Determination of Antioxidant, Antimicrobial Activity, Heavy Metals and Elements Content of Seaweed Extracts

Abstract

The aim of the research was to determine the antioxidant and antimicrobial activity, determination of chemical elements and heavy metals in seaweed extracts of wakame, arame, dulse, laminaria, kombu, and hijiki. Antioxidant activity was determined by DPPH method and the activity ranged from 0.00 to 2641.34 TEAC. The highest antioxidant activity was observed in kombu (2641.34 TEAC) and arame (2457.5 TEAC). Antimicrobial activity was analyzed by disk diffusion method and MIC method. Three G+ bacteria (Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis), three G- bacteria (Salmonella enterica, Pseudomonas aeruginosa, Yersinia enterocolitica), and four yeasts (Candida tropicalis, C. krusei, C. glabrata, C. albicans) were used as model organisms. The size of inhibition zones ranged from 0.00 to 8.67 mm. The minimum inhibitory concentrations of the selected seaweeds ranged from MIC50 98.46 (MIC90 100.25) to MIC50 3.43 µL/mL (MIC90 5.26 µL/mL). The content of selected elements was determined in seaweed samples by ICP-OES. The chemical composition of the algae showed differences between species and the presence of heavy metals. Arsenic, cadmium, and aluminum were confirmed. All seaweed samples contained arsenic ranging from 6.6546 to 76.48 mg/kg. Further investigation of seaweeds is needed to identify the active substances present in the algae that are responsible for antioxidant and antimicrobial activity. This study was carried out to evaluate the antimicrobial and antioxidant activity of extracts from five commonly consumed seaweeds for their ability to inhibit selected microorganisms and to determine the health risk due to heavy metals content. Our study contributes to the evidence that seaweeds have antimicrobial and antioxidant activity and seaweed extracts have for pharmacological applications.

Seaweeds in Food: Current Trends

“…However, these chemical groups mean that seaweeds have a high affinity for other components, e.g., heavy metals. Consequently, seaweeds may accumulate and become a source of arsenic (As), cadmium (Cd), lead (Pb), mercury (Hg), and other compounds [ 53 ]. Therefore, this raises the following questions: (i) does the consumption of seaweed foods and seaweed-based products contribute positively or adversely to human health, and (ii) should their consumption be encouraged or limited?…”

“…Their toxicity depends on the dose, the route of entry, and the duration of exposure, i.e., acute or chronic [ 54 ]. The occurrence of heavy metals in seaweeds depends on environmental factors, such as salinity, temperature, pH, light, and oxygen, and the type of seaweed [ 2 , 53 ]. Furthermore, heavy metal occurrence depends on the availability of metals coming from natural geological sources in addition to urbanization and industrial activities, which can all contribute to the contamination of aquatic systems.…”

Analysis of Antimicrobial Activity of Carrageenan Extracted from Kappaphycus Alvarezii

“…Moreover, environmental factors, seasonal changes and stages of development may affect the production and distribution of bioactive constituents in the seaweed. Other factors affecting active phytochemicals capture include the solvents used, the extraction period and the extraction conditions [49].…”

Assessment of phytochemicals from marine algae Ulva fasciata and Dictyota dichotoma with antioxidant and antimicrobial potential

“…Seaweeds are obscure and inexhaustible sources of diverse bioactive compounds which exhibit tremendous biological activities [1] . The compounds possessing bioactivities are excellent raw materials for the pharmaceutical, cosmetics and food industries [2][3][4] . Because of the increased demand for natural resources in therapeutic industries, seaweeds are getting significant attention because of their potential to produce a great variety of secondary metabolites [1,5] .…”