Toxicogenomics Applied to Cultures of Human Hepatocytes Enabled an Identification of Novel Petasites hybridus Extracts for the Treatment of Migraine with Improved Hepatobiliary Safety

Abstract

Butterbur extracts (Petasites hybridus) are recommended for the prevention of migraine, but pharmacovigilance reports may be suggestive of rare hepatobiliary toxicity. To evaluate its hepatotoxic potential, a series of in vivo and in vitro studies were carried out. Essentially, there were no signs of hepatocellular toxicity at estimated therapeutic C(max) levels of 60 ng/ml. Nonetheless, in a 28-day toxicity study at approximately 200-fold of therapeutic doses, induced liver transaminases and bilirubin elevations were observed. In a subsequent 6-month chronic toxicity study, the initial hepatobiliary effects were reproduced, but at the end of the study, liver function recovered and returned to normal as evidenced by clinical chemistry measurements. To identify possible mechanisms of hepatotoxicity, we investigated liver function in vitro at > 170-fold of therapeutic C(max) levels, including cytotoxicity (lactate dehydrogenase, MTT, and ATP), transaminase activities (alanine aminotransferase and aspartate aminotransferase), albumin synthesis, urea and testosterone metabolism to assay for cytochrome P450 monooxygenase activity. Only with extracts rich in petasin (37% petasin) and at high and well above therapeutic doses, liver toxicity was observed. A toxicogenomic approach applied to hepatocyte cultures enabled hypothesis generation and was highly suggestive for extracts high in petasin content to impair bile acid transport and lipid and protein metabolism. Importantly, neither chronic rat in vivo nor rat in vitro studies predicted reliably hepatotoxicity, therefore reemphasizing the utility of human-based in vitro investigations for the development of safe medicinal products. Finally, toxicogenomics enabled the characterization of a novel butterbur extract with no signals for hepatotoxicity.

Ethnopharmacological in vitro studies on Austria's folk medicine—An unexplored lore in vitro anti-inflammatory activities of 71 Austrian traditional herbal drugs

“…However, recent studies indicated that there were no signs of hepatocellular toxicity at estimated therapeutic C max levels of 60 ng/mL. Nonetheless, when investigating liver function in vitro at >170-fold of therapeutic C max levels, including cytotoxicity (measured by conversion of tetrazolium bromide (MTT) to MTT formazan, intracellular ATP using ATP bioluminescence and lactate dehydrogenase (LDH) activity), transaminase activities (alanine aminotransferase and aspartate aminotransferase), albumin synthesis, urea and testosterone metabolism to assay for cytochrome P450 monooxygenase activity, only rhizome extracts rich in petasin (37% petasin) evoked liver toxicity (Anderson et al, 2009). Lipophilic extracts of Petasites hybridus rhizomes with different content of petasin and isopetasin were investigated for an inhibition of COX-1 and -2 isoenzymes, whereas inhibition of the expression of COX-2 and p42/44 MAP kinase was tested in rat primary microglial cells.…”

HNF4alpha Dysfunction as a Molecular Rational for Cyclosporine Induced Hypertension

“…Written approval for the use of human liver specimens was obtained from patients undergoing hepatic resections with approval of the ethics committee of the Medical School of Hannover. Details regarding the isolation and culture of human hepatocytes in the collagen sandwich were previously described [41].…”

Potential of ‘Omics’ Technologies for Implementation in Research on Phytotherapeutical Toxicology

“…An illustrative example how TGx facilitates the detection of hepatotoxicity not visible in animal experiments was given by Anderson et al (2009). An illustrative example how TGx facilitates the detection of hepatotoxicity not visible in animal experiments was given by Anderson et al (2009).…”