Renal effects of plant-derived oleanolic acid in streptozotocin-induced diabetic rats.
Previous studies from our laboratories indicate that the anti-diabetic effects of Syzygium cordatum (Hochst.) [Myrtaceae] leaf extract in streptozotocin-induced diabetic rats may be attributed in part to mixtures of triterpenes, oleanolic acid (3ss-hydroxy-olea-12-en-28-oic acid, OA) and ursolic acid (3ss -hydroxyl-urs-12-en-28-oic acid, UA). For the bioactive compounds to have potential in diabetes management, they should alleviate or prevent complications of diabetes mellitus, kidney function, and cardiovascular disorders. This study was, therefore, designed to assess whether S. cordatum leaf derived OA influenced renal function evaluated by the ability to increase urinary Na(+) outputs parameters and creatinine clearance (Ccr) of streptozotocin (STZ)-induced diabetic rats. Extraction and fractionation of S. cordatum powdered leaf ethyl acetate-solubles (EAS) yielded mixtures of OA/UA and methyl maslinate/methyl corosolate. Recrystallization of OA/UA mixture using ethanol afforded OA, the structure of which was confirmed by NMR spectroscopy ((1)H & (13)C). Acute effects of OA on kidney function and mean arterial blood pressure (MAP) were investigated in anesthetized rats challenged with hypotonic saline after a 3.5-h equilibration for 4h of 1 h control, 1.5 h treatment, and 1.5 h recovery periods. OA was added to the infusate during the treatment period. Chronic effects of OA were studied in individually caged rats treated twice daily with OA (60 mg/kg, p.o.) for five weeks. By comparison with respective control animals administration, OA significantly increased Na(+) excretion rates of non-diabetic and STZ-induced diabetic rats without affecting urine flow, K(+) and Cl(-) rates. At the end of five weeks, OA treatment significantly (p < 0.05) increased Ccr in non-diabetic (2.88 +/- 0.14 vs. 3.71 +/- 0.30 ml/min) and STZ-diabetic rats (1.81 +/- 0.32 vs. 3.07 +/- 0.16 ml/min) with concomitant reduction of plasma creatinine concentration (n = 6 in all groups). OA also caused significant decreases in MAP in non-diabetic and STZ-induced diabetic rats. These findings suggest that OA may have beneficial effects on some processes associated with renal derangement of STZ-induced diabetic rats.
Disciplines of Human Physiology, Faculty of Health Sciences, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban, South Africa.
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Mapanga
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Tufts
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Shode
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Musabayane
D000704:Analysis of Variance; D000818:Animals; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D001794:Blood Pressure / Q000187:drug effects; D003404:Creatinine / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000188:drug therapy*; D003928:Diabetic Nephropathies / Q000188:drug therapy* / Q000517:prevention & control; D004195:Disease Models, Animal; D005919:Glomerular Filtration Rate / Q000187:drug effects; D007677:Kidney Function Tests; D008297:Male; D009828:Oleanolic Acid / Q000494:pharmacology*; D008517:Phytotherapy / Q000379:methods*; D010936:Plant Extracts / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism; D011336:Probability; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D012964:Sodium / Q000378:metabolism; D013311:Streptozocin / Q000494:pharmacology
D001786:Blood Glucose; D010936:Plant Extracts; D013311:Streptozocin; D009828:Oleanolic Acid; D012964:Sodium; D003404:Creatinine; D011188:Potassium