Technological University Dublin ARROW@TU Dublin
School of Food Science and Environmental Conference papers Health
2008
Antioxidant And Antimicrobial Activity From Six Species Of Edible Irish Seaweeds
Sabrina Cox Technological University Dublin, [email protected]
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Recommended Citation Cox, S. Antioxidant And Antimicrobial Activity From Six Species Of Edible Irish Seaweeds. 2008. 8th Joint Meeting of the Seafood Science and Technology Society and Atlantic Fisheries Technology Conference. North Carolina State University, Department of Food, Bioprocessing and Nutrition Sciences, USA.
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This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 4.0 License Funder: ABBEST Antioxidant and antimicrobial activity from six species of edible Irish seaweeds Sabrina Cox*, Nissreen Abu-Ghannam and Shilpi Gupta
School of Food Science and Environmental Health, Dublin Institute of Technology, Cathal Brugha Street, Dublin 1, Ireland
Introduction Antioxidant Analysis All species of seaweeds exhibited a concentration-dependent DPPH radical scavenging activity. The most effective concentration of seaweed extracts were analysed kinetically over Folin-Ciocalteau Method DPPH Method DPPH assay is based on the concentration of sample required to reduce the DPPH radicals by 24 hours (Fig. 4) 50% (EC50) Himenthalia elongata was most effective against all bacteria inhibiting bacteria from Seaweeds are macroalgae which are macroscopic plants of marine All three species of brown seaweed and Chondrus crispus showed better scavenging capacity the first hour, followed by Laminaria saccharina and Laminaria digitata benthoses. Based on nutrient and chemical composition seaweeds are than Palmaria palmata and Enteromorpha spirulina (Fig. 2) Palmaria palmata and Enteromorpha spirulina increased the lag phase (average 2 classified as Rhodophyta (red algae), Phaeophyta (brown algae) and Himenthalia elongata showed highest antioxidant activity giving 50% reduction of DPPH and 4 hours respectively) after which growth increased Chlorophyta (green algae) radical at 1µg/ml and gave 100% inhibition at 1000µg/ml Chondrus crispus increased the overall growth of the bacteria higher than the control Followed by Laminaria digitata, Laminaria saccharina and Chondrus crispus (all 5µg/ml) Ireland harvests 32,000 tonnes of seaweed per year with an annual Palmaria palmata had an EC of 25µg/ml and Enteromorpha spirulina gave the lowest level Pseudomonas Listeria 50 2.5 2.5 turnover of €15 million (75µg/ml) 2 2 Seaweeds are a known source of bioactive compounds such as antiviral, 1.5 1.5 antifungal, antimicrobial and antioxidants as they contain secondary 100 80 70 1 1
80 OD (600nm) OD (600nm) OD metabolites characterized by a broad spectrum of biological activities 60 Ascorbic acid 0.5 0.5 60 50 Laminaria digitata Seaweeds are exposed to light and high oxygen concentrations which 0 40 0 Laminaria saccharina 0 4 8 12 16 20 24 0 4 8 12 16 20 24 result in free radicals and other strong oxidizing agents being formed, 40 30 Himenthalia Extract(µg) Time (Hrs) Time (Hrs) elongata 20 however seaweeds seldom suffer any serious photodynamic damage which Scavenging(%) activity Chondrus crispus 20 Antimicrobial Analysis Salmonella Enterococcus Palmaria palmata 10 implies that their cells have protective mechanisms and compounds 2.5 2.5 0 Enteromorpha 0 spirulina Seaweeds are a relatively unexploited resource in Ireland thus investigation into Common food spoilage and food Type of bacteria 0 200 400 600 800 1000 Laminaria Laminaria Himenthalia Chondrus Palmaria Enteromorpha 2 2 digitata saccharina elongata crispus palmata spirulina pathogenic bacteria used* Extract (µg) this plentiful resource could provide a promising alternative and natural source 1.5 1.5 Listeria monocytogenes Gram+ Food pathogenic bacteria of bioactive compounds, neutraceuticals and functional foods 1 1
(a) (b) (600nm) OD Salmonella enterica Gram- Food pathogenic bacteria (600nm) OD The main objective of this work was to investigate and evaluate the antioxidant 0.5 0.5 Enterococcus faecalis Gram+ Food spoilage bacteria and antimicrobial activity of six species of edible Irish seaweeds Fig. 2. (a) DPPH free radical scavenging activity of seaweed extracts and (b) EC50 level of each seaweed 0 0 0 4 8 12 16 20 24 Pseudomonas aeruginosa Gram- Food spoilage bacteria extract (Each data point is an average of 6 values) 0 4 8 12 16 20 24 Time (Hrs) Time (Hrs)
*All grown overnight prior to analysis. Adjusted to 0.5 OD using McFarland Standards to Fig. 4. Kinetic analysis of highest concentration of seaweed extract against common food 6 prepare cultures at 1x10 for microtitre analysis. spoilage and food pathogenic bacteria (Each data point is an average of 6 values) Materials and Methods Antimicrobial Analysis Antimicrobial properties of seaweed extracts against two species of gram+ and gram- food pathogenic and food spoilage bacteria are displayed in Fig. 3 Conclusion Three species of Phaeophyta, two Rhodophyta and one Chlorophyta were used in Brown seaweeds had the highest antimicrobial activity this study. Himenthalia elongata gave 100% inhibition of all bacteria at 12.8mg The results of the present work indicated that extracts of Irish seaweeds successfully All extracts inhibited growth of bacteria except Chondrus crispus which increased the growth displayed antioxidant activity of the studied bacteria Himenthalia elongata was most effective (phenolic content 155.3 gallic acid units; This may have been due to high levels of polysaccharides in the extract which supported DPPH EC50 1µg/ml extract) bacterial growth All seaweed extracts except Chondrus crispus had some antimicrobial activity All effective extracts had highest impact at inhibiting Listeria monocytogenes Himenthalia elongata was most successful at inhibiting bacteria (100% inhibition at 12.8mg extract concentration) followed by the other two Phaeophyta Laminaria
100 100 saccharina and Laminaria digitata Chondrus crispus increased the growth of all bacteria 80 80
(%) The present findings appear useful in leading to further experiments to test the 60 60 potential of the extracts to increase the shelf life of food products. The ability of
40 40 Inhibition Inhibition(%) seaweed extracts to quench free radicals is known to take place over a longer period 20 20 of time then rapid acting synthetic antioxidants such as BHA. This may have benefits Results and Discussion 0 0 for extending the shelf-life of processed foods during distribution and storage. 0 4 8 12 16 0 4 8 12 16 Extracts from six species of edible Irish seaweeds were screened for Laminaria digitata extract (mg) Laminaria saccharina extract (mg) antioxidant and antimicrobial activity. 100 100 80 References 80 60 40 Antioxidant Analysis 60 20 0 Nagayama, K., Iwamura, Y., Shibata, T., Hirayama, I., and Nakamura, T. (2002). Journal of Antim- 40 All six species of seaweeds exhibited antioxidant content using the -20 0 4 8 12 16
Inhibition(%) icrobial Chemotherapy, 50, 889-893 -40
Folin-Ciocalteau method for determination phenolic content (Fig. 1) 20 Inhibition(%) -60 Yuan, Y., Bone, D. and Carrington, M. (2005). Food Chemistry, 91, 485-494 -80 Himenthalia elongata showed the highest content of phenolics (155.3 0 -100 gallic acid units) 0 4 8 12 16 -120 Himenthalia elongata extract (mg) Chondrus crispus extract (mg) Acknowledgements 100 100 180 80 80 160 This work is funded by the Dublin Institute of Technology ABBEST Scholarship 140 60 60 120 The authors would like to acknowledge and thank The Marine Institute of Ireland for 40 100 40 80 20 providing funding for attending the conference
60 Inhibition(%) Inhibition(%) 20 0 This work was presented in October 2008 at the 2008 8th Joint Meeting of the 40 Gallic acidGallicunits (720nm) 0 4 8 12 16 20 -20 0 Seafood Science and Technology Society and Atlantic Fisheries Technology 0 0 4 8 12 16 Laminaria Laminaria Himenthalia Chondrus Palmaria Enteromorpha -40 -20 Conference. North Carolina State University, Department of digitata saccharina elongata crispus palmata spirulina Palmaria palmata extract (mg) Enteromorpha spirulina extract (mg) *Corresponding author. Tel: 0035314024374 Food, Bioprocessing and Nutrition Sciences, USA.
Email address: [email protected] Fig. 1. Total phenolic content of seaweed extracts (Each data point is an average Fig. 3. Percentage Inhibition of seaweed extracts against food spoilage and food pathogenic bacteria (Each www.dit.ie of 6 values) data point is an average of 6 values)