Antimicrobial and Antioxidant Properties in Tissues of Mud Crab from Scylla olivacea and Scylla paramamosain

Noorasmin, Bin Mokhtar Ahmad (2020) Antimicrobial and Antioxidant Properties in Tissues of Mud Crab from Scylla olivacea and Scylla paramamosain. Masters thesis, university malaysia sarawak.

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Abstract

ABSTRACT Mangrove crab (genus Scylla) is a kind of mud crab that has long been recognized as a rich source of protein. Several antimicrobial peptides from mud crabs have recently been identified by their antibacterial activity against Gram-positive and Gram-negative bacteria. Meanwhile, antioxidant capabilities found in mud crabs have been linked to cell protection from free radicals. Unfortunately, to date, little is known about the antimicrobial and antioxidant activities of Scylla olivacea and Scylla paramamosain. This study investigates the natural antibacterial and non-enzymatic antioxidant properties from whole tissue extract of two mud crab species, S. olivacea, and S. paramamosain. The data from this study may offer the basis for much future research. In this study, extraction through maceration was utilized to produce tissue extract from S. olivacea and S. paramamosain. The tissue extracts were diluted and tested against five different bacteria through microdilution analysis. These extracts were further characterized through non-enzymatic antioxidant activity. The identities of chemical constituents in the tissue extracts were then identified using Gas Chromatography-Mass Spectrometry (GC-MS). The antibacterial activities were determined using the broth microdilution method. The methanol extract of S. olivacea and S. paramamosain was found to inhibit the growth of Staphylococcus aureus, Klebsiella pneumoniea, Pseudomonas aeruginosa, Escherichia coli, and Salmonella typhi with minimum inhibitory concentration (MIC) and minimum bacteriostatic concentration (MBC) ranging from 1.56-6.25 μg/μL. Additionally, it was revealed that the highest Diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging activity was in the extracts of S. olivacea and S. paramamosain, which were 1.23 mg/mL and 1.28 mg/mL, respectively. In terms of ferric reducing antioxidant potential (FRAP), S. paramamosain extracts in methanol, ethyl acetate, and n-hexane solvent showed better iv results than the S. olivacea extracts. The FRAP value obtained was similar at 1 mg/mL, which is 0.033±0.004 Fe (II)/mg for both methanol and ethyl acetate extract of S. paramamosain. It was observed that the highest nitric oxide scavenging activity for both species was in n-hexane extract with the EC50 values of 0.35 mg/mL and 0.36 mg/mL, respectively. The extract contained 225 compounds with up to 40 reported from previous studies to exhibit antimicrobial, antioxidant, or anti-inflammatory properties. Keywords: Scylla olivacea, Scylla paramamosain, antibacterial, antioxidant, Gas Chromatography-Mass Spectrometry.

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