ITGE950100A1 - ANTIMICOTIC ACTIVITY OF HMG-COA-REDUCTASE INHIBITORS. - Google Patents

Abstract

HMG - CoA - reductase inhibitor compound, having the formula: (FORMULA) where Z is (FORMULA I II) or (FORMULA III) for use as an antifungal.

Description

DESCRIPTION of the patent for industrial invention entitled: "Antifungal activity of HMG-CoA-reductase inhibitors"

TEXT OF THE DESCRIPTION

The present invention relates to compounds having inhibitory activity towards enzymes of the 3-hydroxy-3-methylglutaryl-CoA-reductase type which operate in the sterol synthesis step in a large number of eukaryotes, and in particular it relates to compounds having the formula

for use as antifungals.

All eukaryotic cells (fungi, protozoa, animals) contain different species of sterols which exert, among other functions, such as those of hormone and bile acid precursors, the function of stabilizing the structure of the cell membrane.

Mammalian cells, for example, synthesize their own membrane sterol, cholesterol, starting from acetyl-coenzyme A, but are also able to use the exogenous cholesterol obtained through food. In other eukaryotes, eg fungi, membrane sterol, ergosterol, must always be synthesized "de novo"

Both the cholesterol synthesis process in humans and that of ergosterol in mushrooms are the target of drugs which, with different therapeutic purposes, act on different steps in the biosynthetic pathway of the two molecules.

In particular, a class of substances has been discovered capable of inhibiting the enzymes that catalyze the reduction reaction of 3-hydroxy-3-methylglutaryl coenzyme-A to mevalonic acid, that is the 3-hydroxy-3-methylglutaryl coenzyme A reductase. (hereinafter HMG-CoA reductase). Currently, two such reductases are known, which differ in that one uses NADH, while the other uses NADPH. This synthetic step is the second stage of the sterol synthesis process, and is the seat of a retroactive regulation (feed-back); for this reason it is a decisive stage. The inhibition of these enzymes therefore represents an effective control of the synthesis of sterols, so much so that the substances capable of carrying out this inhibition have long been used in the treatment of hypercholesterolemic subjects.

The substances capable of inhibiting the activity of these enzymes are derived from a molecule extracted from strains of Penicillum, Aspergillus and Monoascus, fungi present in the environment, and known as "compactin". This molecule, despite being able to effectively inhibit HMG-CoA reductases, has proved unsuitable for pharmaceutical use due to its high toxicity.

Conversely, the compounds derived therefrom, such as lovastatin (U.S.A. Patent No. 4231938), simvastatin, pravastatin (U.S.A. Patent No.

4346227) have been successfully used as active ingredients of hypocholesterolemic drugs on the market for some time. Molecules known as fluvastatin, marketed under the brand name Lescol (R), and rivastatin have also recently been synthesized.

. These molecules all have a type group

similar to hydroxymethylglutaric acid which is believed to be the active portion of the molecule as an inhibitor of the enzyme. - Among the molecules mentioned, it is possible to distinguish those which have the active portion in the form (a), that is to say the f-lactone, or in the form (b), that is to say the corresponding hydroxyacid. Lovastatin and simvastatin are in form (a), and as such are not directly active on the enzyme, but are the precursors of the active form. The lactone ring opens in a basic environment or by the action of liver enzymes and the molecule performs its inhibitory function. On the contrary, the molecules in form (b), such as pravastatin, fluvastatin and rivastatin, are directly active on HMG-CoA reductases.

The process of synthesis of ergosterol in mushrooms, as already mentioned above, is also the target of drugs in which the active principle consists of a specific inhibitor of a certain phase of the bosynthetic process. For example, allylamine-based drugs inhibit the enzyme squalene epoxidase, which catalyzes the epoxidation of squalene, while imidazole derivatives such as itraconazole, ketoconazole, and fluconazole, inhibit the enzyme 14-α-demethylase, blocking the transformation of the lanosterol.

Since the biosynthetic processes of sterols in eukaryotes, as already mentioned, are very similar to each other, it is possible that the inhibitors of HMG-CoA reductases are able to exert an antifungal action, inhibiting the synthesis of ergosterol in a decisive phase and regulation of the process itself.

Indeed, in EP-A-0410409, a family of molecules, derivatives of thiazolidine capable of inhibiting HMG-CoA reductases, is described. These molecules are provided with the same active portion of the molecules described above and, in the document, their antifungal activity is also described, together with the cholesterol-lowering activity.

Furthermore, Urbina J.A. et al. (Antimicrob. Agents Chemother .; 1993 Mar; 37 (3): 580-91) describe the effects of lovastatin, used alone and in combination with other ergosterol synthesis inhibiting agents such as ketoconazole and terbinafine, on the growth of the protozoan parasite Trypanosoma (Schizotrypanum) cruzi.

Surprisingly, in the course of the research that gave rise to the present invention, it was possible to verify that the ability of some of the compounds described above, to counteract the <*> production of ergosterol in fungi, and therefore to exert antifungal activity, was particularly pronounced.

The object of the present invention is therefore the compound having the formula:

for use as an antifungal.

A further object of the invention is an antifungal pharmaceutical composition comprising the above compound as an active ingredient, alone or in combination with imidazole, allylamine antifungals.

In fact, a particularly pronounced antifungal activity has been found for compounds having the formulas illustrated above. In the case of the two compounds having Z equal to (I) and Z equal to (II), it seems that their activity can be linked to the p-fluorophenyl group common to both. On the other hand, the origin of the activity of the molecule with Z equal to (III) is different, which is in practice the compound known as simvastatin, treated with a base to obtain the open form of the group that interacts with the enzymatic site, in place of the commonly used lactone form. It is interesting to consider the fact that the antifungal activity shown by this compound is much higher than that of the other compactin derivatives.

Tests have been performed on various strains of fungal cultures, and it has been found that said compounds are generally active against the fungi used in the test and in some cases more active than the commonly adopted antifungals. Advantageously, the compound of the invention showed a synergistic action when it was used in coformulation with another antifungal agent, preferably having an alternative action to that of the compound itself, that is to say able to inhibit a different enzyme, such as the compounds allylamines or imidazole derivatives.

The present invention will become evident from the examples reported below.

Example 1

Multiple series of 90 mm diameter Petri dishes were prepared with cultures of Aspergillus fumigatus, Candida albicans and Trichophyton mentagrophytes strains. 25 mg of fluvastatin, simvastatin treated with KOH, terbinafine and itraconazole were inoculated on each plate series, respectively. The diameters expressed in min of the rarefaction of the cultures were then measured in correspondence with the inocula of the antifungal. The results are reported in table 1.

As can be seen from the data illustrated in table 1, the antifungal behavior, both of fluvastatin and simvastatin treated with KOH, is of absolute importance towards the culture of Aspergillus fumigatus, and expresses values comparable to those of the common antifungals towards the culture of Candida albicans.

Example 2

Series of Petri dishes were prepared similarly to example 1, in which the six binary combinations of the four substances used in the previous example were inoculated, in the dose of 6.25 to 6.25 mg per inoculum. Also in this case, the rarefaction of the cultures at the inoculum was detected. The results are shown in table 2.

Also in this case fluvastin and simvastatin show a marked activity in synergy with the antifungals to which they are combined from time to time, as well as an appreciable action when they are combined with each other. Moreover, given the evident structural affinities with the fluvastatin molecule that was used in the experimental assays, it is also possible to predict completely similar behaviors for rivastatin.

In conclusion, the molecules object of the present invention which are able to inhibit HMG-CoA reductases can act effectively as active ingredients in antifungal drugs, either alone or in combination with other substances with similar action.

Claims (6)

CLAIMS for use as an antifungal, 2. Compound according to claim 1 wherein ' for use as an antifungal 3. Compound according to claim 1 wherein Z is for use as an antifungal 4. Antimotic pharmaceutical composition comprising as the active ingredient at least one compound according to the formula of claim 1, in combination with at least one antifungal agent allylamine 5. Antifungal pharmaceutical composition comprising as the active ingredient the compound according to claim 2, in combination with terbinafine. 6. Antifungal pharmaceutical composition comprising as the active ingredient the compound according to claim 2, in combination with the compound according to claim 3.