Synthesis and cytogenetic studies of structure--biological activity relationship of esters of Hecogenin and aza-homo-Hecogenin with N,N-bis(2-chloroethyl)aminocinnamic acid isomers

The esters of Hecogenin and aza-homo-Hecogenin with N,N-bis(2-chloroethyl)aminocinnamic acid isomers have been prepared and their cytogenetic studies of structure-biological activity relationship were evaluated. The cytogenetic effects (sister chromatid exchanges (SCEs) induction and proliferation rate indices (PRIs) depression) by o-, m- and p-[N,N-bis(2-chloroethyl)amino] cinnamic acid were also investigated. Among the above compounds tested, those of the m-[N,N-bis(2-chloroethyl)amino] cinnamic acid and of the o-[N,N-bis(2-chloroethyl)amino] cinnamic acid ester of aza-homo-Hecogenin were more active in comparison to the others.     

Monoclonal antibody-beta-lactamase conjugates for the activation of a cephalosporin mustard prodrug.

Cephalosporin mustard (CM) was designed as an anticancer prodrug that could be activated in a site-specific manner by monoclonal antibody-beta-lactamase conjugates targeted to antigens present on tumor cell surfaces. Purified beta-lactamases from Bacillus cereus (BC beta L) and Escherichia coli (EC beta L) catalyzed the release of phenylenediamine mustard (PDM) from CM through a fragmentation reaction which occurs after the beta-lactam ring of CM is hydrolyzed. The Km and Vmax values were 5.7 microM and 201 mumol/min per mg for BC beta L and 43 microM and 29 mumol/min per mg for EC beta L, respectively. Conjugates of BC beta L were prepared by combining the F(ab')2 fragments of the maleimide-substituted monoclonal antibodies L6 and 1F5 with thiolated BC beta L. The conjugates showed little loss in enzymatic activity and bound nearly as well as the unmodified F(ab')2 monoclonal antibodies to antigens expressed on the H2981 human lung adenocarcinoma cell line (L6 positive, 1F5 negative). PDM was approximately 50-fold more cytotoxic than CM to H2981 cells. Treatment of the cells with L6-BC beta L followed by CM resulted in a level of cytotoxic activity that was comparable to that of PDM. This was most likely due to activation of CM by conjugate that bound to cell-surface antigens, since pretreatment of H2981 cells with BC beta L or 1F5-BC beta L enhanced the activity of CM to a lesser extent. Thus, we have shown that CM is a prodrug, and that it can be activated with immunological specificity by a monoclonal antibody-beta-lactamase conjugate.     

Cytotoxic steroids with antiestrogenic activity of the 11alpha-acyloxyestra-1,3,5(10)-triene series

Esterification of 3-hydroxyl group in 11-acyloxyestra-1,3,5(10)-trienes with p-[bis(2-chloroethyl)amino]phenylacetic acid led to antitumor steroids displaying antiestrogenic and cytotoxic activities. Our substances exhibit their activities on the model of murine mammary adenocarcinoma Ca-755, with inhibition of the tumor growth being 94-99%. A new approach was used for the 11alpha-hydroxylation of estra-1,3,5(10)-trienes.     

Synthesis and first in vitro cytotoxicity studies of bis(2-chloroethyl) amino group containing polymers. Pharmacologically active polymers: 22

Monomers containing the cytotoxic bis(2-chloroethyl)amino group (nor-nitrogen mustard), linked in deactivated form via urethane and O-acylated hydroxamic acid bonds to polymerizable methacrylic acid derivatives, have been prepared. Besides the homopolymerization, these monomers were copolymerized with hydrophilic comonomers to obtain water-soluble polymers. The linkages used are expected to undergo intracellular enzymatic or hydrolytic cleavage, releasing the cytotoxic bis(2-chloroethyl)amino moiety from the polymeric carrier. Preliminary in vitro cytotoxicity data for the polymers against three rat and mouse experimental tumour lines (Walker 256 carcinosarcoma, L1210 murine leukaemia and ADJ/PC6A plasma cell tumour) are reported. An approximately 10² fold difference in cytotoxic potency was found, depending on the type of the cleavable spacer group.     

Synthesis, characterization and antitumor activity of copper(II) complex with nicotinamido-4-bis(2-chloroethyl)aminobenzaldimine.

Nicotinamido-4-bis(2-chloroethyl)aminobenzaldimine (NBAB) was synthesized and characterized by elemental analysis, IR and 1H NMR spectra. The complex of Cu(NBAB)2(NO3)2 was prepared in ethanol and characterized by elemental analysis, conductivity, cyclic voltammetry, IR, UV-Vis, fluorescence, CD and EPR spectra. The characteristic data suggest that the complex has an elongated octahedral structure, and NBAB behaves as bidentate in the keto form. The antitumor activities of NBAB and the complex against L1210 murine leukemia and K562 were investigated with both the MTT method and the colony formation test. The results in vitro indicate that antitumor activities of NBAB are superior to 2,2'-chlorodiethylamine hydrochloride (nitrogen mustard) for L1210, and inferior to nitrogen mustard for K562, but the antitumor activities of the complex for both cell lines are superior to nitrogen mustard.     

Metabolism of chlorambucil by rat liver microsomal glutathione S-transferase

Clinical efficacy of alkylating anticancer drugs, such as chlorambucil (4-[p-[bis [2-chloroethyl] amino] phenyl]-butanoic acid; CHB), is often limited by the emergence of drug resistant tumor cells. Increased glutathione (gamma-glutamylcysteinylglycine; GSH) conjugation (inactivation) of alkylating anticancer drugs due to overexpression of cytosolic glutathione S-transferase (GST) is believed to be an important mechanism in tumor cell resistance to alkylating agents. However, the potential involvement of microsomal GST in the establishment of acquired drug resistance (ADR) to CHB remains uncertain. In our experiments, a combination of lipid chromatography/electrospray ionization mass spectrometry (LC/ESI/MS) was employed for structural characterization of the resulting conjugates between CHB and GSH. The spontaneous reaction of 1mM CHB with 5 mM GSH at 37 degrees C in aqueous phosphate buffer for 1 h gave primarily the monoglutathionyl derivative, 4-[p-[N-2-chloroethyl, N-2-S-glutathionylethyl] amino]phenyl]-butanoic acid (CHBSG) and the diglutathionyl derivative, 4-[p-[2-S-glutathionylethyl] amino]phenyl]-butanoic acid (CHBSG2) with small amounts of the hydroxy-derivative, 4-[p-[N-2-S-glutathionylethyl, N-2-hydroxyethyl] amino]phenyl]-butanoic acid (CHBSGOH), 4-[p-[bis[2-hydroxyethyl] amino]phenyl]-butanoic acid (CHBOH2), 4-[p-[N-2-chloroethyl, N-2-S-hydroxyethyl]amino]phenyl]-butanoic acid (CHBOH). We demonstrated that rat liver microsomal GST presented a strong catalytic effect on these reactions as determined by the increase of CHBSG2, CHBSGOH and CHBSG and the decrease of CHB. We showed that microsomal GST was activated by CHB in a concentration and time dependent manner. Microsomal GST which was stimulated approximately two-fold with CHB had a stronger catalytic effect. Thus, microsomal GST may play a potential role in the metabolism of CHB in biological membranes, and in the development of ADR.     

Antitumor effects of an antibody-carboxypeptidase g2 conjugate in combination with a benzoic acid mustard prodrug

The F(ab’)₂ fragment of the antitumor monoclonal antibody, A5B7, was covalently linked to the bacterial enzyme carboxypeptidase G2 (CPG2). The resulting conjugate was used in combination with a prodrug of a benzoic acid mustard alkylating agent to treat human colon tumor xenografts in a two-step targeting strategy, antibody-directed enzyme produrug therapy (ADEPT). The prodrug, 4-[(2-chloroethyl) (2-mesyloxyethyl) amino]-benzoyl-l-glutamic acid is rapidly converted by CPG2 to a drug that is at least 15x more toxic in vitro against LS174T colorectal tumor cells than the prodrug. Optimal tumor/ blood ratios of the A5B7-CPG2 were achieved 72 h after administration of the conjugate to athymic mice bearing established LS174T tumor xenografts. Significant antitumor activity was seen in LS174T tumor-bearing mice treated with the conjugate followed 3 d later by the prodrug. In contrast, prodrug, conjugate, or active drug alone did not result in any antitumor activity in this tumor model. These studies demonstrate the advantage of a two-step ADEPT system for the treatment of colorectal cancer.     

Design and synthesis of chromone-nitrogen mustard derivatives and evaluation of anti-breast cancer activity

Chromone has emerged as one of the most important synthetic scaffolds for antitumor activity, which promotes the development of candidate drugs with better activity. In this study, a series of nitrogen mustard derivatives of chromone were designed and synthesised, in order to discover promising anti-breast tumour candidates. Almost all target derivatives showed antiproliferative activity against MCF-7 and MDA-MB-231 cell lines. In particular, methyl (S)-3-(4-(bis(2-chloroethyl)amino)phenyl)-2-(5-(((6-methoxy-4-oxo-4H-chromen-3-yl)methyl)amino)-5-oxopentanamido)propanoate showed the most potent antiproliferative activity with IC₅₀ values of 1.83 and 1.90 μM, respectively, and it also exhibited certain selectivity between tumour cells and normal cells. Further mechanism exploration against MDA-MB-231 cells showed that it possibly induced G2/M phase arrest and apoptosis by generating intracellular ROS and activating DNA damage. In addition, it also inhibited MDA-MB-231 cells metastasis, invasion and adhesion. Overall, methyl (S)-3-(4-(bis(2-chloroethyl)amino)phenyl)-2-(5-(((6-methoxy-4-oxo-4H-chromen-3-yl)methyl)amino)-5-oxopentanamido)propanoate showed potent antitumor activities and relatively low side effects, and deserved further investigation.     

Differences in sequence selectivity of DNA alkylation by isomeric intercalating aniline mustards

Two DNA-targeted mustard derivatives, N,N-bis(2-chloroethyl)-4-(5-[9-acridinylamino]-pentamido)aniline and 4-(9-[acridinylamino]butyl 4-(N,N-bis[2-chloroethyl]-aminobenzamide, which are isomeric compounds where the mustard is linked to the DNA-binding 9-aminoacridine moiety by either a -CONH- or a -NHCO- group, show significant differences in the sequence selectivity of their alkylation of DNA. The CONH isomer is a more efficient alxylating agent than the NHCO compound by an order of magnitude, consistent with the larger electron release of the CONH group to the aniline ring. However, the pattern of alkylation by the two compounds is also very different, with the CONH isomer preferring alkylation of guanines adjacent to 3'- or 5'-adenines and cytosines (for example those in sequences 5'-CGC, 5'-AGC, 5'-CGG and 5'-AGA) while the isomeric NHCO compound shows preference for guanines in runs of Gs. In addition, both isomers alkylate 3'-adenines in runs of adenines. Both compounds also show completely different patterns of alkylation to their untargeted mustard counterparts, since 4-MeCONH-aniline mustard alkylates all guanines and adenines in runs of adenines, while 4-Me2NCO-aniline mustard fails to alkylate DNA at all. These differences in alkylation patterns between the CONH- and its isomeric NHCO- compounds and their relationships between the alkylation patterns of the isomers and their biological activities are discussed.     

Antibody-penicillin-V-amidase conjugates kill antigen-positive tumor cells when combined with doxorubicin phenoxyacetamide

Summary The two monoclonal antibodies (mAb), L6 (anti-carcinoma), and 1F5 [anti-(B-cell-lymphoma)], were chemically linked to the enzyme penicillin-V amidase (PVA), which hydrolyzes phenoxyacetamides, to explore the potential of using mAb-enzyme conjugates for the localizaton of chemotherapeutic drugs at tumor cells. The phenoxyacetamide derivatives of doxorubicin and melphalan were prepared, yielding the less toxic amides, doxorubicin-N-p-hydroxyphenoxyacetamide (DPO) and melphalan-N-p-hydroxyphenoxyacetamide (MelPO). These were hydrolyzed by PVA to doxorubicin and melphalan respectively.In vitro studies with the L6-positive lung carcinoma cell line, H2981, and the 1F5-positive B-cell lymphoma line, Daudi, showed that DPO was 80-fold less toxic to H2981 cells and 20-fold less toxic to Daudi cells than doxorubicin, and its toxicity was substantially increased when the H2981 cells were pretreated with L6-PVA or the Daudi cells were pretreated with 1F5-PVA. The cytotoxic effect was antigen-specific, since only the binding mAb-enzyme conjugate increased the cytotoxicity of the prodrug. MelPO was more than 1000-fold less toxic than melphalan to H2981 cells and more than 100-fold less toxic than melphalan to Daudi cells. Pretreatment with the mAb-PVA conjugates did not enhance the toxicity of MelPO in either cell line, because PVA hydrolyzes the phenoxyacetamide bond of MelPO too slowly to generate a toxic level of melphalan.     

A new approach for evaluating in vivo anti-leukemic activity using the SCE assay. An application on three newly synthesised anti-tumour steroidal esters

Three newly synthesised steroidal esteric derivatives of nitrogen mustard (compounds 1-3) were comparatively studied on a molar basis regarding their ability to induce sister chromatid exchanges (SCEs) in normal human lymphocytes in vitro and therapeutic effects on leukemia P388 bearing mice. Compounds 1 and 3 are modified steroidal esters of p-methyl-m-N,N-bis(2-chloroethyl)amino benzoic acid, and compound 2 is a modified steroidal ester of chlorambucil. All compounds induced statistically significant increases in SCEs and decreases in proliferation rate indices (PRIs) of cultured human lymphocytes and significantly increased the life span of P388 bearing mice. In this study, the doses applied for therapeutic purposes upon leukemia P388 bearing mice in vivo were derived from cytogenetic observations in normal human lymphocytes in vitro. A substantially better therapeutic effect was obtained compared to the effect achieved after the use of quite higher doses related with LD(10) values. We have demonstrated that the order of anti-tumour effectiveness of the treatment schedules of the three newly synthesised compounds tested (at doses derived from cytogenetic observations) coincides with the order of the cytogenetic effects they induce. The SCE assay appears to have an application in the clinical prediction of tumour sensitivity to potential chemotherapeutics.     

Polymyxin permeabilization as a tool to investigate cytotoxicity of therapeutic aromatic alkylators in DNA repair-deficient Escherichia coli strains

Chlorambucil (CLB; N,N-bis(2-chloroethyl)-p-aminophenylbutyric acid) and its biologically active beta-oxidation product phenylacetic acid mustard (PAM; N,N-bis(2-chloroethyl)-p-aminophenylacetic acid) are bifunctional aromatic alkylators. CLB is in wide clinical use as an anticancer drug and also as an immunosuppressant. The chemical structures indicate that CLB and PAM are mutagenic, teratogenic and carcinogenic, but the mode of action has remained obscure. We have investigated the biological effects of CLB and PAM with DNA repair-deficient Escherichia coli strains. In contrast to MNNG (N-methyl-N'-nitro-N-nitrosoguanine), CLB and PAM were not toxic to E. coli, but permeabilization of the outer membrane of the cells through use of polymyxin B nonapeptide (PMBN) rendered them susceptible to these compounds. The importance of DNA repair, shown by reversal of damage and attenuation of the toxicity of CLB and PAM, was indicated by the susceptibility of cells lacking O(6)-methylguanine-DNA methyltransferase I and II (ada ogt). Similarly, the protective role of base excision repair (BER) was substantiated by demonstration of an even more increased susceptibility to CLB and PAM of cells lacking 3-methyladenine-DNA glycosylase I and II (alkA1 tag-1). Cells deficient in mismatch repair (mutS) appeared to be slightly more sensitive than normal cells to CLB and PAM, although no such sensitivity to MNNG was observed. This implicates the role of mismatches in CLB- and PAM-related cytotoxicity. It is generally believed that bifunctional alkylating agents, like CLB and PAM, exert their cytotoxic action via DNA cross-linking. Our results with O(6)-methyltransferase- and 3-methyladenine-DNA glycosylase-deficient cells indicate that removal of the adducts prior to the formation of cross-links is an important mechanism maintaining cell viability. We conclude that PMBN permeabilization provides a valuable tool to investigate genetically engineered E. coli cells, whose outer membrane is not naturally permeable to mutagens or other interesting compounds.     

Generation of 5-fluorouracil from 5-fluorocytosine by monoclonal antibody-cytosine deaminase conjugates.

Cytosine deaminase (CDase) catalyzes the conversion of cytosine to uracil and is also able to convert the clinically used antifungal agent 5-fluorocytosine (5FC) into the anticancer drug 5-fluorouracil (5FU). The enzyme was purified from bakers' yeast in a six-step procedure. Studies indicated that bakers' yeast CDase had a molecular weight of approximately 32 kDa and was composed of two subunits of equal molecular weights. Monoclonal antibodies were covalently attached to CDase, forming conjugates that could bind to antigens on tumor cell surfaces. The combination of L6-CDase and 5FC was equivalent in cytotoxic activity to 5FU when tested against the H2981 human lung adenocarcinoma cell line (L6 positive, 1F5 negative). 5FC alone was noncytotoxic. The activation of 5FC was immunologically specific since 1F5-CDase did not enhance 5FC activity.     

The contribution of alkylation to the activity of quinone antitumor agents

Studies have shown that the quinone group can produce tumor cell kill by a mechanism involving active oxygen species. This cytotoxic activity can be correlated with the induction of DNA double strand breaks and is enhanced by the ability of the quinone compound to bind to DNA by alkylation. The cytotoxic activity and the production of DNA damage by model quinone antitumor agents were compared in L5178Y cells, sensitive and resistant to alkylating agents, to assess the contribution of alkylation to the activity of these agents. The resistant L5178Y/HN2 cells were found to be two fold and six fold more resistant to the alkylating quinones, benzoquinone mustard and benzoquinone dimustard, respectively, than parent L5178Y cells. In contrast, the L5178Y/HN2 cells showed no resistance to the nonalkylating quinones, hydrolyzed benzoquinone mustard and bis(dimethylamino)benzoquinone. The alkylating quinones produced approximately two fold less cross-linking in L5178Y/HN2 cells compared with L5178Y sensitive cells. DNA double strand break formation by hydrolyzed benzoquinone mustard and bis(dimethylamino)benzoquinone was not significantly different in sensitive and resistant cells. However, the induction of double strand breaks by the alkylating quinones benzoquinone mustard and benzoquinone dimustard was reduced by 5-fold and 15-fold, respectively, in L5178Y/HN2 cells. These results show that the alkylating activity of the alkylating quinones cannot directly explain all of the enhanced cytotoxic activity of these agents. Furthermore, they provide strong evidence that the enhanced formation of DNA double strand breaks by alkylating quinone agents is directly related to the ability of these agents to bind to DNA. This increased formation of strand breaks may account for the enhanced cytotoxic activity of the alkylating quinones.     

Induction of LAK-like cells in the peritoneal cavity of mice by inactivated Candida albicans

We have investigated the effect of multiple administrations of inactivated Candida albicans (CA) cells on induction of non-MHC-restricted antitumor cytotoxic responses both in normal and congenitally athymic (nude) mice. Intraperitoneal inoculation of CD2F1 mice with five doses of 2 x 10(7) CA cells over a 2-week interval was associated with the induction of peritoneal exudate cells (PEC) that mediated natural killer cell activity. These cells, in contrast to those elicited by a single dose of CA, killed both NK-sensitive and NK-resistant tumor target cells in vitro. This broad-spectrum, antitumor cytotoxicity peaked 1 day after the last injection of CA, and decreased to control values within 6 (NK-resistant) or 14 (NK-sensitive target cells) days. Cytotoxicity could be recalled to a high level by a boosting injection of CA or a major mannoprotein-soluble antigen (MP) from the Candida cell wall, given 30 days after multiple CA treatment. Upon a 24-hr in vitro incubation, CA-induced peritoneal immunoeffectors lost their killing activity unless human recombinant interleukin-2 (rIL-2) was added to cultures. The non-MHC-restricted cytotoxic PEC activity induced by CA was mainly associated with nonadherent, nonphagocytic large granular lymphocytes (LGL) which exhibited the following phenotypes: (i) asialo GM1+, Lyt 2.2-, and partially Thy 1.2+ (effectors active against NK-sensitive targets) and (ii) asialo GM1+, Lyt 2.2-, and Thy 1.2+ (effectors active against NK-resistant targets). Nude mice also responded to multiple CA inoculations by displaying high cytotoxic activity against NK-sensitive targets and significant cytotoxicity against NK-resistant targets. This cytotoxicity could be recalled on Day +30, and the cytotoxic effectors involved were highly sensitive to anti-asialo GM1 plus complement treatment. Overall, the results add further experimental evidence to the wide range of immunomodulatory properties possessed by C. albicans, and demonstrate that the majority of antitumor cytotoxic activity induced by fungal cells was due to lymphokine-activated killer (LAK)-like effectors.     

Antitumor activity of a thioether-linked immunotoxin: OVB3-PE

A thioether-linked immunotoxin was made between Pseudomonas exotoxin and the monoclonal antibody OVB3. This conjugate, OVB3-PE, was cytotoxic for the human ovarium cancer cell line OVCAR-3 (ID of 2.5 x 10(-12) M) and it was therefore tested for antitumor activity in a nude mouse model of ovarian cancer. This model employs the injection of a lethal number of OVCAR-3 cells into the peritoneal cavity of nude mice. When 0.2-1 micrograms of OVB3-PE was injected intraperitoneally on three successive days beginning 3-5 days after OVCAR-3 cell implantation, the survival of the tumor-bearing mice was increased 2-4-fold compared to that of untreated control mice. Median survival times for control mice ranged from 44 to 50 days while survival times of 150 days or greater were seen in mice treated with OVB3-PE. When OVB3-PE administration was delayed until 2-4 weeks after tumor cell implantation, OVB3-PE treatment also showed antitumor activity, but the duration of survival was less than with the early treatments. OVB3-PE was also cytotoxic for MCF-7 breast carcinoma cells, HT-29 colon carcinoma cells, and A431 epidermoid carcinoma cells.     

Eradication of a large MOPC-315 tumor in athymic nude mice by chemoimmunotherapy with Lyt2+ splenic T cells from melphalan-treated BALB/c mice bearing a large MOPC-315 tumor

Summary We have previously shown that spleen cells from BALB/c mice that are in the process of eradicating a large MOPC-315 tumor following low-dose (2.5 mg/kg) melphalan (l-phenylalanine mustard) therapy are effective in preventing tumor progression upon adoptive transfer into BALB/c mice bearing a barely palpable tumor that had been treated with a subcurative dose of melphalan [Mokyr et al. (1989) Cancer Res 49: 4597]. Here we show that such spleen cells in conjunction with a subcurative dose of drug (adoptive chemoimmunotherapy, ACIT) can cause the complete regression of a large (15–20 mm) s.c. MOPC-315 tumor in a large percentage of T-cell-deficient (athymic nude) tumor-bearing mice. Spleen cells that were effective in ACIT of athymic nude mice displayed in vitro a substantial direct lytic activity against MOPC-315 tumor cells, and the lytic activity was greatly enhanced when the spleen cells were cultured for 5 days with or without mitomycin-C-treated MOPC-315 stimulator tumor cells. The cells responsible for the therapeutic effectiveness of the spleen cells in ACIT of athymic nude mice, as well as the cells responsible for the direct in vitro anti-MOPC-315 lytic activity of the spleen cells, were of the Lyt 2 and not the L3T4 phenotype. Most of the athymic nude mice that completely eradicated a large MOPC-315 tumor as a consequence of ACIT were capable of rejecting a challenge with 30–100 times the minimal lethal tumor dose for 100% of normal BALB/c mice administered more than 1 month after the ACIT. The ability of these athymic nude mice to resist the tumor challenge was associated with the presence of a greatly elevated percentage of cells expressing T cell surface markers in their spleens. Thus, it is conceivable that splenic Lyt 2⁺ T cells from melphalan-treated BALB/c mice bearing a large MOPC-315 tumor mediate their therapeutic effectiveness in ACIT of athymic nude mice bearing a large MOPC-315 tumor, at least in part, through direct cytotoxicity for MOPC-315 tumor cells. In addition, eradication of a large MOPC-315 tumor through cooperation between antitumor immunity and melphalan toxicity endues the athymic nude mice with an elevated percentage of T cells in their secondary lymphoid organs, and these T cells are probably responsible for the long-lasting protective antitumor immunity exhibited by these mice.Supported by research grant IM-435A from the American Cancer Society and research grant B-8806 from the Bane EstateIn partial fulfillment of the requirements for the Doctor of Philosophy DegreeRecipient of Career Development Award CA-01350 from the National Cancer Institute     

Design, synthesis, and biological evaluation of new mitonafide derivatives as potential antitumor drugs

A series of potential DNA-binding antitumor agents, 2-[omega-(alkylamino)alkyl]-6-{[omega-(alkylamino)alkyl]amino}-1H-benzo[de]isoquinolin-1,3(2H)-diones and 1,7-bis{6-[(omega-(dimethylamino)alkyl)amino]-1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl}-4-methyl-4-azaheptanes, have been prepared as mitonafide derivatives. Their DNA-binding ability and cytotoxic activity have been evaluated. Some of the target compounds have shown high DNA affinity as well as relevant cytotoxic properties.     

Elevated natural killer cell responses in mice infected with recombinant vaccinia virus encoding murine IL-2

The role of cytotoxic T cells and NK cells in the recovery of immunodeficient, athymic, nude mice infected with a recombinant vaccinia virus (VV) encoding murine IL-2 was investigated. Kinetic studies with the IL-2-encoding recombinant (VV-HA-IL2) and control (VV-HA-TK) viruses excluded a role for cytotoxic T cells but suggested the possible involvement of NK cells. In athymic nude mice given VV-HA-IL2, NK activity was at least threefold higher than mice infected with VV-HA-TK and this activity persisted for at least 6 days after infection. The effectors mediating the NK-like activity were asialo-GM1+ (as-GM1+), Thy1.2+/-, CD4- and CD8-, the phenotype of conventional NK cells. Elevated NK activity coincided with the rapid clearance of VV-HA-IL2 from ovaries of infected normal CBA/H mice but not from ovaries of CBA beige mice which had no detectable NK activity in spleens or ovaries. The expression of IL-2 in recombinant VV infection probably induces a cascade of immunologic effects of which elevated NK activity is one. We speculate that the chemoattractant and NK activity augmenting effects of IL-2 may contribute to recovery from VV-infection.     

Antitumor activity of diethynylfluorene derivatives of gold(I)

A list of diethynylfluorenes and their gold(I) derivatives have been studied for their antitumor activity as a function of their structure–activity relationships. End-capping the fluoren-9-one unit with gold(I) moieties could significantly strengthen the cytotoxic activity in vitro on three human cancer cell lines with induction of reactive oxygen species generation on Hep3B hepatocellular carcinoma cells and exhibit attractive antitumor activity from in vivo nude mice Hep3B xenograft model with limited adverse effects on vital organs including liver and kidney.