Protective Effect of Sundarban Honey against Acetaminophen-Induced Acute Hepatonephrotoxicity in Rats.

Honey, a supersaturated natural product of honey bees, contains complex compounds with antioxidant properties and therefore has a wide a range of applications in both traditional and modern medicine. In the present study, the protective effects of Sundarban honey from Bangladesh against acetaminophen- (APAP-) induced hepatotoxicity and nephrotoxicity in experimental rats were investigated. Adult male Wistar rats were pretreated with honey (5 g/kg) for 4 weeks, followed by the induction of hepatotoxicity and nephrotoxicity via the oral administration of a single dose of APAP (2 g/kg). Organ damage was confirmed by measuring the elevation of serum alkaline phosphatase (ALP), alanine transaminase (ALT), aspartate transaminase (AST), total protein (TP), total bilirubin (TB), urea, creatinine, and malondialdehyde (MDA). Histopathological alterations observed in the livers and the kidneys further confirmed oxidative damage to these tissues. Animals pretreated with Sundarban honey showed significantly markedly reduced levels of all of the investigated parameters. In addition, Sundarban honey ameliorated the altered hepatic and renal morphology in APAP-treated rats. Overall, our findings indicate that Sundarban honey protects against APAP-induced acute hepatic and renal damage, which could be attributed to the honey's antioxidant properties.

1. Introduction

Honey is a remarkable, complex natural liquid reported to contain at least 181 substances [1]. The supersaturated solution consists of fructose (38%) and glucose (31%) as the major constituents, whereas the rest of the solution's composition is constituted by minor constituents such as phenolic acids, flavonoids, ascorbic acid, certain antioxidant enzymes such as glucose oxidase and catalase, carotenoid-like substances, organic acids, and Maillard reaction products [2]. The minor constituents are reported to be mainly responsible for the antioxidant properties of honey [3]. Honey itself is a unique compound because of its highly variable composition, which depends on its floral source, although other factors such as environment, season, and processing may also have significant effects on the composition of honey [4].

Sundarban in Bangladesh is the largest mangrove forest in the world. Recently, the antioxidant properties of honey collected from this area were investigated and were reported to contain among the highest levels of phenolics, flavonoids, and ascorbic acid [5]. In addition, a significant correlation between the honey's antioxidant composition and 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity or high ferric reducing antioxidant power (FRAP) further confirmed the honey's antioxidant potential observed in vitro. To date, many epidemiological studies have demonstrated the effectiveness of phenolics and flavonoids when used alone or in combination as antitumor [6] or anti-inflammatory agents, in the treatment of cataracts [7] or in reducing the risk of cardiovascular diseases [2]. However, no study has been conducted to investigate the hepato- and nephroprotective effects of honey or Sundarban honey, particularly when administered alone.

Liver disease remains one of the most alarming health issues in the world today. According to world health statistics [8], the strategies for the treatment and prevention of liver disease still have many limitations despite tremendous advances in modern medicine. Because the pathogenesis of liver diseases as well as the causative role of oxidative stress and inflammation in liver diseases is well established [9-11], inhibiting oxidation and inflammatory processes could be one of the most important therapeutic strategies for the treatment and prevention of liver damage. In addition to liver disease, kidney disease is another alarming global public health issue [12, 13], with acute kidney injury becoming an increasingly serious clinical problem, contributing to up to 80% of mortalities [2].

Acetaminophen (paracetamol or N-acetyl-p-aminophenol; APAP) is widely used both as an analgesic and as an antipyretic agent [14]. APAP is a safe drug when administered in therapeutic doses, but its overdose is fairly common due to its availability. Hepatotoxicity and nephrotoxicity are potential complications of APAP overdose, making the assessment of APAP's relative toxicity indispensable. The initial step by which APAP exerts its toxicity is the formation of reactive intermediate N-acetyl-p-benzoquinone imine (NAPQI) by cytochrome p450, which at therapeutic doses, is removed by conjugation with glutathione sulfhydryl (GSH). Overdosing with APAP results in the depletion of cellular GSH, allowing NAPQI to bind to cellular proteins and to initiate lipid peroxidation (LPO), both of which can contribute to hepatic and renal injuries [15]. A number of drugs and chemicals have been used to prevent APAP-induced hepatic and renal damage, such as melatonin, vitamin E, and N-acetyl-cysteine [16], some of which exhibit antioxidant properties. In another study, the hepato- and nephroprotective effects of honey administered in combination with ginseng were established [2]. We postulate that the high antioxidant potential of Sundarban honey may confer similar protective effects when administered singly. In this study, we aimed to investigate the protective effects of Sundarban honey against APAP-induced hepatotoxicity and nephrotoxicity in an experimental rat model.

2. Materials and Methods

2.1. Chemicals

APAP was provided as a gift from Eskayef Bangladesh Limited, Dhaka, Bangladesh. The assay kits used for the determination of bilirubin, creatinine, urea, ALP, AST, and ALT levels were purchased from Standbio Laboratory, 1261 North Main Street, Boerne, TX 78006, USA. The 1,1,3,3-tetraethoxy propane was purchased from Nacalai Tesque, Inc., Kyoto, Japan. All of the chemicals and reagents used were of analytical grade.

2.2. Honey Samples

Multifloral honey samples were collected from the largest mangrove forest of the world, Sundarban, Bangladesh, in February 2013.

2.3. Animals

Adult male Wistar rats (180–210 g) were used in this study. Animals were bred and reared in the animal house facility of the Department of Biochemistry and Molecular Biology, Jahangirnagar University, at a constant room temperature of 23 ± 2°C and in an environment with the humidity ranging between 40% and 70%. The rats were housed in plastic cages with soft wood-chip bedding and received a natural day-night cycle. The rats were provided with a standard laboratory pellet diet and water ad libitum. The experiments were conducted according to the ethical guidelines approved by the Bangladesh Association for Laboratory Animal Science.

2.4. Experimental Design

The animals were randomly divided into 4 groups (with 6 rats in each group). An APAP suspension was prepared with gum tragacanth (0.5%) in normal saline [17]. Group 1, the “control” group, received normal saline for 4 weeks followed by a single dose of 0.5% gum tragacanth. Group 2, the “control + honey” group, received 5 g/kg honey for 4 weeks followed by a single dose of 0.5% gum tragacanth. Group 3, the “honey + APAP” group, received 5 g/kg honey for 4 weeks followed by a single dose of APAP (2 g/kg prepared with 0.5% gum tragacanth). Group 4, the “APAP” group, received normal saline for 4 weeks followed by a single dose of APAP (2 g/kg) suspended with 0.5% gum tragacanth.

All rats were fasted for 18 hours before APAP administration. The choice of APAP doses was based on that established in previous studies [7, 18]. The pretreatment period and dose of honey were also selected based on the results of a recent study [2]. Liver and kidney samples were preserved in 10% formalin for histopathological examination.

2.5. Biochemical Analysis

Standard assay kits were used to determine the levels of total bilirubin, urea, creatinine and activities of ALP, ALT, and AST in serum samples by using a PD-303S Spectrophotometer (APEL, Japan). The serum total protein level was determined according to the method established by Lowry et al. [19]. MDA levels were investigated for products of LPO in the liver and kidney tissues. MDA, which is referred to as thiobarbituric acid (TBA) reactive substance, was measured with TBA at 532 nm according to the method described by Ohkawa et al. [20]. The levels of thiobarbituric acid reactive substance (TBARS) were expressed as nmol of MDA per mg of protein.

2.6. Histopathological Examination

Histopathological examination was conducted on both liver and kidney tissues. Liver and kidney samples were fixed in 10% neutral formalin and were paraffin-embedded. The specimens were cut into sections measuring 5 μm in thickness, followed by staining with hematoxylin-eosin for examination under a light microscope (MZ3000 Micros, Austria). All sections of the liver and kidney samples were examined for characteristic histological changes.

2.7. Statistical Analysis

The results are presented as mean values ± standard deviation (SD). Data were analyzed using SPSS (Statistical Packages for Social Science, version 20.0, IBM Corporation, New York, USA) and Microsoft Excel 2007 (Redmond, Washington, USA). Statistical analyses of biochemical data were conducted by using Tukey's test. A P value of <0.05 was accepted as statistically significant.

3. Results

No deaths or remarkable signs of external toxicity were observed in the groups of rats administered a single APAP dose either alone or in combination with honey.

3.1. Effects of Sundarban Honey and APAP on Serum Hepatic Biomarkers

Serum ALT, AST, and ALP activities as well as TB and TP levels are indicators of hepatic function. The results indicated that administration of APAP alone significantly increased serum levels of biochemical parameters including ALP, ALT, and AST activities and TB level (P < 0.05) while slightly decreasing serum TP level when compared to the control group. The control plus honey treated group exhibit no significant difference from control in terms of any of the investigated biochemical parameters except for the serum ALP activity which was higher than the control. When the honey plus APAP treated group was compared with APAP alone treated group, they had significantly lower hepatic enzymes and TB levels as well as significantly higher TP levels (P < 0.05) (Table 1).

Table 1

The effects of APAP and honey on serum hepatic biomarkers among control and treated rats.

Parameters	Treatment				Percentage change
	Control	Control + honey	Honey + APAP	APAP	Control + honey	Honey + APAP	APAP
ALP (IU/L)	182.81 ± 0.00	190.91 ± 23.31•	192.89 ± 0.00#	315.09 ± 14.16*	4.43%	5.51%	72.36%
ALT (IU/L)	32.69 ± 0.59	32.54 ± 0.54	73.17 ± 2.22#	146.49 ± 0.00*	−0.45%	123.83%	348.12%
AST (IU/L)	108.27 ± 1.01	100.12 ± 0.00	168.85 ± 0.00#	268.98 ± 1.27*	−7.53%	55.95%	148.43%
TB (mg/dL)	0.63 ± 0.03	0.65 ± 0.03	0.74 ± 0.01#	1.36 ± 0.00*	3.17%	17.46%	115.87%
TP (g/dL)	3.27 ± 0.03	3.55 ± 0.23•	3.41 ± 0.12#	3.19 ± 0.01*	8.56%	4.28%	−2.45%

Each value is the mean obtained for six rats ± SD; *symbol in each row indicating the significant difference between control and APAP group; •symbol in each row indicating the significant difference between control and control + honey group; #symbol in each row indicating the significant difference between APAP and honey + APAP at P < 0.05. Percentage change is calculated as 100 × [(value of treatment − value of control)/value of control].

3.2. Effects of Sundarban Honey and APAP on Serum Renal Biomarkers

Table 2 shows the effects of honey and APAP on kidney functions investigated by measuring serum creatinine and urea levels. When compared with control group, the APAP alone treated rats showed a significantly elevated creatinine and urea levels (P < 0.05). The control plus honey treated rats showed no significant changes in serum kidney biomarkers when compared to the control animals. However, pretreatment with Sundarban honey significantly (P < 0.05) reduced serum creatinine and urea levels to control level compared with APAP alone treated group.

Table 2

The effects of APAP and honey on serum renal biomarkers among control and treated rats.

Parameters	Treatment				Percentage change
	Control	Control + honey	Honey + APAP	APAP	Control + honey	Honey + APAP	APAP
Creatinine (mg/dL)	0.73 ± 0.03	0.72 ± 0.02	0.74 ± 0.01#	0.93 ± 0.03*	−1.37%	1.37%	27.39%
Urea (mg/dL)	30.57 ± 2.21	30.43 ± 2.09	31.23 ± 1.41#	47.88 ± 0.97*	−0.46%	2.16%	56.62%

Each value is the mean obtained for six rats ± SD; *symbol in each row indicating the significant difference between control and APAP group; #symbol in each row indicating the significant difference between APAP and honey + APAP at P < 0.05. Percentage change is calculated as 100 × [(value of treatment − value of control)/value of control].

The findings for Sundarban honey were compared with that of Sider honey [2] for the percentage change in similar biological parameters (Table 3). In the other study, the hepatonephrotoxicity in rat was induced by carbon tetrachloride (CCl4).

Table 3

Percentage change of serum hepatic biomarkers for Sundarban honey when compared to another type of honey.

Parameters	Sundarban honey (%)	Sider honey (%)
ALP (IU/L)	92.38	88.24
ALT (IU/L)	64.43	78.31
AST (IU/L)	62.30	82.79
Creatinine (mg/dL)	95.00	112.64
Urea (mg/dL)	96.18	112.51

Percentage of protection conferred by each honey type is calculated as 100 × [(value of APAP or CCl4 − value of honey + APAP or honey + CCl4)/(value of APAP or CCl4 − value of control)].

3.3. Effects of Sundarban Honey and APAP on Hepatic and Renal LPO Levels

Effect of oral administration of “Sundarban honey” on LPO levels on rat liver and kidney tissues was investigated in the study to determine whether “Sundarban honey” has the potential to protect against oxidative damage on hepatic and renal tissues. Following treatment with APAP alone, there was a significant (P < 0.05) augmentation of MDA levels in both liver and kidney tissues as compared with the control rats. Pretreatment with Sundarban honey, however, significantly reduced the MDA levels in the liver and kidney tissues when compared with the levels measured in APAP alone treated group (P < 0.05). When control plus honey treated group was compared with control rats, no significant change in MDA levels was observed (Figure 1).

Figure 1

The effects of APAP and honey on MDA levels (nmol/mg of protein) in liver and kidney tissues. APAP treatment alone caused a significant (P < 0.05) increase in MDA levels in both liver and kidney tissues when compared with the control rats. Honey plus APAP group had significantly reduced the MDA levels in rat liver and kidney tissues when compared with APAP alone treated group (P < 0.05). No significant change was observed when control plus honey treated group was compared with control rats. Each value is the mean obtained for six rats ± SD; ∗ symbol in each bar indicating the significant difference between control and APAP group; # symbol in each bar indicating the significant difference between APAP and honey + APAP at P < 0.05.

3.4. Histopathological Examination of Liver Section

Histopathological examination of the liver section obtained from the control rats and rats treated with only honey showed normal hepatocyte architectures with the presence of the central vein (CV), cytoplasm, and nucleus. The liver tissues of the APAP-treated rats, however, showed marked CV distortion, edema, necrosis, and inflammatory cells, all of which are indicative of hepatic damage. The liver sections of the rats treated with honey followed by APAP intoxication clearly showed changes that indicated beneficial effects (Figure 2).

Figure 2

Hematoxylin-eosin-stained liver sections. (a) The control rat showed normal histopathology. (b) Rats treated with honey also showed normal histopathology. (c) Rats treated with honey followed by APAP intoxication and (d) rats treated with APAP showed morphological changes including CV distortion (blue arrows), inflammatory cells (yellow arrow), edema (green arrows), and necrosis (red arrows).

3.5. Histopathological Examination of the Kidney Section

The control rats and rats treated with only honey showed normal renal tubules and glomeruli. However, rats treated with APAP showed a small glomerulus, severe tubular necrosis, vacuolar degeneration of tubules, epithelial desquamation, and intraluminal casts. APAP-treated rats administered honey, however, showed marked improvement with mild tubular necrosis and vacuolar degeneration (Figure 3).

Figure 3

Hematoxylin-eosin-stained kidney sections. (a) Control rat with normal histopathology. (b) Rats treated with honey. (c) Rats treated with honey followed by APAP intoxication. (d) Rats treated with APAP showing vacuolar degeneration of tubules (yellow arrow), a small glomerulus (green arrows), and intraluminal casts (red arrows).

4. Discussion

The activities of serum ALT, AST, and ALP are the most sensitive biomarkers that can directly indicate the extent of hepatic damage and toxicity [21]. Administration of APAP to rats caused massive elevation in serum ALP, ALT, and AST activities, indicating hepatotoxicity. Pretreatment with Sundarban honey, however, induced the opposite effect, markedly reducing the levels of the above mentioned biomarkers. Serum total bilirubin and total protein levels are correlated to the functions of hepatic cells. Administration of APAP to rats caused a marked increase in TB and decreased TP levels. The rise in bilirubin levels is one of the most important clinical indications of the severity of necrosis, and bilirubin accumulation further indicates the binding, conjugation and excretory capacity of hepatic cells [22]. On the other hand, serum total protein levels can provide information about the severity of liver diseases or necrosis as well as protein synthetic capacity [23]. However, pretreatment with Sundarban honey restored all of the above mentioned parameters significantly, again indicating the honey's role in protecting the liver. It is plausible that the antioxidant compounds present in honey [2, 5, 24] confer protective effects on the liver by preserving membrane integrity [7].

Another highlight of our study was the possible protective effects of Sundarban honey on oxidative damage generated by APAP-induced nephrotoxicity. Serum creatinine and urea levels were significantly increased in groups treated with only APAP; this result is consistent with the findings of a previous study in which APAP was administered to rats [16], confirming the deterioration of renal function. However, the presence of phenolics, flavonoids, ascorbic acids and other antioxidants present in honey [5] may confer nephroprotective effects. This finding is also supported by that of another study in which Ali and Ismail [25] investigated the protective role of honey as a free radical scavenger against amikacin-induced oxidative stresses in the kidneys and observed certain protective effects.

Furthermore, it has been suggested that LPO may contribute to the development of hepatic and renal toxicity. In this study, it was observed that pretreatment with Sundarban honey in APAP-induced toxicity confers significant protection to the liver and kidney from LPO, as evidenced by reduced MDA levels in both liver and kidney tissues. Galal et al. [7] reported the important role played by honey in preventing the formation of hydroxyl radicals and in maintaining cellular integrity and functions. Interestingly, it has been reported that components isolated from honey can promote the production of inflammatory cytokines such as interleukins and tumor necrosis factors [26]. Similarly, it has also been revealed that honey can stimulate the production of inflammatory cytokines important in tissue repair by human monocytic cells [27].

Overall, honey is a source of natural antioxidants that contain a number of phenolic acids, flavonoids, ascorbic acid, tocopherol, catalase, or other antioxidant enzymes and additives. All of these substances operate together to provide a synergistic antioxidant effect, scavenging and eliminating free radicals [28], which may help to inhibit hepatic or renal injury. El Denshary et al. [2] also investigated the role of honey in carbon tetrachloride-induced hepatotoxicity and confirmed honey's potential role in significantly decreasing MDA levels in the liver. It is plausible that the hepatonephroprotective mechanism conferred by the antioxidant activities of phenolics and different flavonoids in Sundarban honey are related to a number of different mechanisms, such as free-radical scavenging, hydrogen donation, singlet oxygen quenching, metal ion chelation, and acting as a substrate for radicals such as superoxide and hydroxyl [2, 29]. Nevertheless, the findings reported herein should be confirmed by studying other types of honey because the phenolic contents of honey are known to be affected by botanical origin [30].

Histopathological changes observed in the liver and kidney tissues further confirmed the hepatonephroprotective effects of Sundarban honey. The histopathological changes in the liver and kidney tissues of APAP-treated rats indicated reduced oxygen perfusion, where the development of liver and kidney diseases may progress as a function of the rate of cell death. However, pretreatment with Sundarban honey produced approximately normal hepatic and renal architecture. The hypothesis used to explain the protective action of Sundarban honey in APAP-induced histopathological alterations is that the phenolics, flavonoids, ascorbic acids, amino acids, and proteins of this honey [5] may scavenge free radicals and inhibit oxidative damage and the consequent degeneration and necrosis of liver and kidney tissues. Korkmaz and Kolankaya [31] reported that the nonprotein sulfhydryl groups in some amino acids and in other components of honey may be involved in the prevention of toxin-induced morphological changes, including CV distortion or degeneration in liver tissues. Halawa et al. [32] also observed that honey can protect liver and kidney cells in rats from oxidative damage. The improvements in the biochemical parameters of animals treated with honey were pronounced and correlated with the histological findings, further confirming the hepato- and nephroprotective effects of Sundarban honey. We tried to integrate our findings of both biochemical and histology and, to the best of our knowledge, this is the first study to describe both the hepato- and nephroprotective effect of honey. However, further study is necessary to elucidate the exact mechanism of the hepatonephroprotection of Sundarban honey and to identify the types of antioxidants present in Sundarban honey.

5. Conclusion

The results of this study demonstrated the favorable hepatonephroprotective action of Sundarban honey against APAP-induced oxidative damage, which was confirmed biochemically and histopathologically. Sundarban honey improves the structural integrity of the cell membrane and ameliorates histopathological changes as well as biochemical perturbations. Therefore, honey can serve as an inexpensive alternative that can be consumed in the daily diet to confer protection against toxin-induced hepatotoxicity and nephrotoxicity.