<![CDATA[Acne is a common skin disorder affecting adolescents and young adults, characterized by inflammation of the pilosebaceous follicles associated with the proliferation of Propionibacterium acnes (P. acnes). The use of synthetic anti-acne agents may cause adverse effects, making natural products a promising alternative. This study aimed to evaluate the antibacterial activity of mangostin isolate against P. acnes, formulate it into a clay mask, and assess the antibacterial effectiveness of the resulting preparation. Antibacterial activity was evaluated using the disc diffusion method at mangostin isolate concentrations of 0.275%, 0.55%, and 1.1% (w/v). Clay mask formulations were prepared using a bentonite–kaolin base in four different formulations. The preparations were evaluated for organoleptic properties, pH, homogeneity, viscosity, drying time, spreadability, adhesiveness, and physical stability using the cycling test method. Antibacterial activity of the clay mask formulations was also assessed against P. acnes. The results showed that mangostin isolate at a concentration of 0.275% produced an inhibition zone diameter of 15.10 ± 0.64 mm, indicating strong antibacterial activity. All clay mask formulations met the required physical evaluation criteria and remained stable during the cycling test. Following formulation, antibacterial activity was retained, although the inhibition zone diameter decreased to the moderate category, ranging from 7.00 to 9.18 mm. These findings suggest that mangostin isolate has potential as a natural antibacterial active ingredient in anti-acne clay mask formulations]]>
