<![CDATA[Rising resistance of acne-associated Gram-positive bacteria, including Cutibacterium acnes (formerly Propionibacterium acnes), Staphylococcus epidermidis, and Staphylococcus aureus, to first-line macrolide and tetracycline antibiotics has become a global dermatological and public-health concern, intensifying the search for plant-derived antibacterial alternatives. Beluntas (Pluchea indica L., Asteraceae) is widely used in Indonesian traditional medicine and contains flavonoids, tannins, saponins, and caffeoylquinic acids; however, the influence of extraction technique on its antibacterial potency against acne-associated bacteria has not been systematically evaluated. This study aimed to compare the in vitro antibacterial activity of P. indica leaf ethanolic extracts prepared by 5-day cold maceration and 60-minute ultrasound-assisted extraction (UAE, <20 kHz) against C. acnes, S. epidermidis and S. aureus. Powdered leaves were extracted with 70% ethanol using either 5-day cold maceration or 60-min UAE. Following concentration with a rotary evaporator, six concentrations (10–60%, w/v) were evaluated using the agar well diffusion method on Mueller–Hinton agar for S. aureus, S. epidermidis and blood agar for C. acnes. Inhibition-zone diameters were interpreted according to the Davis–Stout classification. Phytochemical screening confirmed the presence of flavonoids, triterpenoids, glycosides, saponins and tannins. Maceration produced larger inhibition zones than UAE for all three organisms at every concentration tested (single-measurement values). The largest inhibition was observed against S. aureus with the 60% maceration extract (20.30 mm; very strong category) followed by S. epidermidis (14.70 mm; strong) and C. acnes (13.65 mm; strong). The susceptibility ranking was S. aureus > S. epidermidis > C. acnes. P. Ethanolic leaf extracts of P. indica obtained through maceration exhibited stronger antibacterial activity than those through UAE against acne-associated Gram-positive bacteria. These preliminary findings suggest that beluntas leaf extract is a promising plant-based antibacterial candidate that may help reduce reliance on synthetic antibiotics and support its further development as a complementary or preventive anti-acne ingredient, pending confirmatory studies incorporating appropriate replication and controls. Keywords: Acne Vulgaris, Antimicrobial Resistance, Dermatological Phytotherapy, Maceration, Pluchea Indica, Ultrasound-Assisted Extraction]]>
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