Atividades antioxidante, antimicrobiana e fitotóxica dos extratos etanólicos das macroalgas marinhas vermelhas Bryothamnion seaforthii e B. triquetrum coletadas na praia de Paracuru, Ceará

Abstract

The oceans are unique aquatic environments, consisting of a promising source of natural products. Bioactive compounds of marine origin have become increasingly important in the development of functional foods and new drugs. Algae, one of the earliest forms of life on Earth, dominate marine vegetation and are directly involved in primary production, nutrient retention and ocean diversity. The present study aimed to evaluate the biological potential of the ethanolic extracts of the red marine macroalgae Bryothamnion seaforthii and B. triquetrum, named, respectively, BS and BT. Ethanolic extracts of each macroalga were prepared in 1:10 ethanol (w/V),, and were specifically evaluated for the content of total phenolic compounds (CFT), flavonoid content (TF), antioxidant activity in vitro (DPPH radical-scavenging activity, ferrous ion chelating (FIC) activity, ferric reduction antioxidant power (FRAP), β-carotene bleaching assay (BCB)), antimicrobial activity (antibacterial and antibiofilm activities) and phytotoxic activity against cucumber seeds, Cucumis sativus. The extracts showed yields (%) of 0.82 ± 0.11 (BS) and 0.98 ± 0.08 (BT) and were kept at –24°C until analyses. The CFT values, expressed in mg EAG/g extract, were 34.23 ± 1.78 (BS) and 34.57 ± 1.76 (BT). The TF values, expressed in mg EQ/g extract, were 52.38 ± 3.44 (BS) and 47.18 ± 3.68 (BT). The in vitro antioxidant activity (DPPH, FIC and FRAP) of BS and BT extracts was lower than that of the controls. However, the antioxidant activity of BS and BT extracts, measured by BCB, did not show any significant difference (p > 0.05), when compared to that of ascorbic acid, used as a control, indicating great efficacy, with EC50 values below 50 μg/mL. No antimicrobial activity was observed in BS and BT extracts. BS and BT extracts did not show phytotoxicity in the germination tests against cucumber seeds. The study suggests a more in-depth assessment of the marine macroalgae Bryothamnion seaforthii and B. triquetrum in view of their potential aptitudes for the food, agronomic and therapeutic industries.