Safety assessment of marigold flavonoids from marigold inflorescence residue

Marigold flavonoids, extracted from marigold (Tagetes erecta L.) inflorescence residues, have attracted significant attention with respect to antioxidant, anti-inflammatory and chelating properties. However, the toxicity of marigold flavonoids have not yet been fully investigated.

The main purpose of this study was to assess the safety of marigold flavonoids extracted from Marigold (Tagetes erecta L.) in order to provide information on its nonclinical safety. Thus, the acute oral toxicity, in vitro Ames test, sperm aberration study, bone marrow micronucleus test, subchronic oral toxicity test, and teratogenic potential were carried out in rats or mice.

For an acute oral toxicity test, SD rats and ICR mice (male and female, n = 5) orally received a single dose of 5000 mg/kg marigold flavonoids. Evaluation of marigold flavonoids genotoxic potential with a battery of tests, including an in vitro bacterial reverse mutation test using four mutant strains of Salmonella typhimurium (TA₉₇、TA₉₈、TA₁₀₀、TA₁₀₂), an sperm aberration test and an in vivo micronucleus test using bone marrow cells ICR mice that were orally administered marigold flavonoids, an subchronic oral toxicity study and teratogenic test employing male and female SD rats that were orally administered marigold flavonoids. All animals tests were completed in accordance with GB 15193 for toxicity tests.

In the acute oral toxicity test, marigold flavonoids given at the dose of 5000 mg/kg body weight for 14 days didn't produce any abnormal clinical symptoms or mortality in SD rats and ICR mice (both sex, n = 5). There was no evidence of genotoxicity of marigold flavonoids based on the results of the in vitro bacterial reverse mutation test (up to 1250 μg/plate), the sperm aberration test (up to 5000 mg/kg body weight), the in vivo micronucleus test (up to 5000 mg/kg body weight), the subchronic oral toxicity study (up to 10 g/kg feed dose) and the teratogenic test (up to 1250 mg/kg body weight).

We found that marigold flavonoids are safe with regard to acute toxicity in rats or mice as well as genotoxicity such as mutagenesis or clastogenesis under the present experimental conditions. These results might support the safety of marigold flavonoids as a potential therapeutic material for the traditional use of herbal medicines and for the further development of novel antioxidant.