Aristolochic Acid
aristolochic acid I

Aristolochic Acid is contained in plants belonging to the genus Aristolochia and Asarum.   It is carboxylic acid having phenanthrene skeleton and containing nitro group, which is distinctly rare in natural compounds.

The structure is very unique as an alkaloid but it is an aporphine alkaloid and one of true alkaloids.   Aristolochic Acid I and Aristolochic Acid II, which does not have the methoxy group, are known.

Aristolochic Acid I
CAS No. 313-67-7
IUPAC name 8-methoxy-6-nitro-phenanthro-(3,4-d)-1,3-dioxolo-5-carboxylic acid
Molecular formula C17H11NO7
Molecular weight 341.27684
Melting point 260 - 265
Appearance Yellow powder
Solubility in water Slightly soluble

Aristolochic acid is suspected as a causative substance of Balkan nephropathy through the ages.   However, it is recently confirmed that it is nephrotoxic including carcinogenic.   When exposed with aristolochic acid, aristolochic acid forms DNA adducts, is intravitally kept existing for long time without recovering and removing and develops its toxicities.

In Japan it is not approved to manufacture and distribute crude drugs or herbal medicines containing aristolochic acid to humans and animals.   However, there are many regions, such as China, where plant body containing aristolochic acid is still used as herbal medicines.   Caution should be exercised in buying such a herbal medicine at the particular location or its individual import.

On the other hand, the relatives of Atrophaneura, such as the butterflies, Chinese Windmill (Atrophaneura alcinous) and Birdwing (the genus Ornithoptera and Trogonoptera), use the relatives in the genus Aristolochia as foodplants.   The relatives of Atrophaneura accumulate aristolochic acids in their body during its larval period and keep it for their life span to obtain chemical defence.