Combination of the novel farnesyltransferase inhibitor RPR130401 and the geranylgeranyltransferase-1 inhibitor GGTI-298 disrupts MAP kinase activation and G(1)-S transition in Ki-Ras-overexpressing transformed adrenocortical cells.

To test the Kirsten-Ras (Ki-Ras) alternative prenylation hypothesis in malignant transformation, we used a novel farnesyltransferase inhibitor competitive to farnesyl-pyrophosphate, RPR130401, and a CaaX peptidomimetic geranylgeranyltransferase-1 inhibitor GGTI-298. In Ki-Ras-overexpressing transformed adrenocortical cells, RPR130401 at 1-10 microM inhibited very efficiently the [(3)H]farnesyl but not [(3)H]geranylgeranyl transfer to Ras. However, proliferation of these cells was only slightly sensitive to RPR130401 (IC(50)=30 microM). GGTI-298 inhibited the growth of these cells with an IC(50) of 11 microM but cell lysis was observed at 15 microM. The combination of 10 microM RPR130401 and 10 microM GGTI-298 inhibited efficiently (80%) cell proliferation. These combined inhibitors but not each inhibitor alone blocked the cell cycle in G(0)/G(1) and disrupted MAP kinase activation. Thus, combination of two inhibitors, at non-cytotoxic concentrations, acting on the farnesyl-pyrophosphate binding site of the farnesyltransferase and the CaaX binding site of the geranylgeranyltransferase-1 respectively is an efficient strategy for disrupting Ki-Ras tumorigenic cell proliferation.

Betulinic acid derivatives: a new class of human immunodeficiency virus type 1 specific inhibitors with a new mode of action.

A series of omega-undecanoic amides of lup-20(29)-en-28-oic acid derivatives were synthesized and evaluated for activity in CEM 4 and MT-4 cell cultures against human immunodeficiency virus type 1 (HIV-1) strain IIIB/LAI. The potent HIV inhibitors which emerged, compounds 5a, 16a, and 17b, were all derivatives of betulinic acid (3beta-hydroxylup-20(29)-en-28-oic acid). No activity was found against HIV-2 strain ROD. Compound 5a showed no inhibition of HIV-1 reverse transcriptase activity with poly(C).oligo(dG) as template/primer, nor did it inhibit HIV-1 protease. Additional mechanistic studies revealed that this class of compounds interfere with HIV-1 entry in the cells at a postbinding step.

Betulinic acid derivatives: a new class of specific inhibitors of human immunodeficiency virus type 1 entry.

A novel series of omega-aminoalkanoic acid derivatives of betulinic acid were synthesized and evaluated for their activity against human immunodeficiency virus (HIV). The anti-HIV-1 activity of several members of this new series was found to be in the nanomolar range in CEM 4 and MT-4 cell cultures. The optimization of the omega-aminoalkanoic acid side chain is described. The presence of an amide function within the side chain was found important for optimal activity. RPR 103611 (14g), a statine derivative, was found to be inactive against HIV-1 protease, reverse transcriptase, and integrase as well as on gp120/CD4 binding. "Time of addition" experiments suggested interaction with an early step of HIV-1 replication. As syncytium formation, but not virus-cell binding, seems to be affected, betulinic acid derivatives are assumed to interact with the postbinding virus-cell fusion process.

Triterpene derivatives that block entry of human immunodeficiency virus type 1 into cells.

A series of triterpene compounds characterized by a stringent structure-activity relationship were identified as potent and selective inhibitors of human immunodeficiency virus type 1 (HIV-1) replication. Currently studied botulinic derivatives have 50% inhibitory concentrations (IC50) against HIV-1 strain IIIB/LAI in the 10 nM range in several cellular infection assays but are inactive against HIV-2. These compounds did not significantly inhibit the in vitro activities of several purified HIV-1 enzymes. Rather, they appeared to block virus infection at a postbinding, envelope-dependent step involved in the fusion of the virus to the cell membrane.

omega-[(4-Phenyl-2-quinolyl)oxy]alkanoic acid derivatives: a new family of potent LTB4 antagonists.

A series of omega-[(4-phenyl-2-quinolyl)oxy]alkanoic acid derivatives was prepared which inhibited the binding of the leukotriene B4 to its receptors on guinea pig spleen membranes and on human polymorphonuclear leukocytes. A structure-activity relationship was investigated. The length of the carboxylic acid side chain was important for potent binding activity. The replacement of the oxygen atom at the beginning of the chain with other polar or nonpolar linking groups led to considerable loss of potency, indicating that the oxygen linking atom might be involved in the receptor recognition. alpha-Substitution on the carboxylic acid side chain led to substantially more potent compounds. Substitution on the phenyl ring and on the quinoline ring was also evaluated.

omega-[(4,6-Diphenyl-2-pyridyl)oxy]alkanoic acid derivatives: a new family of potent and orally active LTB4 antagonists.

A series of omega-[(4,6-diphenyl-2-pyridyl)oxy]alkanoic acid derivatives was prepared which inhibited the binding of leukotriene B4 to its receptors on guinea pig spleen membranes and on human polymorphonuclear leukocytes (PMNs) and selectively antagonized the LTB4-induced elastase release in human PMNs. On the basis of these three screens, a structure-activity relationship was investigated. alpha-Substitution on the carboxylic acid side chain led to only small changes in the binding affinities but greatly enhanced the LTB4 antagonist activity. Substitution on the phenyl rings was also evaluated. The terminal carboxylic acid function can be replaced by a tetrazole ring without loss in activity. The best in vitro LTB4 antagonists of this series were investigated in vivo in the inhibition of LTB4-induced leukopenia in rabbits. Compound 9b (RP69698) displayed potent LTB4 antagonist activity, after oral administration, with an ED50 value of 6.7 mg/kg.

Omega-[(omega-arylalkyl)thienyl]alkanoic acids: from specific LTA4 hydrolase inhibitors to LTB4 receptor antagonists.

A series of omega-[(omega-arylalkyl)thienyl]alkanoic acid isomers was prepared and a structure-activity relationship was investigated. These compounds have displayed either LTA4 hydrolase inhibition activities or LTB4 receptor binding activities, or both, depending on the relative orientation of the two side chains on the thiophene ring. Whereas the 2,5-isomers specifically exhibited LTA4 hydrolase inhibition, 3,5-isomers displayed both activities. On the other hand, the "ortho-isomers" specifically inhibited the binding of the LTB4 to its receptor. The side-chain lengths were also important for an optimal inhibition or binding activity. Substitutions on the terminal aromatic ring or on the thiophene nucleus led to small changes in both activities. The most dramatic effect was obtained by substituting the carboxylic acid side chain in the alpha-position with one or two methyl groups, which substantially enhanced the LTB4 receptor binding activity. In the most favorable case, the alpha,alpha-dimethyl derivative RP66153 was found 20-fold more potent than its linear counterpart.

Omega-[(omega-arylalkyl)aryl]alkanoic acids: a new class of specific LTA4 hydrolase inhibitors.

The synthesis and structure-activity profile of a new class of potent and specific LTA4 hydrolase inhibitors are described. Many compounds of this series of omega-[5-(omega-arylalkyl)-2-thienyl]- and omega-[4-(omega-arylalkyl)phenyl]alkanoic acids were found to be potent in vitro inhibitors of the LTB4 production by porcine leukocytes with IC50 ranging from 1 to 10 microM. The side-chain lengths were critical for an optimal activity. Substitutions on the terminal aromatic ring, in the benzene series, by lipophilic and electron-donating substituents substantially enhanced the LTA4 hydrolase inhibition potency. On the other hand, in the thiophene series, the effect of of such substitutions on the LTA4 hydrolase inhibition was rather small. Functionalization within the carboxylic acid side chain by a carbonyl or by a hydroxyl group led to less potent compounds. A metabolically stable LTA4 hydrolase inhibitor, RP64966, was obtained by insertion of an oxygen atom in the beta-position on the carboxylic acid side chain. After oral administration of RP64966 to rats, a plasma extract was found to display potent inhibition of the LTB4 biosynthesis (40% inhibition at 5 mg/kg, po).

Deactivation of singlet molecular oxygen by organo-selenium compounds exhibiting glutathione peroxidase activity and by sulfur-containing homologs.

The bimolecular rate constants (k) of quenching of molecular singlet oxygen 1O2 (1 delta g) by organo-selenium compounds exhibiting glutathione peroxidase activity and by sulfur analogs have been determined by time resolved phosphorescence detection of 1O2 in CD3OD and C6D6, with no solvent effect. The rate constants of quenching by the Se-containing compounds were found to be approximately one order of magnitude higher than those of the S-containing homologs. A linear correlation was observed between log k and the Hammett constant omega ortho with p = -0.89, the rate constant being higher for molecules with an electron-donating substituent and lower for those with an electron-withdrawing substituent. This observation is consistent with the involvement of a charge transfer complex in the deactivation of singlet oxygen.

[Benzisoselenazolinones and their derivatives, a new series of anti-inflammatories and antioxidants]. / Les benzisosélénazolinones et leurs dérivés, nouvelle série d'antiinflammatoires et d'antioxydants.

Ebselen, a benzisoselenazolinone, displays antiinflammatory properties and antioxidant capacity similar to the enzyme glutathione peroxydase. Structural modifications were realized. The presence of substituents ortho to selenium, and in particular of a dipolar group such as -NO2, led to an interesting modification of the pharmacological properties.

Improvement of the gastric tolerance of non-steroidal anti-inflammatory drugs by polyene phosphatidylcholine (Phospholipon 100).

The effect of co-administration with polyene phosphatidylcholine (Phospholipon 100) on the oral gastrotoxicity of various non-steroidal anti-inflammatory drugs (NSAIDs) was studied in the rat. The highly unsaturated phospholipid reduced gastric mucosal lesions measured 3.5 h after oral administration of aspirin, indomethacin, phenylbutazone, diclofenac, piroxicam and sudoxicam to rats which had received a 3 day bread diet followed by 24 h fasting. The extent of reduction of gastrotoxicity varied amongst the individual NSAIDs. Phospholipon 100 also reduced gastric lesions induced by 3 day oral piroxicam and diclofenac administration. A trend towards reduction of oral diclofenac gastrotoxicity was observed following intravenous Phospholipon 100 administration. Phospholipon 100 H (100% saturated phosphatidylcholine) was less effective than Phospholipon 100 in improving acute gastric tolerance to oral phenylbutazone, diclofenac and piroxicam. Administration of the NSAID-Phospholipon 100 combination produced little change in the anti-inflammatory activities of diclofenac on carrageenan paw oedema and diclofenac and piroxicam on adjuvant arthritis in the rat. Combination with Phospholipon 100 offers a novel means for reducing the gastric side-effects of NSAID therapy.