Melastoma malabathricum L. Leaves (senduduk) Extract in a Water-based Emulsion: Physical and Chemical Stability Study and Bacterial Inhibition Activity

Abstract

Melastoma malabathricum L. (MB) is a medicinal plant with therapeutic properties for treating scars resulting from smallpox, pimples, and skin blemishes. The active compound found in MB leaves can create a high-quality and efficient product that can effectively prevent the growth of bacteria. This study investigates the antimicrobial potential and stability of MB leaves extract in a water-based emulsion, emphasizing its application in cosmetic and pharmaceutical formulations. Leveraging traditional uses and scientific findings, the plant’s bioactive compounds, including saponins, flavonoids, tannins, and phenolic acids, are recognized for their antibacterial properties. The research employed solvent extraction techniques, notably the maceration method, to isolate these bioactives, which were incorporated into emulsions at varying concentrations. This study evaluates the antibacterial activity and stability of MB leaves extract in a water-based emulsion. Extracts were prepared using methanol and ethanol at different concentrations and durations. Phytochemical screening confirmed the presence of tannins, saponins, and flavonoids, with 50% methanol yielding the highest bioactive content. The 96-hour methanol extract showed the strongest antibacterial activity against Staphylococcus aureus (14 mm) and Escherichia coli (19 mm). Water-based emulsions with 1% plant extract retained moderate antibacterial effects and maintained stable pH (4.5–5.5) over 21 days at 4°C. These findings support the extract’s potential as a natural antibacterial agent in topical or cosmetic formulations.