Bactericidal Properties, Biofilm Formation Inhibition, and Chemical Profiling of Piper argyrites and Piper betel L.

Betel leaf has been an important medicinal plant for therapeutic purposes since ancient times. This study aims to investigate the ethanolic leaf extracts of Piper betel (PB) and Piper argyrites (PA), native to Satun Province, Thailand. The antibacterial properties of the extracts were evaluated using a disc diffusion assay on four bacterial isolates, including Escherichia coli PT005, Pseudomonas aeruginosa PT00A2, Klebsiella pneumoniae PT00A1, and Staphylococcus aureus RTV01. PB leaf extracts demonstrated a substantial effect on K. pneumoniae PT00A1 with an inhibition zone of 25.77 ± 0.04 mm, while PA leaf extract showed potent activity against E. coli PT005 with an inhibition zone of 17.23±0.44 mm. In addition, both extracts exhibited bactericidal effects, with low MIC and MBC values ranging from 6.3 to 50 µg/mL, as determined by a broth dilution assay. Moreover, biofilm formation inhibition was evaluated using the crystal violet method. The results showed that both extracts effectively inhibited biofilm formation in bacterial strains. PA and PB extracts demonstrated high efficiency in reducing the biofilm formation of S. aureus RTV01, achieving reductions of 94.94% and 88.43%, respectively. The extracts showed a reduction in biofilm formation of 36.18% to 94.94% in the tested strains. The chemical profiles of the plants were analyzed using the GC-MS technique, which revealed that hydroxychavicol was a major constituent of both plant species, with varying amounts and distinct profiles. P. argyrites exhibited a more diverse range of compounds than P. betel. The findings suggest that these betel plant extracts need further investigation for potential therapeutic applications.