A lipophilic prodrug of 1-β-D-arabinofuranosylcytosine (Ara-C), namely N4-[N-(cholesteryl-oxycarbonyl)glycyl]-Ara-C (COCG-Ara-C), was synthesized and its antitumor activity in a liposome-entrapped form was studied. COCG-Ara-C showed an increaesd lipophilicity and almost complete entrapment in liposomes. COCG-Ara-C was hydrolyzed to the parent drug chemically, but the hydrolysis was accelerated in the presence of mouse, rat and human plasma. The in vitro cytoxicity of the prodrug against P 388 leukemia was approximately one-fifth that of Ara-C and four times that of N4-behenoyl-Ara-C (BHAC). For in vivo antitumor activity tests, unilamellar vesicles composed of egg phosphatidylcholine (PC), egg sphingomyelin (SM) and COCG-Ara-C in a molar ratio of 7 : 3 : X (X=0-2.0) were prepared by the combination of controlled dialysis and sequential extrusion. The vesicle size ranged from 108±18 nm to 124±18 nm. In all the antitumor activity studies, chemotherapy was performed intravenously. The antitumor activity of COCG-Ara-C-bearing liposomes against intraperitoneally- or intravenously-inoculated mouse L 1210 leukemia was clearly superior to those of Ara-C and BHAC aqueous solutions. The efficacy of COCG-Ara-C against L 1210 leukemia was dependent upon the dosage form : regardless of implantation route, liposomal COCG-Ara-C showed a more potent activity than free COCG-Ara-C (aqueous solution). Prodrug-bearing liposomes also inhibited the growth of a human lung adenocarcinoma A 549 xenograft implanted under the renal capsule more efficiently than did Ara-C and BHAC aqueous solutions. These results suggest the potential usefulness of COCG-Ara-C-bearing liposomes in cancer chemotherapy.
研究人员合成了 1-β-D-arabinofuranosylcytosine (Ara-C)的亲脂原药,即 N4-[N-(
胆固醇-氧羰基)甘
氨酰]-Ara-C(COCG-Ara-C),并研究了它在脂质体包裹形式下的抗肿瘤活性。COCG-Ara-C 的亲脂性增强,在脂质体中几乎完全被包裹。COCG-Ara-C 通过
化学反应
水解为母体药物,但在小鼠、大鼠和人血浆中
水解速度加快。该原药对 P 388 白血病的体外细胞毒性约为 Ara-C 的五分之一,是 N4-behenoyl-Ara-C(
BHAC)的四倍。在体内抗肿瘤活性测试中,采用控制透析和顺序挤压相结合的方法制备了由鸡蛋
磷脂酰
胆碱(PC)、鸡蛋鞘
磷脂(SM)和 COCG-Ara-C 按 7 : 3 : X(X=0-2.0)的摩尔比组成的单纤胶囊泡。囊泡大小为 108±18 nm 至 124±18 nm。在所有抗肿瘤活性研究中,化疗都是通过静脉注射进行的。COCG-Ara-C脂质体对腹腔注射或静脉注射小鼠L 1210白血病的抗肿瘤活性明显优于Ara-C和
BHAC
水溶液。COCG-Ara-C对L 1210白血病的疗效取决于剂型:无论植入途径如何,脂质体COCG-Ara-C都比游离COCG-Ara-C(
水溶液)显示出更强的活性。与 Ara-C 和
BHAC
水溶液相比,含药脂质体还能更有效地抑制植入肾囊下的人肺腺癌 A 549 异种移植物的生长。这些结果表明,COCG-Ara-C 脂质体在癌症化疗中具有潜在的用途。