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In the United States, approximately 1.1 million adults and adolescents are living with human immunodeficiency virus (HIV) infection and, each year, another 50,000 become infected. At the end of 2008, approximately 20% of the persons living with HIV had an undiagnosed infection. Of those living with HIV at the end of 2008, nearly two thirds were racial/ethnic minorities and half were men who have sex with men (MSM). In 2007, HIV ranked fifth as a leading cause of death among persons aged 35-44 years in the United States but third among blacks or African Americans in this age group. In 40 states with longstanding confidential name-based HIV surveillance systems, 33% of the estimated 41,768 adults and adolescents diagnosed with HIV infection in 2008 developed acquired immunodeficiency syndrome (AIDS) within 1 year and, of these, 44% received their initial diagnosis in an acute care setting, suggesting that they received HIV testing late in the course of the infection. HIV-infected persons who are unaware of their infection or who receive a late diagnosis cannot benefit fully from timely initiation of therapy and are more likely to experience HIV-related morbidity and premature mortality. In addition, persons unaware of their infection are more likely to transmit HIV to others because of a higher prevalence of high-risk sexual behaviors and higher levels of viral RNA that continue to replicate without appropriate antiretroviral treatment.

Cultured human THP-1 monocytes were exposed to serial concentrations of gemifloxacin over 4 h after pre-stimulation with zymogen A for 1 h or Staphylococcus aureus for 2 h. The following parameters were assessed: pH, phagocytosis, c-AMP, NO, TNFalpha, IL-1, IL-6, IL-8 and H2O2 levels, enzyme activities of protein kinase C, NADPH oxidase, SOD, gluthathion reductase, NAG and cathepsin D as well as lipid peroxidation. The reversiblity of these changes was determined in the presence of known blockers of the phagocytic process. The effects of gemifloxacin on DNA synthesis and killing of S. aureus was assessed in bacteria alone and in those bacteria phagocytosed by THP-1 monocytes over 24 h. Gemifloxacin in stimulated THP-1 monocytes over the first 30 min caused an increase in c-AMP, NO, H2O2 and TNFalpha levels and protein kinase C, NADPH oxidase, glutathione reductase, NAG and cathepsin D activities. The pH became more acidic and phagocytosis was stimulated. These parameters were reversed at 1 h and continued to decline until 4 h. Lipid peroxidation was at the highest levels at 1 h and IL-8 levels at 2 h. DNA synthesis and bacterial growth were suppressed at 2 h in both S. aureus alone and bacteria phagocytosed by THP-1 monocytes. These effects were at a higher magnitude at 24 h. Gemifloxacin initiates a phagocyticidal effect of THP-1 monocytes at an early time of 30 min which plays a role in killing bacteria but a higher magnitude of killing of bacteria occurs later by a standard static mechanism. This early action of gemifloxacin should decrease the spread of infection and the inflammatory response since the tissue destruction process was attenuated at 4 h.

Uptake of (14)C-grepafloxacin into human mononuclear (THP-1) cells was determined at pH 7.4, 6.8, or 5.0 over a 4-log antibiotic concentration. Grepafloxacin was taken up by THP-1 monocytes rapidly by both a passive and an active transport mechanism at pH 7.4. Its uptake was initially linear, with equilibrium being reached after approximately 1 h. Efflux followed first-order clearance and was complete within 1 h, suggesting no longterm sequestering of the antibiotic occurred. Neither cell number nor serum protein binding appeared to have any effect on antibiotic uptake. High intracellular concentrations were achieved and the ratios of cellular to extracellular antibiotic concentration (IC/EC) were between 529 and 644 at 0.04 micro g/ml at pH 7.4 and 6.8, suggesting that monocytes may contain sufficient levels of grepafloxacin for affecting bacteriostatic killing. Grepafloxacin disposition within the THP-1 monocytes showed large amounts present in the nucleus and cell sap in stimulated and unstimulated cells, and its presence was evenly distributed throughout the cytosol, nuclei, lysosomes, mitochondria, and ribosomes. After stimulation by zymogen A, Staphylococcus aureus, or Streptococcus pneumoniae, increased amounts of grepafloxacin were found within THP-1 monocytes and isolated phagosome vacuoles. No antibiotic sequestration occurred inside stimulated monocytes, although a sufficient intracellular grepafloxacin concentration was available to kill phagocytized bacteria. Metabolic inhibitors, suppressors of K(+)/Cl(-) and Cl(-) transporters, inhibitors of the phagocytic process, low temperature, and low pH inhibited grepafloxacin uptake by THP-1 monocytes.

Moxifloxacin uptake by human THP-1 monocytes was passive and initially linear and reached equilibrium after approximately 4 h. High intracellular concentrations were achieved and intracellular/extracellular [I/E] ratios were between 1925 and 4575 for the lowest concentration of 0.004 microg/ml at pH 7.4 and 6.9. The uptake of moxifloxacin was reduced by sodium fluoride, -azide, -cyanide, low temperature and low pH. However, the uptake was not affected by any of the ion channel blockers. Adenosine demonstrated marginal competition with moxifloxacin for uptake suggesting a nucleoside transporter may be involved. The sodium-ATPase pump when blocked, also retarded moxifloxacin uptake at 2 and 4 h. This I/E ratio was high compared with other macrolides and indicateed that the monocyte may contain sufficient moxifloxacin levels to conduct the antibiotic throughout systemic circulation to infection sites. Efflux from THP-monocytes was essentially complete after 2 h indicating no long term sequestering of the antibiotic occurred. Disposition of the antibiotic within the THP-1 monocytes showed large amounts present in the nucleus and cytoplasm in stimulated and unstimulated cells. Increased amounts of the drug were found in the THP-1 monocytes as well as the endoplasmic reticulum and the isolated phagosomes after stimulation by zymogen A, Staphylococcus aureus or Streptococcus pneumoniae.

Antimicrobial agents have been reported to exhibit immunomodulatory and anti-inflammatory activities, both in vivo and in vitro (e.g., in human lymphocytes, macrophages and monocytes). The effects of moxifloxacin on cytokine immunomodulatory mediators, free radical generation and hydrolytic enzyme activities in zymogen A-stimulated human THP-1 monocytes were evaluated. An increase in c-AMP levels, protein kinase C activity, and the release of nitric oxide and hydrogen peroxide with a decrease in pH occurred within the first hour. Further, the effects of moxifloxacin were reduced by agents which blocked the oxygen burst, lysosome-phagosome fusion, and the energy generation within the cell. After 4 h, there was a decrease in NAG and cathepsin D activities, lipid peroxidation and the release of pro-inflammatory cytokines. These data indicate that moxifloxacin may modify the acute-phase inflammatory responses through inhibition of cytokine release in monocytes. Moxifloxacin inhibited the release of TNFalpha, IL-1, IL-6, and IL-8 in a concentration-dependent manner across a range of 0.004 to 4 microg/mL. After 4 h, there was a decrease in the release of these cytokines, thus interfering with the inflammation process to reduce infection and its spread. The effects of moxifloxacin appear initially to activate monocytes to kill bacteria through the innate immune process by releasing ROS and lysosomal hydrolytic enzymes as well as phagocytosis of the organism. At a later time the bacteria are killed through a Bacterialstatic mechanism of protein synthesis inhibition and there is a reversal of the effects of moxifloxacin on cytokine release, free radical generation and hydrolytic enzymes so that lipid peroxidation and tissue destruction by the infection process is suppressed.

Alatrofloxacin functions similar to other fluoroquinolone antibiotics in that it not only has antibiotic activity to kill invading organisms by interfering with DNA synthesis, it possesses immunosuppressive activity. In the first hour after bacteria have been phagocytosed by THP-1 monocytes, the drug activates a lytic mechanism involving the release of c-AMP, tumor necrosis factor (TNFalpha), interleukin-1 (IL-1), IL-6 and nitric oxide, with elevations in lysosomal hydrolytic enzyme activities. This effect reverses between 2 and 4 h. At this time, all of these inflammatory processes are returned to normal values or below suggesting that alatrofloxacin reduces the spread of infection and destruction of tissue related to inflammation.

The substituted ethyl-2-phenacyl-3-phenylpyrrole-4-carboxylates were synthesized by a condensation of a beta-chloroenal and an alpha-aminoketone under neutral conditions. They proved to be potent cytotoxic agents against the growth of murine L1210 and P388 leukemias and human HL-60 promyelocytic leukemia, HuT-78 lymphoma, and HeLa-S(3) uterine carcinoma. Selective compounds were active against the growth of Tmolt(3) and Tmolt(4) leukemias and THP-1 acute monocytic leukemia, liver Hepe-2, ovary 1-A9, ileum HCT-8 adenocarcinoma, and osteosarcoma HSO. A mode of action study in HL-60 cells demonstrated that DNA and protein syntheses were inhibited after 60 min at 100 microM. DNA and RNA polymerases, PRPP-amido transferase, dihydrofolate reductase, thymidylate synthase, and TMP kinase activities were interfered with by the agent with reduction of d[NTP] pools. Nonspecific interaction with the bases of DNA and cross-linking of the DNA may play a role in the mode of action of these carboxylates.

The effects of grepafloxacin on the release of cytokines, chemical mediators, hydrolytic enzyme activities, and lipoxygenation in zymogen A- or Staphylococcus aureus-stimulated human THP-1 monocytes were evaluated. Initially, consistent with stimulation of phagocytic mechanisms of the monocytes, increases in cyclic adenosine monophosphate (cAMP) release, nitric oxide [NO] release, and hydrogen peroxide [H(2)O(2)] release, with a small decrease in cellular pH, occurred within 2 h. Enzymatic activities associated with oxygen burst of phagocytic cells (e.g., protein kinase C and nicotinamide adenine dinucleotide phosphate, reduced (NADPH) oxidase) were elevated, suggesting that monocytes attempted to destroy the invading organism through an innate phagocytic cidal immunologic mechanism. After 1-2 h of exposure to grepafloxacin, the oxygen burst and the release of proinflammatory cytokines and chemical mediators were suppressed. After 4 h, suppression of n-acetyl glucosaminidase (NAG) and cathepsin D activities and lipid peroxidation occurred, suppressing the pathogen-induced spread of infection and inflammation. Release of tumor necrosis factor (TNFalpha), interleukin (IL)-1, IL-6, and IL-8 was inhibited by grepafloxacin in a concentration-dependent manner, suggesting a reduction in the acute-phase inflammatory responses initiated by cytokine release from monocytes. Later, S. aureus were killed through inhibition of DNA synthesis, consistent with a bacteriostatic effect. Drug action against invading organisms appears to occur through multiple processes. Modulation of the innate immune system occurs within the first hour, causing the activation of cytokines, chemical mediators, and hydrolytic enzymes. A second phase between 2-4 h appears to involve the suppression of cellular components involved in inflammation and the spread of the infection. The third response, an apparent bacteriostatic inhibition of DNA synthesis, causes bacterial death.

Vanada- and niobatricarbadecaboranyl monohalide complexes proved to be potent cytotoxic agents against murine and human leukemia and lymphoma growth as well as HeLa suspended uterine carcinoma. The vanada complex reduced the growth of KB nasopharynx, Hepe liver, HCT-8 ileum and 1-A9 ovary solid carcinomas. A mode of action study in human HL-60 promyelocytic leukemia cells showed that DNA and purine de novo syntheses were significantly inhibited with suppression of the regulatory enzymes activities of DNA polymerase alpha and PRPP-amido transferase. There was moderate inhibition of RNA synthesis and m-RNA polymerase activity. These complexes did not inhibit human topoisomerase I or II activity, although the niobium complex nicked the DNA. The complexes did activate caspases 3, 6 and 9 which are linked to apoptosis programmed cell death. These vanada- and niobatricarbadecaboranyl monohalide complexes appear to be more specific in their effects on leukemia cell metabolism than other sandwich complexes which have broad effects on multiple enzymes.

Uptake of [14C]-azithromycin into THP-1 human monocytes was determined at pH 7.4, 6.8 or 5.5 over 4-log antibiotic concentrations for 24 h under a number of conditions. Stimulation of cells was with bacteria, latex beads, lipopolysaccharide (LPS), or zymogen A. Subcellular organelle disposition was determined after isolation by ultracentrifugation or sucrose gradients. Hydrolytic enzyme activities and mediators of intracellular inflammation (IL-1, IL-6, IL-8, and TNFalpha) were assessed. Azithromycin uptake into human THP-1 monocytes was initially linear achieving approximately 2% of the extracellular concentration. At pH 7.4, uptake was both passive- and carrier-mediated, but as the pH became more acidic, the uptake was exclusively passive. The intracellular concentration was not pH-dependent over 24 h. Uptake was dependent upon temperature but not the presence of foetal calf serum. Intracellular disposition in zymogen A-stimulated and unstimulated cells was throughout all compartments of the cell, but was higher in the nucleus and cell sap. Phagosomes of stimulated cells contained higher level of the antibiotic. Efflux from THP-1 monocytes was complete between 3 and 4 h. After 1 h treatment with zymogen A, THP-1 monocytes demonstrated an increase in intracellular acidity, protein kinase C, SOD and NAG activities, and NO, H(2)O(2), TNFalpha and IL-1 release over the 1st h. After 2-4 h the pH became alkaline, activities of NADPH reductase, NAG and cathepsin were reduced, and the release of NO, H(2)O(2), TNFalpha and IL-6 were suppressed. Protein synthesis and killing of the bacteria was evident in bacteria kept in monocyte-free medium and those phagocytized by the THP-1 monocytes moderately at 2 h, but more significantly at 24 h. The early killing of the bacteria appears to be a cidal mechanism whereas later, a standard bacteriostatic mechanism was evident. Nevertheless, suppression of these chemical mediators and hydrolytic enzyme activities would reduce the infection and the spread to adjacent areas.

N6-Benzoyladenine-cyanoborane (2), and 6-triphenylphosphonylpurine-cyanoborane (3) were selected for investigation of cytotoxicity in murine and human tumor cell lines, effects on human HL-60 leukemic metabolism and DNA strand scission to determine the feasibility of these compounds as clinical antineoplastic agents. Compounds 2 and 3 both showed effective cytotoxicity based on ED(50) values less than 4 mug/ml for L1210, P388, HL-60, Tmolt(3), HUT-78, HeLa-S(3) uterine, ileum HCT-8, and liver Hepe-2. Compound 2 had activity against ovary 1-A9, while compound 3 was only active against prostate PL and glioma UM. Neither compound was active against the growth of lung 549, breast MCF-7, osteosarcoma HSO, melanoma SK2, KB nasopharynx, and THP-1 acute monocytic leukemia. In mode of action studies in human leukemia HL-60 cells, both compounds demonstrated inhibition of DNA and protein syntheses after 60 min at 100 muM. These compounds inhibited RNA synthesis to a lesser extent. The utilization of the DNA template was suppressed by the compounds as determined by inhibition of the activities of DNA polymerase alpha, m-RNA polymerase, r-RNA polymerase and t-RNA polymerase, which would cause adequate inhibition of the synthesis of both DNA and RNA. Both compounds markedly inhibited dihydrofolate reductase activity, especially in compound 2. The compounds appeared to have caused cross-linking of the DNA strands after 24 hr at 100 muM in HL-60 cells, which was consistent with the observed increased in ct-DNA viscosity after 24 hr at 100 muM. The compounds had no inhibitory effects on DNA topoisomerase I and II activities or DNA-protein linked breaks. Neither compound interacted with the DNA molecule itself through alkylation of the nucleotide bases nor caused DNA interculation between base pairs. Overall, these antineoplastic agents caused reduction of DNA and protein replication, which would lead to killing of cancer cells.

The observation that expression of the IMPDH gene is tightly linked with cellular proliferation and transformation has led to an interest in developing inhibitors that deplete intracellular guanine nucleotide pools. IMPDH exists as 2 isoforms, one of which is induced in tumor cells, type II and thus has led to new interest in this target for the design of isoform-selective anticancer chemotherapeutic agents. Several classes of IMPDH inhibitor are now in use or under development; however, only the 1,5-diazabicyclo[3.1.0]hexane-2,4-diones show selectivity for the type II isoform. In the current study, we further evaluated chemical modification of this class to determine the necessary components for selective type II IMPDH inhibition. The 6-benzoyl-3,3-disubstituted-1,5-diazabicyclo[3.1.0]hexane-2,4-diones were effective cytotoxic agents in human leukemias, lymphomas, breast, glioma and HeLa-S3 suspended uterine carcinoma screens with ED(50) values 0.3 to 12 microM. The agents acted as antimetabolites by inhibiting de novo purine biosynthesis at the key regulatory enzyme IMPDH, resulting in suppression of DNA synthesis and dGTP pool levels within 60 min. Furthermore, the derivatives were specific for the type II isoform as opposed to type I, acting in a competitive manner with K(i) values of 5.1 to 63 microM. Addition of the 6-benzoyl moiety to the bicyclic parent ring structure afforded the most potent agent in the novel class of 1,5-diazabicyclo[3.1.0]hexane-2,4-diones that selectively inhibits type II IMPDH activity., (Copyright 2001 Wiley-Liss, Inc.)

The 2-aldo- and 2-ketopyridine-N(4)-substituted thiosemicarbazones and their copper complexes demonstrated potent cytotoxic activity against a series of murine and human suspended cultured tumor cells. Selected compounds were active against the growth of cultured cells from solid human tumors, i.e. Mck-7 breast effusion, lung A549 and lung MB-9812, bone SOS-2 and clear cell Caki renal tumor. In Tmolt4 T cell leukemia cells the compounds inhibited the syntheses of DNA, RNA and protein over 60 min at 25 to 100 microM. Multiple target sites in nucleic acid metabolism were suppressed by the agents, i.e. DNA polymerase alpha, ribonucleoside reductase, dihydrofolate reductase, de novo purine synthesis, thymidylate synthetase and nucleoside kinases. The total effects of the agents on DNA metabolism led to the reduction of deoxyribonucleotide pools as well as DNA fragmentation.

Inosine 5'-monophosphate dehydrogenase (IMPDH), the rate-limiting enzyme in the de novo pathway for synthesis of guanine nucleotides, is essential for normal cell proliferation and function. New derivatives of the 1,5-diazabicyclo[3.1.0]hexane-2,4-diones were synthesized and examined for antiproliferative effects and selective inhibition of human IMPDH type II activity. The 3,3-disubstituted-6,6-pentamethylene-1,5-diazabicyclo[3.1.0]hexane-2,4-diones proved to be effective antiproliferative agents in tumor cell lines derived from murine and human leukemias, lymphomas, uterine carcinoma, glioma, and breast effusion with ED50 values (concentration of compound that inhibits 50% of cell growth) ranging from 3.3 to 16 microM. The agents acted as antimetabolites suppressing de novo purine biosynthesis at the key regulatory enzyme IMPDH, resulting in the specific suppression of dGTP pool levels by 19 to 64% and DNA synthesis by 39 to 68%. The derivatives were specific inhibitors of IMPDH type II activity as opposed to type I, acting in a competitive manner with respect to inosine 5'-monophosphate, K(i) values of 44.2 to 62 microM. In addition, effects of agents on Tmolt4 cell growth and DNA synthesis could be reversed by coincubation with guanosine. Unlike mycophenolic acid and tiazofurin, the 6,6-pentamethylene-1,5-diazabicyclo[3.1.0]hexane-2,4-diones specifically targeted type II IMPDH, where activity is increased in replicating or neoplastic cells, and did not suppress type I activity, where expression is relatively unaffected by cell proliferation or transformation. Agents were not inhibitors of normal human lung fibroblast cell growth, WI-38, most likely due to the observed isoform selectivity.

3-Ethoxycarbonyl-5-phenyl-1, 3a, 4, 5, 6, 6a-hexahydropyrrolo[3,4-c]pyrazole-4, 6-dione, 2, 2, 6, 6-tetraethyl-1H, 5H-pyrazole[1, 2-a]pyrazole-1, 3, 5, 7-[2H, 6H]-tetraone and 6-ethoxycarbonyl-3-phenyl-3-azabicyclo[3.1.0] hexane-2, 4-dione demonstrated potent cytotoxic activity in the human Tmolt3, Tmolt4 and HL-60 leukemia screens, HuT-78 lymphoma and HeLa suspended uterine carcinoma cell lines. Most notable was the finding that these compounds were significantly more active than the standard cytotoxic agents examined in the MCF-7 breast (ED50 0.2-1.0 microg/ml) and U87MG glioma (ED50 1.3-2. 6 microg/ml) tumor screens. The agents inhibited Tmolt4 leukemia DNA and RVA syntheses after 60 min at 100 microM Multiple enzymes involved with nucleic acid metabolism appeared to be targeted including inhibition of RNA polymerases, ribonucleotide reductase and nucleoside kinase activities, however, inhibition of de novo purine synthesis at the key regulatory enzyme IMP dehydrogenase appeared to be the primary target. The predominant IMPDH isoform (Type II) detected in a number of human cancers, such as leukemias, ovarian and breast, was inhibited by the compounds yielding IC50 values in the microM range. Furthermore, inhibition of IMP dehydrogenase activity led to the selective depletion of dGTP pool levels by two of the compounds. The DNA molecule was not a target of the agents since no alkylation of the bases, cross-linking of the DNA strands or intercalation between base pairs occurred. Yet, the compounds did cause DNA fragmentation after incubating at 100 microuM for 24 h which was consistent with the observed decrease in ct-DNA viscosity.

2,3-Dihydrophthalazine-1,4-diones, indazolones, 3-imino-1-oxoisodolines, homophthalimides, napthalidimides, diphenamides, and 6,7-dihydro-5H-dibenz[c,e]azepines proved to be potent inhibitors of the activity of human Tmolt4 T cell leukemia Type II IMP dehydrogenase (IMPDH). This inhibition was competitive, yielding Ki values in the range of 1.96 to 48.9 microM. The inhibition of Type II IMPDH correlated positively with the inhibition of the growth of Tmolt4 cells, the syntheses of DNA and purine, and the activity of crude IMPDH. The Type II IMPDH isoform is found in rapidly proliferating cells. The isoform present in normal resting cells, Type I IMPDH, was elevated by the compounds at 100 microM. In addition, Compound 5 significantly increased the Type I enzyme activity in a concentration and time dependent manner. The selectivity of these derivatives towards Type II IMPDH will allow for the separation of cellular effects, which should reduce clinical toxicity when treating with antimetabolite IMPDH inhibitors.

It was shown previously that three 1,5-diazabicyclo[3.1.0]hexane-2,4-diones selectively inhibited human Type II IMP dehydrogenase (IMPDH) from Tmolt4 cell leukemia [Barnes et al., Biochemistry 2000;39:13641-50]. The agents acted as competitive inhibitors of this isoform, yet when tested against human Type I at concentrations ranging from 0.5 to 500 microM, Type I was not inhibited. This study focuses on the antineoplastic activity and cellular effects of one of these agents and two new derivatives containing ethoxycarbonyl substitution at position C6. Agents were studied for antiproliferative activity in human Tmolt4 leukemia (EC(50) 3.3 to 9.2 microM) and alterations in the levels of enzymes involved with cellular metabolism, including DNA and RNA syntheses due to IMPDH inhibition. Results reported here demonstrate that 6-ethoxycarbonyl-3,3-disubstituted-1,5-diazabicyclo[3.1.0]hexane-2,4-diones are effective inhibitors of DNA synthesis (30-66% inhibition) due to reductions in dGTP pool levels. Collectively, the three agents proved to be selective inhibitors of human IMPDH Type II activity (K(i) 11-33 microM), leading to cytotoxicity in a number of suspended and solid tumor lines, notably MCF-7 (EC(50) 0.7 to 6.0 microM). In addition, negative cytotoxic actions of these agents on WI-38 cell growth, a normal rapidly growing human line, suggest that specific targeting of Type II IMPDH would help to eliminate cell killing in lines where Type I predominates. Furthermore, effects of agents on DNA synthesis and cell death could be reversed by the addition of exogenous guanosine to the medium. Results from in vitro studies suggest that the 6-ethoxycarbonyl-3,3-disubstituted-1,5-diazabicyclo[3.1.0]hexane-2,4-diones may be used as effective isozyme-selective chemotherapeutic agents.

Small-molecular-weight benzohydroxamic and malonic acids and maleic hydrazide proved to be potent inhibitors of the activity of human Tmolt4 leukaemia Type II IMP (inosine monophosphate) dehydrogenase (IMPDH) activity. They were competitive inhibitors with respect to IMPDH demonstrating Ki values in the range 2.57-41.3 microM, less than half the values of the IC50 (microM) for the inhibition of Type II IMPDH. The IC50 microM values positively correlated with the ability of each compound to inhibit crude IMPDH activity, de-novo purine and DNA syntheses and growth of the T leukaemia cell line. Compounds were not inhibitors of Type I IMPDH. Type I IMPDH predominates in normal resting cells compared with Type II which is found in rapidly proliferating cells. Discovery of agents which would selectivity target IMPDH found in proliferating cells should eliminate any antineoplastic therapeutic toxic effects in normal cells of the body.

The 3,5-pyrazolidinediones proved to be potent cytotoxic agents against the growth of a number of murine and human tumor cell lines, e.g. human THP-I monocytic leukemia, Hut-78 lymphoma, MCF-7 breast effusion, A549 lung carcinoma, U87MG glioma, Hela uterine and A431 epidermoid skin cancer. In human Tmolt4 cell leukemia, the agents substantially suppressed DNA and RNA syntheses after 60 min at 100 microM. The de novo purine biosynthetic pathway appeared to be the major target of the agents with the inhibition of both PRPP-amido transferase and IMP dehydrogenase (IMPDH) activities. Suppression of IMPDH activity was due to the inhibition of both the Type I and II isoforms through an uncompetitive mechanism; however, the Type II isoform was preferentially inhibited at lower concentrations of compounds tested (>50-150 microM). Therefore IMPDH Type II activity, which predominates in cancer cells, was selectively inhibited over the Type I isoform (208-312 microM). The activities of other enzymes examined were inhibited which added to the overall suppression of DNA synthesis, i.e., ribonucleotide reductase, dihydrofolate reductase and nucleoside kinases. The agents caused Tmolt4 DNA strand scission but the DNA molecule itself did not appear to be a target of the compounds since there was no induced cross-linking of the DNA, intercalation between base pairs or alkylation of the DNA bases.

The 1,2,4-triazolidine-3,5-diones, 1-(1-(3-methylphenyl)ethylidineamino)-4,4-diethyl-3,5-azetidinediones, and 4,4-disubstituted-3,5-pyrazolidinediones proved to be potent competitive inhibitors of human Tmolt4 leukemia Type II IMP dehydrogenase [IMPDH] activity, an enzyme isoform which is induced in highly proliferating cells. On the other hand, the 3,5-isoxazolidinediones were shown to be uncompetitive inhibitors of Type II IMPDH activity. The correlation between inhibition of Type II IMPDH activity with the agents' ability to suppress DNA and purine syntheses in these Tmolt4 leukemia cell was positive. Type I IMPDH (i.e., the isoform that is present in normal cells) was not inhibited by these compounds suggesting that these agents would be less toxic to normal cells and have selective inhibition towards proliferating cells.

2-Etheny1-2,3-dihydrophthalazine-1,4-diones were successfully synthesized and proved to be effective cytotoxic agents against the growth of suspended murine and human leukemias and lymphomas. Selected compounds were also active in human HeLa uterine carcinoma, suspended effusion breast MCF-7 and glioma HS683 screens. These agents suppressed P388 lymphocytic leukemia DNA synthesis after 60 min at 100 microM. Their target appeared to be the de novo synthesis pathway with significant inhibition of the activities of both regulatory enzymes of the pathway, i.e. PRPP-amide transferase and IMP dehydrogenase resulting in a reduction in the d[NTP] pool levels for DNA incorporation. The compounds did not affect de novo pyrimidine synthesis and its regulatory enzymes. Very minor reduction by the agents was noted for the nucleoside kinases and the DNA and RNA polymerase activities within 60 min. DNA was not a target of the agents in that there was no alkylation of the nucleotide bases, intercalation between base pairs or cross-linking of the DNA strands; however, the agents did cause P388 DNA strand scission after 24 h at 100 microM.

The 1-(1-phenylalkylideneamino)-2,4-azetidinediones are potent cytotoxic agents against the growth of human and murine leukemias, lymphoma, and suspended HeLa uterine carcinoma. In cell lines cultured from solid human tumors, the agents were more selective with only a few agents demonstrating significant activity against the growth of HCT-8 ileum adenocarcinoma, Saos-2 osteosarcoma, KB nasopharynx, MCF-7 breast effusion, and ovary 1-A9 carcinoma A mode of action study in murine L1210 lymphoid leukemia cells showed that the agents inhibited DNA and RNA syntheses after 60 min. The compounds were potent inhibitors of the de novo purine synthesis suppressing the activity of both regulatory enzymes of the pathway, i.e., PRPP-amido transferase and IMP dehydrogenase. In addition, the agents reduced the activity of ribonucleotide reductase, dihydrofolate reductase, RNA polymerases, and thymidine kinases as well as the reduction of d[NTP] pools. All of these effects would contribute to the overall reduction of DNA and RNA syntheses. The DNA molecule itself was not a target for the agents in that alkylation of nucleoide bases, intercalation between base pairs, and cross-linking of DNA strands did not occur.

The macrolide antibiotics are bacteriostatic agents interfering with protein synthesis but they are taken up by phagocytic cells, e.g. macrophages, neutrophils and fibroblasts which take up infectious organisms into phagosome-lysosomal vaculoes. Recent studies have suggested that these macrolide antibiotics block the spread of infections by mechanisms associated with the inflammation process. Herein is a study with clarithromycin using human THP-1 monocytes, a phagocytic cell which has not been studied to date. Clarithromycin was rapidly taken up by the monocytes (approximately 1%) utilizing both saturable carrier and passive processes at pH 7.4 but was exclusively passive at pH 6.8 and 5.0. The carrier process was energy and temperature dependent and appeared to be linked to certain ion channels. Efflux of the drug was rapid and complete in 1 hr. Intracellular disposition showed 74% in the cell sap and 11% in the nucleus. Upon stimulation with zymogen A or bacteria significant increases of uptake occurred in the isolated lysosome-phagosomes. Examination showed that initially clarithromycin treatment triggered the release of NO, H2O2, IL-1 and TNFalpha from the monocytes, known mediators of inflammation, but also mediators which cause bacterial cell death or apoptosis. The activity of the monocyte marker hydrolytic enzyme NAG was elevated at this time as well as protein kinase C activity. Treatment from 2-4 hr with clarithromycin appeared to reverse this process in that the chemical mediator release was reduced along with the activities of hydrolytic enzymes, e.g. NAG and cathepsin D with no evidence of lipid peroxidation and protective SOD enzyme activity elevation. The latter effects of the antibiotic would be useful in blocking the spread of infection or inflammation from the original site. The normal bacterial static killing effects of clarithromycin was evident at 24 but not 2 hr in both extracellular free bacteria and those bacteria phagocytosed by the THP-1 monocytes.

The 2-furfural semicarbazone and thiosemicarbazone copper and cobalt complexes demonstrated potent cytotoxicity against the growth of suspended leukemias and lymphomas as well as human lung MB9812, colon SW480, ovary 1-A9 and HeLa-S3 uterine carcinoma. In L1210 lymphoid leukemia cell the complexes inhibited preferentially DNA synthesis over 60 min at 25 to 100 microM. The copper and cobalt complexes functioned by multiple mechanisms to suppress synthetic steps in nucleic acid metabolism to reduce deoxynucleotide pools for incorporation into DNA. At high concentrations the complexes suppressed human DNA topoisomerase II activity with DNA nicks and DNA fragmentation but they did not alkylate the bases of DNA, cause intercalation between base pairs or cause cross-linking of DNA strands.

Inosine 5'-monophosphate dehydrogenase (IMPDH) is the rate-limiting enzyme in de novo purine biosynthesis. IMPDH activity results from expression of two isoforms. Type I is constitutively expressed and predominates in normal resting cells, while Type II is selectively up-regulated in neoplastic and replicating cells. Inhibitors of IMPDH activity selectively targeting the Type II isoform have great potential as cancer chemotherapeutic agents. For this study, an expression system was developed which yields 35-50 mg of soluble, purified recombinant Type I and II protein from 1 L of bacteria. In addition, three 1,5-diazabicyclo[3.1.0]hexane-2,4-diones were synthesized and shown to act as specific inhibitors of human recombinant Type II IMPDH. The agents are competitive inhibitors with respect to the endogenous substrate IMP and K(i) values range from 5 to 44 microM but were inactive as inhibitors of the Type I isoform at concentrations ranging from 0.5 to 500 microM. IC(50) values for recombinant Type II inhibition were determined and compared to IC(50) values obtained from Molt-4 cell extracts of IMPDH. Cytotoxicity assays revealed that the compounds inhibited Molt-4 leukemia growth with ED(50) values of 3.2-7.6 microM. Computational docking studies predict that the compounds bind to IMPDH in the IMP-binding site, although interactions with residues differ from those previously determined to interact with bound IMP. While all residues predicted to interact directly with the bound compounds are conserved in the Type I and Type II isoforms, sequence divergence within a helix adjacent to the active site may contribute to the observed selectivity for the human Type II isoform. These compounds represent the first class of selective IMPDH Type II inhibitors which may serve as lead compounds for the development of isoform-selective cancer chemotherapy.

Potent cytotoxic copper(II) complexes of furannic semicarbazones were studied in ethanolic solutions at 25 degrees C. The four ligands used were synthesized in our laboratory, i.e. 2-furfural semicarbazone (FSC), 5-methyl 2-furfural semicarbazone (MFSC), 2-furfural 4-phenyl semicarbazone (FPSC) and 3-(2-furyl) prop-2-enal semicarbazone (FASC). The mathematical analysis was carried out with a recent computer program SIRKO which indicated the formation of one metal-ligand complex in each case and the logarithm of their stability constants are: log beta=2.02, 3.84, 4.58 and 4.52 for ligands FSC, MFSC, FASC and FPSC, respectively. A relation between stability and molecular weight of the ligands is proposed which may prove to be interesting as these complexes are being investigated for their cytotoxic activities.

Complexes containing Ta, Fe, Co, Mo, or W metal centers that are bound to C2B4 or C2B3 small carborane ligands proved to be potent cytotoxic agents in murine and human tissue cultured cells, being more effective in suspended leukemia and lymphomas but surprisingly also effective against the growth of selected solid tumors. These complexes inhibited nucleic acid metabolism, specifically DNA and purine de novo syntheses. Key enzyme activities in nucleic acid metabolism which were inhibited by the complexes were P388 DNA polymerase a, ribonucleotide reductase, dihyrofolate reductase, PRRP-amidotransferase and IMP dehydrogenase. The complexes afforded a moderate amount of DNA-fragmentation in P388 lymhocytic leukemia cells and were moderate inhibitors of human DNA topoisomerase II activity; however, the DNA molecule itself was not a target of the complexes in that there was no evidence that the complexes caused intercalation between base pairs, caused cross-linking of the strands of DNA or alkylated the bases of DNA.

A number of thiosemicarbazones have been tested previously and herein are included three bis(thiosemicarbazones) for comparison to the previous derivatives. In general the uncomplexed thiosemicarbazones were more potent in the cytotoxic screens than the bis(thiosemicarbazone) except in the murine L1210 and the human colon SW480 screens. Mode of action studies have only demonstrated slight differences in the effects of the two types of compounds on nucleic acid metabolism. The symmetrical and unsymmetrical bis(thiosemicarbazones) complexes of copper, nickel, zinc, and cadmium have been examined to compare them to the heterocyclic N(4)-substituted thiosemicarbazones metal complexes. These new derivatives demonstrated excellent activity against the growth of suspended lymphomas and leukemias although it should be pointed out that generally they were not as active as the copper complexes of N(4)-substituted thiosemicarbazones. Nevertheless, selected bis(thiosemicarbazones) complexes were active against the growth of human lung MB9812, KB nasopharynx, epidermoid A431, glioma UM-86, colon SW480, ovary 1-A9, breast MCK-7, and osteosarcoma Saos-2. In human HL-60 promyelocytic leukemia cells the complexes preferentially inhibited DNA and purine syntheses over 60 min. The regulatory enzyme of the de novo purine pathway, IMP dehydrogenase, appeared to be a major target of the complexes. However, minor inhibition of the activities of DNA polymerase alpha, PRPP-amido transferase, ribonucleotide reductase, and nucleoside kinases occurred over the same time period. No doubt these effects of the complexes on nucleic acid metabolism were additive since the d[NTP] pool levels were reduced after 60 min as was DNA synthesis. The symmetrical and unsymmetrical bis(thiosemicarbazones) and their metal complexes did not cause as severe DNA fragmentation as the heterocyclic N(4)-substituted thiosemicarbazone metal complexes; furthermore, their metabolic effects in the tumor cell were more focused on a single synthetic pathway.

The rhenium(I) alkoxo/hydroxo carbonyl complexes were shown to be very potent in suspended tumor cell lines in suppressing growth but were more selective in inhibiting the growth of cultures from solid tumors. Their mode of action in L1210 lymphoid leukemia cells indicated that they were not alkylating agents but interfered with nucleic acid metabolism at multiple enzyme sites, e.g. dihydrofolate reductase, PRPP-amido transferase, thymidine kinase, with DNA strand scission after 60 min incubation. These compounds did not function mechanistically exclusively as cisplatin derivatives causing intrastrand linkages of DNA but rather they mimicked the metal complexes of aminecarboxyboranes, furan oximes, N-substituted thiosemicarbazones, trifluoromethyl borons and ferratricarbadecarbanyl complexes acting as antimetabolites.

The 2,4-disubstituted and 2,3,4-trisubstituted brominated pyrroles were successfully prepared and demonstrated potent cytotoxicity against the growth of suspended murine and human tumors, i.e. leukemia and lymphomas, acute monocytic leukemia, and HeLa-S3 uterine carcinoma. The brominated compounds were more selective in inhibiting the growth of tumors derived from human solid tumors. Nevertheless, activity with some of the derivatives occurred in the human KB nasopharynx, SW-480 colon, and HCT ileum adenocarcinoma, and lung A549 carcinoma screens. In Tmolt4 T cell leukemia cells DNA synthesis was reduced over 60 min from 25 to 100 microM followed by RNA synthesis reduction. De novo purine synthesis was retarded with the regulatory enzyme PRPP-amido transferase being markedly inhibited with less effects on the activities of IMP dehydrogenase, dihydrofolate reductase,, and the nucleoside kinases. After 60 min incubations d[TTP] and d[GTP] pools were marginally reduced. In vitro ct-DNA studies suggest that the agents may affect the DNA molecule itself with increased DNA viscosity and the Tmolt4 studies suggest that DNA cross-linking of DNA strands may be present.

4-Carbethoxy-1-methyl-2-phenacyl-3-phenylpyrrole (9), 4-carbethoxy-2-(4-methoxybenzoyl)-3-(4-methoxyphenyl)pyrrole (10) and 2-(4-methoxybenzoyl)-3,4-bis-(4-methoxyphenyl)pyrrole (11) proved to be potent cytotoxic agents against the growth of murine and human leukemias and lymphomas. Selective toxicity was demonstrated against the growth of solid tumors, e.g., human adenocarcinoma of the colon SW480 and ileum HCT-8, glioma U-87-MG, and rat UMR-106 osteosarcoma. A mode of action study in Tmolt4 leukemia cells demonstrated that the agents inhibited de novo purine synthesis at the regulatory sites PRPP-amido transferase, IMP dehydrogenase as well as dihydrofolate reductase resulting in significant inhibition of DNA synthesis in 60 min. Other biochemical sites which were affected significantly were thymidylate synthetase, DNA polymerase alpha, RNA polymerases, nucleoside kinase and ribonucleoside reductase.

1-Oxoalkyl and 1,2-dioxoalkyl-1,2,4-triazolidine-3,5-diones proved to be potent antineoplastic agents in mouse tumors and potent cytotoxic agents particularly against the growth of suspended tumor cells. The compounds with shorter substituents in position 1 or positions 1 and 2 afforded the better activity. In L1210 lymphoid leukemia cells DNA, RNA, and protein syntheses were inhibited at 100 microM after 60 min. Multiple enzyme sites in nucleic acid metabolism were affected by the compounds, i.e. DNA polymerase alpha, PRPP-amido transferase, dihydrofolate reductase, thymidylate synthetase, and nucleoside kinases. These effects of the agents are probably additive in bringing about inhibition of DNA synthesis and cell death.

2-Acetylpyridine hydrazone derivatives of benzothiazole, benzoxazole, and benzimidazole were found to exhibit potent cytotoxic activity against the growth of suspended leukemia and lymphomas. They were also active in a number of solid tumor screens, e.g. HeLa uterine carcinoma, SOS bone osteosarcoma, lung MB9812, lung A549, Mcf-7 breast growth. In L1210 lymphoid leukemia cells the compounds preferentially inhibited RNA synthesis followed by DNA synthesis at 100 microM after 60 min. The reduction of de novo purine synthesis by the compounds at the regulatory sites PRPP-amido transferase, IMP dehydrogenase and dihydrofolate reductase was responsible for the suppression of nucleic synthesis. Other minor sites where the agents have metabolic effects were thymidylate synthetase and thymidine kinase which would be additive with the overall inhibition of cell growth. The ct-DNA studies suggest that the compounds also interacted with the DNA molecule itself, probably affecting template activity.

4-Hydroxyproline di- and tri-peptides and N-cbz-hydroxypropyl- glycinamides were observed to be potent cytotoxic agents against the growth of suspended single cells, L-1210, Tmolt3, and HeLa-S3. The agents were not as potent against the growth of cultured solid tumor cells. Selected derivatives were investigated for their mode of action in Tmolt3 leukemia cells. The compounds selectively inhibited DNA synthesis at 50 and 100 microM. The target site of action of the agents appeared to be the purine de novo pathway with marked inhibition of the activities of the two regulatory enzymes of the pathway, i.e. PRPP amido-transferase and IMP dehydrogenase. d[NTP] pools were reduced by the agents consistent with their overall reduction of DNA synthesis. Other marginally inhibited targets of the agents were r-RNA polymerase and TMP-kinase activities. The DNA molecule itself did not appear to be a target of these agents.

Heterocyclic thiosemicarbazones, thioureas and their copper, nickel, and cobalt complexes were shown to be potent hypolipidemic agents in male Sprague Dawley rats at 8 mg/kg/day, orally. These agents lowered the activity of rat hepatic rate limiting enzymes for the synthesis of cholesterol and triglycerides. The effects of these agnets on cytoplasmic ATP-dependent citrate lyase, acetyl CoA synthetase and HMG-CoA reductase activities were reduced by a magnitude to explain the reduction of serum cholesterol levels afforded by the compounds. The reduction of acetyl CoA carboxylase, sn-glycerol-3-phosphate synthetase and phosphotidylate phosphohydrolase activities caused by the derivatives is of sufficient magnitude to explain the observed reduction in serum triglycerides after administration of the agents.

The aliphatic dicarboxylic acid surprisingly afforded potent cytotoxicity and in vivo antineoplastic activity. The agents were active against the growth of a variety of leukemias, lymphomas, and suspended HeLa uterine carcinoma. Suppression of growth of cell lines derived from human solid cancers, e.g. SW-480 colon adenocarcinoma, lung MB- 9812, glioma HS-683, and rat osteosarcoma UMR-106 was observed. A mode of action study in L1210 lymphoid leukemia demonstrated that DNA and RNA syntheses were inhibited at multiple sites including ribonucleoside reductase, purine de novo synthesis at PRPP-amidotransferase and IMP dehydrogenase and nucleic acid kinases. These studies could not exclude the possibility that the agents also interacted with the DNA molecule itself interfering with the utilization of the template.

The boronated aromatic amino acids were shown to be potent hypolipidemic agents in mice lowering both serum cholesterol and triglycerides after 16 days. Selective compounds were as effective as the clinical standards. Furthermore, the compounds were effective anti-inflammatory agents reducing local and central pain as well as suppressing LPS induced endotoxic shock in mice. These agents inhibited lysosomal and proteolytic enzymes of the liver and macrophages as a part of their mechanism of action.

A series of 2-acetyl-pyridyl-4N-substituted thiosemicarbazones copper(II) complexes was evaluated for their cytotoxic mode of action in a variety of human and rodent tumor cell cultures. It was determined that these compounds may induce cytotoxicity by affecting several metabolic pathways including a reduction in de novo purine synthesis, and inhibition of IMP dehydrogenase, and DNA polymerase alpha activities. Selected compounds also demonstrated the ability to inhibit L1210 DNA topoisomerase II activity at micromolar concentrations. These agents were able to antagonize etoposide-induced formation of cleavable complexes as measured by K+/SDS precipitation and in vitro cleavage reactions.

Two alkyl-3,4-bis(4-methoxyphenyl)pyrrole-2-carboxylates proved to be potent cytotoxic agents in the murine L1210 lymphoid leukemia screen. DNA synthesis was preferentially inhibited with the major target of the agents being de novo purine biosynthesis at the regulatory enzyme sites of PRPP-amido transferase and IMP dehydrogenase. Other enzymatic activities which were suppressed by the drugs were DNA polymerase alpha, RNA polymerases, ribonucleoside reductase and dihydrofolate reductase. The d[NTP] pools, nucleoside kinase and the pyrimidine pathway were not affected by the presence of drugs. The DNA molecule itself was not the target of the agents, i.e. no alkylation of nucleotide bases, intercalation between bases or cross-linking of DNA strands occurred. The agents did cause L1210 DNA fragmentation after 24 h incubation at 100 microM.

Substituted carboranes and polyhedral hydroborate salts were observed to be potent anti-neoplastic/cytotoxic agents inhibiting the growth of mouse and human leukemias, human uterine, colon adenocarcinoma, lung bronchogenic and gliomas. Amino-o-carborane-hydrochloride 7, one of the more potent compounds, preferentially inhibited Tmolt3 DNA synthesis. The target of the agent appears to be de novo purine synthesis with significant inhibition of the activities of both regulatory enzymes, PRPP-amido transferase and inosine monophosphate dehydrogenase as well as dihydrofolate reductase. The agent also inhibited nucleoside kinase activities leading to reductions in deoxyribonucleotide pools. The DNA molecule itself was not a target of the agent.

Study Objective: To delineate possible explanations for a nonmonotone hematopoiesis, dose-response curve with filgrastim therapy after high-dose chemotherapy, Design: Sequential two-phase study., Settings: University teaching hospital and basic pharmaceutical sciences laboratory., Subjects: Thirty-nine patients with breast cancer or melanoma and 15 normal CF-1 male mice., Interventions: Serial blood samples were obtained from patients after high-dose chemotherapy to evaluate hematopoiesis and tumor necrosis factor-alpha (TNF-alpha) concentrations. Murine hematopoiesis was induced by filgrastim with or without coadministration of lipopolysaccharide., Measurements and Main Results: Detection of plasma TNF-alpha in patients corresponded to substantially slower recovery of granulocytes, erythrocytes, and platelets, and was directly proportional to the prescribed dosage of filgrastim. Lipopolysaccharide stimulated the secretion of TNF-alpha in mice and totally aberrated filgrastim-induced granulopoiesis., Conclusions: This in vivo evidence suggests that regulatory pathways involving endogenous cytokines may override the effect of recombinant cytokines.