Evaluation of in vitro antioxidant activity and free radical scavenging potential of variety of Tagetes erecta L. flowers growing in Bulgaria

Summary. Marigold (Tagetes erecta L.) is well known for its antimicrobial, antiseptic, wound and ulcer healing, antiinflammatory, antioxidant and antiviral properties, and it has a long history of being used as an herbal remedy. T. erecta L. produces a variety of substances that possess pharmacological effects and antioxidant activity. The present study was therefore aimed to analyze the antioxidant activity of extracts and fractions of T. erecta L. flowers, cultivated in Bulgaria. Radical scavenging potential was determined using two different in vitro assays. 1, 1-diphenyl-2-picrylhydrazyl (DPPH) and 2, 2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals. The ethyl acetate fraction of T. erecta L. ethanol extract was found to be the most effective in both assays, DPPH (IC50 4.3±0.4 μg/ml) and ABTS (0.8±0.2 TEAC). The greatest total phenolic content was detected in EtOAc fraction from EtOH extract (517.8 mg/g GAE). It was obtained high quantity of ascorbate and ascorbate/dehydroascorbate ratio more than 1. The quantity of glutathione reduced is low and glutathione reduced/glutathione oxidized ratio was lower than 1. A correlation between radical scavenging capacities of samples with total phenolic compound content was observed. The present study revealed that the EtOAc fraction effectively show the best ability to scavenge the free radicals. Industrial relevance. Herbal medicines have gained increasing attention worldwide for the treatment of chronic diseases because of their effectiveness and small side effects as compared to synthetic drugs.Recently, an attention has been directed toward the antioxidant phytochemicals which have proved as protective against cardiovascular diseases and cancer, associated with overproduction of reactive oxygen species. The present investigations focus has been to discover plant extracts and fractions from T. erecta useful to prevent chronic degenerative diseases, especially those mediated by free radicals damages. The great antioxidant activity indicates the potential of the extracts as a source of natural antioxidants or nutraceuticals with possible application to reduce oxidative stress with consequent health benefits. Keywords. Tagetes erecta L.; in vitro antioxidant activity; free radical scavenging potential; phenols; flavonoids; ascorbate, glutathione.