Diagnosis of Shigella Dysenteriae

The present invention relates to compounds and compositions which are useful for therapeutic treatment of disorders caused by the toxin of Shigella dysenteriae as well as prophylaxis and diagnosis in connection herewith. The invention also relates to a method of therapeutic treatment of mammals including man.

Necrosis of the epithelium of the colon is part of the pathogenesis of bacillary dysenteria after infection with Shigella dysenteriae (see Davis, B. D., Dulbecco, R., Eisen, H. N., and Ginsberg, N. S. (eds) Microbiology Harper and Row, Publishers, Philadelphia, Third Edition, 1980). The necrosis is due to an invasion of the bacterium into the epithelium to produce therein a toxin which appears to inhibit protein synthesis (see Brown, J. E. Rothman, S. W., and Doctor, B. P. (1980) Infect. Immun. 29, 98-107). The purified toxin has a molecular weight of about 70,000 (see Brown, J. E., Griffin, D. E., Rothman, S. W., and Doctor, B. P. (1982) Infect. Immun. 36, 996-1005) and is composed of one heavy and four to five light subunits similar to the case for cholera toxin (see Olsnes, S., and Eiklid, K. (1980) J. Biol. Chem. 255, 284-289). The toxin has recently been purified on a milligram scale (see Brown, J. E., Griffin, D. E., Rothman, S. W., and Doctor, B. P. (1982) Infect. Immun. 36. 996-1005), which has enabled more detailed studies of its mechanism of action.

The present invention has for its purpose to provide a composition or substance which can be used therapeutically for the treatment of disorders due to infection with Shigella dysenteriae and which can also be used for diagnosing the toxin formed by the mentioned bacterium.

In connection with extensive research and experimentation it has now been found that the active receptor substance visavis the toxin of Shigella dysenteriae has the formula (I): ##STR2##

In this formula R.sub.1 is hydrogen or an organic residue, whereas R.sub.2 is hydrogen, alkyl, alkoxy or a carbohydrate residue. In regard to the meaning of R.sub.2 the proviso holds that R.sub.2 is not .beta.-D-Gal Nacp-(1-O) when R.sub.1 is D-Glc or -.beta.-D-Glcp(1-O)-ceramide. Moreover, R.sub.2 is always different from OH,

R.sub.2 =.alpha.-D-GalNAcp-(1-3)-.beta.-D-GalNAcp-(1-O)-,

R.sub.2 =.beta.-D-GalNAcp-(1-3)-.beta.-D-GalNAcp-(1-O)-,

R.sub.2 =.alpha.-L-Fucp-(1-2)-.beta.-D-Galp-(1-3)-.beta.-D-GalNAcp-(1-O)- and

R.sub.2 =.alpha.-L-Fucp-(1-2)-.alpha.-D-Galp-(1-3)-(1-O)-.

In the substance of formula I above it is preferred that OR.sub.1 is in .beta.-configuration.

Examples of active substances within formula I above are the following:

.beta.-D-Galp-(1-3)-.beta.-D-GalNAcp-(1-3)-.alpha.-D-Galp-(1-4)-.beta.-D-Ga lp-(1-4)-.beta.-D-Glcp-(1-O)-ceramide;

.alpha.-D-Galp-(1-3)-.alpha.-D-Galp-(1-4)-.beta.-D-Galp-(1-4)-.beta.-D-Glcp -(1-O)-ceramide; and

.beta.-D-GalNAcp-(1-3)-.alpha.-D-Galp-(1-4)-.beta.-D-Galp-(1-4)-D-Glucitol.

The expression "lower" used in this disclosure refers to a group containing 1-6 carbon atoms, particularly 1-4 carbon atoms and especially 1 or 2 carbon atoms.

R.sub.1 and R.sub.2 in formula I may independently be a carbohydrate residue, but it is also preferred that R.sub.1 is lower alkyl and independently thereof R.sub.2 is lower alkoxy.

The active substance I of the present invention may be used as such or in combination with a pharmaceutically acceptable carrier.

The active substances according to the present invention can be formulated for use in human or veterinary medicine for therapeutic, prophylactic or diagnostic uses. In clinical practice the active constituents are normally administered orally or rectally or by injection in the form of a pharmaceutical preparation containing the active constituents in combination with a pharmaceutically acceptable carrier, which may be solid, semisolid or liquid, or as a capsule, and such compositions constitute a further aspect of the invention. The compounds may also be used as such without carrier and in a form of an aqueous solution for injection. As examples of pharmaceutical preparations there may be mentioned tablets, drops, solutions and suppositories. The active substance usually constitutes from 0.05 to 99% by weight of the preparation, for example from 0.1 to 50% for preparations intended for oral administration.

To manufacture pharmaceutical preparations in the form of dose units for oral application containing a compound according to the invention the active constituents can be admixed with a solid, pulverulent or other carrier, for example lactose, saccharose, sorbitol, mannitol, starch, such as potato starch, corn starch, amylopectin, a cellulose derivative or gelatin and may also include lubricants, such as magnesium or calcium stearate, or polyethylene glycol waxes compressed to form tablets or cause for dragees.

By using several layers of the active drug separated by slowly dissolving layers tablets of delayed release are obtained.

Liquid preparations for oral application can be in the form of elixirs, syrups or suspensions, for example solutions containing from 0.1 to 20% by weight of active substance, sugar and a mixture of ethanol, water, glycerol, propylene, glycol and optionally other additives of a conventional character.

The dose of which the active constituents are administered may vary within wide limits and depend on different factors, such as the severity of the disorder, the age and the weight of the patient and can be individually adjusted. As a conceivable range for the quantity of active constituents that may be administered per day there may be mentioned from 0.1 to 2000 mg of from 1 mg to 2000 mg.

The present invention also has for a purpose to provide a method for therapeutic treatment of mammals including man, and in such treatment a therapeutically active amount of a substance or a composition in accordance with the invention is administered.

The present invention has also for an object to provide use of the composition or substance according to the invention for therapeutic treatment or diagnosis.

In regard to the meaning of substituent R.sub.1 of the formula I above this may be of any type as long as it does not negatively affect the conditions in connection with the use of the invention. Thus, R.sub.1 may be hydrogen, lower alkyl or lower acyl but R.sub.1 may also constitute the residue of a natural or synthetic glycoconjugate, the compound according to the invention thus being a glycoconjugate, for example a glycolipid.

Moreover, R.sub.1 in formula I may be a macromolecular carrier, optionally including a coupling arm. Such carrier can by a synthetically or naturally occurring polypeptide, polysaccharide or other type of polymer or particle.

The invention will in the following be further described in connection with non-limiting examples.

In connection with the creation of the invention a new analysis method has been devised which can be defined as a form of chromatographic binding assay. The principle for same is the following.

A thin layer chromatogram is prepared from pure defined receptor structures and/or receptor structures in a partly unknown mixture extracted from tissue of interest. The thin layer chromatogram is prepared on a surface of silica gel and is treated after the application for avoiding unspecific binding of the substance of interest with a silica gel. The toxin which has been radioactively labelled with I.sup.125 is then transferred to the treated chromatogram. After washing away excess material, autoradiography indicates which substance remains bound to the individual separated receptor structures. In this manner there information is obtained which indicates which structures are active receptors in relation to the applied toxin and which structures do not show a binding capacity.

The foregoing description of the binding specificity may hereby be obtained by comparision of closely related structures. The identity for a receptor (binding substance) is suitably obtained by comparison with structurally known reference substances. The receptor structures utilized in this disclosure are known substances.

The experiment was carried out with a thin layer chromatogram on a surface of silica gel prepared as indicated above. The thin layer chromatogram was detected with anisaldehyde, and autoradiogram was performed after binding with Shigella-toxine labeled with the radioactive iodoisotope I.sup.125.

The results of the toxin binding studies while using a number of carbohydrate structures are given below in the table, a plus indicating active binding capacity, and a minus indicating lack of binding capacity in relation to the toxin. The table also gives the specificity concerning the binding capacity of the structures according to this invention in that already small deviations in the structure from that defined by formula I results in absence of binding.