Staphylococcus aureus is a gram-positive pathogen responsible for causing several infectious diseases and has been shown to be one of the leading causes of skin and soft tissue infections and bloodstream infections. The problem is further exacerbated by the development of antibiotic resistance. This necessitates the discovery of novel molecules showing anti-microbial activity against Methicillin-resistant Staphylococcus aureus (MRSA). The marine environment is taxonomically diverse with several possible sources of natural compounds. It also happens to be a relatively untapped and unexplored environment when compared to its terrestrial counterpart. Antimicrobial activities of marine algal extracts against several microorganisms have been reported. Yet the characterization and further investigation of responsible active principles has not been as widely explored. Based on these facts, we have decided to explore the possibility of discovering anti-MRSA compounds of marine algal extracts of as yet unexplored species and characterize the active principle responsible for the inhibitory activity using analytical techniques such as HPLC, TLC and mass spectrometry. In due course, we have observed an array of phenolic compounds, identified as phlorotannins, showed significant anti-MRSA properties, the structures of which are extensively characterized by different mass spectrometric techniques.