Synthesis and antitumor activities of unsymmetrically substituted 1,4-bis[(aminoalkyl)amino]anthracene-9,10-diones and related systems

Asymmetric enzymatic glycosylation of mitoxantrone

Using a uniquely promiscuous engineered glycosyltransferase (GT) derived from the macrolide-inactivating GT OleD, a single-step asymmetric glucosylation of one 'arm' of the drug mitoxantrone was efficiently achieved in high stereo- and regiospecificity. The synthesis, structural elucidation, and anticancer activity of the corresponding mitoxantrone 4'-β-D-glucoside are described.

Synthesis of DNA-directed pyrrolidinyl and piperidinyl confined alkylating chloroalkylaminoanthraquinones: potential for development of tumor-selective N-oxides

A novel series of 1,4-disubstituted chloroethylaminoanthraquinones, containing alkylating chloroethylamino functionalities as part of a rigid piperidinyl or pyrrolidinyl ring-system, have been prepared. The target compounds were prepared by ipso-displacement of halides of various anthraquinone chromophores by either hydroxylated or chlorinated piperidinyl- or pyrrolidinyl-alkylamino side chains. The chloroethylaminoanthraquinones were shown to alkylate guanine residues of linearized pBR322 (1-20 microM), and two symmetrically 1,4-disubstituted anthraquinones (compounds 14 and 15) were shown to interstrand cross-link DNA in the low nM range. Several 1,4-disubstituted chloroethylaminoanthraquinones were potently cytotoxic (IC50 values: <or=40 nM) in human ovarian cancer A2780 cells. Two agents (compounds 18 and 19) exhibited mean GI50 values of 96 nM and 182 nM, respectively, in the NCI human tumor cell line panel. Derivatization of the potent DNA cross-linking agent 15 to an N-oxide resulted in loss of the DNA unwinding, DNA interstrand cross-linking and cytotoxic activity of the parent molecule.

Synthesis and calculated properties of some 1,4-bis(amino)anthracene-9,10-diones

The synthesis of a number of 1,4-bis(amino)anthracene-9,10-diones containing chlorine or sulfur which are related to the anti-cancer drugs Ametantrone and Mitoxantrone are reported. 1,4-Dichloro-2,3-dihydro-5,8-dihydroxyanthracene-9,10-dione reacts readily with a series of alkylamines to yield the corresponding 1,4-bis(alkylamino)-5,8-dichloroanthracene-9,10-dione after oxidation. The subsequent reaction of the products with ethanethiol or thiophenol gives the corresponding 1,4-bis(alkylamino)-5,8-bis(sulfanyl)anthracene-9,10-dione in good yield. Theoretical calculations at the RHF 6-31G** level indicate that the introduction of either chlorine or the phenylsulfanyl group into the 5- and 8-positions of 1,4-bis(alkylamino)anthracene-9,10-diones results in a lowering of the LUMO energies suggesting that related functionalised derivatives might have lower cardiotoxicities than Mitoxantrone.

Development of Nonsymmetrical 1,4-Disubstituted Anthraquinones That Are Potently Active against Cisplatin-Resistant Ovarian Cancer Cells

A novel series of 1,4-disubstituted aminoanthraquinones were prepared by ipso-displacement of 1,4-difluoro-5,8-dihydroxyanthraquinones by hydroxylated piperidinyl- or pyrrolidinylalkylamino side chains. One aminoanthraquinone (13) was further derivatized to a chloropropylamino analogue by treatment with triphenylphosphine-carbon tetrachloride. The compounds were evaluated in the A2780 ovarian cancer cell line and its cisplatin-resistant variants (A2780/cp70 and A2780/MCP1). The novel anthraquinones were shown to possess up to 5-fold increased potency against the cisplatin-resistant cells compared to the wild-type cells. Growth curve analysis of the hydroxyethylaminoanthraquinone 8 in the osteosarcoma cell line U-2 OS showed that the cell cycle is not frozen, rather there is a late cell cycle arrest consistent with the action of a DNA-damaging topoisomerase II inhibitor. Accumulative apoptotic events, using time lapse photography, indicate that 8 is capable of fully engaging cell cycle arrest pathways in G2 in the absence of early apoptotic commitment. 8 and its chloropropyl analogue 13 retained significant activity against human A2780/cp70 xenografted tumors in mice.

Synthesis and structure–activity correlations of the cytotoxic bifunctional 1,4-diamidoanthraquinone derivatives

Anthraquinone-based compounds are attractive target for the design of new anticancer drugs. We have previously described a series of 1,5- and 1,4-difunctionalized anthraquinones, which exhibit different spectra of potency, together with human telomerase evaluation. The present study details the preparation of further, distinct series of regioisomeric difunctionalized amidoanthraquinone and examines their in vitro cytotoxicity in C6, Hepa G2, and 2.2.15 cell lines. Two structurally related compounds, mitoxantrone and adriamycin, were tested in parallel as positive controls. The structure-activity relationships indicated amido substitution may lead to a different mechanism of cytotoxicity. Compounds, which have -(CH2)n- side chains terminating in basic groups such as aminoalkyl-substituted, showed cytotoxic activity in several cell lines. The exact mode of intercalative binding may be dictated by the positional placement of substituent side chains. Implications for amidoanthraquinone cytotoxicity as potential anticancer agents are discussed. In addition, we further delineate the nature of the pharmacophore for this class of compounds, which provides a rational basis for the structure-activity relationships.

Free radical formation by antitumor quinones

Quinones are among the most frequently used drugs to treat human cancer. All of the antitumor quinones can undergo reversible enzymatic reduction and oxidation, and form semiquinone and oxygen radicals. For several antitumor quinones enzymatic reduction also leads to formation of alkylating species but whether this involves reduction to the semiquinone or the hydroquinone is not always clear. The antitumor activity of quinones is frequently linked to DNA damage caused by alkylating species or oxygen radicals. Some other effects of the antitumor quinones, such as cardiotoxicity and skin toxicity, may also be related to oxygen radical formation. The evidence for a relationship between radical formation and the biological activity of the antitumor quinones is evaluated.