Malays. Appl. Biol. (2018) 47(4): 127–133
ANTIOXIDANT AND ANTIBACTERIAL ACTIVITIES OF
POLYSACCHARIDES AND METHANOLIC CRUDE EXTRACTS
OF LOCAL EDIBLE RED SEAWEED Gracilaria sp.
SUVIK ASSAW1,2*, NURUL LAILI ROSLI1, NUR ADILAH MAT AZMI1, NOOR WINI MAZLAN1 and
NORAZNAWATI ISMAIL2
1School of Marine and Environmental Sciences, Universiti Malaysia Terengganu,
21030 Kuala Nerus, Terengganu
2Institute of Marine Biotechnology, Universiti Malaysia Terengganu,
21030 Kuala Nerus, Terengganu
*E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Accepted 12 September 2018, Published online 25 October 2018
ABSTRACT
Seaweed have been long time utilised in food industries in many applications. Seaweed including edible Gracilaria species (red seaweed) is rich with bioactive compounds and has been proven to possess pharmaceutical and medicinal values including to fight against bacterial infections and cells oxidation. The purpose of this study is to evaluate the potential usage of two different types of local Gracilaria sp. extracts which are polysaccharides agar and methanolic crude extract as natural antioxidant and antibacterial against six bacteria test strains such as Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Vibrio cholera and Enterobacter cloacae. Antibacterial activity was assessed using agar well diffusion method and antioxidant activity was evaluated using DPPH radical scavenging assays. Results revealed that there are differential effects of both extracts as antioxidant and antibacterial. Methanolic crude extract of Gracilaria sp. was found to have moderate antibacterial activity with minimum inhibition concentration of 0.156 mg/ml and significantly (p<0.05) higher antioxidant activity (IC50 = 5.6 mg/ml) compared to polysaccharide extracts. No antibacterial activity was found in all concentrations of polysaccharides extract. Present findings also suggested that Gracilaria sp. could be a potential natural source of antioxidant and antibacterial for nutraceutical and functional food. However, the extraction method used greatly determine the bioactivities of the seaweeds.
Key words: Red seaweed, extraction, functional food, antioxidant, antibacterial
