Polyprenyl Carboxylic Acid Derivatives

This invention relates to new polyprenyl carboxylic acid derivatives and a process for the preparation of the same. The polyprenyl carboxylic acid derivatives according to the present invention have the general formula (I): ##STR3## in which n is an integer of from 2 to 4, R.sub.1 represents hydrogen or a protecting group for the carboxyl group, and R.sub.2 represents a hydroxymethyl, formyl or carboxyl group.

In the above-mentioned general formula (I), the protecting group for the carboxyl group is generally an ester residue. More concretely, examples of the protecting groups include an alkyl (C.sub.1-4) group such as methyl, ethyl, propyl or butyl; an alkenyl group such as allyl, geranyl or farnesyl; a cycloalkyl group such as cyclohexyl; and an aryl group such as phenyl or tolyl.

The compounds of the present invention are of value as intermediates for preparing polyprenyl carboxylic acids having the general formula (A): ##STR4## in which l is an integer of from 4 to 11, and esters thereof, that are heretofore known compounds. The hypotensive activity and the anti-ulcer activity of these compounds are disclosed in Japanese Patent Provisional Publications No. 52(1977)-144614 and No. 54(1979)-5043, respectively.

The compounds of the general formula (A) can be, for instance, prepared from the compounds of the present invention by a process which is conducted via a sulfone derivative as disclosed in Japanese Patent Provisional Publications No. 53(1978)-103444 and No. 53(1978)-103445. The compounds of the general formula (I) in which R.sub.2 represents the hydroxymethyl group can be used as intermediates. Otherwise, the compounds of the general formula (I) in which R.sub.2 represents a formyl or carboxyl group can be reduced to the compound (I) in which R.sub.2 represents the hydroxymethyl group.

The reactions can be, for instance, illustrated as follows: ##STR5##

In the above-illustrated formulae, n is an integer of from 2 to 4, m is an integer, R.sub.3 represents a protecting group for the carboxyl group, and Y represents an aryl or alkyl group.

The compounds of the general formula (A) and esters thereof can be also prepared through the Wittig reaction of a polyprenyl aldehyde with the bromo-compound shown in the above-illustrated reaction equation.

As shown in the above, the employment of the compounds of the invention in the preparation of polyprenyl carboxylic acids and esters thereof can increase the carbon number of the carbon chain by 20 to 30 at a time.

Further, various kinds of polyprenyl alcohols can be prepared from a dihydroxy compound which is obtained by reducing the compounds of the invention, in the same manner as the above-described carbon chain lengthening reaction. Polyprenyl alcohols have been known to be intermediate compounds useful for the preparation of pharmacologically active compounds, and are further known as having hypotensive activity, as disclosed in Japanese Patent Provisional Publications No. 54(1979)-70430 and No. 54(1979)-76513.

As described hereinabove, the compounds of the present invention are of value as intermediates for the preparation of pharmacologically active compounds, and also have anti-ulcer activity and hypotensive activity.

The compounds of the present invention can be obtained by oxidizing microbiologically a polyprenyl carboxylic acid with a microorganism belonging to the genus Nocardia.

The microbiological characteristics of the strain belonging to the genus Nocardia named BPM 1613 that has been deposited with the Fermentation Research Institute, the Agency of Industrial Science and Technology at 1-1-3, Higashi, Tsukuba-Yatabe-machi, Ibaraki-prefecture, Japan, has been added to its permanent collection of microorganisms as FERM-P No. 1609, and which can be employed for the present invention, are given below. The same Nocardia, BPM 1613 has been deposited also with the Institute for Fermentation, Osaka, 17-85 Juso-honmachi 2-chome, Yodogawa-ku, Osaka, Japan, as deposition number IFO 14101. The color is expressed according to the "Color Standard" published by Nippon Shikisai Kenkyusho (Japan Color Research Center), Japan.

The present strain shows characteristic orange to pink color in almost all culture media, as seen from the cultural characteristics given below. A young vegetative cell grows in a mycelial form, and branching is rarely observed. In an aged cultivated system, the hypha is divided to form a bacillus (0.4-0.6.times.1.8-2.4.mu.), Gram positive, No flagellum, Negative on the acid-fast stain according to the Ziehl-Nielsen method. Aerial mycelium is not observed.

(1) Sucrose--Nitrate Agar Medium (30.degree. C.) poor growth; pink colored colony; no diffusive pigment,

(2) Glucose--Asparagine Agar Medium (30.degree. C.) no growth,

(3) Glycerol--Asparagine Agar Medium (30.degree. C.) poor growth; pink colored colony; no diffusive pigment,

(4) Starch Agar Medium (30.degree. C.) no growth,

(5) Tyrosine Agar Medium (30.degree. C.) poor growth; grayish white colored colony; no diffusive pigment,

(6) Nutrient Agar Medium (30.degree. C.) moderate growth; orange colored colony; no diffusive pigment,

(7) Yeast--Malt Agar Medium (30.degree. C.), rich growth; orange colored colony; no diffusive pigment,

(8) Oatmeal Agar Medium (30.degree. C.), moderate growth; orange colored colony; no diffusive pigment,

(9) Calcium Maleate Agar Medium (27.degree. C.), moderate growth; pink colored colony

(10) Ovalbumin Medium (slant, 27.degree. C.), poor growth; white colony

(11) Potato Section Medium (27.degree. C.), moderate growth; pale orange colored colony

(12) Carrot Section Medium (27.degree. C.), moderate growth; pale pink colored colony,

(1) Growth Temperature Range (on Nutrient Agar Medium, slant): 20.degree.-42.degree. C.,

(2) Liquefaction of Gelatin: negative,

(3) Hydrolysis of Starch: negative,

(4) Coagulation of Defatted Milk, Peptonization: negative,

(5) Litmus Milk: no change,

(6) Production of Melanine-like Pigment: negative,

(7) Reduction of Nitrate: positive,

(8) No gas or acid production from L-arabinose, D-xylose, D-glucose, D-fructose, sucrose, D-mannitol, glycerol, lactose, D-galactose, D-mannose, maltose, trehalose, starch,

(9) Catalase Test: negative,

(10) Production of Indole: negative,

(11) Production of Hydrogen Sulfide: negative.

(Pridham-Gottlieb Agar Medium, 30.degree. C., 7 days) L-arabinose (+), D-xylose (+), D-glucose (++), D-fructose (++), sucrose (++), inositol (+), L-rhamnose (-), raffinose (+), D-mannitol (+) (In the above, (++) means moderate growth, (+) means poor growth, and (-) means no growth)

The above-identified strain was cultivated on the Glycerol-Kelner-Morton Medium in accordance with the method described by Arai et al. in Journal of General Applied Microbiology, 9, 119 (1963). The Actinomycetales, The Jena International Symposium on Taxonomy, 273 (1968) gives absorption bands characteristic of the genus Nocardia on the IR spectrum, that is, I: C & E types, II: C type, III: C type, IV: D type.

Upon studying the above-described characteristics of the strain with reference to Bergey's Manual of Determinative Bacteriology, seventh edition, and Waksman's The Actinomycetes, Volume 2, the strain was determined to belong to the genus Nocardia.

A process for the preparation of the compounds of the present invention is described hereinbelow.

The polyprenyl carboxylic acid derivatives (I) of the present invention can be prepared by a process comprising:

cultivating a microorganism belonging to the genus Nocardia and showing oxidizing activity on a compound having the general formula (II): ##STR6## in which n has the same meaning as defined hereinbefore, and

R.sub.3 represents a protecting group for the carboxylic acid group in a culture medium containing a compound of the general formula (II) as the carbon source;

recovering the so-oxidized product; and

hydrolyzing the so recovered product, if necessary, to give the product having the general formula (I): ##STR7## in which n, R.sub.1 and R.sub.2 have the same meanings as defined hereinbefore.

Examples of the protecting groups R.sub.3 for the carboxyl group of the general formula (II) are the same as those of the protecting groups R.sub.1 for the carboxyl group in the aforesaid general formula (I).

Any microorganism showing an oxidizing activity on the compound of the general formula (II) can be employed in this process. For example, the strain genus Nocardia named BPM 1613 mentioned hereinbefore, Corynebacterium equi IAM 1038, Candida lipolytica IFO 0746, and Mycobacterium smegmatis IFO 3083 can be employed.

The cultivation procedure is now described more concretely hereinbelow.

The components of the culture medium can be optionally chosen from those conventionally employed, except for the inclusion of the compound of the general formula (II) as the carbon source. Examples of nitrogen sources include nitrates such as potassium nitrate, sodium nitrate and ammonium nitrate, and ammonium salts such as ammonium chloride, ammonium sulfate and ammonium phosphate, and ammonia and urea. If necessary, inorganic salts such as potassium phosphate, sodium phosphate, magnesium sulfate, ferrous sulfate and manganese sulfate, and organic nutrient sources such as vitamins and amino acids, yeast extract, corn steep liquor, and malt extract containing the vitamins and amino acids, can be incorporated.

The medium is preferably adjusted to be alkaline in the pH range of 7-10. The cultivation is generally carried out under aerobic conditions such as under aeration and agitation at 20.degree.-40.degree. C. for 2-4 days.

After the cultivation is complete, the cultivation product is extracted with an organic solvent such as ethyl ether, benzene or chloroform to recover the compound of the invention. The product can be separated and purified through silica gel column chromatography. The unreacted starting compound can be recovered in the course of the above-mentioned extraction procedure and column chromatography, and can be employed again as the starting compound for the process of the invention.

The carboxyl-protecting group of the resulting compound can be eliminated from the so-obtained product through a conventional method for hydrolysis of carboxylic acid esters. For example, the elimination can be carried out in the presence of a base such as sodium hydroxide or potassium hydroxide.

The microbiological oxidation of the present process gives different products having hydroxymethyl, formyl and carboxyl groups, respectively, at the terminal R.sub.2 group, depending upon the extent of the oxidation. The constitution of the product, accordingly, can be varied depending upon the cultivation conditions and the kinds of protecting groups used for the carboxyl group of the starting compound.

The present invention is further described more in greater detail in the following examples.

The strain (BPM 1613, FERM-P No. 1609) belonging to the genus Nocardia was precultivated under shaking at 30.degree. C. for 4 days in 50 ml of a medium comprising 2% of n-paraffin, 0.5% of NaNO.sub.3, 0.15% of KH.sub.2 PO.sub.4, 0.15% of Na.sub.2 HPO.sub.4, 0.05% of MgSO.sub.4.7H.sub.2 O, 0.001% of FeSO.sub.4.7H.sub.2 O, 0.001% of CaCl.sub.2.2H.sub.2 O, and 0.02% of yeast extract and having the pH value of 7.2.

Then, the so obtained precultural broth was inoculated, in the volume ratio of 8%, into a jar fermentor (for fermentation of 1 liter medium) with a medium having the same composition as defined above except substituting the n-paraffin (2%) with the compound of the general formula (II) (1%). The cultivation was carried out under aeration-agitation conditions at 30.degree. C. for 3 days. After the cultivation was complete, the cultivation product was extracted with ethyl ether. The solvent was distilled off, and the residue was purified by silica gel column chromatography. In the chromatography, hexane and ethyl ether were employed as the developing solvents.

The products obtained in the above process are set forth in Table 1.