Phytochemical composition and antibacterial activity of Philippine pomelo (Citrus maxima L.) fruit peel ethanolic extract as potential shower gel ingredient

Abstract

The Philippine Pomelo <i>(Citrus maxima L.)</i> is the largest fruit in the <i>Rutaceae</i> family and is widely found in the country. The peel, which is often discarded, contains antimicrobial compounds that are capable of inhibiting bacterial growth. This study aimed to investigate the phytochemical composition and antibacterial activity of <i>Citrus maxima L.</i> (Philippine Pomelo) fruit peel ethanolic extract, assessing its potential as shower gel ingredient. The results revealed that the ethanolic extract of pomelo peel demonstrated significant antibacterial effects against <i>Staphylococcus aureus, Staphylococcus epidermidis,</i> and <i>Escherichia coli,</i> with the highest inhibition observed in <i>E. coli.</i> In contrast, no inhibition zone was observed against <i>Shigella sonnei,</i> suggesting that the extract's antimicrobial properties are strain-specific. The MIC results indicated that extract concentrations of 62.5 µg/ml, 125 µg/ml, and 250 µg/ml could inhibit the growth of <i>S. aureus, E. coli,</i> and <i>S. epidermidis,</i> respectively. MBC results consistently supported these findings. Contradictory results between elevated absorbance values-likely affected by the extract's turbidity, and the observed antimicrobial activity was detected in the MIC50 value of <i>C. maxima L.</i> extract suggesting interference. Phytochemical analysis also confirmed the presence of phenols, tannins, terpenoids, flavonoids, and glycosides. The well-diffusion antimicrobial susceptibility test showed that combining the ethanolic extract with shower gel created a larger zone of inhibition compared to using the gel alone. These findings highlight the potential of pomelo peel extract as an antibacterial component in shower gel.