Antitumor agents. 8. Synthesis and cytotoxic activity of O,O'-bis(acrylyl)-alpha,omega-alkanediols

Cytotoxic esters of 1,1-bis-(4-hydroxyphenyl)-2-phenyl-but-1-ene with selective antitumor activity against estrogen receptor-containing mammary tumors

Both hydroxy groups of 1,1-bis-(4-hydroxyphenyl)-2-phenyl-but-1-ene (1) were esterified with the beta-chloropropionate (2), beta-bromopropionate (3) and acrylate functions (4). Linkage of these cytotoxic moieties reduced the estrogen receptor affinities of these compounds, especially in the case of the beta-haloesters only slightly compared with the affinity of the unsubstituted carrier molecule 1. The estrogenic potencies of the derivatives 2-4 and of 1 were nearly identical. The alkylating activities increased in the order 2, 3, and 4. Because of their alkylating activities, all cytotoxic esters showed an irreversible mode of binding to the estrogen receptor. In vitro, 3 in particular, exerted better growth inhibition of the hormone-dependent MCF-7 cell line than of the hormone-independent MDA cell line. In vivo, all cytotoxic derivatives caused almost complete inhibition of the growth of the hormone-dependent MXT M3.2 mouse mammary tumor, whereas growth of the hormone-independent MXT-Ovex tumor was much less inhibited. In all tumor models, the antitumor effect of the cytotoxic esters was better than that of the unsubstituted carrier. Therefore, the antitumor activity of these esters could be due not only to their improved pharmacokinetic properties compared to 1, but also to a selective estrogen receptor-mediated cytotoxic action.

Synthesis of alpha-methylenebeutyrolactams as potential antitumor agents

A series of 1-aryl-3-methylene-2-pyrrolidinones was synthesized via a three-step reaction sequence. 1,4-Bis-[N-(3-methylene-2-oxopyrrolidino)]benzene, which can undergo alkylation at two sites, was also prepared. These compounds are related to the known antitumor agents alpha-methylenebutyrolactones. Attempts to prepare bis-alpha-methylenelactams, in which the heterocyclic rings are joined through their nitrogen atoms by an alkylene bridge, were unsuccessful. All of the alpha-methylenelactams were screened in B16 melanocarcinoma and P-388 lymphocytic leukemia tumor systems but failed to show significant activity.

Sesquiterpene antitumor agents: inhibitors of cellular metabolism

Helenalin and tenulin injected into CF1 male mice bearing Ehrlich ascites tumors inhibit DNA synthesis and DNA polymerase enzymatic activity in the tumor cells. Helenalin inhibited protein synthesis. Both drugs increased the concentration of adenosine 3',5'-monophosphate, and interfered with glycolytic and mitochondrial energy processes. Cholesterol synthesis was also inhibited, resulting in lower serum cholesterol levels in tumor-bearing animals. Data obtained in vitro indicate that the cyclopentenone-bearing sesquiterpene lactone and related compounds do not alkylate puring bases of nucleic acids but rather undergo a Michael-type addition reaction with the sulfhydryl groups of reduced glutathione and l-cysteine. Thus, the inhibition of cellular enzyme activities and metabolism that has been observed with these drugs might be explained by the occurrence of a Michael-type teaction.