Anti-Inflammatory and Cytoprotective Effect of Kaempferia galanga Extracts by Targeting NF-κB Activity

Background and Objective: Skin disease and inflammation are often treated with traditional medicine, which has been the case since ancient times. Controlling activation and gene expression of inflammatory signalling pathways, such as the Nuclear Factor-kappa B (NF-κB) pathway, is important for protecting the skin from adverse inflammation and preventing the acceleration of pathologic disease processes. Therefore, the present study aimed to identify natural anti-inflammatory products that could target NF-κB activity by screening Indonesian medicinal plants, with particular focus given to Kaempferia galanga extracts as promising candidates. Material and Methods: We investigated the inhibition of NF-κB activation in 35 natural medicinal plants (1‒35) cultivated in Indonesia traditionally used to treat skin disease symptoms. Specifically, a 4T1 cell line, a breast cancer cell line and RAW 264.7 macrophages expressing the firefly luciferase gene under the control of an NF-κB response element were used for this purpose. Inhibition of NF-κB activity and cell viability were determined by reporter assays and WST-8 methods. Result: Based on the screening of 35 natural medicinal plants, we identified two K. galanga extracts (29 and 35) from different rhizome types that strongly suppressed NF-κB activity without affecting cell viability. In further investigation of the anti-inflammatory effects of these extracts, Tumour Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL) was found to cause cellular damage to human HaCaT keratinocytes: however, both extracts 29 and 35 from K. galanga had protective effects against TRAIL. Conclusion: Collectively, these results indicate that the identified K. galanga extracts represent potential candidates for the development of novel anti-inflammatory natural medicines.