Screening of Extracts of Diwal (Pholas orientalis) for Antimicrobial Activities

Abstract

Diwal or Angel wing (Pholas orientalis) is one of the commercially important bivalve in the Philippines. There are areas in Region 6, Philippines that are declared "diwal sanctuaries" to protect the resource from continuous exploitation. Diwal is considered a delicacy and to add to its saleability, extracts of its different parts (siphon, mantle, body meat and gills) were bioactivity screened for antimicrobial properties. Cold methanol and PBS (phosphate buffer saline) extracts were assayed against gram-positive (Staphylococcus aureus and Micrococcus luteus) and gram-negative (Pseudomonas aeruginosa and Vibrio harveyi) bacteria for antibacterial activity and against three fungal strains: Aspergillus niger, Trichoderma sp., and Candida albicans for antifungal activity. Three doses (100 500, and 1,000 mg/mL) of the extracts were used in the bioassay with Chloramphenicol (10 mg/mL) for antibacterial and Ketoconazole (10 mg/mL) for antifungal serving as positive controls. All extracts of Diwal in both cold methanol and PBS extracts did not show any antibacterial activities. It did have antifungal activities but only in a 1000 mg/mL dose of cold methanol and PBS extracts of body meat and cold methanol extract of the mantle. Of the three fungal strains tested, Trichoderma sp, a fungus that caused skin dermatitis in humans, exhibited a zone of inhibition. So, there is potential for Diwal extract as an antifungal agent. Preparations of Diwal body meat and mantle extracts should be tested for its affectivity especially against dermatitis. Extraction of Diwal parts should also be done using nonpolar solvents to further assess its potential as a promising source for identifying novel drug lead compounds that might ultimately benefit the ongoing global search for clinically useful antimicrobial agents.

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