 cells (IC₅₀ < 1 μM), moderate antiproliferative activity toward MDA-MB-231, HepG2, PANC, Bel7402, and MGC803 cancer cells (IC₅₀ < 10 μM), and was nontoxic to the human normal VEC and HSF cells. In vivo efficacy studies demonstrated that DMAKO-20 (10 mg/kg, i.v. on every the other day, 8 times in 14 days) resulted in 59.3% reduction in HCT-15 xenograft volume. It was as effective as the toxic antimetabolite 5-FU but revealed neither toxicity nor death in mice. The mechanistic investigations indicated that DMAKO-20 underwent the tumor-specific CYP1B1-catalyzed bioactivation to afford nitric oxide and active naphthoquinone mono-oximes, which exhibited combined anticancer effects. It was defined as a representative of the “Multi-target Anticancer Prodrugs Activated by Specific Enzymes in cancer cells”. The produced active metabolites exerted anticancer effects by the direct nucleophilic alkylation and the induction of the apoptosis of cancer cells through activation of the mitochondrial pathway. The discovery of DMAKO-20 and the illustration of its molecular mechanisms may provide a new strategy to overcome the nonselective toxicity of the current chemotherapeutics.

中文翻译：

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DMAKO-20作为一种新的多靶点抗癌前药，被肿瘤特异性CYP1B1酶激活。

为减少天然紫草素，链烷宁及其合成类似物的普遍毒性并增强这些化学疗法对癌细胞的选择性，设计，合成并评估了一种新型的5,8-二甲基链烷肟肟衍生物（DMAKO-20）其两个强的抗肿瘤活性在体外和体内。对HCT-15，HCT-116和K562细胞（IC ₅₀ <1μM）表现出有效的生长抑制作用，对MDA-MB-231，HepG2，PANC，Bel7402和MGC803癌细胞具有中等的抗增殖活性（IC ₅₀ < 10μM），并且对人正常的VEC和HSF细胞无毒。体内功效研究表明DMAKO-20（10 mg / kg，iv。每隔一天，在14天中有8次）导致HCT-15异种移植物体积减少了59.3％。它与毒性抗代谢物5-FU一样有效，但在小鼠中既没有毒性也没有死亡。机理研究表明，DMAKO-20经历了肿瘤特异性的CYP1B1催化的生物活化作用，以提供一氧化氮和活性的萘醌单肟，它们共同表现出抗癌作用。它被定义为“被癌细胞中特定酶激活的多靶点抗癌前药”的代表。产生的活性代谢产物通过直接亲核烷基化和通过激活线粒体途径诱导癌细胞凋亡而发挥抗癌作用。