Protective Potential effect of Gloriosa superba Linn. against lead Nitrate Induced Oxidative stress in Rats.

 

Vadapalli Umarani1*, Muvvala Sudhakar1, Alluri Ramesh2

1Department of Pharmacology, Malla Reddy College of Pharmacy, Dhulapally (Via Hakimpet), Maisammaguda, Secunderabad 500014, Andhra Pradesh, India

2Department of Pharmacology, Vishnu Institute of Pharmaceutical Education and Research, Telangana, India.

*Corresponding Author E-mail: ranileo.rani@rediffmail.com

 

ABSTRACT:

Gloriosa superba Linn. is an inexpensive and efficient source to provide all the required nutrients and medicinal benefits for a healthy and rejuvenating body. The present investigation has been undertaken to evaluate the role of Gloriosa superba Linn. in modifying the lead nitrate induced biochemical alterations in albino rats. Administration of lead nitrate in rats induces oxidative stress, which leads to the generation of free radicals in the body. These free radicals interact with tissue leading to liver and kidney damage. Exposure to lead significantly increased malondialdehyde levels with a significant decrease in superoxide dismutase and catalase activities, and the concentration of GSH in the liver and kidneys of rats. Significantly increased levels of AST, ALT, ALP, BUN and serum creatinine and decreased levels of total protein were observed. The administration of lead significantly decreased the body weight and organ weights at the end of the experimental period. Statistically significant decrease in hemoglobin, red blood cell and total leukocyte count was observed. Pretreatment of hydroalcoholic extract of Gloriosa superba Linn. to lead exposed rats significantly ameliorated lead-induced oxidative stress in tissues and produced improvement in hematological parameters over lead-exposed rats, indicating the beneficial role of Gloriosa superba Linn. to counteract the lead-induced oxidative stress.

 

KEYWORDS: Lead nitrate, Gloriosa superba Linn. oxidative stress, liver, kidney.

 

 


1. INTRODUCTION:

Lead is not known to have any biological role. Increasing concern has been expressed about the rapidly rising level of chemicals in the environment, particularly lead, which has well-known hazardous effects. Many metals play important roles in the functioning of enzymes, cell-signaling processes, and gene regulation.

 

 

This ubiquitous environmental pollutant enters the atmosphere from production of iron, steel, coal, oil and batteries, as well as from smelters, solid waste, and tobacco smoke. Lead can disrupt biological systems by altering the molecular interactions, cell signaling and cellular function. The toxic effect of lead nitrate is well documented in mammals, in which it leads to a broad range of physiological, biochemical, and behavioral dysfunctions (Courtois E et al., 2003). Lead exposure occurs mainly through the respiratory and gastrointestinal systems. Liver is a frequent target for many toxicants (Meyer SA et al., 2001). Autopsy studies of lead-exposed humans indicate that among soft tissue, liver is the largest repository (33%) of lead, followed by kidney. Lead-induced hepatic damage is mostly rooted in lipid per oxidation (LPO) and disturbance of the prooxidant–antioxidant balance by generation of reactive oxygen species (ROS) (Gurer H et al., 2000; Bechara EJH et al., 2004). 

 

The currently approved treatment for lead intoxication is to give chelating agents, such as meso-2,3-dimercaptosuccinic acid (DMSA) and monoisoamyl DMSA (MiADMSA), which form an insoluble complex with lead and shield it from biological targets, thereby reducing its toxicity (Flora SJ et al., 2007).

 

However, these chelators are potentially toxic (Flora SJS et al., 2007) and often fail to remove lead from all body tissues (Cory-Slechta DA et al., 1987). Moreover, because they are hydrophilic or lipophobic (Ding GS et al., 1991; Bosque MA et al., 1994), they cannot cross the cell membrane to capture intracellular lead. Thus, drugs with lipophilic properties are needed.

 

The human diet, which contains many natural compounds, is essential in protecting the body against the development of diseases.Recent trends in controlling and treating diseases favor natural antioxidants.

 

Gloriosa superba lilies valued much for their distinctive, showy and vividly colored blooms. While it’s unusual climbing habits makes Gloriosa superbaLinn. an eye catching addition to any home garden, its extreme toxicity requires the most cautious of handling. Gloriosa superba is one of the medicinal plant grown as a commercial crop and will give good returns. Among the medicinal crops it gives more returns like cash crops. The generic name Gloriosa means ‘full of glory’ and superba means ‘superb’, alluding to the striking red and yellow flowers. Gloriosa is a genus of ten species in the plant family Colchicaceae.

 

Vitamin E is a fat soluble vitamin with numerous biological functions (Flora, 2002)14. It possesses powerful anti-oxidative properties, operative in the membrane to prevent lipid peroxidation by obstructing the free radical chain reaction. Sajitha et al., (2010)15 reported that vitamin E administered to rats counteracted the deleterious effect of lead by scavenging free radicals and thus preventing oxidative stress. Lead induced ALAD inhibition in the erythrocytes was found to be reversed by the treatment with vitamin E (Rendon-Ramirez et al., 2007)16. Vitamin E was also found to be helpful in restoring thyroid dysfunction by maintaining the hepatic cell membrane architecture disrupted indirectly by lead induced lipid peroxidation. Effect of vitamin E in combination with other antioxidants has been found to be more pronounced than its individual administration. Flora et al (2003)17 reported that co-administration of vitamin E with monoisoamyl derivative (MiADMSA), which is a thiol chelator, exerts an elevated recovery from lead burden in rats. Interestingly, α-tocopherol is capable of reducing ferric iron to ferrous iron (i.e. to act as a pro-oxidant). Moreover, the ability of α-tocopherol to act as a pro-oxidant (reducing agent) or antioxidant depends on whether all of the α-tocopherol becomes consumed in the conversion from ferric to ferrous iron or whether, following this interaction, residual α-tocopherol is available to scavenge the resultant ROS (Yamamoto and Nike, 1988).

 

The present study was designed to investigate the effect of Gloriosa superba Linn. against lead nitrate-induced chronic toxicity considering the measurement of hematological parameters (Hb, RBC and TLC counts), blood biochemical variables (ALT, AST, ALP, Total protein, BUN, Creatinine) and markers of oxidative stress by determination of malondialdehyde (MDA) levels as an indicator of lipid peroxidation, reduced glutathione (GSH), catalase (CAT), Superoxide dismutase (SOD) in liver and kidney.

 

2. MATERIALS AND METHODS:

2.1. Collection of plant material:

The tubers of Gloriosa Superba were collected from Tamilnadu, India and authenticated from Department of Botany, Osmania university.

 

2.2. Preparation of the hydroalcoholic extract:

The tubers were separated from Gloriosa Superba Linn. and were shade dried individually. The dried tubers were ground to powder. This dried powder was used for soxhlet extraction. Extraction was done by using the soxhlet apparatus at a temperature below 60oC for 72 hours. Powder was extracted with 70% water and 30% ethanol. The solvent thus obtained was evaporated under vacuum to get a semi-solid form of the extract. Percentage yield was 14% with respect to dried powder. Oral suspension containing 50mg/kg, 100mg/kg, and 200mg/kg, of extract was selected for the evaluation of the activity.

 

2.3. Chemicals:

Lead nitrate was purchased from Central Drug House (India). All other chemicals were of analytical grade and obtained from Qualigens (India/Germany), SD Fine Chemicals (India), HI MEDIA (India), Erba and Span Diagnostics Ltd (Hyderabad).

 

2.4. Animals:

Adult male Sprague–Dawley rats (150 ± 10 g body weight) were obtained from the departmental animal facility where they were housed under standard husbandry conditions (25 ± 2 °C temp., 60–70% relative humidity and 12 h photoperiod) with standard rat feed and water ad libitum. Experiments were conducted in accordance with the guidelines set by the Committee for the Purpose of Control and Supervision of Experiments on Animals (CPCSEA), India and experimental protocols were approved by the Institutional Animal Ethics Committee (CPCSEA/1217/2016/02).

 

2.5. Experimental Design:

The albino rats were divided into six groups of 6 rats each. Rats receiving lead nitrate were given 10 mg/kg body weight lead nitrate: 1.25 mg lead nitrate dissolved in 1 ml distilled water and given by oral route (Sharma et al., 2010).   1/5th,1/10th and 1/20th of the LD50 dose i.e. 50mg/kg,100mg/kg and 200mg/kg of the extract was selected for evaluation of lead induced hepatic and renal damage was carried for 21 days.

·         Group 1: normal control group received normal water.

·         Group 2: Lead nitrate- 10 mg/kg, p.o daily for 21days.

·         Group 3: Lead nitrate +Vitamin E (10 mg/kg, p.o. + 100 mg/kg, p.o.) daily for 21days.

·         Group 4: Lead nitrate + HEGS (10 mg/kg, p.o. + 50 mg/kg, p.o.),

·         Group 5: Lead nitrate +HEGS (10 mg/kg, p.o. + 100 mg/kg, p.o.),

·         Group 6: Lead nitrate + HEGS (10 mg/kg, p.o. + 200 mg/kg, p.o.),

 

Thirty six Wistar Albino male rats of weight 200g-250g were selected for this study. Animals were divided into six groups of six animals each. Group 1: Control group (received distilled water 1ml), Group 2: Lead Nitrate (10 mg/kg, p.o.), Group 3:  Lead Nitrate + vitamin E (10 mg/kg, p.o. + 100 mg/kg, p.o.), Group 4: Lead Nitrate + HEPT (10 mg/kg, p.o. + 50 mg/kg, p.o.), Group 5: Lead Nitrate + HEPT (10mg/kg, p.o.+100 mg/kg, p.o.),Group 6: Lead Nitrate + HEPT(10 mg/kg, p.o. + 200 mg/kg, p.o.). All the groups were treated once daily for a period of 21 days. The animals were weighed and behavioral observations were recorded before and at the end of the experiment. After the administration of last dose, the animals were given rest overnight and then on the next day, they were sacrificed under light ether anesthesia. The organs were removed, cleaned, washed with phosphate buffer saline (pH 7.4) for various studies.

 

On completion of the experimental period, animals from all groups (group 1, 2, 3, 4,5 and 6) were sacrificed on 22nd day after initiation of the experiment by cervical decapitation. Blood was collected in heparinized tubes; serum was isolated to assess various biochemical variables. Tissue samples (liver and kidney) of each animal were immediately processed for the biochemical analysis. All assays were performed with freshly isolated samples. The samples were maintained at −20 °C before performing assays (not more than 7 days).

2.6. Blood Biochemical Analysis:

Blood samples were allowed to stand at room temperature for 30 min and serum was isolated by centrifugation at 1000 × g for 15 min and used for estimation of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) (Reitman and Frankel), ALP (Fiske and Subbarow), Creatinine (Bowers LD., 1980), Blood Urea Nitrogen (BUN) and total protein (Ohkawa H et al.,).

 

2.7. Biochemical Assays:

Liver and kidney were minced separately and homogenized (10% w/v) in ice-cold 0.1 M sodium phosphate buffer (pH 7.4). The homogenate was centrifuged at 10,000 rpm for 15–20 min at 4°C twice to get the enzyme fraction. The supernatant was used for biochemical assays.

 

2.7.1. Lipid peroxidation (LPO):

LPO was estimated colorimetrically by measuring malondialdehyde (MDA) formation as described by Nwanjo and Ojiako, 2005. In brief, 0.1 ml of homogenate was treated with 2 ml of a 1:1:1 ratio of TBA–TCA–HCl (TBA 0.37%, TCA 15%, HCl 0.25 N) and placed in water bath at 65°C for 15 min, cooled, and centrifuged at 5,000 rpm for 10 min at room temperature. The optical density of the clear supernatant was measured at 535 nm against a reference blank. The MDA formed was calculated by using the molar extinction coefficient of thiobarbituric acid reactants (TBARS; 1.56×105l/mole cm−1). The product of LPO was expressed as nmol of MDA formed per g of tissue.

 

2.7.2. Superoxide dismutase (SOD):

Hepatic and renal SOD activity was assayed according to the method of Marklund and Marklund, 1974. For the control, 0.1 ml of 20 mMpyrogallol solution was added to 2.9 ml of Tris buffer and mixed, and reading was taken at 420 nm after 1.5 and 3.5 mins. The absorbance difference for 2 min was recorded and the concentration of pyrogallol was adjusted in such a way that the rate in change of absorbance per 2 min was approximately 0.020–0.023 optical density units.

 

Liver and kidney extract (200 µl) was treated with 10 µl of 25% triton X-100 and kept at 4°C for 30 min. To 2.8 ml of Tris buffer, 0.1 ml of treated sample was added and mixed, and the reaction was started by adding 0.1 ml of adjusted pyrogallol solution (as for control). Reading was taken at 420 nm after 1.5 and 3.5 mins and the difference in absorbance was recorded. The enzyme activity was expressed as U/ml of extract and 1 U of enzyme is defined as the enzyme activity that inhibits auto-oxidation of pyrogallol by 50%.

 

2.7.3. Catalase (CAT):

Catalase (CAT) activity was estimated following the method of Aebi, 1993. The homogenate (100 µl) was treated with ethanol (10 µl) and placed on an ice bath for 30 min. To this, 10 µl of 25% triton X-100 was added and again kept for 30 min on ice. To 200 µl phosphate buffer (0.1 M), 50 µl of treated liver and kidney homogenate and 250 µl of 0.066 M H2O2 (prepared in 0.1 M phosphate buffer, pH 7.0) were added in a cuvette. The decrease in optical density was measured at 240 nm for 60 s. The molar extinction coefficient of 43.6 cm−1 was used to determine CAT activity. One unit of activity is equal to the moles of H2O2degraded/min/mg protein.

 

2.7.4. Glutathione (GSH)

Reduced glutathione (GSH) was determined by the method of Ellman, 1959. In brief, 1 ml of supernatant was taken after precipitating 0.5 ml of liver and kidney homogenate with 2 ml of 5% TCA. To this, 0.5 ml of Ellman's reagent (0.0198% DTNB in 1% sodium citrate) and 3 ml of phosphate buffer (1 M, pH 8.0) was added. The color developed was read at 412 nm. Reduced GSH concentration is measured by using a drawn standard curve and was expressed as mg/g of tissue.

 

2.9. Statistical Analysis:

The experimental results were expressed as the Mean ± SEM with six rats in each group. The intergroup variation between various groups were analyzed statistically using one-way analysis of variance (ANOVA) using the Graph Pad Prism version 5.0, followed by Dunnett’s multiple comparison test (DMCT). Results were considered statistically significant when P < 0.05.

 

3. RESULTS:

3.1. Assessment of Blood Biochemical variables:

Table 1displays the results of enzymatic activities of AST, ALT, ALP and Total protein levels in control, HEGS extract treated group, lead nitrate-exposed group and HEGS +lead nitrate treated groups. These enzymes are normally embedded in the hepatocyte plasma membrane, mainly in the canalicular domain. The alteration in these enzymes indicates the damage to the cell. Table 1shows the toxicological profile of lead nitrate on various blood biochemical variables. The activities of AST, ALT and ALP were significantly increased and total protein levels were significantly decreased in lead nitrate-exposed group when compared with the control group (P ≤ 0.01). Treatment with HEGS extract reversed lead induced alterations (P ≤ 0.01) in different blood variables significantly towards control.

 

Lead exposure produced significant increase (P<0.01) in BUN and Creatinine levels in lead control group when compared to normal control group. Pretreatment of hydroalcoholic extract ofGloriosa superba before lead exposure showed significant decrease (P<0.05) in BUN and Creatinine levels in HEGS +LD when compared to lead control group (Table 2).

 

Table 1: Effect of Gloriosa superba Linn. on Serum parameters in lead induced hepatotoxicity in rats.

GROUPS

AST

ALT

ALP

TP

(IU/L)

(IU/L) 

(IU/L)

(gm/dl)

Normal

33.8

35.55

0.16

12.09

Control

±2.03

±2.22

±1.42

±2.03

Lead

48.3 a

44.7a

0.20#

8.03#

(100mg/kg)

±9.3

±3.72

±2.24

±3.9

Lead (10mg/kg)+

33.2

35.5

0.16

12.05

Vit E(100mg/kg)

±2.45

±3.72

±2.24

±3.33

HEGS (50mg/kg)+Lead

39.7 **

36.9 **

0.17 **

10.4**

(10mg/kg)

±3.4

±5.3

±2.24

±3.9

HEGS (100mg/kg)+Lead

40.6 **

38.9 **

0.17 **

10.7 **

(10mg/kg)

±3.4

± 5.5

± 2.26

±3.9

HEGS (200mg/kg)+Lead

40.8**

37.9 **

0.18 **

10.8 **

(10mg/kg)

±3.3

±5.5

± 2.24

±3.9

Values are expressed as mean ± SEM, n=6. # P<0.001 vs normal control, a P<0.01 vs normal control, **   P<0.01 vs lead control. The intergroup variation between various groups were analyzed statistically using Dunnett’s multiple comparison test. 

 

Table 2: Effect of Gloriosa superb Linn. on Serum Parameters on Lead Induced Nephrotoxicity in rats.

GROUPS

BUN

CREATININE

(mg/dl)

(mg/dl)

Normal

0.16

1.2

control

±0.006

±1.5

Lead

0.20 #

2.7#

(10mg/kg)

±0.005

±3.6

Lead+Vit E 0.16

1.2

(100mg/kg)

±0.004

±2.3

HEGS (50mg/kg) + Lead

0.17

1.8**

(10mg/kg)

±2.24

±2.9

HEGS (100mg/kg) + Lead

0.19

1.8**

(10mg/kg)

±2.24

±2.6

HEGS (200mg/kg) + Lead

0.19

1.8**

(10mg/kg)

±2.25

±2.9

Values are expressed as mean ± SEM, n=6. # P<0.01 vs normal control, ** P<0.05 vs lead control. The intergroup variation between various groups were analyzed statistically using Dunnett’s multiple comparison test. 

 

3.2. Body and organ weight changes:

 It illustrates the changes in the body, liver and kidney weights of treated rats and control. As shown in the figure, lead nitrate induced a significant (p < 0.01) reduction on the average body weight of rat and the organs weight (liver and kidney) also decreased. However, pretreatment with HEGS improved the body weight and organs weight.

 

3.3. Determination of Lipid Peroxidation, Catalase, SOD and Reduced Glutathione Contents:

Table 3 and 4 shows the results of lipid peroxidation and reduced glutathione, SOD and catalase levels in all groups. Administration of lead nitrate to rats induced an increase in lipid peroxidation with a concomitant decline in reduced glutathione, SOD and catalase levels, in liver and kidney (P ≤ 0.01). This confirms that lead nitrate accentuate lipid peroxidation an indicator of tissue damage and GSH, SOD and Catalase are presumed to be an important endogenous defenses against peroxidative destruction of cellular membranes. Thus alterations in both the parameters were significantly recouped by the treatment with Gloriosa superba extract.


 

Table 3: Effect of Gloriosa superba Linn.on MDA and CAT on Lead induced hepatotoxicity and nephrotoxicity in rats.:

Groups

MDA(nm/g)

CATALASE(k/min)

LIVER

KIDNEY

LIVER

KIDNEY

Control

37±0.11

40.7±0.57

1.6±0.52

37.5±0.5

Pb (NO₃)₂ (10mg/kg)

81±0.09

57.1±0.66^

40.21±1.6^

24.5±0.72^

Pb (NO₃)₂+Vitamin E (100mg/kg)

77±0.11

33.4±0.66#

30.37±0.11#

38.5±0.43#

HEGS (50mg/kg)+Pb(NO₃)₂(10mg/kg)

52±0.13*

47.2±0.34*

51.67±2.15*

28.6±0.51*

HEGS (100mg/kg) + Pb (NO₃)₂(10mg/kg)

42±0.11**

45.2±0.4**

68.01±1.95**

30.06±0.46**

HEGS (200mg/kg) + Pb (NO)₂ (10mg/kg)

41±0.12***

39.1±0.43***

61.6±0.42***

35.2±0.33

Values are expressed as mean ± SEM. n=6; ^p<0.0001 compared normal group, #p<0.0001compared to lead group, *p<0.0001 compared to lead group, **p<0.0001 compared to lead group, ***p<0.0001 compared to lead group. Pb(NO3)2----Lead Nitrate

 

Table 4: Effect of Gloriosa superba Linn. on GSH and GR on lead induced hepatotoxicity and nephrotoxicity in rats.:             

Groups

GR

GSH (mcg/ml)

LIVER

KIDNEY

LIVER

KIDNEY

Control

45.33±0.66

42.56 ±0.54

14.4±0.88

12.4±0.88

Pb(NO₃)₂(10mg/kg)

28.2±0.35^

21.6± 0.42^

3.5±0.71^

2.5±0.71^

Pb(NO₃)₂+Vit E(100mg/kg )

30±0.11#

33.4±0.66#

4.02±0.11#

5.02±0.11#

HEGS (50mg/kg) + Pb (NO₃)₂(10mg/kg)

33.51±0.54*

34.3± 0.69*

7.8±1.42*

8.8±1.42*

HEGS (100mg/kg) + Pb(NO₃)₂(10mg/kg)

37.3±0.51**

35.2±0.44**

9.8±1.5**

10.8±1.5**

HEGS (200mg/kg) + Pb (NO₃)₂ (10mg/kg)

41±0.12***

39.1±0.43***

13.1±1.61***

12.1±1.6***

Values are expressed as mean ± SEM. n=6; ^p<0.0001 compared normal group, #p<0.0001compared to lead group,*p<0.0001 compared to lead group, **p<0.0001 compared to lead group, ***p<0.0001 compared to lead group. Pb(NO3)2----Lead Nitrate

 


4. DISCUSSION:

Lead is a wide spread constituent of earth's crust (Herbert, 1999). It can cause hypertension, developmental defects, neurological problems, renal dysfunction, and anemia. In recent years dietary plants with antioxidant property have been receiving considerable attention. It is believed that these plants can protect tissues against the damaging effect of free radicals (Osawa and Kato, 2005). The role played by natural compounds in the modulation of the toxic effects of lead nitrate is little known. The present study demonstrates the efficacy ofGloriosa superba in treating lead nitrate toxicity. Our results indicate a significant alternation in the peroxidative process following lead nitrate exposure. The increase in LPO level and decrease in the endogenous antioxidant enzymes SOD, CAT, and GSH by lead nitrate (Fig 2, 3) are consistent with earlier reports (Mohammed et al., 2008; Adanaylo and Oteiza, 1999).

 

Cellular systems are well protected from ROS-induced cell injuries by an array of defenses composed of various antioxidants with different functions. Whenever the ROS present in the cellular system overpower these defense systems, they cause oxidative stress or cell injury, leading to the development of diseases. It has been revealed that lead toxicity leads to free radical damage via two separate pathways: (1) the generation of ROS, including hydroperoxides, singlet oxygen, and hydrogen peroxide and (2) the direct depletion of antioxidant reserves (Ercal et al., 2001).

 

The cell membrane is the main target of the oxidative damage produced by xenobiotics, including heavy metals (Halliwell and Gutteridge, 1989). This is mainly due to changes in polyunsaturated fatty acids having double bonds, largely present in the phospholipids of membranes (Slater, 1985). Lead is known to produce oxidative damage by enhancing peroxidation of membrane lipids, and LPO is a deleterious process carried out solely by free radicals. In fact, LPO is an outcome of the chain of events involving initiation, propagation, and termination reactions (Halliwell, 1996). Unchecked peroxidative decomposition of membrane lipids is catastrophic for living systems. The lipid peroxides produced are degraded into a variety of products, including alkanals, hydroxyl alkanals, ketones, and alkenes (Halliwell and Gutteridge, 1989). All these products inactivate cell constituents by oxidation or cause oxidative stress by undergoing radical chain reactions ultimately leading to loss of membrane integrity.

 

LPO can also adversely affect the function of membrane-bound proteins, such as enzymes and receptors. Several studies have focused on the possible toxic effects of lead on membrane components and identified a correlation between these effects and lead-induced oxidative damage. Yiin and Lin (Yiin and Lin, 1995) demonstrated a marked enhancement in MDA concentration following incubation of linoic, linolenic, and arachidonic acid with lead. According to Caylak et al. (Caylak et al., 2007), lead might have a direct peroxidative activity or act indirectly by providing conditions suitable for LPO. Direct peroxidative activity of lead may be associated with ROS generation, such as H2O2, atomic oxygen, and hydroxyl radicals (Ding et al., 2000). Usually, the deleterious effects of oxidative stress i.e. generation of free radicals are counteracted by endogenous antioxidant enzymes, mainly SOD, CAT, and GSH (Winterbournn, 1993) and the levels of these antioxidants decrease.

 

In the present study, the activities of SOD and CAT, and the concentration of GSHwere reduced by lead nitrate, thus exposing the tissues to peroxidative damage. CAT and SOD are metalloproteins accomplishing their antioxidant functions by enzymatically detoxifying peroxides (OOH), H2O2, and O2·. These antioxidant enzymes depend on various essential trace elements and prosthetic groups for proper molecular structure and enzymatic activity. The pathogenesis of lead toxicity is multifactorial, as lead directly interrupts enzyme activation, competitively inhibits trace mineral absorption, and binds to sulfhydryl proteins (interrupting structural protein synthesis) (Slater, 1985).

 

New findings revealed that GSH depletion is another important mechanism of lead toxicity. GSH is a tripeptide-containing cysteine with a reactive –SH group and reductive potency. GSH is an important cellular antioxidant defense system against free radical overproduction, and decreasing its cellular concentration impairs cellular defenses against oxidative stress (Dickinson et al., 2003). It can act as a non-enzymatic antioxidant by direct interaction of the –SH group with ROS, or it can be involved in the enzymatic detoxification reactions for ROS as a cofactor or a coenzyme (Gurer et al., 1998). It possesses carboxylic acid groups, an amino group, a –SH group, and two peptide linkages as sites for reactions of metals. Lead binds exclusively to the –SH group, which decreases the GSH levels and can interfere with the antioxidant activity of GSH.

 

Liver enzymes such as AST, ALT and ALP are marker enzymes for liver function and integrity (Adarmoye et al., 2008). These enzymes are usually elevated in acute hepatotoxicity or mild hepato-cellular injury, but tend to decrease with prolonged intoxication due to liver damage (Cornelius, 1979). In our study, administration of lead nitrate led to a significant rise in AST, ALT and ALP activities, and conversely decreased total protein level (Table 1). These results are in accordance with our previous findings (Sharma et al., 2009).

 

The increased levels of AST and ALT have been attributed to the damaged structural integrity of the liver. Lead causes cell lysis by affecting the K+–Ca2+ channels. Cytoskeleton alterations induce increased susceptibility to lysis (Serrani et al., 1997).

In our study, decrease in total protein levels was observed in liver tissue, which is in agreement with El-Zayat et al. (1996), who found a decrease in hepatic total protein content in response to lead intoxication. The inhibitory role of lead in protein synthesis may be due to its damaging effect on DNA and RNA (Shalan et al., 2005). Lead is associated with DNA damage through base pair mutation, deletion, or oxygen radical attack on DNA. Moreover, Pb2+ disturbs intracellular Ca2+ homeostasis (Simons, 1993) and damages the endoplasmic reticulum, which in turn results in reduction of protein synthesis.

 

An alteration in serum urea, uric acid and creatinine was observed in lead nitrate administrated albino rats (Ashour et al., 2007). In the present study administration of lead nitrate showed an increase in the serum creatinine and BUN levels (Table 2).

 

In the present study, treatment of rats with lead resulted in significant weight loss which improved significantly when pretreated with Gloriosa superba extract. This result was corroborated as evident by the biochemical alterations.

 

5. CONCLUSION:

It show that HEGS treatment partly mitigates lead nitrate-induced changes in hepatic and renal-biochemical and hematological parameters. This could be due to its antioxidant nature, which combines free radical scavenging with metal chelating properties. The healing effect of  HEGS was also confirmed by all the above observations, which suggest that the Gloriosa superba(HEGS) extract was effective in bringing about functional improvement of hepatocytes and nephrons.

 

HEGS can be given to human populations exposed to environmental toxicants and can provide protection against toxic effects without being appreciably harmful itself. Moreover, efforts are needed for the choice of appropriate dose, duration of treatment, and possible side-effects on major organs.

 

6. CONFLICTS OF INTEREST STATEMENT:

The authors declare that there are no conflicts of interest.

 

7. ACKNOWLEDGEMENTS:

The authors are thankful to the authorities of Malla Reddy College of Pharmacy, Secunderabad, for providing support to this study.

 

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Received on 18.06.2019            Modified on 14.07.2019

Accepted on 31.07.2019            © A&V Publications All right reserved

Asian J. Res. Pharm. Sci. 2019; 9(3):186-192.

DOI: 10.5958/2231-5659.2019.00029.8