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How garden egg helps glaucoma, heart disease patients

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Wednesday, July 29, 2009

Eating a plate-full of garden egg could be another way of beating glaucoma and heart diseases.

Nigerian researchers have demonstrated how a meal of garden egg would be of benefit to patients suffering from raised intraocular pressure (glaucoma) and convergence insufficiency, as well as in diseases associated with hyperlipidemia such as ishcaemic heart diseases and arteriosclerosis.

Botanically called Solanum melongena, garden egg or bitter tomato is an economic flowering plant belonging to the family Solanaceae and widely distributed throughout the temperate and tropical regions. Members are mostly herbaceous plants, and the fruit is berry and the seeds have large endosperm and are grown mainly for food and medicinal purposes.

Several cultivars of Solanum fruits (Garden egg or egg plant) are found throughout Nigeria and cultivated domestically. Phytochemical analysis indicates that Solanum contains steroid alkaloid flavonoids. Solanium fruits contain approximately 92.5 per cent of water, one per cent of protein, 0.3 per cent fat and six per cent carbohydrate.

Glaucoma refers to a group of diseases that affect the optic nerve and involves a loss of retinal ganglion cells in a characteristic pattern. It is a type of optic neuropathy. Raised intraocular pressure is a significant risk factor for developing glaucoma (above 22 mmHg or 2.9 kPa). One person may develop nerve damage at a relatively low pressure, while another person may have high eye pressure for years and yet never develop damage. Untreated glaucoma leads to permanent damage of the optic nerve and resultant visual field loss, which can progress to blindness.

Hyperlipidemia is an elevation of lipids (fats) in the bloodstream. These lipids include cholesterol, cholesterol esters (compounds), phospholipids and triglycerides. They are transported in the blood as part of large molecules called lipoproteins.

Ischemic heart disease is a spectrum of diseases of the heart caused by decreased oxygen supply to the myocardium (muscle of the heart). Ischemic heart disease is a sequela of coronary artery disease.

Arteriosclerosis refers to stiffening of arteries. Arteriosclerosis is a general term describing any hardening (and loss of elasticity) of medium or large arteries (from the Greek Arterio, meaning artery, and sclerosis, meaning hardening).

It has been shown that the prevalence of atherosclerosis and ischaemic heart disease is on the increase in the world and recently in Africa.

Researchers suggest that the clinical consequences of these conditions are serious and exert major research efforts to improve knowledge of its pathogenesis and thereby provide a more rationed approach to its prophylaxis and therapy.

The study on garden egg and glaucoma is titled "Effects of Solanum melongena (garden egg) on some visual functions of visually active Igbos of Nigeria". The study was published in Journal of Ethnopharmacology by S. A. Igwe of the Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, Abia State University, Uturu; Dora N. Akunyili of the Department of Pharmacology and Therapeutics, University of Nigeria Teaching Hospital, Enugu; and C. Ogbogu of the School of Optometry, Abia State University, Uturu.

The effects of bolus consumption of 10 gram of S. melongena were undertaken on visually active male volunteers so as to determine its ocular complications.

Results of the study showed that the pupil size was reduced (23 per cent), Near Point of Convergence (NPC) was decreased (nine per cent) and the Anecortave Acetate (AA) was increased (22 per cent) and the intraocular pressure dropped by 25 per cent while there was no effect on Visual Acuity (VA), and the habitual phoria. Anecortave (rINN) is a novel angiogenesis inhibitor used in the treatment of the exudative (wet) form of age-related macular degeneration (blindness).

The miotic effect lowered the intraocular pressure appreciably and the reduced NPC, which was still within normal range did not produce any vision discomfort. The increased AA and convergence excess positively correlated provide an efficient visual mechanism.

The researchers concluded: "It is suggested that S. melongena would be of benefit to patients suffering from raised intraocular pressure (glaucoma) and convergence insufficiency."

Researchers have also examined the Hypolipidaemic potentials of Solanum melongena and Solanum gilo on hypercholesterolemic rabbits.

Hypolipidemic agents, or antihyperlipidemic agents, are a diverse group of pharmaceuticals that are used in the treatment of hyperlipidemias. They are called lipid-lowering drugs (LLD) or agents. There are several classes of hypolipidemic drugs. They may differ in both their impact on the cholesterol profile and adverse effects. For example, some may lower the "bad cholesterol" low density lipoprotein (LDL) more so than others, while others may preferentially increase high density lipoprotein (HDL), "the good cholesterol". Clinically, the choice of an agent will depend on the patient's cholesterol profile, cardiovascular risk, and the liver and kidney functions of the patient, evaluated against the balancing of risks and benefits of the medications.

Hypercholesterolemia (high blood cholesterol) is the presence of high levels of cholesterol in the blood. It is not a disease but a metabolic derangement that can be secondary to many diseases and can contribute to many forms of disease, most notably cardiovascular disease. It is closely related to the terms "hyperlipidemia" (elevated levels of lipids) and "hyperlipoproteinemia" (elevated levels of lipoproteins).

Elevated cholesterol in the blood is due to abnormalities in the levels of lipoproteins, the particles that carry cholesterol in the bloodstream. This may be related to diet, genetic factors (such as LDL receptor mutations in familial hypercholesterolemia) and the presence of other diseases such as diabetes and an underactive thyroid. The type of hypercholesterolemia depends on which type of particle (such as low density lipoprotein) is present in excess.

High cholesterol levels are treated with diets low in cholesterol, medications, and rarely with other treatments including surgery (for particular severe subtypes). This is also increased emphasis on other risk factors for cardiovascular disease, such as high blood pressure.

The researchers found that Solanum melongena and Solanum gilo have strong hypolipedemic effect which combined with improved HDL/ LDL ratio is an indication of the possible use of this fruit in the treatment of diseases associated with hyperlipidemia such as ishcaemic heart diseases and arteriosclerosis.

The study was published in the Pakistan Journal of Nutrition by A.A. Odetola of the Department of Biochemistry, University of Ibadan,; Y.O. Iranloye and O. Akinloye of the Department of Chemical Pathology, College of Health Sciences, Ladoke Akintola University of Technology, Osogbo, Osun State.

The fresh, ripe fruits of Solanum melongena and Solanum gilo were investigated for their possible hypolidemic potentials in hypercholesterolemia induced in New Zealand white rabbits by feeding the animals with normal diet supplemented with one per cent cholesterol and groundnut oil for three weeks. Hypercholesterolemic rabbits were thereafter treated with normal diet supplemented with 10 per cent of each fruit for six weeks.

Rabbits fed with normal diet and hypercholesterolemic diets through out the experiment were used as negative and positive controls respectively. There was a significant increase in the weight of hypercholesterolemic rabbits, both test (Groups D and E) and control (Groups B and C) compared with normal control (Group A).

It was observed that the hypercholesterolemic rabbits treated with normal diet elicited a significant reduction in fasting serum cholesterol (11.52 per cent), triglyceride (16.5 per cent) and LDL cholesterol (41.13 per cent) but a significant increase in HDL cholesterol (16.48 per cent) and also in the HDL/LDL ratio (1.10), four weeks after replacement of high cholesterol diet with normal diet. This positive response was however more pronounced in fruits treated rabbits.

Solanum melongena and Solanum gilo significantly reduced serum total cholesterol by 65.40 and 52.69 per cent respectively, triglyceride by 47.7 and 27 per cent, LDL cholesterol by 85 and 83 per cent respectively. They also increased significantly serum HDL by 24.7 and 25 per cent respectively leading to increased HDL/LDL cholesterol ratio (3.37 and 3.25 respectively). This trend was also similar with liver lipid levels.

Histopathological examination of the liver and aorta paraffin section stained with Haematoxylin and Eosine showed fewer lesions in the hypercholesterolemic rabbits treated with Solanum fruits compared with control hypercholesterolemic rabbits. These observations demonstrated that Solanum melongena and Solanum gilo have strong hypolipedemic effect which combined with improved HDL/LDL ratio is indication of the possible use of this fruit in the treatment of diseases associated with hyperlipidemia such as ishcaemic heart diseases and arteriosclerosis.

The importance of serum lipoprotein disturbances and abnormal lipid metabolism characterised by hyperlipidaemia or hyperlipoproteinmia as etiological factors in the development of coronary heart diseases and potentiating of arteriosclerosis is now supported by a considerable body of evidence amassed from epidemiological and population studies

In fact, it is almost accepted that arteriosclerosis is a disorder of lipid transport and metabolism. Cholesterol by-product would form thick, tough deposit called plague on the inner wall of the arteries, stiffening them and then starving the heart of blood, creating choke point where a clot could stop the flow entirely. Apart from the lipid from the diet source, the body in turn manufactures its own cholesterol. Inefficient clearance of excess cholesterol for reasons that are largely genetic, resulting in accumulation of cholesterol in the blood, and deposition of lipid in the minor layer of arterial wall causes arteriosclerosis.

Studies have, however, reported that increased HDL appears to retard or prevent the development of arteriosclerosis while reduced levels are associated with increased risk for coronary artery diseases.

Furthermore, blood lipid levels, particularly total cholesterol and LDL cholesterol

are usually related to promoting arteriosclerosis, hence interventions that lower these lipid levels can retard or reverse the progression of this processes.

An indication of possible hypolipidemic potentials of solanum emerged from the study of Sultana et al., 1995, who found that a reaction mixture of solanum and cichorium containing calf thymus DNA and free radical generating system protected DNA against oxidative damage of its deoxyribose sugar moiety. This author concluded that this mixture has both hepatoprotective and hypolipidemic potentials.

The earliest investigations of experimentally induced atherosclerosis were done in rabbit model by feeding with milk, meat and egg established that the atherosclerosis causing component of the diet was cholesterol. This has formed the basis for the use of cholesterol and groundnut oil to induced hyperlipidemia in the study. A significant increase (P 0.05) in the serum lipid level of the experimental animals (B, C, D and E) three weeks after feeding them with cholesterol supplemented diet (that is stage II), coupled with fatty liver, extracellular lipid and thickened intima containing foam cells in the aorta of rabbits are evidence in support of the observation of Ignatowski 1980 and Kritchersky, 1970.

The weight-gain (1.66 ± 0.06kg) in hyperlipidemic control rabbits was significantly higher (P 0.05) than weight-gain (0.80 ± 0.02kg) in control rabbits fed with standard diet. Excessive weight-gain as in obesity has been implicated as a risk factor for development of hypertension, ischaemic heart diseases and heart failure.

Hypolipidemic properties have been confirmed in many plants and plant products in medicinal use. Polichetti et al. (1996) reported that soy bean lecithin was effective in the dietary treatment of mild cholesterolemia by stimulating the ApoA1 (high density lipoprotein). Bhandari and Zater (1998) also found that the ethanolic extract of ginger (200mg/kg) lowered serum triglycerides lipoproteins, phospholipids as well as serum and tissue cholesterol.

In addition they showed that animals receiving ginger extract with cholesterol showed a lower degree of atherosclerosis. Flavonoids extracted from the fruits of Solanum melongena (Brinjal) at a dose of 1mg/100g BW/day showed significant hypolipidemic action in normal and cholesterol fed rats (Sudheesh et al., 1997).

It may therefore be concluded from the evidences from this study, that S. melongena and S. gilo possess hypolipidemic potentials and may therefore be useful for prophylaxic and therapeutic treatment of clinical conditions associated with hyperlipidaemia such as atherosclerosis. Further studies are in progress to isolate the active ingredient and elucidate the exact mechanism of action of these fruits.

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Author: By Chukwuma Muanya
Source: Nigeria Guardian News
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