Medicaments Containing Pichia or Extracts Thereof

The present invention relates to the use of Pichia, in particular Pichia fermentans, or extracts of Pichia as such, as a medicament.

Pichia is a yeast belonging to the Saccharomycetaceae family and to the Saccharomycoideae sub-family comprising numerous genera. These genera are defined for example in "The Yeasts" (LODDER, North Holland Publishing Company, 1970, pages 405 to 554). The species Pichia fermentans, which has been more especially studied by the Applicants, is known and can be obtained form several collections of micro-organisms, for example from the CENTRAALBUREAU VOOR SCHIMMEL CULTURES (DELFT, Netherlands), under No. CBS 187.

To the Applicants' knowledge, Pichia has never been studied with a view to therapeutic use. Yeasts belonging to a different genus, such as Saccharomyces cerevisiae, have been used in therapeutic applications, in particular as protective or regenerative agents for the intestinal bacterial flora.

Moreover, certain authors have studied extracts of Saccharomyces cerevisiae or their glucanes as regards their effect on the reticulo-endothelial system (RIGGI and Di Luzio, Am J. Physiol. (1961) 200, 2, pages 297-300) or as regards their anti-tumor action (HAMURO and colleagues, C.A., (1978), 89, 40 704 b).

Now, the Applicants have found that Pichia, notably Pichia fermentans as well as its extracts, in particular the insoluble glucanes, have exceptional pharmacological properties that justify their use as medicaments in the treatment of infectious diseases: non-specific immunostimulation, potentialisation of the action of antibiotics, and increase in the activity of vaccines.

The Pichia strains may be cultivated and grown in a known manner on culture and fermentation media conventionally used for yeasts. The cells obtained may be dried at 50.degree. in vacuo, but are preferably lyophilised (freeze dried).

The extracts according to the invention, which are in principle insoluble glucanes, may be isolated from the cell walls of Pichia, for example by the method described by Bell and Northcote (J. Chem. Soc. (1950), p. 1944-47), if necessary modified, for example according to Peat and colleagues (idem, 1958a, p. 3862-3868). The principle consists of removing first the proteins, lipids and mannans by alkaline treatment (for example with a diluted strong alkali such as sodium hydroxide), and then the glycogen and the soluble glucanes by acid treatment (for example with acetic or hydrochloric acid), from the cellular mass obtained by fermentation. The extract may be dried by atomization.

The following examples illustrate the preparation of these products.

(a) Preparation of yeast sediments

The yeast sediment (the sediment placed in the bottom of the vat to start fermentation) is prepared from the stock culture for the Pichia fermentans strain. The latter is obtained by incubating yeast for 48 hours at 30.degree. C. on sloped agar containing:

The culture is separated from the sloped agar via a tube, using about 10 ml of sterile physiological serum. The suspension thus obtained is added, while maintaining sterile conditions, to a 6-liter volume Erlenmeyer flask containing 1.5 liter of fermentation medium of the following composition:

Incubation is carried out for 24 hours at 27.degree..+-.1.degree. in a rotary agitator operating at about 115 revs./minute.

(b) Fermentation

The contents of the Erlenmeyer flask as obtained above (about 3 liters) are inoculated in a sterile fermentation vat containing 100 liters of medium (2) described above. Fermentation is carried out for 20 hours while aerating at a rate of 20 m.sup.3 /hour. The contents of the vat are then centrifuged in order to collect the mass containing the Pichia cells.

2.8 kg of a cellular mass are obtained (74% moisture).

255 g of cells ready for use are obtained by drying in vacuo at 50.degree. C. 1 kg of the cellular mass obtained in Example 1.

An alternative, which can be used in order to obtain a product that is easier to store and use, is as to lyophilise the cellular mass obtained in Example 1; in this way 252 g of utilisable cells are obtained from 1 kg of cellular mass.

1 kg of freshly centrifuged cellular material obtained according to Example 1 is treated with 3 liters of a 6% sodium hydroxide solution for 11/2 hours at 80.degree. C.; the residue is collected by centrifugation (4000 revs./minute for 15 minutes) and is then treated with 5 liters of a 3% sodium hydroxide solution for 18 hours at ambient temperature. The solution is recentrifuged and the insoluble product is retreated with a 3% sodium hydroxide solution for 2 hours at 80.degree. C. The solution is centrifuged and the centrifuge deposit is taken up in 3 liters of water. The suspension thus obtained is adjusted to a pH of 4.5 with acetic (or hydrochloric) acid and is heated at 80.degree. C. for 2 hours while stirring. The residue obtained by centrifugation is washed 3 times with 1 liter of boiling water each time, is taken up in 2.5 liters of a 0.02M sodium acetate solution, and is then autoclaved at 1 bar atmosphere for 11/2 hour.

The insoluble fraction is washed with water, then with ethanol and acetone, and is dried in vacuo at a maximum temperature of 50.degree. C. The product obtained is ground and provides 15.5 g of a cream colored powder.

An alternative method is lyophilisation, and 14.2 g of extract can be obtained starting from the same quantity of cells.

A further method is atomization, and 15.3 g of extract can be obtained starting from the same quantity of cells. This extract has a particle size between 5 and 30.mu., which enables use without further treatment.

Analysis: C=45.15%; H=7.42%; 0=47.4% N<0.2% P: absent.

The action of pancreatic amylase on the extract releases only a few traces of reducing compounds, thus indicating the absence of glycogen.

The extract according to the invention is remarkable in that it is insoluble in water, alkaline or acid diluted solutions, and the usual organic solvents such as ethanol, diethyl ether, ethyl acetate, acetone, chloroform, etc.

It is found however that it is very slightly soluble in dimethyl sulphoxide (DMSO).

Specific rotary power: .vertline..alpha..vertline..sub.D.sup.20 .congruent.-60.degree. (C=0.2; DMSO).

Infra-red: the spectrum obtained using a KBr prism has a characteristic absorption band at 885 cm.sup.-1.

The presence of such IR absorption band is proof that the Pichia extract contains .beta. bonds and specifically .beta.1--3 bonds. The partial hydrolysis of the extract confirms the presence of a major part of .beta.1--3 bonds and also of some .beta.1--6 bonds.

According to the methylation test (Hakomori method, Methods of Enzymology 28 178-195, 1972), the observed presence of sugar bonded in .notident.1--3--6 means that the Pichia extract in fact has a branched structure, which is believed to correspond to the following formula (presumed formula): ##STR1## in which G=glucose unit,

x+y+z=about 40 and

n=about 26.

It is to be noted that the above formula does not indicate the exact position of the .beta.1--6 bonds within the chains, which simply have been placed so that the above proportion (one .beta.1--6 bond for 9 to 10 glucose units) is satisfied.

The polymerization degree as determined according to the method of Manners et al. (Manners, Masson, Patterson, Carbohyd. Res. 17 (1971) 109-104), is 1320 (.+-.100) which corresponds to a molecular weight of about 200,000 to 230,000.

Thus the Pichia extract according to the invention, which will be called "glucans" hereafter in the text, consists essentially of branched .beta. (1--3)- and .beta. (1--6)-D-glucans comprising about one .beta. (1--6) bond for 9 to 10 glucose units, said glucans having a molecular weight of about 200,000 to 230,000.

The Pichia yeasts, in particular Pichia fermentans as well as the glucanes extracted therefrom, have been subjected to pharmacological tests.

No toxicity was observed when Pichia fermentans or its glucanes were administered orally to mice.

The LD.sub.50 of these glucanes administered intraperitoneally is greater than 500 mg/kg.

The animals used were female IOPS IFFA CREDO mice weighing 18-20 grams and fed for one week before the test on a diet containing no yeast but containing the necessary dosage of vitamins.

The mice were split up into 2 batches each containing 10 animals:

1 infected control batch

1 infected batch treated with Pichia.

The animals were infected intravenously with a highly pathogenic strain of Staphylococcus aureus (Institut Pasteur Strain No. 54 146), and the Staphylococcus aureus used was reactivated by being passed through mice before the test. A culture in nutrient broth incubated for 16 hours at 37.degree. C. was diluted to 1/100 and then used to infect the mice. Each mouse received intravenously, under these conditions, about 6.times.10.sup.5 virulent germs.

The experimental schedule was as follows:

The number of dead mice in each batch is noted every day. This test was carried out 5 times and the following results, expressed in terms of the number of surviving mice, were obtained.

As can be seen, the number of dead mice in the treated batch is less than the number of dead mice in the control batch.

In view of the virulence of the injected pathogen, a substantial protection is conferred by the oral administration of Pichia.

This protection can be attributed to a non-specific immunostimulation.

The animals used were female IOPS IFFA CREDO mice weighing 18-20 grams, fed for 8 days before the test on a diet free from yeasts but containing the necessary amount of vitamins.

The mice were divided into 2 batches:

1 infected control batch

1 infected batch treated either with Pichia or with its glucanes.

The tests were carried out on mice infected intravenously with about 1.times.10.sup.6 Staphylococcus aureus pathogens (Institut Pasteur Strain 54.146) prepared as described previously.

The treatment was given intraperitoneally.

for Pichia fermentans, in a dosage of 50 mg/kg

for the glucanes of Pichia fermentans, in a dosage of 10 mg/kg.

The experimental schedule was as follows:

The number of dead mice in each batch is noted every day.

The following tables show the number of surviving animals for several tests.

As can be seen, the number of dead mice is less in the treated batches than the number of dead mice in the control batches, whether treatment is effected with whole cells of Pichiafermentans or its glucanes.

Given the virulence of the injected pathogen, intraperitoneal injection of Pichia or its glucanes confers a high degree of protection.

This protection can be attributed to a non-specific immunostimulation.

Cultures of Pichia kluyveri (ATCC 9768), Pichia membranae faciens (ATCC 26288 and CBS 107) and Pichia polymorpha (ATCC 18577 and CBS 6.2) are grown and treated in the same manner as described above in Example 1 for Pichia fermentans. Whole cells of Pichia are lyophilized as in Example 2 above, and glucanes thereof are obtained by the process of Example 3 above. The immunostimulative effect produced through oral treatment is tested by the method described previously. The results are shown in the table below:

The immunostimulative effect produced through intraperitoneal treatment is tested by the method described previously. The results are shown in the table below:

The animals used were female SPF IFFA-CREDO mice weighing 18-20 grams, fed for one week before the tests on a diet free from yeast but containing the necessary dosage of vitamins.

These mice were divided into 4 batches each containing 10 mice.

batch 1: infected control batch

batch 2: antigen control batch ("vaccine")

batch 3: received the specific antigen and were also infected

batch 4: as per batch 3, but treated in addition with Pichia glucanes.

The antigen in this case is a Staphylococcus aureus culture (Institut Pasteur 54.146) administered in a non-lethal dosage.

The culture is grown for 16 hours in nutrient broth and is then diluted immediately before vaccination to 1.times.10.sup.-4, representing about 1.times.10.sup.4 germs/ml.

The mice of batches 1, 3 and 4 were infected with a highly pathogenic strain of reactivated Staphylococcus aureus (Institut Pasteur 54.146). A nutrient broth culture incubated for 16 hours at 37.degree. was injected undiluted and intravenously to infect the mice (i.e. 1.times.10.sup.8 germs/ml).

The number of dead mice in each batch is noted every day. The following table gives the survival rate as a function of time.

100% of the animals infected with a superlethal dose of Staphylococcus aureus were dead within 24 hours.

The animals that had been vaccinated once 9 days before the superlethal infection are slightly protected since they all die only after 8 days.

As may be seen from the results in the tables, treatment by glucanes administered intraperitoneally in addition to vaccination protects the animals not only by increasing the survival time but also by reducing the mortality rate.

Given the very high degree of virulence of the injected pathogen, the potentialization conferred by the glucanes on a specific prevaccination is quite considerable. This potentialization can in this case also be attributed to an immunostimulation.

In this test, a therapeutic treatment for 2 days using glucanes in a dosage of 10 mg/kg was combined with a short-term course of antibiotic treatment (single injection of penicillin) in a normal therapeutic dosage (30,000 units/kg).

The animals used were the same strain as in the previous tests, and were fed on the same diet.

The mice were divided into 4 batches each containing 5 mice:

batch 1: infection control

batch 2: treated with Pichia glucanes

batch 3: received 1 injection of penicillin

batch 4: received Pichia glucanes and 1 injection of penicillin.

The test was carried out on mice infected intravenously with about 1.times.10.sup.6 reactivated Staphylococcus aureus pathogens (Institut Pasteur 54.146).

A culture in nutrient broth incubated for 16 hours at 37.degree. C. as diluted to 1/100 and used to infect the mice.

The experimental schedule was as follows:

The number of dead mice is noted every day, and the following table gives the number of surviving mice observed in each batch.

As before, protection is conferred by Pichia glucanes alone, although used as a therapeutic treatment in this test (3/5).

Penicillin conferred a slight protection on the animals (2/5).

The combination of glucanes with the same dosage of penicillin potentialized the antibiotic action of the latter (4/5).

The tests described above show that the administration of Pichia fermentans or its glucanes on the one hand reduces, by non-specific immunostimulation, the mortality rate in animals infected with a pathogen, and on the other hand potentializes the action of antibiotics and vaccines. This yeast can thus be used to reinforce the resistance of an organism to infectious agents and to improve the immune defense system.

Since the Pichia fermentans yeasts and glucanes extracted therefrom are non-toxic, they may be used in the prevention and/or treatment of acute or chronic infectious diseases, in particular diseases of the oto-rhino-laryngeal and/or pulmonary systems, but may also be used to treat any other illness of viral or bacterial origin.

Pichia fermentans and its glucanes may be used as medicaments alone or in combination with one or more antibiotics.

The whole cells of Pichia may be administered orally in daily dosages of 100 to 2000 mg (dry product) per day, preferably in capsules containing the lyophilised cells and, if desired, with convention excipients, or as ampules for oral consumption, the cells being suspended in their culture medium.

The Pichia glucanes may also be administered orally (a gastroresistant form) in daily dosages of 20 to 500 mg, preferably 50-200 mg, or may also be used in the form of injectable suspensions in an amount of 5 to 100 mg per day. The use of these glucanes in the form of skin creams or aerosols may also be considered. An aerosol dosage of about 5-50 mg per day, preferably 5-10 mg per day, is contemplated. The contemplated treatment involves daily dosages for 5 to 8 days, repeated after one week if necessary. The oral form is contemplated for general use in treating infectious diseases. The aerosol form is contemplated for treatment of diseases of the upper respiratory and pulmonary system, particularly for immuno-depressed subjects, such as post-operative, radiation treatment and burn victim situations or those suffering from chronic respiratory diseases.

Example of the composition of an injectable suspension:

Example of an aerosol

Example of the composition of an oral form

This form consists in neutral microgranules on which micronized glucanes are fixed and which are protected by three successive Eudragit L coatings. The composition of said form is as follows:

The neutral microgranules may be a 70/30 mixture of sucrose and starch on which the active substance is applied by successive coatings. An example of a suitable material is that sold under the trademark "NUPAREL" by Edward Mendell, Inc.