[The main diseases of pigs]. / Les principales maladies du porc.

Several pathologies which were once mortal within pig farms have disappeared from our territory, numerous polysystemic diseases remain. If antibiotherapy is sometimes effective, vaccination can prevent a certain number of pathologies while there is no preventive of curative treatment for others. Moreover, all the pig's organs are susceptible to being targeted by pathogenic agents. Here again, vaccines and antibiotic treatments are available.

Linker structure-activity relationships in fluorodeoxyglucose chlorambucil conjugates for tumor-targeted chemotherapy.

Nitrogen mustards, such as chlorambucil (CLB), can cause adverse side-effects due to ubiquitous distribution in non-target organs. To minimize this toxicity, strategies of tumor-targeting drug delivery have been developed, where a cytotoxic warhead is linked to a tumor-cell-specific small ligand. Malignant cells exhibit marked glucose avidity and an accelerated metabolism by aerobic glycolysis, known as the Warburg effect, and recognized as a hallmark of cancer. A targeting approach exploiting the Warburg effect by conjugation of CLB to 2-fluoro-2-deoxyglucose (FDG) was previously reported and identified two peracetylated glucoconjugates 2 and 3 with promising antitumor activities in vivo. These results prompted us to investigate the importance of the spacer in this tumor-targeting glucose-based conjugates. Here we report the chemical synthesis and an in vitro cytotoxicity evaluation, using a 5-member panel of human tumor cell lines and human fibroblasts, of 16 new CLB glucoconjugates in which the alkylating drug is attached to the C-1 position of FDG via different linkages. We studied the structure-activity relationships in the linker, and evidenced the positive impact of an aromatic linker on in vitro cytotoxicity: compound 51 proved to be the most active FDG-CLB glucoside, characterized by a bis-aromatic spacer tethered to CLB through an amide function.

Design, synthesis and in vitro drug release investigation of new potential 5-FU prodrugs.

In order to identify new efficient prodrugs of 5-fluorouracil (5-FU) and to develop an original targeting approach using 2-fluoro-2-deoxyglucose (FDG) as a potential drug carrier, eight original 5-FU derivatives were synthesized: 5-FU was attached by the N1 position of the pyrimidinic ring to the C1 position of the FDG structure either by direct coupling (2a) or via various spacers (3, 6a-c, 10b and 19). A new sensitive high-performance liquid chromatography method was developed to simultaneously quantify 5-FU and its derivatives in human plasma and other relevant media at physiological temperatures. Half-lives were determined from the degradation profiles of these conjugates. Slow degradation of compounds 2a, 3, 10b and 19 was observed in vitro at 37 °C, but no 5-FU release was noticed. By contrast, the in vitro drug release profiles of compounds 6a-c followed pseudo-first-order kinetics, and 5-FU was found in all the media. The antiproliferative activity of the eight compounds was assessed in vitro by a fluorometric assay against two human solid cancer cell lines and one healthy cell line. A correlation was found between the activities of the compounds and their ability to release 5-FU efficiently.

Preclinical investigation of tolerance and antitumour activity of new fluorodeoxyglucose-coupled chlorambucil alkylating agents.

Our strategy is to increase drug accumulation in target tumour cells using specific "vectors" tailored to neoplastic tissue characteristics, which ideally are not found in healthy tissues. The aim of this work was to use 2-fluoro-2-deoxyglucose (FDG) as a drug carrier, in view of its well-known accumulation by most primary and disseminated human tumours. We had previously selected two FDG-cytotoxic conjugates of chlorambucil (CLB), i.e. compounds 21a and 40a, on the basis of their in vitro profiles. Here we investigated the antitumour profile and tolerance of these compounds in vitro and in vivo in two murine cell lines of solid tumours. In vitro, we found that micromolar concentrations of compounds 21a and 40a inhibited proliferation of B16F0 and CT-26 cell lines. Interestingly, compounds 21a and 40a were found to act at different levels in the cell cycle: S and subG1 accumulation for 21a and G2 accumulation for 40a. In vivo, a single-dose-finding study to select the Maximum Tolerated Dose (MTD) by the intraperitoneal route (IP) showed that the two peracetylated glucoconjugates of CLB were less toxic than CLB itself. When given to tumour-bearing mice (melanoma and colon carcinoma models), according to a "q4d × 3" schedule (i.e., three doses at 4-day intervals) both compounds demonstrated a promising antitumour activity, with Log Cell Kill (LCK) values higher than 1.3 in both B16F0 and CT-26 models. Hence compounds 21a and 40a are good candidates for further works to develop new highly active antineoplastic compounds.

Synthesis and cytotoxic properties of new fluorodeoxyglucose-coupled chlorambucil derivatives.

Frequently used in the treatment of malignant cells, alkylating agents, like most anticancer substances, produce adverse side effects caused by the toxicity of the agents toward normal tissues and lose efficiency through poor distribution to target sites. Our approach to developing more selective drugs with low systemic toxicity is based on the premise that the body distribution and cell uptake of a drug can be altered by attaching a neoplastic cell-specific uptake enhancer, such as 2-fluoro-2-deoxyglucose (FDG), the radiotracer most frequently used in PET for tumor imaging. Two properties of deoxyglucose, namely preferential accumulation in neoplastic cells and inhibition of glycolysis, underpin this targeting approach. Here, we report the synthesis of 19 new chlorambucil glycoconjugates in which the alkylating drug is attached to the C-1 position of FDG, directly or via different linkages. This set of compounds was evaluated for in vitro cytotoxicity against different human normal and tumor cell lines. There was a significant improvement in the in vitro cytotoxicity of peracetylated glucoconjugates compared with the free substance. Four compounds were finally selected for further in vivo studies owing to their lack of oxidative stress-inducing properties.

New 3- and 4-hydroxyfuranones as anti-oxidants and anti-inflammatory agents.

Two series of new furanones substituted by methylsulfonylphenyl or methylsulfamidophenyl moieties were found to protect against oxidation damage by inhibiting or quenching free radicals and reactive oxygen species in in vitro experiments. The effect on lipid peroxidation was also examined. In addition, we investigated the activity of products in two models of inflammation: phorbol ester-induced ear edema in mice and carrageenan-induced paw edema in rat. The most powerful compounds and with reducing activity against DPPH (IC50=1779 and 57 microM, respectively), superoxide anion quenching capacity (IC50=511 and 49 microM, respectively), lipid peroxidation inhibitory effect and anti-inflammatory properties (about 50-65% inhibition of edema at 200 mg/kg ip in both tests used) were selected for further pharmacological and toxicological tests because of their attractive profile for the treatment of inflammatory diseases.

Novel 4,5-diaryl-3-hydroxy-2(5H)-furanones as anti-oxidants and anti-inflammatory agents.

In order to study the effect of phenol moieties on biological activities of ascorbic acid derivatives, we synthesized 13 novel 4,5-diaryl-3-hydroxy-2(5H)-furanones 5a-m with various substitution patterns. Compound 5 g bearing a 2,3-dihydroxy phenyl ring on the 5-position of the heterocycle appeared to be the most powerful anti-oxidant furanone with reducing activity against DPPH (IC(50)=10.3 microM), superoxide anion quenching capacity (IC(50)=0.187 mM) and lipid peroxidation inhibitory effect (IC(50)=0.129 mM). To ascertain determinant molecular features for anti-oxidant activities, structure-activity relationships were studied. Lipophilicity and molecular parameters related to electron distribution and structure (difference in heats of formation between the compound and its radical or its cation radical, energy of the highest occupied molecular orbital, HOMO) were found to correlate with the anti-oxidant action of compounds 5 in the different tests used. Oxygen-derived free radicals are known to contribute to inflammatory disorders; therefore we have investigated effects of compounds 5 in two models of inflammation: phorbol ester-induced ear edema in mice (TPA-test) and carrageenan-induced paw edema in rat. At 100 mg/kg ip in the TPA-test, the anti-inflammatory activity of compounds 5 was potent compared with that of indomethacin and ketorolac and all the results suggested a cyclooxygenase inhibition in the emergence of such properties. The combined pharmacological actions of compounds 5 associated with a favorable therapeutic index prompt with interesting perspectives for their use in heart and brain disorders as well as in inflammatory diseases.