Definition
Aristolochic acids (AAs) are a group of structurally related nitrophenanthrene carboxylic acids found primarily in plants of the genus Aristolochia (family Aristolochiaceae). The most studied members are aristolochic acid I (AA‑I) and aristolochic acid II (AA‑II), which are implicated in nephrotoxicity, mutagenesis, and carcinogenesis in humans and experimental animals.
Overview
Aristolochic acids were first isolated in the 1950s during investigations of traditional herbal medicines that contained Aristolochia species. They have been identified as the primary toxic constituents responsible for a syndrome known as aristolochic acid nephropathy (AAN), also referred to as Balkan endemic nephropathy when occurring in certain geographic regions. Exposure can occur through ingestion of contaminated herbal preparations, use of unregulated weight‑loss or detoxification products, or occupational contact with plant material. International health agencies have issued warnings and restrictions on the use of Aristolochia‑containing products due to the compounds’ renal and carcinogenic hazards.
Etymology/Origin
The name “aristolochic” derives from the genus Aristolochia, itself originating from the Greek words aristos (ἀριστος, “best”) and lochē (λοχη, “birth” or “origin”), historically referencing the perceived medicinal virtues of the plants. The suffix “‑ic acid” indicates the acidic nature of the isolated compounds.
Characteristics
- Chemical structure: Aristolochic acids consist of a phenanthrene backbone bearing a nitro group (–NO₂) and a carboxylic acid moiety. AA‑I is 8‑methoxy‑6‑nitrophenanthrene‑1‑carboxylic acid; AA‑II lacks the methoxy substitution.
- Physical properties: They are solid crystalline substances, poorly soluble in water but soluble in organic solvents such as dimethyl sulfoxide (DMSO) and methanol.
- Biological activity: AAs form covalent DNA adducts (predominantly 7‑deoxyadenosine adducts) after metabolic activation by nitroreductases, leading to specific mutational signatures (A:T→T:A transversions). This genotoxic mechanism underlies their carcinogenic potential, particularly in the urothelium and renal tubules.
- Toxicology: Acute exposure can produce interstitial nephritis, while chronic exposure results in progressive renal fibrosis and eventual renal failure. The International Agency for Research on Cancer (IARC) classifies aristolochic acid as a Group 1 carcinogen (carcinogenic to humans).
- Regulation: Many jurisdictions have prohibited the sale and use of Aristolochia extracts in dietary supplements and traditional medicines. The United States Food and Drug Administration (FDA) has issued safety alerts, and the European Medicines Agency (EMA) has withdrawn related herbal products from the market.
Related Topics
- Aristolochia (plant genus)
- Balkan endemic nephropathy
- DNA adducts and mutational signatures
- Nephrotoxicity and renal fibrosis
- IARC Group 1 carcinogens
- Herbal medicine regulation and safety
This entry reflects current scientific consensus as of 2026; ongoing research may further elucidate the pharmacokinetics and risk assessment of aristolochic acids.