Antioxidant, anti-inflammatory, and antibacterial activities against acne-causing bacteria of Miliusa velutina (A.DC.) Hook.f. & Thomson extracts

Abstract

Context: Acne is often associated with bacterial infection, inflammation, and oxidative stress. In Thailand, Miliusa velutina has traditionally been used to relieve pain and to heal wounds. Given its biological properties, M. velutina extracts may represent an alternative approach to treat acne. Aims: To characterise M. velutina extracts regarding their antioxidant and anti-inflammatory properties and antibacterial activity against acne-causing bacteria. Methods: We prepared crude methanolic and aqueous extracts of M. velutina leaves and stem bark by maceration. We evaluated the antioxidant activity of the extracts by using four in vitro methods and determined the total phenolic and flavonoid contents. We tested the anti-inflammatory activity of the extracts by examining their ability to inhibit nitric oxide production in RAW 264.7 macrophages. We tested the antibacterial activity against acne-causing bacteria by using the agar diffusion method and by determining the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). Results: The methanolic bark extract showed potent antioxidant properties, denoted by its ability to scavenge the ABTS and DPPH radicals and its iron-reducing power and total antioxidant activity. The methanolic leaf extract presented the best ability to inhibit nitric oxide production, with a half maximal inhibitory concentration (IC50) of 7.20 ± 1.92 µg/mL. Additionally, M. velutina extracts exhibited antibacterial activity against Cutibacterium acnes, Staphylococcus epidermidis, Staphylococcus aureus, methicillin-resistant S. aureus and Pseudomonas aeruginosa, with the MIC and MBC ranging from 0.49 to 62.50 mg/mL. Conclusions: These findings indicate that M. velutina extract can be used as a novel therapeutic agent for acne treatment owing to its antioxidant, anti-inflammatory and antibacterial properties.