Aristolochic acid B

The herb of Aristolochia debilis Sieb. et Zucc.

Production, characterization of a monoclonal antibody against aristolochic acid-II and development of its assay system.[Pubmed:18457371]

Am J Chin Med. 2008;36(2):425-36.

Aristolochic acid-II (AA-II) conjugated with bovine serum albumin (BSA) was used as an antigen for immunizing BALB/c mice. Isolated splenocytes from the immunized mice were fused with an aminopterin-sensitive mouse myeloma cell line, SP2/0-Ag14, to produce hybridoma cells that secreted a monoclonal antibody (MAb) against AA-II. The selected hybridoma was subsequently cloned by limited dilution method. For MAb, the isotype and an estimated dissociation constant (K(D)) of the MAb were determined. The MAb was used to establish an ELISA method. Accuracy and variation assays, as well as determinations of the specificity and sensitivity, were also carried out and the linear range was 0.19-13 microg/ml. The anti-AA-II MAb showed a very high specificity for AA-II and had low cross-reactivities against the other aristolochic acid (AAs) (CR: AA-I, 3.4%; AA-VIIa, 0.86%) or aristololactam-I (AL-I) (CR<0.07%) except AA-IIIa which has 17% of cross activity. Anti-AA-II MAb also showed negligible cross-reactivity (<0.5%) toward other natural compounds with different chemical structures including barbaloin, sennoside A, rutin, glycyrrhizin, caffeic acid etc. This is the first time that an ELISA method was successfully established for the application of anti-AA-II MAb.

N6-adenyl arylation of DNA by aristolochic acid II and a synthetic model for the putative proximate carcinogen.[Pubmed:1665354]

Chem Res Toxicol. 1991 Sep-Oct;4(5):581-6.

Aristolochic acid II (AAII), one of the major components of the carcinogenic plant extract aristolochic acid, is known to be mutagenic and to form DNA adducts in vitro and in vivo. The major fluorescent DNA adduct formed upon xanthine oxidase mediated reduction in the presence of calf thymus (CT-) DNA or deoxyadenosine was isolated by means of preparative HPLC and identified by fluorescence, UV/vis absorbance, and 1H NMR spectroscopy as 7-(deoxy-adenosin-N6-yl)aristolactam II. As a model proximate carcinogen, N-chloroaristolactam II was prepared chemically from aristolactam II, the reduction product of AAII. This model compound was spectroscopically characterized and found to react directly with CT-DNA without any activation, forming the same deoxyadenosine adduct. HPLC analysis with fluorescence monitoring detected this adduct in vivo in the liver DNA of Wistar rats treated orally with AAII. These results confirm the anticipated metabolic activation mechanism of AAII as occurring via a cyclic nitrenium ion.

Comparison of the mutagenicity of aristolochic acid I and aristolochic acid II in the gpt delta transgenic mouse kidney.[Pubmed:22245565]

Mutat Res. 2012 Mar 18;743(1-2):52-8.

Aristolochic acid (AA) is known to be a potent mutagen and carcinogen. Aristolochic acid I (AAI) and aristolochic acid II (AAII), the two major components of AA, differ from each other by a single methoxy group. However, their individual mutagenic characteristics in vivo are unclear. In the present study, we compared their DNA adduct formation and mutagenicities in the gpt delta transgenic mouse kidney. The dA-AAI, dG-AAI, dA-AAII and dG-AAII were identified in the kidney two days after intragastric administration of AAI or AAII at 5mg/kg. The concentration of DNA adducts formed by AAII was approximately 2.5-fold higher than that formed by AAI (p<0.05). The mutant frequency induced by AAII was nearly two-fold higher than that induced by AAI (p<0.05) following administration of 5mg/kg AAI or AAII, five times per week for six weeks. Investigation of the mutation spectra showed no statistically significant difference between AAI- and AAII-treated mice (p>0.05). A:T to T:A transversion was the predominant type of mutation in both treated groups, the GC-associated mutation rates, however, differed between the AAI and AAII treatments. The in vivo metabolic pathways of AAI and AAII are different, and this may affect their mutagenicity. In the present study, we measured the levels of AAI and AAII in the kidney and plasma of gpt delta transgenic mice at multiple time points after a single intragastric dose of 1 or 5mg/kg of either component. Our results showed that the levels of AAII in both kidney and plasma were considerably higher than those of AAI (p<0.01). The present study indicated that AAII showed more carcinogenic risk than AAI in vivo, and this may be, at least partly, the result of its increased levels in kidney and plasma.

Aristolochic acid B is one of the major components of Aristolochic acids (AA) which are natural products derived from taxa in the Aristolochiaceae. Aristolochic acid is known to be a potent mutagen and carcinogen. Aristolochic acid B showes more carcinogenic risk than Aristolochic acid A in vivo.

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