Anti-Inflammatory and Cytoprotective Effect of Kaempferia galanga Extracts by Targeting NF-_KB 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-_KB) 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-_KB activity by screening Indonesian medicinal plants, with particular focus given to Kaempferia galangaextracts as promising candidates. Material and Methods: We investigated the inhibition of NF-kB 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-_KB response element were used for this purpose. Inhibition of NF-_KB 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 galangaextracts (29 and 35) from different rhizome types that strongly suppressed NF-_KB 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 galangahad protective effects against TRAIL. Conclusion: Collectively, these results indicate that the identified K galangaextracts represent potential candidates for the development of novel anti-inflammatory natural medicines.