Phospholipase A2 (PLA2); Natural products; Aristolochic acids (AA) analog

The role of phospholipase A(2) in Arabidopsis root growth and microtubule organisation was investigated using a specific inhibitor, aristolochic acid. At 0.5-1.5 microm concentrations, this inhibitor reduced root elongation and caused radial swelling of the root tip. The normally transverse cortical microtubules in root tip cells became progressively more disorganised with increasing concentrations of the inhibitor. Microtubule disorganisation also occurred in leaf epidermal cells of Allium porrum. We propose that phospholipase A(2) is involved in microtubule organisation and anisotropic growth in a manner similar to that reported previously for phospholipase D, thus broadening the significance of phospholipid signalling in microtubule organisation in plants [1].

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Aristolochic acids I and II (AA-I/II) are carcinogenic principles of Aristolochia plants, which have been employed in traditional medicinal practices and discovered as food contaminants. While the deleterious effects of AAs are broadly acknowledged, there is a dearth of information to define the mechanisms underlying their carcinogenicity. Following bioactivation in the liver, N-hydroxyaristolactam and N-sulfonyloxyaristolactam metabolites are transported via circulation and elicit carcinogenic effects by reacting with cellular DNA. In this study, we apply DNA adduct analysis, X-ray crystallography, isothermal titration calorimetry, and fluorescence quenching to investigate the role of human serum albumin (HSA) in modulating AA carcinogenicity. We find that HSA extends the half-life and reactivity of N-sulfonyloxyaristolactam-I with DNA, thereby protecting activated AAs from heterolysis. Applying novel pooled plasma HSA crystallization methods, we report high-resolution structures of myristic acid-enriched HSA (HSAMYR) and its AA complexes (HSAMYR/AA-I and HSAMYR/AA-II) at 1.9 Å resolution. While AA-I is located within HSA subdomain IB, AA-II occupies subdomains IIA and IB. ITC binding profiles reveal two distinct AA sites in both complexes with association constants of 1.5 and 0.5 · 106 M−1 for HSA/AA-I versus 8.4 and 9.0 · 105 M−1 for HSA/AA-II. Fluorescence quenching of the HSA Trp214 suggests variable impacts of fatty acids on ligand binding affinities. Collectively, our structural and thermodynamic characterizations yield significant insights into AA binding, transport, toxicity, and potential allostery, critical determinants for elucidating the mechanistic roles of HSA in modulating AA carcinogenicity [3].

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 [2].

[1]. The phospholipase A2 inhibitor, aristolochic acid, disrupts cortical microtubule arrays and root growth in Arabidopsis. Plant Biol (Stuttg). 2008 Nov;10(6):725-31.

[2]. Comparison of the mutagenicity of aristolochic acid I and aristolochic acid II in the gpt delta transgenic mouse kidney. Mutat Res. 2012 Mar 18;743(1-2):52-8.

[3]. Structural and mechanistic insights into the transport of aristolochic acids and their active metabolites by human serum albumin. J Biol Chem. 2024 May 22;300(7):107358.

Aristolochic acid C is an aristolochic acid that is phenanthrene-1-carboxylic acid substituted by a methylenedioxy group at the 3,4 positions, by an hydroxy group at position 6, and by a nitro group at position 10. It has a role as a carcinogenic agent, a metabolite, a mutagen, a nephrotoxin and a toxin. It is a C-nitro compound, a member of aristolochic acids, an aromatic ether, a cyclic acetal, a monocarboxylic acid and an organic heterotetracyclic compound.
Aristolochic acid C has been reported in Aristolochia kankauensis, Aristolochia kaempferi, and other organisms with data available.

C16H9NO7

327.24

327.037

C, 58.72; H, 2.77; N, 4.28; O, 34.22

4849-90-5

165274

Light yellow to orange solid powder

1.7±0.1 g/cm3

658.7±55.0 °C at 760 mmHg

287-292ºC

352.1±31.5 °C

0.0±2.1 mmHg at 25°C

1.821

2.76

2

7

1

24

535

0

NBFGYDJKTHENDP-UHFFFAOYSA-N

InChI=1S/C16H9NO7/c18-8-2-1-7-3-11(17(21)22)13-10(16(19)20)5-12-15(24-6-23-12)14(13)9(7)4-8/h1-5,18H,6H2,(H,19,20)

10-hydroxy-6-nitronaphtho[2,1-g][1,3]benzodioxole-5-carboxylic acid

Aristolochic Acid C; KB-265706; AR-1C0215; Aristolochic acid C; 4849-90-5; ARISTOLOCHICACIDC; 10-hydroxy-6-nitrophenanthro[3,4-d][1,3]dioxole-5-carboxylic acid; Phenanthro[3,4-d]-1,3-dioxole-5-carboxylicacid, 10-hydroxy-6-nitro-; CHEMBL603494; Phenanthro[3,4-d]-1,3-dioxole-5-carboxylic acid, 10-hydroxy-6-nitro-; Aristolochiac acid C; AR1C0215; KB265706; FT-0662284;

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: This product requires protection from light (avoid light exposure) during transportation and storage.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~125 mg/mL (~381.97 mM)

Solubility in Formulation 1: ≥ 2.08 mg/mL (6.36 mM) (saturation unknown) in 10% DMSO + 40% PEG300 +5% Tween-80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 + to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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 (Please use freshly prepared in vivo formulations for optimal results.)