Inhibition by 9alpha-fluoromedoroxyprogesterone acetate (FMPA) against mammary carcinoma induced by dimethylbenz[a]anthracene in rats and angiogenesis in the rabbit cornea - comparison with medroxyprogesterone acetate (MPA).

Medroxyprogesterone acetate (MPA) is currently used therapeutically in the treatment of mammary and endometrial carcinomas. In order to develop a more potent and useful drug, we synthesized the novel compound, 9alpha-fluoromedoroxyprogesterone acetate (FMPA), by fluorinating MPA, and we also previously reported that FMPA displays more potent anti-angiogenic activity in the chorioallantoic membrane assay than MPA. In the present study, we investigated (1) the effects of FMPA on rat mammary carcinomas induced by dimethylbenz[a]anthracene (DMBA) to determine the anti-tumor activity, (2) the effect on angiogenesis in rabbit corneal assays, and (3) compared these results with those for MPA. FMPA inhibited the growth of mammary carcinomas in a dose-dependent manner (7.5, 30 and 120 mg/kg). Almost complete involution of the carcinomas was observed at doses of 30 and 120 mg/kg. MPA also inhibited the growth of carcinomas at doses of 30 and 120 mg/kg, but no involution of carcinomas was observed even at 120 mg/kg. FMPA significantly and MPA to a lesser degree inhibited carcinogenesis at 120 mg/kg within their treatments. In rabbit corneal assays, FMPA significantly inhibited angiogenesis (IC50 value=0.085 microg/pellet). MPA also significantly inhibited angiogenesis (IC50 value=0.60 microg/pellet). From these results, we conclude that FMPA is potentially more effective in the treatment of mammary carcinomas than MPA.

Anti-angiogenic activity of a novel synthetic agent, 9alpha-fluoromedroxyprogesterone acetate.

9Alpha-fluoromedroxyprogesterone acetate (FMPA) is a novel synthetic analog of medroxyprogesterone acetate (MPA), widely used as therapeutic agent for breast and endometrium cancers. FMPA showed almost the same binding affinities to the progesterone and glucocorticoid receptors as MPA. In the rabbit corneal assay, FMPA, MPA and fumagillin significantly inhibited the angiogenic response induced by rat mammary tumor at doses of 0. 1, 1 and 50 microg/pellet, respectively, so FMPA showed greater anti-angiogenic activity than MPA and fumagillin. In the mouse dorsal air sac method, FMPA inhibited the mouse sarcoma 180 cell-induced angiogenesis by oral administration at a dose of 200 mg/kg. FMPA inhibited the activity of plasminogen activator (PA) in bovine endothelial cells. These results suggest that FMPA may be useful for diseases associated with angiogenesis by oral administration.

Purification and properties of carbonyl reductase from rabbit kidney.

An enzyme catalyzing the metabolic reduction of acetohexamide, an oral antidiabetic drug, has been purified from the cytosolic fraction of rabbit kidney to apparent homogeneity by various chromatographic techniques. The purified enzyme consists of a single polypeptide chain with a molecular weight of 28,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme requires NADPH as a cofactor and has an optimal pH of 6.0. A variety of xenobiotic carbonyl compounds including acetohexamide are effectively reduced by the enzyme. Flavonoids (quercetin and quercitrin) are potent inhibitors for the enzyme, but pyrazole or barbiturates have little effect on the enzyme activity. These findings clearly indicate that the enzyme can be classified as one of the carbonyl reductases. The enzyme also shows both prostaglandin 9-ketoreductase and 3 alpha-hydroxysteroid dehydrogenase activities. Judging from the Kcat/Km values of the enzyme for 4-pyridylketones with a straight-chain alkyl group, a hydrophobic pocket that binds most strongly to a straight-chain alkyl group of five carbon atoms in length appears to be located in the substrate-binding region of the enzyme.

Inhibitory effect of drugs with a ketone group on reduction of acetohexamide catalyzed by carbonyl reductase from rabbit kidney.

The reduction of acetohexamide catalyzed by carbonyl reductase from rabbit kidney was inhibited by befunolol, moperone, levobunolol, daunorubicin and loxoprofen, which have a ketone group within their chemical structures and are substrates for the enzyme. A significant correlation was observed between the common logarithm of Vmax/Km values of the enzyme for befunolol, moperone, levobunolol and daunorubicin and the percentage inhibition of the enzyme, confirming that these drugs are competitive substrates of the enzyme with respect to acetohexamide. However, the plot for loxoprofen, a nonsteroidal anti-inflammatory drug with a ketone group, was apparently distant from the regression line obtained. Although nonsteroidal anti-inflammatory drugs with a ketone group such as suprofen and fenbufen were not reduced by the enzyme, they strongly inhibited the reduction of acetohexamide catalyzed by the enzyme.

Total syntheses of novel cytocidal beta-carboline alkaloids, oxopropalines D and G.

A new type of beta-carboline nucleus, N-methoxymethyl-4-methyl-beta-carboline (4) was synthesized by thermal electrocyclic reaction of a 1-azahexatriene system, involving the indole 2,3-bond. The key compound N-methoxymethyl-1-methoxycarbonyl-4-methyl-beta-carboline (2) was then prepared in a four-step sequence. The total synthesis of oxopropaline G (1e) was achieved from this key compound in four steps. Furthermore, the enantioselective total syntheses of (+)-oxopropaline D (1c) and its enantiomer were also achieved by application of the Sharpless oxidation-procedure in nine steps from 2.

Inhibition of increasing effect of vanadate on glycogen content and lipoprotein lipase activity in fat pads by 5-N,N-hexamethylene amiloride.

Sodium orthovanadate (vanadate) increased the glycogen content in isolated rat fat pads in a dose-dependent manner up to 2 mM. Biochanin A, a specific inhibitor of tyrosine kinases, inhibited the increasing effect of vanadate or insulin on both glycogen content and lipoprotein lipase (LPL) activity in fat pads. The increasing effect of vanadate on glycogen content was not decreased by the replacement of Na+ with choline ion in the incubation medium. 5-N,N-Hexamethylene amiloride, a potent inhibitor of the Na+/H+ exchange system, showed a 50%-inhibition of the vanadate-increased LPL activity and glycogen content at 25 and 80 microM, respectively, suggesting that mechanisms of the inhibition differ in part between the vanadate actions. Furthermore, a similar inhibitory profile of the vanadate-increased glycogen content was observed with incubation in the presence of absence of Na+ in the medium. These results suggest that the activation of the Na+/H+ exchange system by vanadate is not involved in an increase in the glycogen content in fat pads.

Synthesis and antitumor activity of 20(S)-camptothecin derivatives: carbamate-linked, water-soluble derivatives of 7-ethyl-10-hydroxycamptothecin.

Novel 36 derivatives (6), bonding the phenolic hydroxyl group of 7-ethyl-10-hydroxycamptothecin (4) with diamines through a monocarbamate linkage, were synthesized and their antitumor activity was evaluated in vivo. The derivatives were soluble in water as their HCl salts with the E lactone ring intact and exhibited significant antitumor activity. One of the derivatives, 6-27 showed excellent activity against L1210 leukemia and other murine tumors. The structure of its hydrochloride trihydrate (CPT-11) was determined by spectroscopic and crystallographic methods.

Catalytic properties of carbonyl reductase from rabbit liver for analogs of acetohexamide and 4-acetylpyridine.

A correlation was observed between the values of specificity constant (kcat/Km) of carbonyl reductase from rabbit liver for acetohexamide analogs and their partition coefficients. This result indicates that the hydrophobicity in straight-chain alkyl groups of acetohexamide analogs plays an important role in the catalytic activity and substrate-binding capacity of the enzyme. Furthermore, the double logarithmic plots of kcat/Km values of the enzyme for 4-acetylpyridine analogs with a straight-chain alkyl group up to five carbon atoms against their partition coefficients gave a straight line. On the other hand, the plots for 4-acetylpyridine analogs with a straight-chain alkyl group over five carbon atoms and with a branched-chain alkyl group were away from the straight line. It is reasonable to postulate that a hydrophobic pocket is located in the substrate-binding domain of the enzyme.

Synthesis of dibenzoylmethane derivatives and inhibition of mutagenicity in Salmonella typhimurium.

Twenty dibenzoylmethanes with methyl, methoxy, bromo, chloro, or fluoro substitution on either one or both benzene rings were synthesized and assayed for inhibition of the mutagenicity of 2-nitrofluorene in S. typhimurium TA98. 2,2-Dimethoxy, 3,3-dimethoxy and 3,3,4,4-tetramethoxydibenzoylmethane was as active as dibenzoylmethane. None of the halogen-substituted dibenzoylmethanes were active. These results demonstrate that dibenzoylmethanes can inhibit the mutagenicity of 2-nitrofluorene, and that modifications made on the benzene rings of dibenzoylmethane cannot enhance the antimutagenicity of this parent compound.

Synthesis of a new potent anti-angiogenic agent, 17 alpha-acetoxy-9 alpha-fluoro-6 alpha-methylprogesterone (9 alpha-fluoromedroxyprogesterone acetate [FMPA]).

A new anti-angiogenic agent, 17 alpha-acetoxy-9 alpha-fluoro-6 alpha-methylprogesterone (9 alpha-fluoromedoroxyprogesterone acetate [FMPA, 9] was synthetized in a 10-step sequence. FMPA (9) had about two orders of magnitude stronger anti-angiogenic activity than medroxyprogesterone acetate (MPA), as estimated in a bioassay involving chorioallantoic membranes of growing chick embryos.

Pharmacokinetics of 9alpha-fluoromedroxyprogesterone acetate in rats: comparison with medroxyprogesterone acetate.

Medroxyprogesterone acetate (MPA) is widely used in endocrine therapy for breast cancer and other diseases. Recently, it has been demonstrated that 9alpha-fluoromedroxyprogesterone acetate (FMPA) also has anti-tumour activity in chemical-induced rat mammary tumour and its activity is greater than that of MPA. In the present study, the physico-chemical properties of FMPA and MPA and their pharmacokinetics in female rats were investigated. Partition coefficients (log P) of FMPA and MPA were 3.1 and 3.8, respectively, while the solubilities of FMPA and MPA in phosphate buffer saline were 3.8 and 1.1 microg/mL, respectively. When the two agents were intravenously or orally administered into female rats, there was no significant difference between their plasma concentrations. However, unmetabolized drug excreted into urine accounted for 4.7 and 0.7% of the intravenous dose of FMPA and MPA, respectively. The free fraction of FMPA in rat plasma was approximately four times that of MPA. Assuming the well-stirred model, hepatic intrinsic clearances of FMPA and MPA were estimated to be 64 and 293 L/h per kg, respectively. In addition, the free fraction of FMPA in blood is estimated to be higher than that of MPA, which may explain the higher anti-tumour activity.