Abstract
Context: Sorghum straw (dried leaves and stem fiber) extracts and infusion are employed in the management of several ailments in folklore, and it is also a natural dye source used in food preparation.
Objective: This study sought to investigate the modulatory effect of dietary inclusion of Sorghum straw dye on cisplatin-induced nephrotoxicity and antioxidant status in rats.
Materials and methods: Adult male rats were randomly divided into four groups of six animals each. Groups I (normal rats) and II (control rats) were fed with basal diet while Groups III and IV were fed with diets containing 0.5% and 1% sorghum straw dye, respectively. Nephrotoxicity was induced in Groups I–IV on the 20th day by the administration of a single dose of cisplatin solution (7 mg/kg body weight, i.p.) and the experiment was terminated 3 d after. Thereafter, the kidney and plasma of the rats were analyzed for kidney function (creatinine, urea, uric acid, and blood urea nitrogen) and antioxidant indices [superoxide dismutase (SOD), catalase, glutathione-S-transferase (GST), malondialdehyde (MDA), vitamin C, and reduced glutathione (GSH)].
Results: The average feed intake of the rats in all the groups ranged from 9.0 to 9.5 (g/rat/day). Furthermore, the result indicated that administration of cisplatin caused significant (p < 0.05) elevation in plasma creatinine (2.2 mg/dL), uric acid (39.3 mg/dL), urea (81.4 mg/dL), and blood urea nitrogen (38.0 mg/dL) as well as a concomitant decrease in kidney antioxidant indices in control rats as against the normal rats. However, diets supplemented with 0.5 and 1.0% sorghum straw dye significantly reversed the plasma creatinine and the kidney antioxidant indices to near normal levels.
Discussion and conclusion: The study suggests that dietary inclusion of sorghum straw dye as colorants could protect against oxidative stress and cisplatin-induced nephrotoxicity.
Introduction
Nephrotoxicity involves kidney damage or dysfunction arising from direct or indirect exposure to drugs, industrial, and environmental chemicals. Cisplatin [cis-diamminedichloroplatinum (II)] (CDDP), an anti-neoplastic drug used in the treatment of many solid-tissue cancers has its chief side effect in nephrotoxicity (Arany & Safirstein, Citation2003; Sreedevi et al., Citation2010). And this may be due to the fact that the kidney which is the major route of cisplatin excretion also accumulates it to a greater degree than other organs (Ronald et al., Citation2010; Yao et al., Citation2007). Oxidative stress, inflammation, and apoptosis are some of the mechanisms already established to explain cisplatin-induced acute kidney injury (Yamamoto et al., Citation2010). Nevertheless, a number of strategies have been proposed for the management of cisplatin-induced nephrotoxicity, since there is no specific treatment, with the use of some synthetic drugs been popular. However, these drugs have some associated risks and side-effects (Launay-Vacher et al., Citation2008; Ronald et al., Citation2010; Yao et al., Citation2007), prompting the need for alternative remedy, preferably of plant origin (plant foods/extracts) with little or no side effect.
Plants with pigments/dye have been employed in folklore for the treatment and management of several ailments since time immemorial. Sorghum bicolor (L.) Moench (Poaceace) is one of the numerous species of sorghum grasses raised mainly for grain and as fodder plants for pasture. The plant is native to tropical and subtropical regions of the world (Mutegi et al., Citation2010). In southwestern Nigeria, sorghum straw (dried leaves and stems) extracts and infusion are used as therapy in the management of anemia and sickle cell, and has also found its use as an antimalarial, anthelminthic, and insecticide (Ilori & Odukoya, Citation2005; Okpuzor et al., Citation2008). The therapeutic roles of sorghum and its extracts have been linked to its phytochemical constituents, such as anthocyanin (Awika & Rooney, Citation2004). Furthermore, findings have shown that anthocyanin possess vasoprotective and anti-inflammatory properties (Lietti et al., Citation1976), inhibits lipid peroxidation and radical scavenging ability (Tsuda, Citation2000), anticancer and chemoprotective properties (Karaivanova et al., Citation1990), as well as anti-neoplastic properties (Kamei et al., Citation1995). However, despite the known therapeutic properties of S. bicolor, there is dearth of information on its nephroprotective property. Hence, this study sought to investigate the effect of sorghum straw dye supplemented diets on cisplatin-induced nephrotoxicity in rats.
Materials and methods
Materials
Sorghum straw was purchased at Oja Oba market in Akure metropolis, Nigeria. The sample was authenticated by Mr. K. Adejobi of the Department of Crop, Soil and Pest Management, Federal University of Technology, Akure, Nigeria, and a voucher specimen (no. 4456b) was deposited at the herbarium. The sample was sun-dried, ground into fine powder, and stored in an air-tight container prior to dye/pigment extraction. Cisplatin was obtained from Korea United Pharm. Inc. Except stated otherwise, all other chemicals and reagents were of analytical grade and the water was glass distilled. All the kits used for bioassay were sourced from RANDOX Laboratories Ltd., Crumlin, Co. Antrim, UK. Diet ingredients were purchased from VITAL Feeds, Jos, Nigeria.
Animals
The handling and use of the animals were in accordance with NIH Guide for the care and use of laboratory animals. Adult male rats weighing about 145–165 g were used for this experiment. The animals were sourced from a private animal colony in Akure, Nigeria. The rats were maintained at 25 ± 2 °C on a 12 h light/dark cycle with free access to food and water. They were acclimatized under these conditions for 2 weeks prior to the commencement of the experiments. The experimental study was approved by the Institutional Animal Ethical Committee.
Extraction of sorghum straw dye
The red dye was prepared using a slightly modified method of Adetuyi et al. (Citation2007). Briefly, 100 g of the sorghum straw powder was soaked in 1.8 L of distilled water and kept overnight (12 h). Thereafter, the mixture was filtered and the filtrate collected before the residue was rinsed with another 200 mL of distilled water. This again was filtered and the filtrate collected and added to the previous one. The filtrate was then lyophilized and designated as the red dye, which was kept in an air-tight container prior to the experiment.
Quantification of total and monomeric anthocyanin in sorghum straw dye
A modification of the pH differential method reported by Fuleki and Francis (Citation1968) was used for the quantitative determination of total and monomeric anthocyanin in the red dye. Briefly, 0.2 mL aliquots of the dye solution was added to 2.8 mL of buffer, pH 1.0 (consisting of 125 mL of 0.2 N KCl and 385 mL of 0.2 N HCl), and another 0.2 mL of the dye solution was added to 2.8 mL of buffer, pH 4.5 (consisting of 400 mL of 1 N sodium acetate, 240 mL of 1 N HCl, and 360 mL distilled water) solution. Thereafter, the absorbance readings at 482 nm for the two solutions were taken. Total anthocyanin content was determined using the absorbance of the solution in pH 1.0 buffer, while monomeric anthocyanin content was determined from the differences between absorbance in pH 1.0 and 4.5 buffers. Finally, the anthocyanin content was calculated and expressed as mg luteolinidin equivalent/100 g of sample (luteolinidin, ε = 31 700 M−1 cm−1).
Experimental design and induction of nephrotoxicity
The animals were randomly divided into four groups of six animals each. Groups I and II were fed basal diet (50% skimmed milk, 36% corn starch, 10% groundnut oil, and 4% mineral and vitamin premix) (Oboh et al., Citation2010), while Groups III and IV were fed basal diet supplemented with 0.5% and 1% sorghum straw dye, respectively, for 20 d before cisplatin administration. On day 20, Group I received sterile water (1 mL/kg, i.p.), while nephrotoxicity was induced in Groups II, III, and IV by intraperitoneal administration of a single dose of cisplatin (7 mg/kg body weight) solution (Makwana et al., Citation2012). The experiment was terminated 3 d after the cisplatin administration. The animals were decapitated after an overnight-fast by cervical dislocation and the blood was rapidly collected by direct heart puncture into an EDTA bottle, and the kidney was rapidly isolated, weighed, and kept on ice.
Analytical procedures
Plasma was assayed for uric acid, urea, creatinine, and blood urea nitrogen (BUN) using commercially available kits (Randox Laboratories, Crumlin, UK). Kidney lipid peroxidation was determined by thiobarbituric acid (TBA) reaction (Ohkawa et al., Citation1979) and quantified as malondialdehyde (MDA) content. Superoxide dismutase (SOD) activity was determined by the method of Alia et al. (Citation2003), catalase (CAT) activity was determined according to Sinha (Citation1972), reduced glutathione (GSH) content was assayed according to Ellman (Citation1959), and GST activity was determined according to the method of Habig et al. (Citation1974). Kidney vitamin C content was determined according to Benderitter et al. (Citation1998) and total protein content was determined according to Lowry et al. (Citation1951).
Data analysis
The results of replicate readings were pooled and expressed as mean ± standard deviation. A one-way analysis of variance was used to analyze the results, and Duncan multiple test was used for the post hoc (Zar, Citation1984). Statistical package for Social Science (SPSS, SPSS Inc., Chicago, IL) 16.0 for Windows was used for the analysis. Significance level was taken at p < 0.05.
Results
shows that sorghum straw dye contains total anthocyanin (7.8 mg luteolinidin equivalent/100 g) and monomeric anthocyanin (2.6 mg luteolinidin equivalent/100 g) as its major phenolic constituents.
Table 1. Anthocyanin content of sorghum straw dye.
As shown in , the average feed intake of the animals in all the groups did not differ significantly (p > 0.05) from each other. Furthermore, summarizes the effect of diets supplemented with sorghum straw dye (0.5% and 1%) on the average weight gain/loss (%) of the experimental animals. As revealed by the result, significant weight increase was observed for animals in all the groups prior to cisplatin administration. However, this weight gain was more pronounced in Groups I–III animals than in Group IV animals. Nevertheless, observations made 3 d after cisplatin administration revealed a significant weight loss in Groups II–IV to which cisplatin was administered. Despite this observed weight loss, rats fed diets supplemented with 0.5% (Group III) and 1% (Group IV) sorghum straw dye prior to cisplatin administration showed improvement in their body weight in comparison to the control rats (Group II).
Table 2. Effect of diets supplemented with sorghum straw dye on average fed intake in cisplatin administered rats.
Table 3. Effect of diets supplemented with sorghum straw dye on average weight gain/loss in cisplatin (7 mg/kg i.p.) administered rats.
presents the effect of diets supplemented with sorghum straw dye (0.5% and 1%) on kidney function as typified by plasma creatinine, uric acid, urea, and BUN levels. Significant (p < 0.05) elevation in plasma creatinine, uric acid, urea and BUN levels was observed in the control rats (Group II) in comparison with the normal rats (Group I). However, the protective effect of the diets supplemented with sorghum straw dye was most felt on the plasma creatinine level; where there is a marked decrease in the elevated creatinine level (Group II) as the inclusion of the dye increases from 0.5% (Group III) to 1% (Group IV). But the diets supplemented with sorghum straw dye did not modulate plasma urea and uric acid levels in the treated rats.
Table 4. Effect of diets supplemented with sorghum straw dye on plasma kidney function indices in cisplatin (7 mg/kg i.p.) administered rats.
Furthermore, the effect of diets supplemented with sorghum straw dye (0.5% and 1%) dye on kidney non-enzymatic antioxidant indices (GSH, vitamin C, and MDA contents) is present in . Administration of cisplatin resulted into significant (p < 0.05) depletion/reduction in kidney GSH and vitamin C contents with a concomitant increase in the kidney MDA content of the experimental rats (Group II). However, diets supplemented with sorghum straw dye (0.5% and 1%) protected against alteration in these kidney non-enzymatic antioxidant indices in Groups III and IV animals, respectively.
Table 5. Effect of diets supplemented with sorghum straw dye on kidney non-enzymatic antioxidant (GSH, vitamin C and MDA) indices in cisplatin (7 mg/kg i.p.) administered rats.
Furthermore, alteration in the kidney enzymatic antioxidant indices (SOD, GST, and CAT) was observed following cisplatin administration as exemplified by the decrease in the activities of these enzymes (). However, diets supplemented with sorghum straw dye (0.5% and 1%) protected against depletion of these kidney antioxidant enzymes (Groups III and IV) with the exception of CAT, whereas there is no significant (p > 0.05) difference between Groups II and IV animals.
Table 6. Effect of diets supplemented with sorghum straw dye on kidney enzymatic antioxidants (SOD, GST and catalase) in cisplatin (7 mg/kg i.p.) administered rats.
Discussion
Sorghum straw dye is rich in phytochemicals such as anthocyanin () which has been reported to exhibit strong antioxidant and therapeutic properties (Awika & Rooney, Citation2004; Lietti et al., Citation1976). Anthocyanin has been employed as colorants in food preparation and confectionary production. In addition to impacting desirable color, anthocyanin is also reported to improve the antioxidant and therapeutic properties of foods.
The observed average feed intake and average weight gain/loss of the rats in each group during the 23 d experiment ( and ) suggest that the inclusion of sorghum straw dye in rat diets, neither affected appetite nor causes loss of body weight. This finding is consistent with an earlier study, where dietary inclusion of red sorghum straw dye caused no significant difference in the daily feed intake and weight gain of rats (Oboh et al., Citation2010). However, the weight loss observed 3 d after cisplatin administration () is consistent with an earlier study which suggests cisplatin administration may lead to significant loss of body weight (Özdemir et al., Citation2002). The weight loss associated with cisplatin administration has been attributed to its stimulation of lipolysis and β-oxidation coupled with its suppression of lipogenesis (Garcia et al., Citation2013). Although the process through which sorghum straw red dye protects against cisplatin-induced weight loss cannot be categorically stated, it is suggested that anthocyanin and other polyphenol constituents of the red dye may be involved in the regulation of lipid homeostasis.
Elevation in kidney function biomarkers such as creatinine, uric acid, urea, and BUN is an indication of reduced renal functions (Arneson & Brickell, Citation2007), and estimation of plasma creatinine and uric acid has been employed as key tests to assess impaired renal function (Amin-ul et al., Citation2010). Induction of acute renal damage or nephrotoxicity has been achieved through the administration of cisplatin to experimental animals (Ronald et al., Citation2010; Sreedevi et al., Citation2010); thus, the observed elevation in plasma creatinine, uric acid, urea, and BUN levels in the cisplatin administered rats is an indication of impaired renal function. This is consistent with earlier studies by Abdel-Wahab et al. (Citation2011), Makwana et al. (Citation2012) and Arunkumar et al. (Citation2012). However, the modulation of the plasma creatinine and uric acid levels in rats fed diets supplemented with the sorghum straw dye suggests its ability to regulate renal function. This, however, may be due to some bioactive phytoconstituents such as anthocyanin and some other phenolic compounds in the sorghum dye. Sorghum is a rich source of various phytochemicals such as anthocyanins (), tannins, phenolic acids, phytosterols, and policosanols, with potentials to significantly impact human health (Awika & Rooney, Citation2004). Anthocyanins have been shown to posses several therapeutic properties like hepaprotective and anti-inflammatory (Lietti et al., Citation1976), anti-cancer and chemoprotective (Karaivanova et al., Citation1990), and antineoplastic (Kamei et al., Citation1995).
Furthermore, the elevated kidney MDA content as observed in the cisplatin administered rats is an indication of increased lipid peroxidation. And it is consistent with earlier studies where administration of cisplatin caused lipid peroxidation and inflammation (Arivarasu et al., Citation2013; Ronald et al., Citation2010; Sreedevi et al., Citation2010). This increased lipid peroxidation may be resulting from depletion in the exogenous antioxidant system such as SOD, GST, and CAT (); it is consistent with an earlier study where depletion in SOD, CAT and GST in rat kidney resulted in increased MDA concentration (Arivarasu et al., Citation2013). This compromised kidney endogenous antioxidant status is an indication that cisplatin-induced nephrotoxicity is a function of oxidative stress (Ahmed, Citation2010; Yao et al., Citation2007). However, the observed reduction in the kidney MDA content and restoration of SOD, GST, and CAT activities in rats fed sorghum straw dye supplemented diets suggested improvement in the endogenous antioxidant status. Sorghum anthocyannins are potent antioxidants, capable of inhibiting lipid peroxidation and scavenging reactive oxygen species (ROS) such as (Awika & Rooney, Citation2004). Previous studies have reported that nephroprotective property of some plant foods and extracts is through antioxidant properties exhibited by their constituent phytochemicals (Ahmed, Citation2010; Sreedevi et al., Citation2010).
In addition, the observed decrease in the kidney GSH level in the cisplatin-administered rats is an indication of oxidative stress. This finding is consistent with earlier studies where GSH depletion was suggested to result from interaction between cisplatin and biomolecules containing sulphydryl groups (Khoshnoud et al., Citation2011; Mohamed et al., Citation2013). Likewise, the reduced kidney vitamin C content in the cisplatin administered rats may be related to depleted GSH storage because, GSH is necessary for the recycling of vitamin C (Murray et al., Citation2003). Thus, the restoration of GSH and vitamin C levels in the rats fed with diets supplemented with sorghum straw dye indicates an improvement in the endogenous antioxidant status. Sorghum straw dye is rich in polyphenolic phytochemicals such as anthocyannins () which are strong antioxidants and could provide a sparing effect on the in vivo GSH store, mop-up free radicals, and augment the body’s antioxidant status. Reduced GSH could play a role as an antioxidant agent by scavenging ROS such as hydroxyl radicals, and singlet oxygen (Halliwell & Gutteridge, Citation1989). Vitamin C is one of the several reported exogenous antioxidants that help to build the body’s defenses against free radicals (Bashandy & Al-Wasel, Citation2011). Previous reports have shown that natural products containing antioxidants such as vitamin C could exhibit good nephroprotective properties (Bashandy & Al-Wasel, Citation2011; Sreedevi et al., Citation2012).
Conclusion
Administration of cisplatin to experimental animals caused acute renal damage and nephrotoxicity; which was linked to depletion in the antioxidant status and oxidative stress. However, this damage was ameliorated by diets supplemented with sorghum straw dye. The nephroprotective effect of the dye is suggested to be an indication of possible antioxidant effect of its constituent phytochemicals such as anthocyanin. Hence, the use of S. bicolor straw dye as food colorants/additive could be a cheap dietary strategy for the management of cisplatin-induced impaired renal damage following cisplatin treatment.
Declaration of interest
The authors declare no conflict of interest.
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