Evaluation of chemical constituents of Stoechospermum marginatum and its potential for antioxidant and antimicrobial activity

Seaweeds are considered one of the prosperous sources of bioactive compounds with enormous biological activities. Seaweed resources are still unexplored for its multiple activities. The present study is focused to evaluate the biochemical and structural composition, and antioxidant, antimicrobial activity of a brown seaweed Stoechospermum marginatum. Bioactive substances such as alkaloids, tannins, flavonoids, steroids, and phenols were determined by the qualitative analysis of phytochemicals. Moreover, quantitative analysis of seaweed extract obtained from Soxhlet extraction method using methanol as solvent revealed the significant existence of phenolic compound, flavonoids, and tannins. Phytochemical constituents of the extract were confirmed by UV visible spectroscopy, FTIR, NMR and HPLC analysis. This study revealed the presence of secondary metabolites, and functional groups that are responsible for biological activities. The antioxidant assays for S. marginatum used were as follows: DPPH radical scavenging activity (44.03 +/- 0.307%), H2O2 scavenging activity (31.60%), metal chelating activity (47.33 +/- 0.665%), ferrous iron reducing assay, and total antioxidant activity (47.92 +/- 0.001%). The findings obtained from this study exhibited that the extracts yielded a great potential of antioxidant activities. Besides, bioactive extracts showed excellent antimicrobial activity against the tested pathogens. The extract had effective activity against Bacillus subtilis strain (13 mm inhibition zone). It is noticeable that the seaweed S. marginatum can be utilized as a novel substance to replace many toxic synthetic antioxidants and antimicrobial agents available in the pharmaceutical industry.