Antioxidant effects of maslinic acid in livers, hearts and kidneys of streptozotocin-induced diabetic rats: Effects on kidney function

Renal Failure (Impact Factor: 0.94). 12/2013; 36(3). DOI: 10.3109/0886022X.2013.867799
Source: PubMed


Abstract Studies indicate that hyperglycemia-induced oxidative stress triggers the development of microvascular and macrovascular complications in diabetes. Accordingly, we hypothesized that maslinic acid (MA) prevents these complications due to its antioxidant properties. We, therefore, investigated the effects of 5-week MA treatment of streptozotocin (STZ)-induced diabetic rats on anti-oxidative status of cardiac, hepatic and renal tissues as well as on kidney function. Proximal tubular effects of MA were studied in anesthetized rats challenged with hypotonic saline after a 3.5 h equilibration for 4 h of 1 h control, 1.5 h treatment and 1.5 h recovery periods using lithium clearance. MA was added to the infusate during the treatment period. Oral glucose tolerance responses to MA were monitored in rats given a glucose load after an 18 h fast. Compared with untreated diabetic rats, MA-treated diabetic animals exhibited significantly low malondialdehyde (MDA, a marker of lipid peroxidation) and increased the activity of antioxidant enzymes; superoxide dismutase and glutathione peroxidase in hepatic, cardiac and renal tissues. The expressions of gastrocnemius muscle GLUT4 and kidney GLUT1 and GLUT2 were assessed to elucidate the mechanism of the hypoglycemic effects of MA. MA-treatment diminished the expression of GLUT1 and GLUT2 in diabetic kidney and reduced glycemia values of diabetic rats. MA administration increased urinary Na(+) outputs and additionally the FENa indicating that at least part of the overall reduction in Na(+) reabsorption occurred in the proximal tubules. These results suggest antioxidant effects of MA can ameliorate oxidative stress and improve kidney function in diabetes mellitus.

54 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: Protective effects of maslinic acid (MA) at 10, 15 or 20 mg/kg body weight/day against alcohol-induced acute hepatotoxicity in mice were examined. Mice were administrated by MA for 3 weeks, and followed by alcohol treatment. Results showed that MA pre-intake at three doses resulted in its accumulation in liver; and dose-dependently lowered cytochrome P450 2E1 activity and protein expression at 23.5-51.2% and 21.4-62.3%, respectively (P<0.05). MA pre-intake decreased subsequent alcohol-induced reactive oxygen species, interleukin-6, tumor necrosis factor-alpha, monocyte chemoattractant protein-1, nitric oxide and prostaglandin E2 production; retained glutathione content; maintained catalase and glutathione peroxidase activities; and declined cyclooxygenase-2 and total nitric oxide synthase activities in liver (P<0.05). Furthermore, MA pre-intake suppressed 17.3-51.7% nuclear factor kappa (NF-κ)B p50, 23.5-58.8% NF-κB p65, 25.6-62.4% p-p38 and 24.1-63.0% p-JNK expression in liver (P<0.05). Histological data indicated that MA intake at test doses attenuated hepatic inflammatory infiltrate. These findings support that maslinic acid is a potent preventive agent against acute alcoholic liver disease.
    Food and Chemical Toxicology 10/2014; 74. DOI:10.1016/j.fct.2014.09.018 · 2.90 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Purpose: The triterpene oleanolic acid (OA) is known to possess antihypertensive actions. In the present study we to compared the effects of the triterpene on mean arterial blood pressure (MAP) and kidney function following acute administration in normotensive animals with those of its related oleanane synthetic derivatives (brominated oleanolic acid, Br-OA and oleanolic acid methyl ester, Me-OA). We also used experimental models of hypertension to further explore the effects of sub-chronic oral OA treatment and evaluated influences on oxidative status. Methods: OA was extracted from dried flower buds of Syzygium aromaticum using a previously validated protocol in our laboratory. Me-OA and Br-OA were synthesized according to a method described. Rats were supplemented with lithium chloride (12 mmol L-1) prior to experimentation in order to raise plasma lithium to allow measurements of lithium clearance and fractional excretion (FELi) as indices of proximal tubular Na+ handling. Anaesthetized animals were continuously infused via the right jugular with 0.077M NaCl. MAP was measured via a cannula inserted in the carotid artery, and urine was collected through a cannula inserted in the bladder. After a 3.5 h equilibration, MAP, urine flow, electrolyte excretion rates were determined for 4 h of 1 h control, 1.5 h treatment and 1.5 h recovery periods. OA, Me-OA and Br-OA were added to the infusate during the treatment period. We evaluated sub-chronic effects on MAP and kidney function in normotensive Wistar rats and in two animal models of hypertension, spontaneously hypertensive rats (SHR) and Dahl salt-sensitive (DSS) rats, during 9-week administration of OA (p.o.). Tissue oxidative status was examined in these animals at the end of the study. Increasing evidence suggests that and renal function disturbances and oxidative stress play major roles in the pathogenesis of hypertension. Results: Acute infusion OA and oleanane derivatives displayed qualitatively similar effects in decreasing MAP and increasing urinary Na+ outputs. The drugs increased the FENa and FELiwithout influencing GFR indicating that at least part of the overall natriuretic effect involved proximal tubular Na+ reabsorption. Sub-chronic OA administration (p.o.) also elicited hypotensive responses in Wistar, DSS and SHR rats. The MAP lowering effect was more marked in hypertensive animals and were positively correlated with increased urinary Na+excretion. Compared with respective control rats, OA treatment reduced malondialdehyde (MDA, a marker of lipid peroxidation) and increased activities of antioxidant enzymes; superoxide dismutase and glutathione peroxidase in hepatic, cardiac and renal tissues. Conclusions: OA and oleanane derivatives have similar effects on MAP, kidney function and oxidative stress. The amelioration of oxidative stress and blood pressure lowering effects by OA are more marked in hypertensive animals and correlated with an increased urinary Na+ output. Novelty of the Work: The results of this study are novel in that they show 1) a correlation between blood pressure reduction and increased urinary Na+ excretion by OA, 2) a more marked MAP reduction in hypertensive animals and 3) a drug-induced decrease in proximal tubule Na+ reabsorption. The results may also be clinically relevant because OA is effective via oral administration. © 2015 Madlala et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
    PLoS ONE 06/2015; 10(6):e0128192. DOI:10.1371/journal.pone.0128192 · 3.23 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Maslinic acid (MA) is a natural compound whose structure corresponds to a pentacyclic triterpene. It is abundant in the cuticular lipid layer of olives. MA has many biological and therapeutic properties related to health, including antitumor, anti-inflammatory, antimicrobial, antiparasitic, antihypertensive, and antioxidant activities. However, no studies have been performed to understand the molecular mechanism induced by this compound in melanoma cancer. The objective of this study was to examine the effect of MA in melanoma (B16F10) cells grown in the presence or absence of fetal bovine serum (FBS). We performed cell proliferation measurements, and the reactive oxygen species (ROS) measurements using dihydrorhodamine 123 (DHR 123) and activities of catalase, glucose 6-phosphate dehydrogenase, glutathione S-transferase, and superoxide dismutase. These changes were corroborated by expression assays. FBS absence reduced cell viability decreasing IC 50 values of MA. The DHR 123 data showed an increase in the ROS level in the absence of FBS. Furthermore, MA had an antioxidant effect at lower assayed levels measured as DHR and antioxidant defense. However, at higher dosages MA induced cellular damage by apoptosis as seen in the results obtained.
    Evidence-based Complementary and Alternative Medicine 06/2015; 2015(Article ID 272457):11 pages. DOI:10.1155/2015/272457 · 1.88 Impact Factor