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 Table of Contents  
Year : 2015  |  Volume : 4  |  Issue : 3  |  Page : 171-178

The protective effect of Punica granatum (pomegranate) against glaucoma development

1 Department of Zoology, Faculty of Science (Girls), Al-Azhar University, Cairo, Egypt
2 Department of Biochemistry and Nutrition, Research Institute of Ophthalmology, Giza, Egypt

Date of Web Publication9-Dec-2015

Correspondence Address:
Anhar M Gomaa
Department of Biochemistry and Nutrition, Research Institute of Ophthalmology, Giza, P.O. Box: 12111
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/2278-0521.171429

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Background: Primary open-angle glaucoma is the most common type of glaucoma. Objectives: This study aims to explore the anti-glaucoma activity of pomegranate (Punica granatum), against hydroxylpropylmethylcellulose (HPMC). Materials and Methods: Twenty-four rabbits were used and divided into four groups such as Group 1: Control, Group 2: Glaucoma rabbits, Group 3: Normal rabbits fed on commercial diet containing 20% pomegranate, and Group 4: Glaucoma rabbits fed on commercial diet containing 20% pomegranate. Intraocular pressure (IOP) levels were determined. The activities of catalase (CAT), superoxide dismutase (SOD), and reduced glutathione (GSH) were assessed. The level of malondialdehyde (MDA) and nitric oxide (NO) and lipid profiles (total cholesterol [TC], triacylglycerol [TAG], low-density lipoprotein-cholesterol [LDL-C], high-density lipoprotein-cholesterol [HDL-C], and very low-density lipoprotein-cholesterol [VLDL-C]), and liver functions were also measured. Results: A significant decrease in IOP was observed in glaucoma rabbits treated with diet containing 20% pomegranate. A significant increase in the levels of reduced GSH (P < 0.011), CAT (P < 0.034), and SOD (P < 0.001) activities was observed in the rabbits fed on diet containing 20% dried pomegranate comparing to glaucoma group. The levels of MDA and NO were decreased after pomegranate administered. In glaucoma group, the levels of lipid profiles TC, TAG, LDL-C, HDL-C, and VLDL-C were 166.5 ± 0.96, 175.00 ± 3.61, 82.2 ± 3.85, 41.5 ± 2.1, and 35.00 ± 0.72 (mg/dl), respectively. After rabbits fed on 20% dried pomegranate, the levels of lipid profiles were improved. Conclusion: The results suggest that pomegranate is very efficient to reduce IOP in HPMC experimental rabbits induced glaucoma. This protective effect appears to occur by maintaining the antioxidant defense system, possibly by preventing depletion of antioxidant enzymes and inhibition of lipid peroxidation. We suggest that pomegranate act as a protective and may be useful in improving the complications of glaucoma and stop the progression glaucoma development.

Keywords: Catalase, glaucoma rabbits, hydroxylpropylmethylcellulose, intraocular pressure, lipid profiles, malondialdehyde, nitric oxide, oxidative stress, pomegranate, primary open-angle glaucoma, superoxide dismutase

How to cite this article:
Kamal ENS, Gomaa AM, Aziz MA, Ebrahim NF, Ahmed SS. The protective effect of Punica granatum (pomegranate) against glaucoma development. Saudi J Health Sci 2015;4:171-8

How to cite this URL:
Kamal ENS, Gomaa AM, Aziz MA, Ebrahim NF, Ahmed SS. The protective effect of Punica granatum (pomegranate) against glaucoma development. Saudi J Health Sci [serial online] 2015 [cited 2020 May 29];4:171-8. Available from: http://www.saudijhealthsci.org/text.asp?2015/4/3/171/171429

  Introduction Top

Glaucoma is an ocular disorder with multi-factorial etiology, characterized by a slow and progressive degeneration of retinal ganglion cells and optic nerve axons.[1] Glaucoma is the second leading cause of blindness. The most important risk factor for glaucoma is intraocular pressure (IOP) elevation; progressive visual loss is associated with increased IOP, which damages the optic nerve.[2] Normal IOP is maintained through a balance between the aqueous humor and the amount drained. In glaucoma, excess fluid typically builds up because of a blockage of the drainage channels or filtering tissue called the trabecular meshwork. Other risk factors for the development of glaucoma include older age,[3] family history, diabetes, hypertension,[4] drugs, cigarette smoking,[5] myopia,[4] and oxidative stress.[6],[7],[8] Oxidative stress can cause chronic changes in the aqueous and vitreous humor, which may induce alterations in the trabecular meshwork and the optic nerve head that are seen in glaucoma.[9] Oxidative damage in the cellular components of the trabecular meshwork could directly affect the regulation of extracellular matrix structure and lead to an alteration of flow of the aqueous humor.[10] Medicinal plants have been used as traditional treatment for glaucoma for thousand years worldwide.[11],[12]

Pomegranate (Punica granatum), a small tree originating in the Orient, belongs to the Punicaceae family.[13] Pomegranate fruit is a rich source of polyphenolic compounds such as anthocyanins and hydrolyzable tannins, which account for 92% of the antioxidant activity of the whole fruit.[14] In addition to, punicalagin, punicalin, ellagic acid and gallic acid as demonstrated by Seeram et al.,[15] pomegranate is important in prevention of prostate cancer,[16] inflammation,[17] reductions of blood pressure, arthritis, and anemia;[18] pomegranate is also serving as an anti-allergic [19] and anti-diabetic.[20]

Because there is sufficient evidence that oxidative stress plays a role in the pathogenesis of glaucoma, there is an increasing interest in developing suitable antioxidant nutrients, both of synthetic and plant origin that could be effective in glaucoma.[21] Prevention or stop the progression of glaucoma disease, particularly the raised IOP, is the primary goal in the Research Institute of Ophthalmology. The present study was performed to investigate the protective effect of pomegranate (P. granatum) on protecting against development of glaucoma and in improving or stop the progression glaucoma in a rabbits model of chronic and moderately-elevated IOP.

  Materials and Methods Top


Hydroxylpropylmethylcellulose (HPMC), glutathione (GSH), pyrogallol, thio-barbituric acid, 5,5' dithio-bis-2-nitrobenzoic acid, tris HCl buffer, phosphate buffer, glacial metaphosphoric acid, and (N, N, N', N'-tetra methyl thylene diamine), 1, 1, 3',3'- tetra-ethoxy propane.

Commercial diet

A commercial diet from the animal house of Research Institute of Ophthalmology was used as basal diet. The commercial diet consists mainly of not more than 64% carbohydrates, not <17% protein, not <2.67% fat, not <10.33% fiber, and not <6% of vitamins and minerals mixture.[22]

Experimental diet

Dried pomegranate was used as 20% of commercial diet and served as experimental diet. Fresh fruit of pomegranate procured from the local supermarket was gently washed with cold water just before drying to remove dirt, bacteria, and insects. Pomegranate was peeled, and its edible portion (seed coat) dried in an electric dehydrator, drying times ranged from 6 to 36 h. A dehydrator should have a heat source, a thermostat, and some method of air circulation. Distribute the peeled pomegranate fruits on trays in a single layer and start the dryer at 60°C. After 2–3 hours, lower the dryer temperature to 45°C adequate air flow can reduce drying times. If necessary, rotate the trays to ensure the even drying. When you think the food is sufficiently dry, remove a piece and allow it to cool completely, and then check for dryness.[23] The dried seeds added to commercial diet by a 20% of commercial diet

Experimental animals model of glaucoma

In our study, we designed a rabbit model of chronic, moderately-elevated IOP for studying glaucoma and demonstrated efficacy P. granatum as a source of flavonoids, and different antioxidant to reverse a trait of experimental glaucoma induced by a series of injections of HPMC to the anterior chamber of the rabbit eye as described by

Zhu and Cai.[24] HPMC resulted in IOP elevation during the first 2 weeks. Chronic, moderately-elevated IOP, was induced by injections of 0.15 µl 2% of HPMC twice per week in the anterior chamber of the glaucoma rabbits group. All procedures on the rabbits were under general anesthesia using a mixture of ketamine (50 mg/kg bw) and xylazine (10 mg/kg bw).

Experimental animal design

At the start of the experiment, rabbits were housed randomized individually in polyethylene cages and served as the experimental groups. Twenty-four New Zealand male pigmented rabbits weighing 1000–1200 g were housed in the Research Institute of Ophthalmology, Giza, Egypt. Animals were fed ad libitum and maintained in temperature controlled room on and a 12 h light period from 6 am to 6 pm dark cycle. Rabbits were divided into four groups each comprising of six animals. The four groups were classified as follows: Group 1, healthy rabbits fed on commercial diet and served as normal control group; Group 2, rabbits fed on commercial diet and injected in anterior chamber of the eye with a dose of 0.15 µl 2% of HPMC twice per week to induced glaucoma (glaucoma group); Group 3, normal rabbits fed on commercial diet containing 20% dried pomegranate and served as positive control (normal fed on pomegranate); and Group 4, rabbits fed on commercial containing 20% dried pomegranate and injected with a dose of 0.15 µl 2% of HPMC twice per week and served as glaucoma treated group (glaucoma fed on pomegranate).

Intraocular pressure measurement

The IOP was measured after 7 days of HPMC injection using the Schiotz indentation tonometer (Eichtabelle, Germany Weiss and Co and Theodore Hamblin Ltd) after instillation of the local anesthetic eye drops (ketamine 50 mg/kg body weight and xylazine 10 mg/kg body weight). In each eye, IOP was measured using two weights and the average IOP was calculated for each measuring.

Clinical examination

Both eyes of rabbits were investigated by tonometer to ensure the induction of glaucoma. Glaucoma could be seen obviously by the increase of IOP in glaucoma group (Groups 2 and 4) and all groups were under observation until the end of the experiment. The progression of glaucoma was observed by tonometer weakly until the end of the experiment (2 months).

Biochemical assessment

At the end of the experiment, rabbits were fasted overnight; rabbits were under anesthesia and the IOP measured. Blood sample was drawn from the marginal ear vein with vaccum syringes. Moreover, blood samples were collected using heparinized capillary tubes into two separated tubes. The first tube was containing Na2 ethylene di-amine tetra acetic acid (EDTA). Whole blood used to determine GSH content and superoxide dismutase (SOD), then centrifuged to separate plasma for determination of catalase (CAT) activity, the second tube without EDTA was used to separate serum to determine malondialdehyde (MDA), nitric oxide (NO), Lipid profiles (total cholesterol [TC], triacylglycerols [TAG], high-density lipoprotein-cholesterol [HDL-C], low-density lipoprotein-cholesterol [LDL-C], and very low-density lipoprotein-cholesterol [VLDL-C]), and liver functions enzymes aspartate transaminase and alanine transaminase (AST and ALT). All samples were kept in a deep freezer under −20°C until used. Serum TC was measured according to the method of Allain et al.[25] TAG was analyzed according to the method described by Fossati and Prencipe.[26] HDL-C was measured using the method of Lopes-Virella et al.,[27] and LDL-C was estimated as described by Tietz.[28] CAT activity was determined according to the method described by Aebi.[29] SOD activity was assessed using the method described by Marklund and Marklund.[30] Reduced GSH was assessed according to the method of Beutler et al.[31] MDA was determined according to the method described by Draper and Hadley [32] and NO was assessed according to the method of Moshage et al.[33] AST and ALT were measured according to standardized method of Schumann.[34] Finally, VLDL-C was calculated according to the equation of Friedewald et al.[35]

Histological studies

At the end of the experiment, the rabbits were sacrificed, and specimens were taken from the cornea. Histological preparation of the cornea was done according to the method described by


Statistical analysis

SPSS software program (version 10.0 for Windows) was used for data analysis. Data were analyzed using one-way ANOVA, mean and standard error (SE) were descriptive measures of data. Least significant difference multiple comparison tests were then carried out. P values were significant at <0.05.

  Results Top

Intraocular pressure

The mean of IOP value for control rabbit eyes was 14.54 ± 0.81 mmHg. HPMC resulted in IOP elevation in glaucoma group during the 1st week to approximately 26.5 ± 0.92 mmHg. The highest pressure measurements were obtained during the 2nd weeks after glaucoma induction (32.86 ± 2.47 mmHg). This IOP proved to be stable at this level until the end of the experiment [Table 1].
Table 1: Comparison mean intraocular pressure (mmHg) in groups feed with pomegranate with the control and glaucoma groups

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In normal group fed on 20% dried pomegranate, the IOP was 12.9 ± 0.38 and 12.3 ± 9.52 (mmHg) at the 1st and 2nd weeks, respectively. The P- value showed not significant change comparing to control group, but there was a highly significant decrease of IOP comparing to glaucoma group (P < 0.0001) in both 1st and 2nd weeks.

In glaucoma group fed on 20% dried pomegranate (treated group), the IOP was 24.8 ± 0.96 and 12.43 ± 1.07 (mmHg) at the 1st and 2nd weeks, respectively. The P < value is not showed significant change comparing to control group and highly significant decrease comparing to glaucoma group (P < 0.0001) at the 2nd week. The values of IOP were stable from the 2nd week until the end of the experiment [Table 1].

Biochemical assessment

The mean ± SE and P values of CAT, SOD activities, reduced GSH, MDA, and NO for normal control, glaucoma, and normal group fed on 20% dried pomegranate, and glaucoma fed on 20% dried pomegranate groups are provided in [Table 2].
Table 2: Mean±SE and percentage change of CAT, SOD activities, reduced GSH, MDA, and NO oxide for different studied groups

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As shown in [Table 2], in normal control group, the mean ± SE and values of CAT, SOD activities, and reduced GSH were 286.7 ± 2.36 (U/l), 422.7 ± 2.69 (U/ml) and 85.33 ± 3.33 (mg/dl), respectively, while the levels of MDA and NO were 3.40 ± 0.29 (nmol/ml) and 20.80 ± 0.34 (umol/l), respectively.

In glaucoma group, the mean ± SE values of CAT, SOD activities, and reduced GSH were 209.7 ± 19.46 (U/l), 388.5 ± 2.81 (U/ml), and 68.8 ± 5.7 (mg/dl), respectively. The P value shows a highly significant decrease when compared to control group. The data of MDA and NO in glaucoma group were 5.47 ± 0.26 (umol/ml) and 22.9 ± 0.48 (umol/L), respectively. The P value shows a highly significant increase when compared to normal control group. The percent changes were increased to 37.8% and 10.1%, respectively as compared to normal control group.

In normal control fed on 20% dried pomegranate, the mean ± SE of CAT, SOD activities, reduced GSH, MDA, and NO were 265.5 ± 16.4 (U/l), 426.0 ± 10.2 (U/ml),

97.2 ± 1.08 (mg/dl), 3.02 ± 0.41 (nmol/ml), and 22.2 ± 0.98 (umol/l), respectively, and the P values showed nonsignificant changes in all parameter when compared to normal control values. On the other hand, there was a highly significant increase in antioxidant enzyme (CAT, SOD, and reduced GSH) and decrease in oxidative stress markers (MDA and NO) was also noticed compared to the values of glaucoma group.

The data of glaucoma group fed on 20% dried pomegranate are shown in [Table 2]. As shown in [Table 2], the mean ± SE values for antioxidant enzyme were 254.8 ± 15.9 (U/l) concerning to CAT and 406.7 ± 3.32 (U/ml), concerning to SOD activities, while the mean value ± SE of reduced GSH was 80.5 ± 4.9 (mg/dl). In addition, the levels of MDA and NO were 3.07 ± 0.008 (nmol/ml) and 19.9 ± 0.61 (umol/l), respectively. There was no significant change in the levels of all parameters except the level of SOD activities comparing to normal control values. However, there was a highly significant improvement in all parameters comparing to the data of glaucoma group.

As shown in [Table 3], the mean ± SE and P - values of TC, TAG, HDL-C, LDL-C, and VLDL-C in normal group were 152.6 ± 2.47, 148.7 ± 1.65, 48.5 ± 2.2, 73.4 ± 2.35, and 29.5 ± 0.22 (mg/dl), respectively.
Table 3: Mean±SE and percentage change for serum TAGs, TC, HDL-C, LDL-C, and VLDL-C for different studied groups

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In glaucoma group, the mean ± SE of T.C, TAG, HDL-C, LDL-C, and VLDL-C in glaucoma group were 166.5 ± 0.96, 175.0 ± 3.61, 41.5 ± 2.1, 82.2 ± 3.85, and 35.0 ± 0.72 (mg/dl), respectively.

On the other hand, in normal control fed on commercial diet containing 20% dried pomegranate, the mean ± SE of T.C, TAG, HDL-C, LDL-C, and VLDL-C in normal group were 144.2 ± 3.0, 140.7 ± 3.72, 52.7 ± 3.3, 64.3 ± 5.1, and 28.13 ± 0.74 (mg/dl), respectively, and there were not significant change in all lipid profiles comparing with the control values.

As shown in [Table 3], the data also show in glaucoma group fed on 20% dried pomegranate, the mean value of TC, TAG, HDL-C, LDL-C, and VLDL-C were 131.00 ± 3.46, 159.8 ± 5.58, 52.0 ± 0.58, 47.0 ± 3.62, and 31.96 ± 1.11 (mg/dl), respectively, and the P value of TC and LDL-C showed a highly significant decrease comparing to control group. While there is no significant change concerning to TAG, HDL-C and VLDL-C compared to control group.

The mean ± SE values of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) for all groups are provided in [Table 4]. As shown in [Table 4], the mean ± SE and P values of ALT and AST in normal group were 26.83 ± 1.01 (U/L) and 22.83 ± 1.49 (U/L), respectively and in glaucoma group, the mean ± SE of ALT and AST were 22.67 ± 1.69 and 26.0 ± 2.77 (U/L) respectively. The P value shows no significant change in both enzymes when compared to control group.
Table 4: Mean±SE and percentage change of serum ALT and serum AST for different studied groups

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In normal control fed on 20% dried pomegranate, the mean ± SE of ALT and AST were 22.0 ± 1.77 and 24.33 ± 0.76 (U/L), respectively, and the P values of ALT and AST showed nonsignificant change when compared to normal control values and glaucoma values. The data of glaucoma group fed on 20% dried pomegranate as shown in this [Table 4], the mean ± SE for ALT and AST were 25.33 ± 2.63 and 26.83 ± 2.75 (U/L), respectively. In addition, there was no significant change in the levels for the two parameters comparing to normal control and glaucoma values.

Histopathological results

As shown in [Figure 1], a light micrograph of control cornea of rabbit showing its five layers from outside in words, corneal epithelium (EP), Bowman's layer (B), substantia propria or stroma (S) with keratoctes (K), Descemet's membrane (D), and endothelium (E). The main histopathological changes in glaucoma were observed on the endothelium while the epithelium and stroma appeared more or less normal. Light microscopic examination showed pyknosis of some nuclei and highly vacuolated cytoplasm of the endothelial cells [Figure 1]b. Light micrograph of rabbit's cornea of glaucoma group fed on pomegranate endothelial liming shows no deviation from the control with exception of slight vacuolation of the cytoplasm [Figure 1]d.
Figure 1: A light micrograph of cornea control (a), glaucoma (b), normal fed on pomegranate (c), and glaucoma fed on pomegranate (d)

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  Discussion Top

Glaucoma is the second most cause blindness or prevalent eye condition, after cataracts in Egypt. This is showing in the number of patients attending the outpatient's clinic in the Research Institute of Ophthalmology suffering from glaucoma. Primary open-angle glaucoma (POAG) accounts for around 70% of the total glaucoma cases worldwide. Free radicals are highly reactive due to their extreme instability. In biological reactions, free radicals have been reported to be involved in tissue disorders caused by peroxidation. In glaucoma, antioxidant levels decrease may be involved in the development of glaucoma. It is emphasized that most eye disease cases are thought to be diet related. Numerous epidemiological studies have shown an inverse association between fruit and vegetable consumption and eye diseases.[37],[38],[39] Therefore, interest in the health benefits of fruit and vegetable consumption is increasing.[40] The rabbit eye is closer to the human eye than the eye of the rat.[41]

We demonstrated that a series of eight injections of HPMC into the anterior chamber of rabbit eyes during the experiment leads to a moderate elevation of IOP, which remains increased until the end of the experiment. Iomdina et al.[42] show that elevated IOP may have a direct impact on mitochondria. Mitochondria are usually primary source of reactive oxygen species. Increased mitochondrial oxidative stress contributed to apoptosis and development of glaucoma. HPMC-induced glaucoma with elevated IOP and optic nerve degeneration can be produced. Characteristic changes occurred in the optic nerve, including destruction of the optic nerve axons and appearance of numerous vacuoles. Furthermore, the Baltimore Eye Survey evaluated the relationship between IOP and POAG. Oxidative stress has been implicated to be a cause of increased IOP by triggering trabecular meshwork degeneration and thus contributing to alterations in the aqueous outflow pathway.[43]

Over the past few years, consumer demand-based research on functional foods gave a basis for traditional using of pomegranate.[44],[45],[46],[47] In this study, the results of IOP for the control group within normal range. This result is in agreement with Jabbarpoor Bonyadi et al.[48] Our data show that in glaucoma group, the percent changes were decreased to −26.9%, −8.09% and −22.9% concerning to CAT, SOD activities, and GSH, respectively comparing to normal control group. A superoxide scavenger of Cu, Zn-SOD, and CAT were used as active oxygen scavengers to identify the free radicals species formed. However, in HPMC-induced experimental glaucoma, the levels of MDA and NO were increased. This suggests that higher serum levels of MDA and NO-oxidative stress markers-in glaucoma group reflect or correlate similar findings by different investigation such as Ko et al.;[49] Nucci et al.[50] who suggested that peroxidation may be involved in the development of glaucoma. On the other hand, after rabbit's consumption 20% dried pomegranate, the percentage of CAT, SOD, and GSH were increased, while the percentage of MDA and NO were decreased when compared to the data of glaucoma group. Our results suggested that lipid peroxidation was responsible for different complications in POAG. In addition, SOD and CAT were found to act as defense enzymes to the oxidative stress in glaucoma. Significant increase was observed in the activities in the previous enzymes. Our results found a protective effect of pomegranate in rabbits induced glaucoma. This effect was associated with higher GSH level as well as lower levels of MDA and NO in response to pomegranate in glaucoma treated groups as compared to glaucoma untreated group. Also, pomegranate enhanced or maintained the free-radical scavenging activity of the antioxidant enzymes such as CAT, GSH reductase, and SOD to values comparable to control values, whereas resulted in 9.71 reduction of MDA values compared to controls and −43.9% compared to glaucoma group. It could be postulated that pomegranate act as a potent source of flavonoids,[15],[51] which provide an additional support to the elevation of SOD, CAT activities, and GSH level and decrease in MDA. In addition, ellagic acid derivatives and anthocyanins are predominant in pomegranate known for their properties in scavenging free radicals and inhibiting MDA as mentioned by Noda et al.[51]

NO is an important intercellular messenger in the eye. NO is produced in biological tissue by NO synthase would become pathogenic in the progress of glaucomatous optic neuropathy. Our results show that in glaucoma group, histopathological changes observed in the endothelium cell of the rabbit's cornea [Figure 1]b compared to the negative control [Figure 1]a. We suggested that NO released from endothelial cells and contribute to vasodilatation. NO may play a role in increasing local blood flow and decreasing vascular resistance and in the regulation of ocular vessel tone.[52],[53] Our results indicated that in glaucoma group has significantly higher levels of NO compared to the control group [Table 2] and the percentage change was increased by 10.1% comparing to normal control group. After rabbit's consumption 20% dried pomegranate, the data show no significant change [Figure 1]d comparing to control [Figure 1]c, and a highly significant decreased comparing to glaucoma group. Our data were in agreement with Tsai et al.;[54] Toda and Nakanishi-Toda [52] who found that the levels of NO may be increased in glaucoma. In spite of NO production associated with increased oxidative stress, the present data speculated that protective effect of pomegranate leading to improve in the IOP levels and pomegranate may be neuro protective by causing vasodilatation and increased blood flow in the glaucomatous tissue. In addition, NO acts as an antioxidant against harmful free radicals such as superoxide anions,[55] also, NO can interact with oxygen or metals, such as copper or iron, to modulate outflow resistance of the trabecular meshwork as reported by Haefliger et al.[56]

Several mechanisms are considered POAG etiology factors, but metabolic disorders such as hypercholesterolemia, hypertriglyceridemia may have an important role in glaucoma.[57],[58] The results of lipid profiles in normal group fed on 20% pomegranate proved the effect of pomegranate in improving lipid parameters in normal case. This is obviously clear in the percentage of TC, TAG, LDL-C, and VLDL-C, which decreased to −5.5%, −5.3%, −12.4%, and −4.6%, respectively in that group. The percentage change of lipid profiles in glaucoma group show an increase in all lipid profiles to 9.1%, 17.7%, 11.9%, and 18.6%, respectively, except the level of HDL-C, which decreased to 14.4% compared to controls.

In our model, consumption of 20% dried pomegranate resulted in a significant reduction in lipid profiles up to −19.7% reduction in TC, a −8.7% decrease in TAG, a −42.8% decrease in LDL-C, and −8.7% decrease in VLDL-C levels compared to the values of glaucoma group [Table 3]. In the current study, data revealed an elevation in TC, TAG, LDL-C, and VLDL-C in glaucoma group comparing with control group. The data suggested that hyperlipidemia with higher IOP has risk factors in glaucoma and decrease in outflow causes an elevation in IOP. These results confirmed with the results of Panchami et al.[59] who found a positive association between POAG and dyslipidemia. Epidemiological studies have demonstrated that elevated serum levels of the TC, TAG, LDL-C and VLDL-C in glaucoma and lower levels of HDL-C.[59],[60] Data in this table also confirmed with Esmaillzadeh et al.[61] who investigated the cholesterol-lowering effects of pomegranate and found that statistically significant decreases were observed in TC, LDL-C and suggested that this effect may be due to oleanolic acid, ursolic acid, and gallic acid (active components in pomegranate) which recognized as anti-hyperlipidemic properties as reported by Li et al.[62] and Jang et al.[63]

Although both control group and glaucoma treatment 20% dried pomegranate demonstrated more or less similar levels of AST and ALT, there was slightly decreased in level of AST (−5.1%) and also slightly increased (17.5%) concerning to ALT [Table 4]. The current study found no relation between liver function and POAG.

Considering the above facts, results from this study indicate that pomegranate shows a strong therapeutic effect on the rabbit model of chronic, moderately-elevated IOP. The results emphasized that treatment with 20% dried pomegranate decreases in IOP and also decrease the oxidative damage and can prevent the development of glaucoma by maintaining antioxidant enzymes levels. These beneficial effects were attributed to the wide range of phytochemicals found in pomegranate. All these activities may be related to diverse phenolic compounds present in pomegranate include anthocyanin and nonanthocyanin phenols.[64],[65],[66] All the phenolic classes have received considerable attention because of their physiological functions, including free radical scavenging.[67] Gil et al.[14] have demonstrated that one of the ellagitannins, punicalagins, is responsible for over 50% of the antioxidant activity of the pomegranate juice. The antioxidant activity of phenolics is mainly due to their redox properties which make them act as reducing agents, hydrogen donors, and singlet oxygen quenchers. Sentandreu et al.[68] detected a total of 151 phenols, 64 not previously reported in pomegranate juice including several cyanidin and pelargonidin tri-hexoside derivatives.

  Conclusion Top

Through the last few years, nutrition information became sufficient for recommend to patients suffering from different eye diseases such as cataract and glaucoma to consume fruits and vegetables rich in antioxidants to treat or delay the development of the eye diseases. The researchers recommended with consumption of pomegranate daily, because it act as a protective effect against glaucoma development. In HPMC-induced glaucoma rabbits, pomegranate reduced IOP improvement and stopped the progression of glaucoma.

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Conflicts of interest

There are no conflicts of interest.

  References Top

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  [Figure 1]

  [Table 1], [Table 2], [Table 3], [Table 4]


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