title: In vitro bioassay investigations of the endocrine disrupting potential of steviol glycosides and their metabolite steviol, components of the natural sweetener Stevia.
abstract: The food industry is moving towards the use of natural sweeteners such as those produced by Stevia rebaudiana due to the number of health and safety concerns surrounding artificial sweeteners. Despite the fact that these sweeteners are natural; they cannot be assumed safe. Steviol glycosides have a steroidal structure and therefore may have the potential to act as an endocrine disruptor in the body. Reporter gene assays (RGAs), H295R steroidogenesis assay and Ca(2+) fluorimetry based assays using human sperm cells have been used to assess the endocrine disrupting potential of two steviol glycosides: stevioside and rebaudioside A, and their metabolite steviol. A decrease in transcriptional activity of the progestagen receptor was seen following treatment with 25,000 ng/ml steviol in the presence of progesterone (157 ng/ml) resulting in a 31% decrease in progestagen response (p=<0.01). At the level of steroidogenesis, the metabolite steviol (500-25,000 ng/ml) increased progesterone production significantly by 2.3 fold when exposed to 10,000 ng/ml (p=<0.05) and 5 fold when exposed to 25,000 ng/ml (p=<0.001). Additionally, steviol was found to induce an agonistic response on CatSper, a progesterone receptor of sperm, causing a rapid influx of Ca(2+). The response was fully inhibited using a specific CatSper inhibitor. These findings highlight the potential for steviol to act as a potential endocrine disruptor.
authors.affiliation: Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Northern Ireland, United Kingdom.
authors.forename: Maeve
authors.initials: M
authors.lastname: Shannon
authors.affiliation: Department of Growth and Reproduction, Copenhagen University Hospital, Rigshospitalet, Denmark; Department of Cellular and Molecular Medicine, Faculty of Health Sciences, Center for Healthy Ageing, University of Copenhagen, Copenhagen, Denmark; International Center for Research and Research Training in Endocrine Disruption of Male Reproduction and Child Health (EDMaRC), Rigshospitalet, University of Copenhagen, Denmark.
authors.forename: Anders
authors.initials: A
authors.lastname: Rehfeld
authors.affiliation: Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Northern Ireland, United Kingdom.
authors.forename: Caroline
authors.initials: C
authors.lastname: Frizzell
authors.affiliation: Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Northern Ireland, United Kingdom.
authors.forename: Christina
authors.initials: C
authors.lastname: Livingstone
authors.affiliation: Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Northern Ireland, United Kingdom.
authors.forename: Caoimhe
authors.initials: C
authors.lastname: McGonagle
authors.affiliation: Department of Growth and Reproduction, Copenhagen University Hospital, Rigshospitalet, Denmark; International Center for Research and Research Training in Endocrine Disruption of Male Reproduction and Child Health (EDMaRC), Rigshospitalet, University of Copenhagen, Denmark.
authors.forename: Niels E
authors.initials: NE
authors.lastname: Skakkebaek
authors.affiliation: Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Northern Ireland, United Kingdom.
authors.forename: Ewa
authors.initials: E
authors.lastname: Wielogórska
authors.affiliation: Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Northern Ireland, United Kingdom. Electronic address: l.connolly@qub.ac.uk.
authors.forename: Lisa
authors.initials: L
authors.lastname: Connolly
mesh_terms: D002460:Cell Line; D045744:Cell Line, Tumor; D002470:Cell Survival; D045786:Diterpenes, Kaurane / Q000494:pharmacology* / Q000633:toxicity; D052244:Endocrine Disruptors / Q000494:pharmacology* / Q000633:toxicity; D017930:Genes, Reporter; D012739:Gonadal Steroid Hormones / Q000096:biosynthesis; D006801:Humans; D008297:Male; D011980:Receptors, Progesterone / Q000187:drug effects; D013094:Spermatozoa / Q000187:drug effects*; D013256:Steroids / Q000096:biosynthesis; D036625:Stevia / Q000737:chemistry*; D013549:Sweetening Agents / Q000494:pharmacology* / Q000633:toxicity
chemical_list: D045786:Diterpenes, Kaurane; D052244:Endocrine Disruptors; D012739:Gonadal Steroid Hormones; D011980:Receptors, Progesterone; D013256:Steroids; D013549:Sweetening Agents; C012042:steviol; C025474:rebaudioside A
keywords: CatSper; Endocrine disruptors; In vitro bioassays; Reproductive disorders; Stevia; Steviol