Antibacterial and toxicity studies of phytochemicals from Piper betle leaf extract

The methanolic and ethanolic Piper betle L. (PB) extracts (PBM and PBE, respectively) yielded 14.14 % and 8.23 %, respectively. The phytochemicals in the PB extract were alkaloids, flavonoids, coumarins, tannins, terpenoids, cardiac glycosides, and saponins, whereas steroids and pholbatannins were obtained from Piper retrofractum (PR) and Glycosmis pentaphylla (GP) extracts, and anthaquinones were found only in the GP extract. Furthermore, only the PB extract exhibited antibacterial activities against Vibrio parahaemolyticus, Staphylococcus aureus, Escherichia coli, Bacillus cereus, and Pseudomonas aeruginosa with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values ranging 0.24–3.91 mg/mL. The highest bactericidal activity was observed against V. parahaemolyticus. PBM and PBE extracts had total phenolic contents of 130 ± 4.46 and 147.69 ± 0.03 mg gallic acid equivalents (GAE)/g, respectively, with scavenging activity (IC₅₀) of 0.03 mg/mL. The total phenolic contents were significantly decreased, whereas antibacterial activities remained stable (>50 % at 65 °C for 12 h). Toxicity evaluation showed that PBM and PBE caused hemolysis in a dose-dependent manner, with IC₅₀ values of 0.24 and 0.44 mg/mL, respectively. Both extracts were moderately toxic to Artemia salina (LC₅₀ = 0.58–0.61 mg/mL). Finally, the PB extract exhibited inhibitory activities against lipase, glucoamylase, and trypsin. Based on these findings, crude extracts of PB have the potential to be used as antibacterial, antidiabetic, anti-obesity, and dietary supplements.