WO1998056369A1

WO1998056369A1 - A pharmaceutical composition for lowering glucose level in blood

Info

Publication number: WO1998056369A1
Application number: PCT/IL1998/000258
Authority: WO
Inventors: Yeshayahu Kats (Shai)
Original assignee: Technion Research & Development Foundation Ltd.
Priority date: 1997-06-09
Filing date: 1998-06-04
Publication date: 1998-12-17
Also published as: AU7547098A; IL121038A0

Abstract

A pharmaceutical composition for lowering glucose level in blood is disclosed. According to the invention, the composition comprises phenyl pyruvate derivatives and particularly phenyl pyruvate as an active ingredient. The pharmaceutical composition is generally provided either by enteral administration or by a parenteral one.

Description

A PHARMACEUTICAL COMPOSITION FOR LOWERING GLUCOSE LEVEL IN BLOOD

The present invention relates to pharmaceutical compositions to be useful against diabetes mellitus. More particularly, the invention relates to a pharmaceutical composition containing an active ingredient for lowering the level of glucose in blood.

BACKGROUND OF THE INVENTION

Diabetes mellitus is a well-known disease characterized ₀ by the presence of excessive amounts of glucose in blood and in an excess above a certain level also in urine, and manifested by various metabolic disorders, caused by an insulin deficiency or by a faulty utilization of insulin. It is considered as one of the leading diseases in morta- ₅ lity as well as morbity.

Once, it was supposed that the pancreatic islet cells are necessary for a complete utilization of carbohydrates in the animal body. In some cases, the diabetic condition may be the result of a decrease in the formation and _n secretion of insulin by the pancreas, while in others the defect may be primarily the result of an altered activity of other mechanisms such as insulin resistance and insu- lin receptor defects. The amount of glucose which is excreted in the urine may be small or very great and indicates the severity of the disease. In this case, the metabolism of fats is increased to an extent that the 5 ketone constituents, which are the intermediary products of fat metabolism are not completely oxidized as in a normal person; these substances also will accumulate in the blood being excreted in the urine. Diabetes mellitus is a risk factor for a wide variety of

₁₀ diseases such as: heart disease, myocardial infarction, peripheral vascular diseases, chronic renal failure, blindness, cerebral vascular accident such as stroke, and many others. Diabetes mellitus, consists of two types:type I, which is _lc- an insulin-dependent diabetes mellitus (IDDM) and type II which is a non-insulin dependent diabetes mellitus (NIDDM) . In the latter case, the glucose utilization is impaired due to some inbalances between the supplementation and the needs. While the type I is treated only with

_2Q a strict diet and various preparations of insulin, the type II may be treated with a special low-glucose diet, oral anti-hypoglycemic agents, such as sul fonylureas or insul in. The complications caused by diabetes are quite serious and may manifest in skin infections of all kinds, digestive troubles, gangrene of the upper and lower extermi- ties, the most serious complication being coma. Various suggestions can be found in the literature on the use of amino acids against diabetes mellitus, in spite of several papers which mentioned that these acids have unique brain-damag ng properties. For instance, reports published by many investigators on monosodium gluta ate ₀ mentioned that this compound induces hypothalamic damage when given to imature animals.

According to a relatively recent U.S. Patent No.4, 829, 087 N-acetyl cystein is suggested against diabetes mellitus claiming that it enhances the glucose-induced insulin 5 secretion of the Islets of Langerhans of the pancreas in a person. The results as illustrated in the graphs which are given in this patent are quite encouraging. However, there are many publications in the literature which mention that cysteine causes severe brain damage. In o addition, cysteine derivatives cause lower blood glucose levels in animals, which of course is a factor to be considered by the respective patients. Hypoglycemia causes severe damages on the brain development. There are many publications which mention that hypoglycemia, even _<-when asymptomatic, is associated with developmental and severe neurological deficits. Thus, for instance in a number of reports by J.W. Olney et al . (Nature 227, August 8,1970, 609-510; Science 248, 596,1990) it is mentioned that L-cysteine and derivatives thereof which belong to the family of excitatory acidic amino acids, are characterized by their neuro-toxici ty , both in vivo and in vitro. Thus in the above reference, it is mentioned that in several tests carried out on mice, 57 necrotic hypo- thalamic neurones were found even after a relatively low oral dose of L-cysteine compared with zero whe phenyl- alanine and L-glycine were tested. Accordingly, it is suggested a demand that the respective nutrition should contain a low concentration of these amino acids, in order to provide an adequate margin of safety against the brain damaging potential.

In a review, Panten U on "Effects of keto-mono-carboxyl c acids upon insulin secretion and metabolism of isolated pancreatic islets", it was mentioned that "pyruvate had no significant effects upon insulin secretion". At the 4th annual Meeting of the Israel Society for Neurosciences (Israel. J. Med. Sci . 31, 762, 1995) a report was presented on this subject, the conclusion being that L-cysteine induces a long-term neuro-behavioural injury in mice, which concur with the pathomorphological pattern of L-cysteine brain injury. The above brief review clearly indicates that there is a long felt need for providing a safe solution against diabetes mellitus which could avoid the use of the known dangerous compounds suggested up to now. It is an object of the present invention to provide a pharmaceutical composition for lowering the level of glucose in the bloood, which does not impart any undesi ed effects.

BRIEF DESCRIPTION OF THE INVENTION.

₁₀ The invention relates to a pharmaceutical composition for a rapid and effective lowering the level of glucose in the blood of a human being, comprising a phenyl pyruvate as the active ingredient in an amount to be sufficient to provide the respective result. The phenyl pyruvate may be

, ,- administered either entral or by a parentral administration. Tests parried out in-vivo with mice, using this reagent, showed to be very effective in lowering the glucose level in the blood. Without being bound to any theory, it seems that phenyl pyruvate releases insulin

20 from the β-cells generated in the pancreas. DETAILED DESCRIPTION OF THE INVENTION .

Phenyl pyruvate is produced in the body if the activity of the hepatic enzyme phenylalanine hydroxylase is impaired. This occurs in a group of inherited disorders named phenyl-ketonuria (PKU) , is which phenylalanine does accumulates in the blood at high concentrations. PKU is expressed by severe mental retardation, seizures, hypo- pigmentation and eczema. The treatment consists in low phenylalanine diet. Dorland et al showed that high blood levels of phenyl pyruvate are present during pregnancy in a PKU matter and hence probably in the fetus, but did not harm the newborn thus suggesting that phenyl pyruvate perse is not toxic to the brain. Phenylalanine and its metabolites were screened for their effects on blood glucose levels, but none of them affect blood glucose. This can be noticed from the following Table 1.

TABLE 1: Effect of phenylalanine and its metabolites on blood glucose in mice.

Agent Dose injected

(per g of body weight) phenyl alanine 2.5 g phenyl lactate (-) phenyl acetate (-) phenyl acetyl gluta ine (-)

(-) means no effect.

Blood injection was measured 30 minutes after injection of the agent.

Blood glucose was measured 30 min after injection of agent. The sign (-) in the above Table means no effect. On the contrary, it was found that phenyl pyruvate caused a dose dependent decrease in blood glucose levels. The hypoglycemic effect started 30 minutes after injection and continued up to 2 hour post-injection. At a hour post injection, rebound hypoglycemia developed. This observation indicates a specific hypoglycemic effect of phenyl- pyruvate. The mechanism of phenyl pyruvate on brain-damagi g potential, was tested by administering various doses of this compound to mices. The blood glucose revealed a dose-related hypoglycemia at low dose, but at the higher doses it was substantially zero. Plasma insulin was measured following a treatment with phenyl pyruvate and an increase in insulin plasma levels was noticed, at 15 minutes after injection. Phenyl pyruvate is a well known compound found in nature or commercially available. Its beneficial effect was determined by measuring the glucose level in mices of various ages, by subcutaneous determined injections. From the results of the experiments which were carried out, it was found that by administration of phenyl yruvate and glucose, a complete protection of the brain exists, without causing any harmful injury.

Phenyl pyruvate is a known compound and tests carried out with it show that high levels of this compound tested during pregnancy on fetal fluid and tissues, did not cause any damage to the newborn.

The beneficial effect caused by phenyl pyruvate on the lowering the glucose level in blood according to the present invention, is quite unexpected in view of a prior review which pointed out that pyruvate had no any effect upon the insulin secretion. DETAILED DESCRIPTION OF THE FIGURES

FIGURE 1: illustrates the effect of phenylpyruvate on blood glucose levels for 2.5 mg/g (1) and 1.0 mg/g (2), compared with control (o) FIGURE 2: illustrates the glucose blood level after a treatment with phenylpyruvate with the doses as follows: 2.5 mg/g (1); 1.0 mg/g (2) and 0.5 mg/g, compared with control (o) . FIGURE 3: illustrates the glucose resusciation after a treatment with phenylpyruvate: 6 mg/g phenylpyruvate (1) + 6mg/g glucose, compared with control (o) FIGURE 4: illustrates the glucose resusciation after a treatment with lower amounts of phenylpyruvate and glucose, compared with control (o) .

The invention will be hereafter illustrated by the following Examples, which show the beneficial effect imparted by phenylpyruvate in lowering the level of glucose in blood.

EXAMPLE 1 .

Phenylpyruvate, 1.0 g per g body weight was injected to mice. Between 20 to 30 min post injection, blood glucose fall from 70 mg % to 35-40 mg %. The decline continued until 60 min post-injection and then climbed to base line or higher levels.

EXAMPLE 2.

Glucose, 6 mg per g body weight was injected to mice. Hyperglycemia of 140 mg % occured. Phenyl pruvate 2.5 mg per body weight was injected. Blood glucose fall to 10 mg % within 30 min post injection. Co-administration of glucose 6 mg per g body wt and phenylpyruvate 2.5 mg per g of body wt , prevented hypoglycemia and normalized blood glucose levels were found during 2 hours following post injection.

It should be pointed out that phenylpyruvate releases insulin from pancreatic islets in vitro. Thus, following phenylpyruvate injection to mice, the insulin plasma levels increased within 5 to 10 minutes post-injection. This does suggest that the observed hypoglycemia is mainly a result of the insulin release but peripheral hypoglycemic effect of phenylpyruvate may also be a possibility . Although the invention was illustrated using only phenylpyruvate, a person skilled in the art will deduce that other derivatives or esters of pyruvic acid will also exhibit hypoglycemic effects in vivo, without being outside of the invention as covered by the appended Claims. Thus, another useful derivative is an ester of pyruvic acid such as pyruvate decarboxylase.

Claims

C L A I S :

1. A pharmaceutical composition for a rapid and effective lowering the level of glucose in the blood of a being, comprising a phenyl yruvate as the active ingredient in an amount to be sufficient to provide the respective result .

2. The pharmaceutical composition according to Claim 1, to be administered by entral of by a parentral administration.

3. The pharmaceutical composition according to Claim 1, which imparts a complete protection of the brain, without causing any harmful injury.

4. The pharmaceutical composition according to Claim 1, wherein the insulin plasma levels, increases a few minutes after its injection.

5. The pharmaceutical composition according to Claims 1 to 4, wherein the phenylpyruvate releases insulin from the ╬▓-cel s which are generated in the pancreas.

6. The pharmaceutical composition according to Claims 1 to 4, wherein the blood glucose revealed a dose-related hypoglycemia at low dose, but it was subtantially zero at high doses.