Investigation of Chemical Composition and Antibacterial Activity of Ink from Sea Hare Dolabella auricularia

This study was conducted to determine the chemical composition of ink from sea hare (Dolabella auricularia) of Pujada Bay, City of Mati, Davao Oriental. The proximate and mineral composition were determined by using the standard official methods of the Association of Official Analytical Chemists (AOAC).  The presence of secondary metabolites was investigated by using different qualitative tests, namely Froth test (saponins), Libermann-Buchard (sterols), Bate-Smith and Metacalf (flavonoids), Dragendorff and Maeyer (alkaloids), Keller-kiliani (glycoside), ferric chloride (tannins) and Bortnträger (anthraquinones). Its antibacterial activity against Escherichia coli and Staphylococcus aureus was determined by using agar well diffusion method. The results for proximate analyses showed that ink contained 90.4 % moisture, 2.044 % ash, 5.324 % crude fat and 0.75 % protein. The mineral analyses were 0.25 % phosphorous, 578 µg/g potassium, 0.662 % sodium, 310.8 µg/g calcium, 664 µg/g magnesium, 2.146 µg/g iron and 1.898 µg/g zinc. Secondary metabolites screening revealed that ink contained saponins, steroids and flavonoids. Further, the ink extract showed weak antibacterial factor.  This is the first study conducted on the ink of sea hare in Davao region and its preliminary results showed that it is a good source of primary and secondary metabolites. These findings can be added to the potential medicinal value of sea hare and a basis for further chemical studies that will hopefully lead to the discovery of compounds with pharmacological importance.