Genotoxicity assessment of Hypericum perforatum dry extracts in the Ames test based on the “bracketing and matrixing” concept

HMPs derived from Hypericum perforatum, herba (St. John’s wort) play an important role in treating mild to moderate depressive episodes and mental exhaustion, for example. The genotoxic safety of these HMPs has already been assessed and reviewed in recent years. However, further data on the genotoxic potential of Hypericum perforatum, herba preparations would allow to evaluate the therapeutic safety of the herbal drug and preparations thereof in accordance with the genotoxicity guideline of the HMPC of the EMA. Accordingly, their genotoxic potential was tested using the “bracketing and matrixing” concept, whereby extracts are tested at and between the extremes of their extraction solvents (ranging in strength from polar to non-polar), to cover the entire spectrum of the drug’s constituents. In the present study, five dry extracts of Hypericum perforatum, herba, representing the full range of potential extraction solvent polarities (water, ethanol 50% (v/v), methanol 80% (v/v), ethanol 80% (v/v), and n‑heptane) were tested using the Ames test, according to the OECD and HMPC guidelines. No mutagenic effects were observed for any of the five test strains in two independent experiments with and without metabolic activation (plate incorporation test and pre-incubation test), even at the highest concentrations (5000 µg/plate), in accordance with the OECD guideline No. 471.

Publication History

Received: 25 June 2025

Accepted after revision: 11 November 2025

Accepted Manuscript online:
11 November 2025