This study was aimed to investigate the potential use of Morus alba stem extract for treatment of inflammatory acne through its inhibitory activities against acne-causing bacteria, free radicals, prostaglandin (PG)-E2 and tyrosinase enzyme. The antibacterial studies found that among Propionibacterium acnes, Staphylococcus epidermidis and Staphylococcus aureus, the extract specifically inhibited P. acnes with MIC and MBC of 3.125 mg/ml and 12.5 mg/ml, respectively. It also exhibited the ability to scavenge free radicals including DPPH, superoxide and nitric oxide radicals with IC50 values of 32.07, 67.29 and 12.12 µg/ml, respectively. Moreover, the extract could significantly inhibit the production of PGE2, a potent inflammatory mediator. Additionally, it presented potent anti-tyrosinase activity (5.76 ± 1.58 µg/ml) and was significantly more effective than kojic acid (30.61 ± 13.35 µg/ml), offering great benefits to reduce post inflammatory hyperpigmentation. These findings suggest potential application of the extract in cosmeceutical formulations for inflammatory acne.
