Potential Antioxidant and Anti-Inflammatory Effects of Lonicera japonica and Citri Reticulatae Pericarpium Polyphenolic Extract (LCPE)

Dermatitis is an inflammatory condition of the outer layer of the skin that causes itching, blisters, redness, swelling, and often exudation, scabs, and peeling. Among them, purulent inflammation is a symptom that often occurs on the skin and appears in the form of boils and acne. Various studies are being conducted to treat these inflammatory diseases. Accordingly, Lonicera japonica and Citri Reticulatae Pericarpium Polyphenolic Extract (LCPE), which uses herbal preparations such as Lonicera japonica, Citri Reticulatae Pericarpium, and Glycyrrhiza uralensis, has been used to suppress inflammation since ancient times, and its anti-inflammatory effect can be observed in skin keratinocytes after inducing inflammation. In this study, the major polyphenolic compounds in LCPE were quantitatively determined by analyzing the data through peak values using high-performance chromatography (HPLC-MS/MS) coupled with mass spectrometry. Additionally, bioactive compounds targeting 2,2-diphenyl-1-picrylhydrazyl (DPPH) were analyzed by ultrafiltration integrated with LC. Several compounds with the most significant effects were selected (chlorogenic acid, narirutin, and isorhamnetin). Skin keratinocytes induced by lipopolysaccharide (LPS) were treated with LCPE to show its anti-inflammatory effects. After LCPE treatment, inflammation-mediating cytokines such as cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) were decreased. In addition, nuclear factor kappa (NF-кB) and mitogen-activated protein kinase (MAPK) were inhibited in important pathways related to inflammation. Lastly, molecular modeling was performed to determine binding scores with inflammation-related proteins using molecular docking for the selected compounds. According to these results, LCPE is effective in treating keratinocytes induced by LPS and reducing inflammation and has potential antioxidant effects, and the polyphenol components have been identified.