gentamicin ( gm ) is one of the amino glycoside drugs used in gram - negative infections . nephrotoxicity is specified by renal dysfunction , which is distinguished by increasing serum levels of blood urea nitrogen ( bun ) and creatinine ( cr ) . compounds such as lycopene , metformin , garlic , vitamin e , probucol , and erythropoietin could prevent renal damage induced by gm . furthermore , several studies have suggested that supplementations of herbal extracts such as ginkgo biloba , bauhinia variegata , pongamia pinnata flower , and grape seed may attenuate gm - induced nephrotoxicity . althaea officinalis ( marshmallow , marshmallow , or a common marshmallow ) , the member of malvaceae family , is well - known for its medicinal properties . it is demonstrated that a. officinalis has potential therapeutic benefits in lipomia , inflammation , gastric ulcer , and platelet aggregation . the pharmacological and antioxidant activities of a. officinalis refer to various compounds such as polysaccharides and flavonoids present in the plant . in the present study , we attempted to investigate the effect of a. officinalis flower extract ( aofe ) as an antioxidant against nephrotoxicity - induced by gm in male rats . adult male wistar rats ( animal centre , isfahan university of medical sciences ) were used in this study . this research was approved in advance by the isfahan university of medical sciences ethics committee . dried violet flowers of a. officinalis preparation of the extract was fulfilled in two steps ; first , 600 ml ethanol 70% was added to 150 g prepared powder and the total mixture was shaken for 24 h at the temperature of 23 - 25c . , 600 ml ethanol 96% was added to the material remained from the first step and again the total mixture was shaken for 24 h at the temperature of 23 - 25c . the extract obtained after filtration in this step was mixed with the yield of the first step . then , the total extract was incubated at the temperature of 50c for 48 h and finally 100% dried extract was obtained . group 1 ( n = 6 ) as negative control group received aofe 250 mg / kg / day for 9 days , and saline was added from day 3 ongroups 2 ( n = 5 ) as positive control group received saline during the study and gm ( 100 mg / kg / day ) was added from day 3 ongroup 3 ( n = 6 ) received aofe 50 mg / kg / day for 9 days , and gm ( 100 mg / kg / day ) was added from day 3 on . groups 4 ( n = 7 ) and 5 ( n = 6 ) had the same regimen of group 3 except aofe dose which were 250 mg / kg / day and 500 mg / kg / day , respectively . all administrations were done intraperitoneally . at the end of the experiment , blood samples were obtained via heart puncture , and the serum was kept at 20c to measure the serum levels of bun and cr . finally , the animals were killed . the kidneys were removed and weighed immediately . left kidney was fixed in formalin and staining was performed to detect the tissue damage . group 1 ( n = 6 ) as negative control group received aofe 250 mg / kg / day for 9 days , and saline was added from day 3 on groups 2 ( n = 5 ) as positive control group received saline during the study and gm ( 100 mg / kg / day ) was added from day 3 on group 3 ( n = 6 ) received aofe 50 mg / kg / day for 9 days , and gm ( 100 mg / kg / day ) was added from day 3 on . groups 4 ( n = 7 ) and 5 ( n = 6 ) had the same regimen of group 3 except aofe dose which were 250 mg / kg / day and 500 mg / kg / day , respectively . blood samples were obtained via heart puncture , and the serum was kept at 20c to measure the serum levels of bun and cr . finally , the animals were killed . the kidneys were removed and weighed immediately . left kidney was fixed in formalin and staining was performed to detect the tissue damage . the left kidney was fixed in 10% neutral formalin and embedded in paraffin . after slicing , hematoxylin and eosin staining was performed to examine tissue damage including tubular atrophy , cast , debris , and necrotic materials in the tubular lumen . intensity of tubular lesion was scored from 1 to 4 , while zero score was assigned to normal tissue without damage . the two groups were compared with regard to the serum levels of bun and cr , and kidney weight ( kw ) by independent student 's t - test . the parameters were analyzed by one - way anova followed by least significant difference test among the groups . the kidney tissue damage score ( ktds ) was compared using kruskal  wallis or mann  whitney tests . preparation of the extract was fulfilled in two steps ; first , 600 ml ethanol 70% was added to 150 g prepared powder and the total mixture was shaken for 24 h at the temperature of 23 - 25c . , 600 ml ethanol 96% was added to the material remained from the first step and again the total mixture was shaken for 24 h at the temperature of 23 - 25c . the extract obtained after filtration in this step was mixed with the yield of the first step . then , the total extract was incubated at the temperature of 50c for 48 h and finally 100% dried extract was obtained . group 1 ( n = 6 ) as negative control group received aofe 250 mg / kg / day for 9 days , and saline was added from day 3 ongroups 2 ( n = 5 ) as positive control group received saline during the study and gm ( 100 mg / kg / day ) was added from day 3 ongroup 3 ( n = 6 ) received aofe 50 mg / kg / day for 9 days , and gm ( 100 mg / kg / day ) was added from day 3 on . groups 4 ( n = 7 ) and 5 ( n = 6 ) had the same regimen of group 3 except aofe dose which were 250 mg / kg / day and 500 mg / kg / day , respectively . blood samples were obtained via heart puncture , and the serum was kept at 20c to measure the serum levels of bun and cr . finally , the animals were killed . group 1 ( n = 6 ) as negative control group received aofe 250 mg / kg / day for 9 days , and saline was added from day 3 on groups 2 ( n = 5 ) as positive control group received saline during the study and gm ( 100 mg / kg / day ) was added from day 3 on group 3 ( n = 6 ) received aofe 50 mg / kg / day for 9 days , and gm ( 100 mg / kg / day ) was added from day 3 on . groups 4 ( n = 7 ) and 5 ( n = 6 ) had the same regimen of group 3 except aofe dose which were 250 mg / kg / day and 500 mg / kg / day , respectively . blood samples were obtained via heart puncture , and the serum was kept at 20c to measure the serum levels of bun and cr . finally , the animals were killed . the kidneys were removed and weighed immediately . left kidney was fixed in formalin and staining was performed to detect the tissue damage . the left kidney was fixed in 10% neutral formalin and embedded in paraffin . after slicing , hematoxylin and eosin staining was performed to examine tissue damage including tubular atrophy , cast , debris , and necrotic materials in the tubular lumen . intensity of tubular lesion was scored from 1 to 4 , while zero score was assigned to normal tissue without damage . the two groups were compared with regard to the serum levels of bun and cr , and kidney weight ( kw ) by independent student 's t - test . the parameters were analyzed by one - way anova followed by least significant difference test among the groups . gentamicin itself induced nephrotoxicity , which was confirmed by increasing in the serum levels of bun and cr as well as elevating in ktds and kw ( p < 0.05 ) [ table 1 ] . administration of various doses of aofe accompanied with gm did not attenuate the serum levels of bun and cr ; rather it increased the values ( p < 0.05 ) . high dose of aofe aggravated renal damage induced by gm in comparison with other groups ( p < 0.05 ) [ figure 1 ] . sample images from group 1 treated with aofe alone and group 5 treated with gm plus high dose of aofe are demonstrated in figure 2 . bun and cr serum levels , ktds , and kw g/100 g body weight in the experiment groups blood urea nitrogen ( bun ) and creatinine ( cr ) serum levels , kidney tissue damage score ( ktds ) , and kidney weight g/100 g of body weight in the experiment groups . gentamicin ( gm ) , althaea officinalis flower extract ( aofe ) 50 + gm , aofe 250 + gm , and aofe 500 + gm groups received saline , aofe 50 mg / kg / day , aofe 250 mg / kg / day , and aofe 500 mg / kg / day for 9 days , respectively , and gm ( gm ; 100 mg / kg / day ) was added from day 3 on . indicates significant difference from aofe 250 + gm group sample images from group 1 treated with althaea officinalis flower extract ( aofe ) alone ( left ) and group 5 treated with gm plus high dose of aofe ( right ) . the aim of this study was to investigate whether aofe could ameliorate nephrotoxicity induced by gm in the male rat . we observed that aofe administration did not ameliorate nephrotoxicity induced by gm ; rather it intensified renal failure . gm induces renal dysfunction , which is characterized by increase in levels of cr , uric acid , and bun . in addition , it is accompanied with tissue alterations such as glomerular congestion , disruption of glomerular capillaries , vacuolar degeneration of tubular epithelial cells , and hyaline cast formation . furthermore , the present study indicated that gm enhanced normalized kw probably due to edema caused by tubular necrosis . useful properties of a. officinalis flower were documented in the literature , but we did not obtain positive results in the administered doses . it is demonstrated that administration of 50 mg / kg dose of a. officinalis flower result in a significant increase in serum hdl cholesterol level . also , antiinflammatory and antiulcerogenic effects of the extract were observed at doses of 50 , 100 , and 250 mg / kg . in contrast , we observed that doses of 50 and 250 mg / kg of aofe aggravated the increased levels of bun and cr induced by gm . in addition , aofe at the dose of 500 mg / kg aggravated both renal dysfunction and tissue damage . it has reported that increasing the dose of aofe to 500 mg / kg significantly decreased stool water content . it is also reported that high doses of some antioxidants provide a harmful effect on survival of the subjects . therefore , it is possible that aofe at the doses lower than 50 mg / kg may ameliorate nephrotoxicity induced by gm . although aofe acts as an antioxidant , doses of aofe used in the current study did not ameliorate nephrotoxicity induced by gm , and it is necessary to test doses lower than 50 mg / kg .
background : gentamicin ( gm ) is used as antibiotic for gram - negative infections , but its administration is limited due to a side - effect of nephrotoxicity . it was attempted to investigate the effect of althaea officinalis flower extract ( aofe ) against nephrotoxicity induced by gm in male rats.methods:30-year-old male wistar rats were divided into five groups . 
 group 1 as a negative control group received aofe 250 mg / kg / day . 
 groups 2 - 5 received saline , aofe 50 mg / kg / day , aofe 250 mg / kg / day , and aofe 500 mg / kg / day for 9 days , respectively , and gm ( 100 mg / kg / day ) was added from the 3rd day on . at the end of the experiment , blood samples were obtained , animals were sacrificed , and the kidneys were removed immediately.results:gentamicin ( in group 2 ) significantly increased serum levels of blood urea nitrogen and creatinine as well as the pathological damage score ( p < 0.05 ) when compared with group 1 . 
 low dose of aofe did not decrease the nephrotoxicity induced by gm while the high dose of aofe aggravated renal toxicity ( p < 0.05).conclusions : although aofe acts as an antioxidant , at the doses used in the current study did not ameliorate nephrotoxicity induced by gm .