Quantitation of Aristolochic Acids in Corn, Wheat Grain, and Soil Samples Collected in Serbia: Identifying a Novel Exposure Pathway in the Etiology of Balkan Endemic Nephropathy

Abstract

While to date investigations provided convincing evidence on the role of aristolochic acids (AAs) in the etiology of Balkan endemic nephropathy (BEN) and upper urothelial cancer (UUC), the exposure pathways by which AAs enter human bodies to cause BEN and UUC remain obscure. The goal of this study is to test the hypothesis that environmental pollution by AAs and root uptake of AAs in the polluted soil may be one of the pathways by which AAs enter the human food chain. The hypothesis driving this study was that the decay of Aristolochia clematitis L., a AA-containing herbaceous plant that is found growing widespread in the endemic regions, could release free AAs to the soil, which could be taken up by food crops growing nearby, thereby transferring this potent human nephrotoxin and carcinogen into their edible parts. Using the highly sensitive and selective high-performance liquid chromatography coupled with fluorescence detection method, we identified and quantitated in this study for the first time AAs in corn, wheat grain, and soil samples collected from the endemic village Kutles in Serbia. Our results provide the first direct evidence that food crops and soil in the Balkans are contaminated with AAs. It is possible that the presence of AAs in edible parts of crops originating from the AA-contaminated soil could be one of the major pathways by which humans become exposed to AAs.

An Integrated View of Aristolochic Acid Nephropathy: Update of the Literature

“…In this regard, they showed that the roots of maize plant and cucumber were capable of absorbing AA confirming the possible involvement of naturally occurring root uptake in food chain contamination. Subsequently, AA were also identified in corn, wheat grain and soil samples collected from the endemic village of Kutles in Serbia providing the first direct evidence that food crops and soil are contaminated with AA in Balkan countries and thereby strengthening the intoxication pathway proposed earlier [60]. Finally, another recent study tested the hypothesis that AA could be translocated and bioaccumulated in food crops to cause chronic dietary poisoning [61].…”

Liquid chromatography–tandem mass spectrometry analysis of aristolochic acids in soil samples collected from Serbia: Link to Balkan endemic nephropathy

“…The mixture was then subjected to ultrasonication at 50°C for 1 h to extract AAs from the soil. Following centrifugation at 6000 g for 10 min, 1 mL of the sample extract was reacted with 20 mg of pre‐activated zinc dust at 60°C for 15 min to reduce AAs to their respective aristolactams (ALs; Figure ) . After cooling to room temperature, 50 μL of internal standard, benz[ cd ]indol‐2(1 H )‐one (200 ng/mL), was spiked to the samples, which were vortex‐mixed and centrifuged at 13 800 g for 5 min prior to analysis using the LC/MS/MS method described below.…”

“…Since the 1990s, the use of AA‐containing herbs has been prohibited for preparing herbal medicines in many countries, including the USA . Despite the worldwide ban on the use of AA‐containing Aristolochia plants as traditional herbal medicine and in herbal remedies, it was estimated that over a hundred million people are potential victims of AA poisoning, due to the traditional practice of Chinese herbal medicine, the misuse of AA‐containing herbs and environmental exposure …”

“…It was not until 2007 that AAs were identified to be the disease‐causing agent of BEN . It is suspected that BEN is an environmentally induced disease caused by the dietary intake of AA‐tainted food . Such food contamination was speculated to have been caused by the commingling of AA‐containing seeds of Aristolochia clematitis L. (commonly known as birthwort) with wheat grains during the harvesting process.…”

“…There is some emerging evidence suggesting that AAs are environmental pollutants released into cultivation soil as the dead mass of A. clematitis decomposes . Free AAs in the contaminated soil are then taken up by food crops via root absorption and translocated into their edible parts .…”