Antioxidant and Antibacterial Activities of the Protein Extracts from Four Species of Underutilized Marine Bivalves


by:Gleann P. Salido, Nicole Pauline P. Plagata, Ma. Lorena M. Serisola, Karmelie Jane M. Monaya, Reysyl Caroline B. Garferio, Rhoda Mae C. Simora*


Crude tissue proteins were extracted from the underutilized marine bivalves: Placuna placenta, Placuna ephippium, Scapharca inaequivalvis, and Marcia hiantina by aqueous and acidic extraction methods. Partial purification of the crude extracts was done through ammonium sulfate precipitation followed by membrane dialysis. The resulting filtrate was then subjected to centrifugal ultrafiltration to produce fractions of 10-20 kDa molecular weight. Highest total soluble proteins were observed in M. hiantina extracts at 16.20 mg/ml for hot water extraction (HWE), 11.13 mg/ml for cold water extraction (CWE), and 11.68 mg/ml for acetic acid extraction (AAE) (P<0.05). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) bands indicate low molecular weight peptides (<14 kDa) were present in HWE and AAE extracts of P. placenta and CWE of S. inaequivalvis. Highest 2, 2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant activity was observed in M. hiantina CWE at 54.09 % (P < 0.05). Highest antibacterial activity against Bacillus cereus was observed in AAE and HWE extracts of P. placenta, with minimum inhibitory concentration (MIC) of 124.34 μg/ml and 195.71 μg/ml, respectively. Results of this study indicate that the protein extracts of these underutilized marine bivalves may have promising antioxidant and antibacterial activities which can be potential sources of bioactive compounds. It also confirmed the potential of using aqueous extraction to liberate the peptides, which is a more costeffective alternative to chemical and enzymatic hydrolysis.

Keywords: marine bivalves, bioactive peptides, antioxidant activities, antimicrobial activities, aqueous extraction