The compound of formula I ##STR1## in which R.sup.1 is alkyl; and R is alkyl, naphthyl, benzhydryl, fluorophenylmethyl, phenethyl, 1-(fluorophenyl)ethyl, 5-chloro-2-methoxyphenyl, trifluoromethoxyphenyl, trifluoromethylphenyl, methylsulfanylphenyl or pyridyl are useful for increasing blood serum HDL levels.

This application claims the benefit of U.S. application Ser. No. 
60/007,661, filed Nov. 28, 1995. 
BACKGROUND OF INVENTION 
Numerous studies have demonstrated that both the risk of coronary heart 
disease (CHD) in humans and the severity of experimental atherosclerosis 
in animals are inversely correlated with serum HDL cholesterol (HDL-C) 
concentrations (Russ et al, Am. J. Med., 11 (1951) 480-493; Gofman et al, 
Circulation, 34 (1966) 679-697; Miller and Miller, Lancet, 1 (1975) 16-19; 
Gordon et al, Circulation, 79 (1989) 8-15; Stampfer et al, N. Engl. J. 
Med., 325 (1991) 373-381; Badimon et al, Lab. Invest., 60 (1989) 455-461). 
Atherosclerosis is the process of accumulation of cholesterol within the 
arterial wall which results in the occlusion, or stenosis, of coronary and 
cerebral arterial vessels and subsequent myocardial infarction and stroke. 
Angiographical studies have shown that elevated levels of some HDL 
particles appears to be correlated with a decrease in the number of sites 
of stenosis in the coronary arteries of humans (Miller et al, Br. Med. J., 
282 (1981) 1741-1744). 
There are several mechanisms by which HDL may protect against the 
progression of atherosclerosis. Studies in vitro have shown that HDL is 
capable of removing cholesterol from cells (Picardo et al, 
Arteriosclerosis, 6 (1986) 434-441). Data of this nature suggests that one 
antiatherogenic property of HDL may lie in its ability to deplete tissues 
of excess free cholesterol and eventually lead to the delivery of this 
cholesterol to the liver (Glomset, J. Lipid Res., 9 (1968) 155-167). This 
has been supported by experiments showing efficient transfer of 
cholesterol from HDL to the liver (Glass et al, Circulation, 66 (Suppl. 1) 
(1982) 102; MacKinnon et al, J. Biol. Chem., 261 (1986) 2548-2552). In 
addition, HDL may serve as a reservoir in the circulation for apoproteins 
necessary for the rapid metabolism of triglyceride-rich lipoproteins (Grow 
and Fried, J. Biol. Chem., 253 (1978) 1834-1841; Lagocki and Scanu, J. 
Biol. Chem., 255 (1980) 3701-3706; Schaefer et al, J. Lipid Res., 23 
(1982) 1259-1273). Accordingly, agents which increase HDL cholesterol 
concentrations are useful as anti-atherosclerotic agents, particularly in 
the treatment of dyslipoproteinemias and coronary heart disease. 
U.S. Pat. No. 5,137,904 discloses a group of thiohydantoin derivatives of 
the formula 
##STR2## 
in which Z is alkyl, phenylalkyl, phenyl or substituted phenyl, where the 
substituent is a halogen, alkyl, alkoxy or halogenated alkyl group; X is 
phenyl, halophenyl, alkyl, alkenyl, or alkynyl; and Y is S or O. These 
compounds inhibit collagen-induced and ADP-induced platelet aggregation. 
EP 0584694 and WO 93/18057 disclose a group of imidazolidin-3-yl benzoyl or 
alkanoyl amino acid derivatives as inhibitors of cell-cell adhesion for 
use in inhibition of thrombocyte aggregation, metastasis and osteoclast 
formation. Chronic administration for prevention of arteriosclerosis and 
thrombosis is disclosed. 
##STR3## 
in which Y=--(CH.sub.2).sub.n --CO-- or --Ph--CO--. 
JP 04,297,461 discloses a group of 2-thiohydantoin compounds of the 
following formula, said to be useful as anti-bacterial, anti-viral, 
anti-inflammatory and anti-rheumatic agents: 
##STR4## 
where R.sup.1 is lower alkyl, lower alkenyl, phenyl(lower)alkyl or 
substituted phenyl with 1-3 groups chosen from lower alkyl, lower alkoxy, 
halogen, lower alkoxycarbonyl or hydroxy; 
R.sup.2 is either hydrogen or alkanoyl; and 
R.sup.3 is hydrogen, lower alkyl, phenyl, phenyl (lower) alkyl, or a lower 
alkylthio, lower alkyl group that can be substituted with one to three 
phenyl groups that have had a lower alkoxy group. 
EP 0578516 discloses a group of 2-thiohydantoins, said to be useful 
anti-androgenic agents for treatment of various cancer, of the formula: 
##STR5## 
where X is oxygen or sulfur; 
Y is oxygen, sulfur or NH 
R.sup.1 and R.sup.2 are cyano, nitro, halogen, trifluoromethyl, or a free 
or esterified carboxylic acid or salt; 
R.sup.3 is hydrogen, alkyl, alkenyl, alkynyl, aryl or aryl-alkyl; 
R.sup.4 and R.sup.5 are hydrogen, optionally substituted alkyl, or 
cycloalkyl. 
U.S. Pat. No. 5,411,981 discloses compounds closely related to EP 0578516, 
supra, where R.sup.4 and R.sup.5 are both methyl. 
U.S. Pat. No. 3,923,994 discloses a group of 3-aryl-2-thiohydantoin 
derivatives of the following formula, which have anti-arthritic activity: 
##STR6## 
where R.sup.1 and R.sup.2 are hydrogen, chloro, bromo, fluoro or alkyl of 
1-2 carbon atoms. 
JP 73 87,030 discloses a group of 3-phenyl-2-thiohydantoin derivatives 
useful as herbicides. 
U.S. Pat. No. 4,473,393 discloses a group of pesticidal thiohydantoin 
compositions. 
DESCRIPTION OF INVENTION 
In accordance with this invention there is provided a group of substituted 
2-thioxo-imidazolidin-4-one derivatives that are useful for increasing HDL 
cholesterol concentration in the blood of a mammal. These substituted 
2-thioxo-imidazolidin-4-one derivatives are depicted by structural formula 
I: 
##STR7## 
in which R.sup.1 is alkyl of 1 to 6 carbon atoms; and 
R is alkyl of 1 to 6 carbon atoms, naphthyl, benzhydryl, 
fluorophenylmethyl, phenethyl, 1-(fluorophenyl)ethyl, 
5-chloro-2-methoxyphenyl, trifluoromethoxyphenyl, trifluoromethylphenyl, 
methylsulfanylphenyl or pyridyl. 
Of these compounds, the preferred members are those in which R.sup.1 is 
alkyl of 1 to 3 carbon atoms; and R is alkyl of 1 to 4 carbon atoms, 
2-naphthyl, benzhydryl, 4-fluorophenylmethyl, phenethyl, 
1-(4-fluorophenyl)ethyl, 5-chloro-2-methoxyphenyl, 
4-trifluoromethoxyphenyl, 2-trifluoromethylphenyl, 2-methylsulfanylphenyl 
or 3-pyridyl. 
The compounds of the invention can be prepared readily according to the 
following reaction scheme or modification thereof using readily available 
starting materials, reagents and conventional synthetic procedures. It is 
also possible to make use of variants of these process steps, which in 
themselves are known to and well within the preparatory skill of the 
medicinal chemist. In the following reaction scheme, R.sup.2 is hydrogen 
or alkyl of 1 to 6 carbon atoms and X is a halogen. 
##STR8## 
N-Substituted amino acids (2a) were prepared by reacting the corresponding 
a-halo acids (1) with the appropriate amines (excess). The reaction was 
carried out either neat or in water at ambient temperature for 18 hours. 
One equivalent of the amine scavenges the hydrohalide formed during the 
alkylation forming the amine hydrohalide (2b) as a side product. The 
N-alkyl amino acids (2a) were either purified by crystallization from an 
appropriate solvent, or reacted with the isothiocyanates as crude product 
mixtures containing the amine hydrohalide salt. Reaction of 2a with 
isothiocyanates is carried out in chloroform or methylene chloride in the 
presence of a base such as triethyl amine. The mixture is heated at reflux 
for 3 to 18 hours. The reaction affords either the thiourea (3a) or the 
thiohydantoin (4) directly (depending on the nature of R.sup.1). 
Cyclization of 3a to the thiohydantoin (4) is accomplished by refluxing in 
ethanol for 2 to 3 hours in the presence of base (triethyl amine). In the 
case of reacting the crude product mixture (2a & 2b) with isothiocyanates, 
the thiourea (3b) is formed as a side product along with 4. Purification 
of 4 was achieved by 1) fractional crystallization, 2) flash 
chromatography, 3) extracting 3b in 2N hydrochloric acid or 4) 
precipitating 3b as its hydrochloride salt from an appropriate solvent 
such as ethyl acetate or diethyl ether. 
This invention also provides pharmaceutical compositions comprised of the 
2-thioxo imidazolidin-4-one derivatives either alone or in combination 
with excipients (i.e. pharmaceutically acceptable materials with no 
pharmacological effects). Such compositions are useful in the treatment of 
atherosclerotic conditions such as dyslipoproteinemias and coronary heart 
disease, in that they increase the blood serum high density lipoprotein 
concentration of mammals treated with the compounds. 
The precise dosage to be employed depends upon several factors including 
the host, whether in veterinary medicine or human medicine, the nature and 
severity of the condition being treated, the mode of administration and 
the particular active substance employed. The compounds may be 
administered by any conventional route, in particular enterally, 
preferably orally in the form of tablets or capsules. Administered 
compounds can be in the free form or pharmaceutically acceptable salt form 
as appropriate, for use as a pharmaceutical, particularly for use in the 
prophylactic or curative treatment of atherosclerosis and sequelae (angina 
pectoris, myocardial infarction, arrhythmias, heart failure, kidney 
failure stroke, peripheral arterial occlusion, and related disease 
states). These measures will slow the rate of progress of the disease 
state and assist the body in reversing the process direction in a natural 
manner. 
Any suitable carrier known to the art can be used to prepare the 
pharmaceutical compositions. In such a composition, the carrier may be a 
solid, liquid or mixture of a solid and a liquid. Solid compositions 
include powders, tablets and capsules. A solid carrier can be one or more 
substances which may also act as a flavoring agent, lubricant, 
solubilizer, suspending agent, binder, or tablet disintegrant. In powders, 
the carrier is a finely divided solid which is in admixture with the 
finely divided active ingredient. In tablets the active ingredient is 
mixed with a carrier having the necessary binding properties in suitable 
proportions and compacted in the shape and size desired. Suitable solid 
carriers are magnesium carbonate, magnesium stearate, talc, sugar, 
lactose, pectin, dextrin, starch, gelatin, tragacanth, methyl cellulose, 
hydroxymethyl cellulose, sodium carboxymethyl cellulose, a low melting 
wax, cocoa butter, and the like. Encapsulating materials may also be 
employed with the compounds of this invention, and the term "composition" 
is intended to include the active ingredient in combination with an 
encapsulating material as a formulation, with or without other carriers. 
Cachets may also be used in the delivery of the anti-atherosclerotic 
medicament of this invention. 
Sterile liquid compositions include solutions, suspensions, emulsions, 
syrups and elixirs. The compounds of this invention may be dissolved or 
suspended in the pharmaceutically acceptable carrier, such as sterile 
water, sterile organic solvent or a mixture of both. Preferably the liquid 
carrier is one suitable for parental injection. Where the compounds are 
sufficiently soluble they can be dissolved directly in normal saline with 
or without the use of suitable organic solvents, such as propylene glycol 
or polyethylene glycol. If desired, dispersions of the finely divided 
compounds can be made-up in aqueous starch or sodium carboxymethyl 
cellulose solution, or in a suitable oil, such as arachis oil. Liquid 
pharmaceutical compositions which are sterile solutions or suspensions can 
be utilized by intramuscular, intraperitoneal or subcutaneous injection. 
In many instances a liquid composition form may be used instead of the 
preferred solid oral method of administration. 
It is preferred to prepare unit dosage forms of the compounds for standard 
administration regimens. In this way, the composition can be subdivided 
readily into smaller doses at the physicians direction. For example, unit 
dosages may be made up in packeted powders, vials or ampoules and 
preferably in capsule or tablet form. The active compound present in these 
unit dosage forms of the composition may be present in an amount of from 
about one gram to about fifteen grams or more, for single or multiple 
daily administration, according to the particular need of the patient. The 
daily dose of active compound will vary depending upon the route of 
administration, the size, age and sex of the patient, the severity of the 
disease state, and the response to the therapy as traced by blood analysis 
and the patients recovery rate. By initiating the treatment regimen with a 
minimal daily dose of about one gram, the blood levels of HDL and the 
patients symptomatic relief analysis may be used to determine whether a 
larger dose is indicated. Based upon the data presented below, the 
projected daily dose for both human and veterinary use will be from about 
10 to about 200 milligrams/kilogram per day. However, in general, 
satisfactory results are indicated to be obtained at daily dosages in the 
range of from 400 milligrams to about 2000 milligrams, conveniently 
administered in divided doses two to four times a day. 
The ability of the compounds of this invention to increase blood serum HDL 
levels was established by the following standard experimental procedure 
for determination of HDL cholesterol: 
Male Sprague-Dawley rats weighing 200-225 g are housed two per cage and fed 
Purina Rodent Chow Special Mix 5001-S supplemented with 0.25% cholic acid 
and 1.0% cholesterol and water ad libitum for 8 days. Each test substance 
is administered to a group of six rats fed the same diet with the test 
diet mixed in as 0.005-0.1% of the total diet. Body weight and food 
consumption are recorded prior to diet administration and at termination. 
Typical doses of the test substances are 5-100 mg/kg/day. 
At termination, blood is collected from anesthetized rats and the serum is 
separated by centrifugation. Total serum cholesterol is assayed using the 
Sigma Diagnostics enzymatic kit for the determination of cholesterol, 
Sigma Procedure No. 352, modified for use with ninety-six well microtiter 
plates. After reconstitution with water the reagent contains 300 U/l 
cholesterol oxidase, 100 U/l cholesterol esterase, 1000 U/l horse radish 
peroxidase, 0.3 mmoles/l 4-aminoantipyrine and 30.0 mmoles/l 
p-hydroxybenzenesulfonate in a pH 6.5 buffer. In the reaction cholesterol 
is oxidized to produce hydrogen peroxide which is used to form a 
quinoneimine dye. The concentration of dye formed is measured 
spectrophotometrically by absorbance at 490 nm after incubation at 
25.degree. C. for 30 minutes. The concentration of cholesterol was 
determined for each serum sample relative to a commercial standard from 
Sigma. 
HDL cholesterol concentrations in serum are determined by separation of 
lipoprotein classes by fast protein liquid chromatography (FPLC) by a 
modification of the method of Kieft et al., J. Lipid Res., 32 (1991) 
859-866. 25 ul of serum is injected onto Superose 12 and Superose 6 
(Pharmacia), in series, with a column buffer of 0.05M Tris 
(2-amino-2-hydroxymethyl-1,3-propanediol) and 0.15M sodium chloride at a 
flow rate of 0.5 ml/min. The eluted sample is mixed on line with 
Boehringer-Mannheim cholesterol reagent pumped at 0.2 ml/min. The combined 
eluents are mixed and incubated on line through a knitted coil (Applied 
Biosciences) maintained at a temperature of 45.degree. C. The eluent is 
monitored by measuring absorbance at 490 nm and gives a continuous 
absorbance signal proportional to the cholesterol concentration. The 
relative concentration of each lipoprotein class is calculated as the per 
cent of total absorbance. HDL cholesterol concentration, in serum, is 
calculated as the percent of total cholesterol as determined by FPLC 
multiplied by the total serum cholesterol concentration. 
Test compounds were administered at a dose of 100 mg/kg. The duration of 
treatment was eight days. The compounds of the present invention increase 
HDL cholesterol concentrations as summarized in Table I: 
TABLE I 
______________________________________ 
Compound of HDL Cholesterol Level 
Example Increase (%) 
______________________________________ 
1 57 
2 29 
3 39 
4 39 
5 265 
6 26 
7 95 
8 65 
9 115 
10 49 
11 30 
12 62 
______________________________________