A comparative study on the antioxidant activity of Gladiolus dalenii Van Geel and nine commonly used substances to compare the antioxidant activity of foods and medicinal plants

Reactive species, such as the free radicals produced during cell metabolism, are described as the main cause of oxidative stress, a process responsible for the development of degenerative diseases. Thus, the investigation of natural products containing chemical components with antioxidant capacity becomes necessary, since the frequent ingestion of these products may prevent the occurrence of this adverse event. In this perspective, total phenols (TPC) and total flavonoids (TFC) of the crude methanolic extract (MCE) and ethyl acetate fraction (EAF) obtained from Gladiolus dalenii bulbs were quantified and their antioxidant capacity evaluated and compared with that of gallic acid (GA), tannic acid (TA), pyrogallol (PyG), n-propyl gallate (nPG), quercetin (Qtn), rutin (Rut), butylated hydroxytoluene (BHT), 6-hydroxy-2,5,7-tetramethyl-chroman-2-carboxylic acid (Trolox) and ascorbic acid (Asc) using 1,1-diphenyl-2-picryl hydroxyl (DPPH) free radical scavenging method. The study revealed that the antioxidant activity of MCE (EC₅₀=6.550 ± 0.31 µg/mL) and EAF (EC₅₀=5.960 ± 0.61 µg/mL) was higher effect than Rut (EC₅₀=9.110 ± 0.04 µg/mL) and BHT (EC₅₀=11.18 ± 0.03 µg/mL), and in turn lower than that of the other substances analyzed. The antioxidant activity found for G. dalenii extracts may be due to the high level of TPC found in this species.