In vitro bioactivities of essential oils used for acne control

Summary Essential oils are used in skincare products for perfuming and aromatherapy purposes. In this study, the bioactivities of seven essential oils commonly used and claimed for skincare namely citronella grass (Cymbopogon nardus L.), lemongrass (Cymbopogon citratus DC), Kaffir lime (Citrus hystrix DC), holy basil (Ocimum sanctum L.), sweet basil (Ocimum basilicum L.), plai (Zingiber cassumunar Roxb) and ginger (Zingiber officinale Roscoe) were investigated. Investigation of the in vitro susceptibility of the oils against Propionibacterium acnes (P. acnes) using the broth microdilution technique revealed that citronella grass oil exhibited the lowest minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) at 0.005–0.3 and 0.6–1.2 μl/ml, respectively. The MIC and MBC values of lemongrass oil were 0.6 μl/ml and those of kaffir lime oil and holy basil oil were 5 μl/ml. Antioxidant activity using the DPPH free radical scavenging assay showed that the IC50 values of holy basil oil (0.03 μl/ml), plai oil (6.9 μl/ml) and citronella grass oil (2 μl/ml) were lower than that of ascorbic acid (7.9 μl/ml). Anti-inflammatory activity of the oils determined using the 5-lipoxygenase inhibition assay found that IC50 values of holy basil oil (0.04 μl/ml), kaffir lime oil (0.05 μl/ml) and citronella grass oil (0.15 μl/ml) were less than that of nordihydroquaretic acid (1.7 μg/ml). Since P. acnes has a role in the inflammation of acne leading to scar formation, citronella grass oil may help to relieve acne blemishes. However, further investigation in the form of clinical studies would be necessary.