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    Assessment of heavy metal traces (Copper and lead) in the soft tissue of Oysters Crassostrea virginica
    Balboa, Dexter G. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2010-04-05)
    The bivalve mollusk Crassostrea virginica is abundant in Brgy. Calaparan, Arevalo and Brgy. Bacong, Dumangas; and are widely consumed by the residence as food. Bioaccumulation of Copper and Lead in the soft tissues of C. virginica from Brgy. Calaparan, Arevalo and Brgy. Bacong, Dumangas were measured and checked if they are still within the permissible levels of Copper and Lead in food based on Median International Standards for metals compiled by the Food and Agricultural Organization of the United Nations. Metal concentrations (μg/g) were determined using Flame Atomic Absorption Spectrophotometer. Mean concentrations of the heavy metals in C. virginica from Calaparan, Arevalo- Cu 27.829, Pb 1.2133; Bacong, Dumangas- Cu 57.834, Pb 0.1338. These levels of Copper and Lead in oyster tissue from both sites are within the the range of Median International Standards for metals and are safe for human consumption. Statistical analysis through one- way ANOVA (F > Fcrit, showed significant difference between sites (Fcrit = 18.51282) for Copper (F value, 215.06569) but not for Lead (F value, 2.25151). The study also provided further solid evidence that bivalve like Crassostrea virginica can recover and concentrate environmentally derived and anthropogenic traces of heavy metals.
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    Production and bioactivity characterization of protein hydrolysate from Portuguese oyster (Crassostrea angulata)
    Gomez, Honey Lyn R. (University of the Philippines Visayas, 2019-06)
    It has been shown that oysters represent diversified peptides with a variety of biological importance. In the present study, the use of proteomics techniques and bioinformatics tool was carried out to predict the potential bioactivities of Portuguese oyster (Crassostrea angulata). Mascot database search have identified 8 proteins from C. angulata and 5 of which were selected for in silico analysis. Interestingly, BIOPEPUWM database analysis predicted that pepsin (pH > 2) can theoretically release highest number of peptides with biological activities, predominantly angiotensin-1 converting enzyme (ACE) and dipeptidyl peptidase (DPP-IV) inhibitory activities, followed by stem bromelain and papain. To confirm the reliability of these predictions, C. angulata proteins were assessed in vitro. Results showed that all the hydrolyzed samples possessed inhibitory effect against ACE and DPP-IV, with pepsin hydrolysate (PEH) having the strongest activity of 78.18% and 44.34%, respectively. Further fractionation of PEH revealed that fractions with low molecular weight (MW) such as <1 kDa fraction (Fl) and 1-5 kDa fraction (F2) can demonstrate higher ACE and DPP-IV inhibitory activity compared to crude PEH and >5 kDa fraction (F3), but not to a great extent. Overall, the results obtained from in vitro analyses corresponded with the in silico predictions. Findings of this study thereby suggest the applicability of in silico technique for rapid and reliable identification of bioactive peptides from food proteins and determination of suitable enzyme capable for the release of these peptides. Moreover, proteins from C. angulata can be considered as potential sources of peptides with potential pharmaceutical and nutraceutical application.