Testing of a Standardized Extract of Sceletium tortuosum (Zembrin®) According to OECD Genotoxicity Guidelines 471, 487 and 474
Hans Verhagen
*
Food Safety & Nutrition Consultancy, Couwenhoven 4214, 3703 EE Zeist, The Netherlands.
Erzsébet Béres
Toxi-Coop Zrt., Arácsi út 97, 8230 Balatonfüred, Hungary.
Stella Fekete
Toxi-Coop Zrt., Arácsi út 97, 8230 Balatonfüred, Hungary.
Adél Vértesi
Toxi-Coop Zrt., Arácsi út 97, 8230 Balatonfüred, Hungary.
Gábor Hirka
Toxi-Coop Zrt., Arácsi út 97, 8230 Balatonfüred, Hungary.
Ralph Tettey-Amlalo
HG&H Pharmaceuticals (Pty) Ltd, The Braes, 193 Bryanston Drive, Bryanston 2191, South Africa.
Henk FJ Hendriks
Hendriks Nutrition Support for Business, Laan van Cattenbroeck 70, 3703BP Zeist, The Netherlands.
*Author to whom correspondence should be addressed.
Abstract
Aims: The genotoxic safety of the extract Zembrin® of the medicinal plant S. tortuosum was evaluated. Sceletium tortuosum (L.) N.E.Br. (S. tortuosum) is a succulent plant found in South Africa. Whereas the number of toxicological evaluations of Zembrin® is limited, the purpose of this paper is to report on the genotoxic safety of Zembrin® by describing Zembrin®’s effects in a set of three genotoxicity tests according to OECD guidelines and under Good Laboratory Practice.
Study Design: Genotoxic safety was evaluated performing three standard genotoxicity tests according to OECD guidelines 471, 487 and 474.
Place and Duration of Study: Assays were performed at Toxi-Coop Zrt., Arácsi út 97 and Ady E. utca 12, 8230 Balatonfüred, Hungary in 2023.
Methodology: Assays were run in compliance with internationally accepted guidelines included the bacterial reverse mutation assay (OECD 471), the in vitro mammalian cell micronucleus test (OECD 487) and the in vivo mouse micronucleus test (OECD 474).
Results: Zembrin® extract, in concentrations varying from 16 up to 5000 µg/plate, did not change the mutation rates of the various Salmonella strains and the E. coli strain tested without and with metabolic activation in an in vitro OECD 471 mutation assay. Zembrin® extract did also not show an increased frequency of micronuclei without and with metabolic activation in an in vitro OECD 487 assay using L5178Y tk+/- cells. However, a dose dependent increase was found at the two higher concentrations (2500 and 5000 μg/mL) in the absence of metabolic activation. Since results were not clearly negative in the initial in vitro genotoxicity test, as per existing EFSA Guidance a confirmatory in vivo test was conducted. In an in vivo OECD 474 test in which the test substance was administered intravenously, frequency of micronucleated polychromatic erythrocytes was not increased.
Conclusion: Therefore, based on the outcome of the three genotoxicity tests, it can be concluded that Zembrin® is not of genotoxic concern.
Keywords: Sceletium tortuosum, Zembrin®, mesembrine-type alkaloids, genotoxicity, OECD guideline 471, OECD guideline 474, OECD guideline 487