Antimicrobial activity of natural mollusc shells: A review

The need to develop novel, antimicrobial drug candidates to abate antimicrobial resistance is a global research priority. The structural and environmental diversity of marine organisms such as molluscs provides a great opportunity for bioprospecting i.e. the discovery of new bioactive substance. This review discusses the compounds derived solely from mollusc shells namely calcium carbonate (CaCO₃), calcium oxide (CaO) and the organic matrix extract, with a focus on their antimicrobial activity. To assess the possibility of utilizing these fractions for bioprospecting, a Strength-Weakness-Opportunities-Threat (SWOT) analysis was carried out. This review shows that shell type and extraction techniques employed determines the kind of compounds extracted in the organic matrix as well as its solubility and antimicrobial activity. The efficacy of CaCO₃ in antimicrobial study lies in its transformation to CaO. The low yield of organic matrix when compared with CaO is one of the limitations of its use in bioprospecting. CaO exhibits stronger and broader antimicrobial properties when compared to the other bioactive fractions. Its multifaceted mechanism of antimicrobial activity highlights its potential as the most promising fraction for antimicrobial drug development.