Several studies point out that oxidative stress maybe a major culprit in diabetic nephropathy. Aqueous extract of Hibiscus sabdariffa L. (HSE) has been demonstrated as having beneficial effects on anti-oxidation and lipid-lowering in experimental studies. This study aimed at investigating the effects of Hibiscus sabdariffa L. on diabetic nephropathy in streptozotocin induced type 1 diabetic rats. Our results show that HSE is capable of reducing lipid peroxidation, increasing catalase and glutathione activities significantly in diabetic kidney, and decreasing the plasma levels of triglyceride, low-density lipoprotein (LDL) and increasing high-density lipoprotein (HDL) value. In histological examination, HSE improves hyperglycemia-caused osmotic diuresis in renal proximal convoluted tubules (defined as hydropic change) in diabetic rats. The study also reveals that up-regulation of Akt/Bad/14-3-3γ and NF-κB-mediated transcription might be involved. In conclusion, our results show that HSE possesses the potential effects to ameliorate diabetic nephropathy via improving oxidative status and regulating Akt/Bad/14-3-3γ signaling.
Oxidative stress is the major contributor to acetaminophen (AAP)-caused liver damage. It promotes mitochondrial oxidative stress and collapses the mitochondrial membrane potential to cause cell death. We have previously shown that a polyphenol extract of Hibiscus sabdariffa L. (HPE) potentiated the antioxidative effect. We further examined in this study the possible mechanism of HPE against AAP-caused liver damage. BABL/c mice were orally fed with HPE (100, 200 or 300 mg/kg) for two weeks prior to an i.p. injection of 1000 mg/kg of AAP. The mice were decapitated 6 h after the AAP injection to collect the blood and liver for further determination. The results show that pretreating with HPE increased the level of glutathione (GSH), decreased the level of lipid peroxidation, and increased catalase activity in the liver. A histopathological evaluation shows that HPE could decrease AAP-induced liver sterosis accompanied by a decreased expression of AIF, Bax, Bid, and p-JNK in the liver. An in vitro assay revealed that HPE could reduce AAP-induced death of BABL/c normal liver cells (BNLs), reverse the lost mitochondrial potency and improve the antioxidative status, similarly to the results of the in vivo assay. We show in this study that HPE possessed the ability to protect the liver from AAP-caused injury. The protective mechanism might be regulated by decreasing oxidative stress and attenuating the mitochondrial dysfunction.
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