WO1994025030A1

WO1994025030A1 - SUBSTITUTED DIOXOLO[4,5-g]FURO[3',4':6,7]INDOLIZINO[1,2-b]QUINOLINONES

Info

Publication number: WO1994025030A1
Application number: PCT/US1994/004865
Authority: WO
Inventors: William Dennis Kingsbury; Israil Pendrak; David Alan Berges
Original assignee: Smithkline Beecham Corporation
Priority date: 1993-05-03
Filing date: 1994-05-03
Publication date: 1994-11-10

Abstract

The present invention provides a method of treating viral infections by using antiviral substituted dioxolo[4,5-g]furoindolizino[1,2-b]quinolinone compounds and pharmaceutical compositions thereof.

Description

SUBSTITUTED DIOXOLO^^-^FUROtS'^'rό lINDOLIZINOCl^- b]QUINOLINONES

SCOPE OF THE INVENTION This invention relates to antiviral compounds, pharmaceutical compositions thereof, and a method of treating viral infections. More specifically, this invention relates to certain dioxolofuro[3',4':6,7]indolizino[l,2-b]quinolinyl derivatives which have antiviral activity.

BACKGROUND OF THE INVENTION Certain lH-pyrano[3',4':6,7]indolizino[l,2-b]quinolinones are known to have cytotoxic and antiviral activity. Camptothecin is an example of one such compound. It is a water-insoluble, cytotoxic alkoloid produced by Camptotheca acuminata trees indigenous to China and Nothapodytes foetida trees indigenous to India. Camptothecin and a few close congeners are the only class of compounds known to inhibit eukaryotic topoisomerase I. The cytotoxic and antitumor activity of camptothecin and its close congeners is due to inhibition of eukaryotic topoisomerase I {Cancer Res. 1988, 48, 1722; Molec. Pharmacol. 1988, 34, 755.) Compounds that are related in structure to camptothecin but do not inhibit eukaryotic topoisomerase I are not cytotoxic to mammalian cells and have no antitumor activity (/. Med. Chem. 1988, 32, 715; Cancer Res. 1989, 49, 1465; Cancer Res. 1989, 49, 4358).

Camptothecin has been shown to have an effect on viruses by a number of investigators in laboratory settings. Although camptothecin has demonstrated antiviral activity in in vitro tissue culture systems, camptothecin and its close analogs that have an E-ring hydroxylactone moiety cannot be considered as useful in vivo antiviral agents because they inhibit mammalian topoisomerase I, inhibit host cell DNA replication, and are cytotoxic to mammalian cells. Furthermore, camptothecin is not expected to be attractive for drug development as an antiviral agent because of unacceptable dose-limiting toxicity, unpredictable toxicity, poor aqueous solubility, and/or unacceptable shelf life stability.

There is a need for new antiviral agents. Substituted indolizino[l,2- b]quinolinones that lack the E-ring α-hydroxy lactone moiety of camptothecin have been shown to be non-cytotoxic to mammalian cells and to lack antitumor activity (Ann. Rev. Pharmcol. Toxicol. 1977, 17, 117; /. Med. Chem. 1989, 32, 715). This is because these compounds do not contain the essential structural features required to inhibit eukaryotic topoisomerase I. But it has been found that some substituted indolizino[l,2-b]quinolinones lacking the E-ring hydroxylactone moiety do have antiviral activity without the undesirable features of camptothecin. As such they are useful for treating viral infections.

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides a method for treating viral infections, which method comprises administering to an infected host in need thereof an effective amount of a compound of Formula I, or a pharmaceutically acceptable salt thereof, alone or in combination with a carrier, diluent or excipient

wherein: R is H or lower alkyl; and

R' is H or NH2-

Another aspect of the present invention also provides a composition comprising a compound of Formula I in combination with an acceptable carrier, excipient, or diluent, particularly a pharmaceutically acceptable carrier, excipient, or diluent.

DETAILED DESCRIPTION OF THE INVENTION

The terms below, defined as follows, are used in describing the present invention throughout this application. The phrase "lower alkyl" refers to an alkyl group of 1 to 6 carbon atoms in any isomeric form, particularly the normal or linear form. Salts of any sort may be made from the present compounds, provided there is an acidic group present or a sufficiently basic nitrogen. Particularly preferred are the pharmaceutically acceptable salts of the instant compounds. These latter salts are those which are acceptable in their application to a pharmaceutical use. By that it is meant that the salt will retain the biological activity of the parent compound and the salt will not have untoward or deleterious effects in its application and use in treating diseases.

Pharmaceutically acceptable salts are prepared in a standard manner. The parent compound in a suitable solvent is reacted with an excess of an organic or inorganic acid, in the case of acid addition salts of a base moiety, or an excess of organic or inorganic base in the case where there is an acid group. Representative acids are hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid, acetic acid, maleic acid, succinic acid or methanesulfonic acid. Cationic salts are readily prepared from metal bases such as sodium, potassium, calcium, magnesium, zinc, copper or the like and ammonia. Organic bases include the mono or disubstituted amines, ethylenediamine, piperazine, amino acids, caffeine, and the like.

Here and throughout this application, the compounds of the present invention are numbered according to structural formula II:

II

If a chiral center or some other form of an isomeric center is created by some combination of substituents in a compound of the present invention, all forms of such isomer(s) are intended to be covered herein. Inventive compounds containing a chiral center may be used as a racemic mixture or the mixture may be separated and an individual enantiomer may be used alone.

The present invention provides a method for the treatment of viral infections comprising administering to an infected host, including humans, in need thereof an effective amount of a compound of Formula I as described hereinabove, or a pharmaceutically acceptable salt thereof, alone or in combination with a carrier, excipient or diluent.

The present compounds and the present method are useful in treating certain DNA replicating animal virus infections. More specifically, these compounds and the present method are especially useful in treating the following pathogens in humans:

Herpes Simplex virus types 1 and 2;

Cytomegalovirus;

Varicella Zoster virus; Epstein Barr virus; and

Papilloma virus (multiple types). Animal pathogens which are treatable with these compounds and by the present method include, but are not limited to:

Equine Herpes virus; Porcine Herpes virus; and

Marek's disease virus.

No unacceptable toxicological effects are expected when compounds of the present invention are administered in accordance with the present invention.

A preferred method of treating viral infections according to the present invention uses compounds of Formula I where R^' and R are H.

Another preferred method of treating viral infections according to the present invention uses compounds of Formula I where R is H and R is CH3.

Yet another preferred method of treating viral infections according to the present invention uses compounds of Formula I where R is NH2 ^anc R s H. The most preferred compounds of the present invention are:

7-ethyl-9,12-dihydro-7-hydroxy-3H,13H-dioxolo[4,5-_<g]furo[3',4': 6,7]indolizino[l,2-b]quinolin-10-one.

7-ethyl-9,12-dihydro-7-methoxy-3H,13H-dioxolo[4,5- g]furo[3',4':6,7]indolizino[l,2-b]quinolin-10-one;

14-amino-7-ethyl-9, 12-dihydro-7-hydroxy-3H, 13H-dioxolo[4,5-g] - f uro [3 ',4' : 6,7] indolizino[ 1 ,2-b] quinolin- 10-one. The most preferred compounds for use in the method of the present invention include the above-named most preferred inventive compounds. The compounds of the present invention can be prepared from starting materials whose syntheses have been described. 7-Ethyl-7-hydroxy-7,8,l 1,13- tetrahydro-10H-dioxolo[4,5-^]-pyrano[3',4':6,7]indolizino[l,2-b]quinolin-8,ll- dione was prepared as described in Wani, et al;. J. Med. Chem. 1986.29, 2358. 15- Amino-7-ethyl-7-hydroxy-7,8,l l,13-tetrahydro-10H-dioxolo[4,5- g]pyrano[3\4':6,7]indolizino[l,2-b]quinolin-8,l 1,-dione is disclosed in published European Patent Application No. 0418099 A2.

The dihydrofuran ring may be formed by a three-step process comprising: (i) reducing the lactone ring of a 7-ethyl-7-hydroxy-7,8,ll,13-tetrahydro-10H- dioxolo[4,5-g]pyrano[3',4':6,7]indolizino[l,2-b]quinolin-8,l 1-dione to form a 7- ethyl-7,8 dihydroxy-7,8,10,13-tetrahydro-l lH-dioxolo[4,5- g]pyrano[3',4':6,7]indolizino[l,2-b]quinolin-ll-one with, for example, sodium borohydride as described by T.R. Govindachari, K.R. Ravindranath, and N.J. Viswanathan, J. Chem. Soc. Perkin Trans. I. 1974. 1215 for the corresponding reduction of camptothecin; (ii) oxidizing the product of the above reduction to produce an 8-fomιyloxymethyl-7-(l-oxopropyl)dioxolo[4,5-g]indolizino[l,2- b]quinolin-9(l lH)-one with, for example, sodium metaperiodate in aqueous acetic acid; and (iii) and treatment of the product of the above oxidation with a base, for example potassium carbonate, in aqueous methanol to effect cleavage of the formyl group and spontaneous cyclization. The 7-hydroxy group can be derivatized in the form of an ether by treatment with an alcohol under acid catalysis, for example, with Dowex AG50W-X8(Η⁺) ion exchange resin. These reactions are illustrated in Scheme I.

SCHEME I The assay used to test the compounds of the present invention for antiviral activity is well-known. A generalized description of the assay follows.

Well plates are seeded with the appropriate cells at a concentration of lxlO⁵ cells per well suspended in 0.5 mL of Earle's Minimum Essential Medium (EMEM) containing 10% fetal bovine serum (FBS) and antibiotic and antimycotic solution. After the cells are 80-90% confluent (24 hours), old medium is removed and washed with Hank's buffered saline solution (HBSS). Cells are then infected for 1 hour at 37°C with 100-200 plaque forming units per well of a herpes simplex virus suspended in 250 mL HBSS. Following adsorption, the following are added: A) 250 mL/well 2 x EMEM containing Human IgG (Sigma Chemical Co.,

St. Louis, Mo.) (ca. 0.1 mg/mL);

B) 250 mL/well EMEM containing 10% FBS and antibiotic/antimycotic solution; and

C) 250 mL/well HBSS containing appropriately diluted compound. After 24-48 hours (best time determined by observation of plaques under a microscope), old medium is aspirated off. Each well is stained with a selected stain solution (0.5% crystal violet in MeOH:H2θ 7:3) and then rinsed with water, air dried, and the plaques are counted. Compound effectiveness is evaluated in terms of percent plaque reduction as compared to untreated, infected controls. This assay can be used to test compound activity against many other viruses besides herpes simplex by simply modifying the cell type used in the first step to match the virus being tested, and otherwise following the procedure outlined above. Other cell types which can be used in this assay include mouse mammary tumor cells, human lung fibroblasts, sheep chorioplexus cells, and green monkey kidney cells.

Alternatively, other assays can be used to determine the antiviral activity of the present compounds. Such assays include the following types: cell count, clonogenic, cytopathic effect, dish-colony formation, microtiter-growth inhibition, thymidine incorporation and yield reduction. Each of these assays is well-known and is available either from the literature or from a commercial testing lab.

The present invention provides pharmaceutical compositions prepared from the compounds of Formula I. These compositions have both a human and veterinary utility, and comprise an excipient or carrier which is acceptable for the intended pharmaceutical end use and at least one inventive compound. For example, if a veterinary use is intended, the carrier may be a liquid, or spray, or may be formulated in a solid, non-degradeable or degradeable form for insertion in the rumen. Selected excipients and carriers may be employed to prepare compositions acceptable or adaptable for human use.

An effective amount of the pharmaceutical compositions of the present invention may be contained in one embodiment, such as in a single pill, capsule, or pre-measured intravenous dose or pre-filled syringe for injection. Alternatively, as is frequently the case, the composition will be prepared in individual dose forms where one unit, such as a pill, will contain a sub-optimal dose but the user will be instructed to take two or more unit doses per treatment. When the composition is presented as a cream, it will contain a discrete amount of drug and the user will apply some amount of the cream one or more times until the disease is in remission or has been effectively treated. Concentrates for later dilution by the end user may also be prepared, for instance for IV formulations and multi-dose iηjectable formulations.

Carriers or diluents contemplated for use in these compositions are generally known in the pharmaceutical formulary arts. Reference to useful materials can be found in well known compilations such as Remington's Pharmaceutical Sciences.

Mack Publishing Co., Easton, Pa.

The nature of the composition and the pharmaceutical carrier or diluent will, of course, depend upon the intended route of administration, for example whether by intravenous and intramuscular injection, parenterally, topically, orally, or by inhalation.

For parenteral administration the pharmaceutical composition will be in the form of a sterile injectable liquid such as an ampule or an aqueous or nonaqueous liquid suspension. For topical administration the pharmaceutical composition will be in the form of a cream, ointment, liniment, lotion, paste, spray or drops suitable for administration to the skin, eye, ear, nose or genitalia.

For oral administration the pharmaceutical composition will be in the form of a tablet, capsule, powder, pellet, atroche, lozenge, syrup, liquid, or emulsion. The pharmaceutical carrier employed may be, for example, either a solid or liquid. When the pharmaceutical composition is employed in the form of a solution or suspension, examples of appropriate pharmaceutical carriers or diluents include: for aqueous systems, water, for non-aqueous systems: ethanol, glycerin, propylene glycol, olive oil, corn oil, cottonseed oil, peanut oil, sesame oil, liquid paraffins, and mixtures thereof with water; for solid systems: lactose, terra alba, sucrose, talc, gelatin, agar, pectin, acacia, magnesium stearate, stearic acid, kaolin and mannitol; and for aerosol systems: dichlorodifluoromethane, chlorotrifluoroethane and compressed carbon dioxide. Also, in addition to the pharmaceutical carrier or diluent, the instant compositions may include other ingredients such as stabilizers, antioxidants, preservatives, lubricants, suspending agents, viscosity modifiers and the like, provided that the additional ingredients do not have a detrimental effect on the therapeutic action of the instant compositions. Similarly, the carrier or diluent may include time delay material well known to the art, such as glyceryl monostearate or glyceryl distearate alone or with a wax, ethylcellulose, hydroxypropylmethylcellulose, methylmethacrylate and the like. A wide variety of pharmaceutical forms can be employed. Thus, if a solid carrier is used, the preparation can be tableted, placed in a hard gelatin capsule in powder or pellet form or in the form of a troche or lozenge. The amount of solid carrier will vary widely but preferably will be from about 25 mg to about 1 gram. If a liquid carrier is used, the preparation will be in the form of a syrup, emulsion, soft gelatin capsule, sterile injectable solution or suspension in an ampule or vial or nonaqueous liquid suspension. To obtain a stable water soluble dose form, a pharmaceutically acceptable salt of the compound of Formula I is dissolved in an aqueous solution of an organic or inorganic acid or base. If a soluble salt form is not available, the compound of Formula I may be dissolved in a suitable co-solvent or combinations thereof. Examples of such suitable cosolvents include, but are not limited to, alcohol, propylene glycol, polyethylene glycol 300, polysorbate 80, glycerin and the like in concentrations ranging from 0-60% of the total volume. It will be appreciated that the actual preferred dosages of the compounds used in the compositions of this invention will vary according to the particular complex being used, the particular composition formulated, the mode of administration and the particular site, host and disease being treated. It is expected that these compounds will be active in the concentration ranges of two commercial antiviral drugs, Cytovene (ganciclovir) and Zovirax (acyclovir). The latter is manufactured in 200 mg capsules with instructions for treating herpes simplex viral infections by taking one capsule every 4 hours, but not to exceed 5 capsules per day.

Claims

We claim:

A method for treating viral infections comprising administering to an infected host in need thereof an effective amount of a compound of Formula I, or a pharmaceutically acceptable salt thereof, alone or in combination with a carrier, diluent or excipient

wherein:

R is -H or lower alkyl; and

R" is -H or -NH₂.

The method of claim 1 wherein said compound is 7-ethyl-9,12-dihydro-7- hydroxy-3H,13H-dioxolo[4,5-^]furo[3',4':6,7]indolizino[l,2-b]quinolin-10- one.

The method of claim 1 wherein said compound is 7-ethyl-9,12-dihydro-7- methoxy-3H, 13H-dioxolo[4,5-g]furo[3',4':6,7]indolizino[ 1 ,2-b]quinolin- 10- one.

4. The method of claim 1 wherein said compound is 14-amino-7-ethyl-9,12- dihydro-7-hydroxy-3H, 13H-dioxolo[4,5-£]furo[3',4':6,7]indolizino[ 1 ,2- b]quinolin-10-one. A compound of Formula I

wherein:

R is -H or lower alkyl; and

R^* is -H or -NH₂.

6. The compound of claim 5 wherein said compound is 7-ethyl-9,12-dihydro-7- hydroxy-3H,13H-dioxolo[4,5-^]furo[3',4':6,7]indolizino[l,2-b]quinolin-10- one.

7. The compound of claim 5 wherein said compound is 7-ethyl-9,12-dihydro-7- methoxy-3H,13H-dioxolo[4,5-^]furo[3',4':6,7]indolizino[l,2-b]quinolin-10- one.

8. The compound of claim 5 wherein said compound is 14-amino-7-ethyl-9, 12- dihydro-7-hydroxy-3H, 13H-dioxolo[4,5-g]furo[3',4':6,7]indolizino[ 1 ,2- b] quinolin- 10-one.

9. A formulation comprising a compound as claimed in claim 5 in admixture with a carrier.

10. The formulation of claim 9 wherein the carrier is a pharmaceutically acceptable excipient. 11. The method of claim 1 where the viral infection is caused by a herpes simplex virus.

12. The method of claim 11 wherein said virus is herpes simplex type 1 and the infected host is a mammal.

13. The method of claim 11 wherein said virus is herpes simplex type 2 and the infected host is a mammal.

14. The method of claim 1 wherein said virus is cytomegalovirus and the infected host is a mammal.

15. The method of claim 1 wherein said virus is varicella zoster and the infected host is a mammal.