In vivo validation of DNA adduct formation by estragole in rats predicted by physiologically based biodynamic modelling

Abstract

Estragole is a naturally occurring food-borne genotoxic compound found in a variety of food sources, including spices and herbs. This results in human exposure to estragole via the regular diet. The objective of this study was to quantify the dose-dependent estragole-DNA adduct formation in rat liver and the urinary excretion of 1'-hydroxyestragole glucuronide in order to validate our recently developed physiologically based biodynamic (PBBD) model. Groups of male outbred Sprague Dawley rats (n = 10, per group) were administered estragole once by oral gavage at dose levels of 0 (vehicle control), 5, 30, 75, 150, and 300mg estragole/kg bw and sacrificed after 48h. Liver, kidney and lungs were analysed for DNA adducts by LC-MS/MS. Results obtained revealed a dose-dependent increase in DNA adduct formation in the liver. In lungs and kidneys DNA adducts were detected at lower levels than in the liver confirming the occurrence of DNA adducts preferably in the target organ, the liver. The results obtained showed that the PBBD model predictions for both urinary excretion of 1'-hydroxyestragole glucuronide and the guanosine adduct formation in the liver were comparable within less than an order of magnitude to the values actually observed in vivo. The PBBD model was refined using liver zonation to investigate whether its predictive potential could be further improved. The results obtained provide the first data set available on estragole-DNA adduct formation in rats and confirm their occurrence in metabolically active tissues, i.e. liver, lung and kidney, while the significantly higher levels found in liver are in accordance with the liver as the target organ for carcinogenicity. This opens the way towards future modelling of dose-dependent estragole liver DNA adduct formation in human.

Determination and risk assessment of naturally occurring genotoxic and carcinogenic alkenylbenzenes in nutmeg-based plant food supplements

“…In a previous study by Paini et al . () such a PBD model for liver DNA adduct formation was developed and validated in an in vivo study for estragole DNA adduct formation in the liver of rats. This study also revealed that not only bioactivatoin to the reactive 1′‐sulfooxymetabolite but also DNA adduct formation in rat liver was linear with the dose of estragole (Paini et al ., , ).…”

“…This study also revealed that not only bioactivatoin to the reactive 1′‐sulfooxymetabolite but also DNA adduct formation in rat liver was linear with the dose of estragole (Paini et al ., , ). Development of such PBD models for liver DNA adduct formation in human could be achieved by combining the existing human PBK models with data on alkenylbenzene concentration‐dependent DNA adduct formation in isolated human hepatocytes as done for rat hepatocytes exposed to estragole previously (Paini et al ., , Paini et al ., ). Such studies in primary hepatocytes are likely to also account for possible repair and stability of the alkenylbenzene adducts and would thus provide insight in whether formation of adducts, even during a short period, could have irreversible effects and thus be deleterious, or whether they are likely to be repaired, thereby decreasing risk.…”

In vivo validation and physiologically based biokinetic modeling of the inhibition of SULT-mediated estragole DNA adduct formation in the liver of male Sprague-Dawley rats by the basil flavonoid nevadensin

“…The first group, representing the control group, was dosed once with 150 mg/kg bw estragole only. In a study by Paini et al , the dose of 150 mg/kg bw was the lowest dose of estragole able to induce significant levels of estragole DNA adducts (E‐3′‐ N 2 ‐dGuo) in the liver of male outbred Sprague‐Dawley rats 48 h after gavage compared to the solvent control (vehicle) group. The second group was dosed once with 150 mg/kg bw estragole and 87.2 mg/kg bw of nevadensin.…”

Modern methodologies and tools for human hazard assessment of chemicals

“…These models can be used to extrapolate from benchmark dose causing 10 % extra tumour incidence (BMD 10 ) down to the so-called virtual safe dose (VSD) (the dose resulting in one in a million extra tumour incidence upon life time exposure). Additionally, a PB-TD model was developed, by measuring formation of estragole DNA adducts in rat primary hepatocytes and was further validated in vivo with male SD rats (Paini et al, 2012). Additionally, a PB-TD model was developed, by measuring formation of estragole DNA adducts in rat primary hepatocytes and was further validated in vivo with male SD rats (Paini et al, 2012).…”