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      Medicinal herbal extracts -- renal friend or foe? Part one: the toxicities of medicinal herbs.

      1 , ,

      Nephrology (Carlton, Vic.)

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          Abstract

          In recent years, an increasing percentage of people from industrialized countries have been using complementary and alternative medicines (CAM). This, combined with numerous warnings regarding the potential toxicity of these therapies, suggests the need for practitioners to keep abreast of the reported incidence of renal toxicity caused by the ingestion of medicinal herbs. The goal of the present two-part series, on the toxic or beneficial effects of medicinal herbs on renal health, is to provide practitioners with a summary of the most recent information as well as the means by which evidence for benefit or toxicity has been found. In this first article, we explore in vivo evidence of toxicity. Included are nephrotoxicity from aristolochic acid and other components within herbs, herb--drug interactions resulting in adverse renal effects, and renal toxicity from contaminants within the extracts. The review aims to provide a guide to encourage future toxicity studies and rigorous clinical trials.

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          Most cited references 41

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          Urothelial carcinoma associated with the use of a Chinese herb (Aristolochia fangchi)

          Chinese-herb nephropathy is a progressive form of renal fibrosis that develops in some patients who take weight-reducing pills containing Chinese herbs. Because of a manufacturing error, one of the herbs in these pills (Stephania tetrandra) was inadvertently replaced by Aristolochia fangchi, which is nephrotoxic and carcinogenic. The diagnosis of a neoplastic lesion in the native urinary tract of a renal-transplant recipient who had Chinese-herb nephropathy prompted us to propose regular cystoscopic examinations and the prophylactic removal of the native kidneys and ureters in all our patients with end-stage Chinese-herb nephropathy who were being treated with either transplantation or dialysis. Surgical specimens were examined histologically and analyzed for the presence of DNA adducts formed by aristolochic acid. All prescriptions written for Chinese-herb weight-reducing compounds during the period of exposure (1990 to 1992) in these patients were obtained, and the cumulative doses were calculated. Among 39 patients who agreed to undergo prophylactic surgery, there were 18 cases of urothelial carcinoma (prevalence, 46 percent; 95 percent confidence interval, 29 to 62 percent): 17 cases of carcinoma of the ureter, renal pelvis, or both and 1 papillary bladder tumor. Nineteen of the remaining patients had mild-to-moderate urothelial dysplasia, and two had normal urothelium. All tissue samples analyzed contained aristolochic acid-related DNA adducts. The cumulative dose of aristolochia was a significant risk factor for urothelial carcinoma, with total doses of more than 200 g associated with a higher risk of urothelial carcinoma. The prevalence of urothelial carcinoma among patients with end-stage Chinese-herb nephropathy (caused by aristolochia species) is a high.
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            Antioxidative activity of natural products from plants.

             Megan F. Liu,  Z. Wang,  H. Ng (2000)
            A variety of flavonoids, lignans, an alkaloid, a bisbenzyl, coumarins and terpenes isolated from Chinese herbs was tested for antioxidant activity as reflected in the ability to inhibit lipid peroxidation in rat brain and kidney homogenates and rat erythrocyte hemolysis. The pro-oxidant activities of the aforementioned compounds were assessed by their effects on bleomycin-induced DNA damage. The flavonoids baicalin and luteolin-7-glucuronide-6'-methyl ester, the lignan 4'-demethyldeoxypodophyllotoxin, the alkaloid tetrahydropalmatine, the bisbenzyl erianin and the coumarin xanthotoxol exhibited potent antioxidative activity in both lipid peroxidation and hemolysis assays. The flavonoid rutin and the terpene tanshinone I manifested potent antioxidative activity in the lipid peroxidation assay but no inhibitory activity in the hemolysis assay. The lignan deoxypodophyllotoxin, the flavonoid naringin and the coumarins columbianetin, bergapten and angelicin slightly inhibited lipid peroxidation in brain and kidney homogenates. It is worth stressing that the compounds with antioxidant effects in this assay, with the exception of tetrahydropalmatin and tanshinone I, have at least one free aromatic hydroxyl group in structure. Obviously, the aromatic hydroxyl group is very important for antioxidative effects of the compounds. None of the compounds tested exerted an obvious pro-oxidant effect.
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              Harmless herbs? A review of the recent literature.

               Edzard Ernst (1998)
              Herbal medicines have become a popular form of therapy. They are often perceived as being natural and therefore harmless. This article reviews the recent literature on the adverse effects of herbal remedies. Examples of allergic reactions, toxic reactions, adverse effects related to an herb's desired pharmacological actions, possible mutagenic effects, drug interactions, drug contamination, and mistaken plant identities are provided. Because of underreporting, our present knowledge may well be just the "tip of the iceberg." Little is known about the relative safety of herbal remedies compared to synthetic drug treatments, although for some herbal remedies, the risks may be less than for conventional drugs.
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                Author and article information

                Journal
                Nephrology (Carlton)
                Nephrology (Carlton, Vic.)
                1320-5358
                1320-5358
                Oct 2004
                : 9
                : 5
                Affiliations
                [1 ] School of Medicine, University of Queensland, Queensland, Australia. kwojciko@scu.edu.au
                Article
                NEP310
                10.1111/j.1440-1797.2004.00310.x
                15504145

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