Study of total phenolic content and antioxidant capacity of the ethanolic extracts of two medicinal plants, Hibiscus sabdariffa L. and Amaranthus caudatus L.

Abstract

Nowadays, the replacement of synthetic antioxidants with natural antioxidants of plant origin in the food industry has been widely considered. In addition, the results of scientific researches demonstrate that consumption of plants with high antioxidant capacity reduces the incidence of many diseases such as all types of cancer, cardiovascular and Alzheimer's diseases and also helps the treatment process of the diseases. In this research, the total phenolic content of the ethanolic extracts of Hibiscus sabdariffa L. calyces and Amaranthus caudatus L. flowers was measured by Folin-Ciocalteu method and also the antioxidant capacity of two extracts was studied using FRAP and DPPH methods. The results showed that the total phenolic content of A. caudatus and H. sabdariffa ethanol extracts were 3.25 ± 0.34 and 1.73 ± 0.21 mg GAE g-1 extract, respectively. The results of two FRAP and DPPH assays also indicate the significant antioxidant capacity of these two plants extracts. The comparison of EC50 obtained from the DPPH assay of two extracts showed that the antioxidant activity of the A. caudatus extract is higher than that of H. sabdariffa, and therefore there is a direct relationship between the total phenolic content of the ethanolic extracts and their antioxidant activity. Overall, the results of the present study show that these two medicinal plants can be used in the food and pharmaceutical industries, which requires more scientific research on them. [ABSTRACT FROM AUTHOR]