구실잣밤나무 (Castanopsis cuspidata var. sieboldii) 잎 추출물의 생리 활성 평가 및 폴리페놀 화합물의 분리와 동정

Abstract

Adequate amounts of reactive oxygen species(ROS) play a beneficial role in the human body by inactivating various pathogens. However, excessive secretion of ROS in the body causes intracellular damage and various diseases. In order to suppress oxidative damage caused by free radicals, cells must secrete enzymes that inhibit the accumulation of ROS or remove free radicals through antioxidants to maintain homeostasis in the body. Polyphenol compounds, which are representative antioxidants, provide health benefits by inducing reducing properties, acting as antioxidants and free radical scavengers. Accordingly, research on the development of various useful materials using natural products containing antioxidants is being actively conducted. Castanopsis cuspidata var. sieboldii (CCS) is a warm-temperate species inhabiting the Korean Peninsula, Japan, China, and Taiwan, and has been traditionally used for medicinal purposes. Several researchers have confirmed that the bioactive components produced in the aerial parts of CCS have anti-inflammatory, antioxidant and whitening effects. However, isolation and identification studies of compounds centered on antioxidant activity in CCS leaves have not been investigated. In this study, 1.5 kg of CCS leaves (CSL) were extracted with 15L of 70% ethanol and used as a crude extract. CSL was divided into five fractions using n-hexane, chloroform, ethyl acetate, n-butanol and water, and the yields of each fraction were 13.03g, 5.27g, 51.22g, 44.74g, and 15.93g. Also, the antioxidant activity of sub-fraction was determined with DPPH free radical scavenging activity assay and ABTS cation radical scavenging activity assay. The antioxidant contents was confirmed by total polyphenol contents (TPC) and total flavonoid contents (TFC). Of these, the ethyl acetate fraction which has the highest antioxidant activity was separated and purified using medium liquid chromatogram (MPLC) equipped with a C18 column. Through the HPLC qualitative analysis, it was confirmed that CSL and CSL-EA contained various polyphenols. Finally the polyphenol compound 1 present in the highest antioxidant activity fraction was isolated. The chemical structure of compound 1 isolated from CSL-EA was described based on NMR and LC-MS/MS spectrum analysis. Based on these results, we suggest that extracts, fractions and compounds isolated from CSL provide promising antioxidant capabilities and suggest potential natural substances in pharmaceutical and cosmetic industries.