Background: The Mediterranean thistle Atractylis gummifera L. (Asteraceae; AG) has diterpenoid glucosides; atractyloside and
carboxyatractyloside that interact with mitochondrial protein adenine nucleotide translocator (ANT) and resulted in ATP inhibition.
Despite its well-known toxicity, acute poisonings still occur with this plant. Although most symptoms are attributed to
ANT and diterpenoids interaction, in-depth investigation of the effects of AG extract on various cellular processes has not been
performed.

Objective/method: We tested in vitro induction of mitochondrial permeability transition pore (MPTP) opening in bovine liver
mitochondria and evaluated its cytotoxicity and genotoxicity using Allium cepa test. Cell division, mitotic index (MI) and total
chromosomal and mitotic aberrations (TAs), that all seem potentially affected by ATP shortage, were studied in root cells of
Allium cepa exposed to Atractylis gummifera extract.

Results: With the two different doses of two purified AG fractions, stronger induction of MPTP was observed compared to
the induction with the standard pure atracyloside. Aqueous AG extract exerted inhibition root growth in A. cepa at 6 different
doses. The TAs was increased in a dose-dependent manner too, while mitotic index was decreased at the same doses. Evaluation
of mitotic phases revealed mitodepressive effect of AG on A. cepa roots.

Conclusion: This work highlights cellular and mitochondrial adverse effects of Atractylis gummifera extracts. A purified fraction
that likely corresponds to ATR derivatives induces MPTP opening leading to swelling of mitochondria and its dysfunction. Allium
cepa test provides the evidence for A. gummifera genotoxicity and cytotoxicity.

Keywords: Atractylis gummifera; Allium cepa test; mitochondrial permeability transition pore; genotoxicity; cytotoxicity; chromosomal
aberration; mitotic index.