Introduction: The rise of antibiotic resistance and superbugs drives the search for new antibiotics today. Meanwhile, the green mussel Perna viridis is a cultivated and marketed staple bivalve in the Philippines due to its fast repro-duction, high protein content, and tolerance to environmental variables. Although some studies have analyzed the antimicrobial activity of P. viridis, zoochemical analyses and further evaluation of its antimicrobial activity, such as determining the minimum inhibitory concentration (MIC), remains unexplored.

Objectives: The study evaluated the zoochemicals present in crude methanolic extract of P. viridis by qualitative screening and thin-layer chromatography analysis. It further evaluated the crude extract for its antimicrobial activity against common pathogenic bacteria and plant pathogenic fungi.

Materials and Methods: The zoochemicals in crude methanolic extract of P. viridis were screened using qualitative spotting methods and thin-layer chromatography (TLC). The antimicrobial activity of the extract was evaluated against the bacteria Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis, and the fungi Colletotrichum capsici, Lasiodiplodia theobromae, and Rhizopus sp. using disk diffusion assay and two-fold microdilution.

Results: Qualitative screening and thin-layer chromatography analysis of the crude extract revealed detectable amounts of alkaloids, saponins, terpenoids, sterols, and polyphenols. All of the tested bacteria were susceptible to the extract with P. aeruginosa (19.00±0.82 mm) and S. aureus (19.33±0.47 mm) as the most inhibited with MICs of 2.60±0.63 and 3.65±1.69 mg/mL, respectively. However, for the three fungi tested, only the growth of the fungus L. theobromae (7.33±0.94 mm) was inhibited with a MIC of 33.33±11.79 mg/mL.

Conclusion: It can be inferred that the zoochemicals detected in the crude extract of P. viridis contributed to its antimicrobial activity.

Key Words: Antibacterial agent, Antifungal agent, Green mussel, Plant pathogenic fungi, Secondary metabolites