Identification of the biologically active constituents of Camellia japonica leaf and anti-hyperuricemic effect in vitro and in vivo

Abstract

Camellia japonica L. is a plant of which the seeds are used as a folk medicine, and it is native to South Korea, Japan and China. In previous study, triterpenes, flavonoids, tannins and fatty acids which have antiviral, antioxidant and anti inflammatory activity were reported from C. japonica leaf and flower. In Korea, the seed from this plant is used as a traditional medicine and in folk remedies for the treatment of bleeding and inflammation. However, the major issue associated with the use of the seed as a medicinal and/or functional food ingredient is its application to the pharmaceutical and food industry. First, the productivity of seed extract is very much less than that of the leaf. Second, the beneficial usage of the seed extract as an alternative medicine and functional source is not yet clear. Thus, in this study, we focused on another part of the plant, the leaf, and found that the extract of Camellia japonica leaf has a high concentration of vitamin E, rutin and other biologically active compounds related to hyperuricemia. We aimed to investigate the biological activities, namely the antioxidant activities, xanthine oxidase (XO) inhibitory activity and anti‑hyperuricemic effects of extract from C. japonica leaf and the phytochemicals contained therein. Ethanol extracts of C. japonica leaf (ECJL) were prepared, and the extract was used with respect to antioxidant activities, total phenolic contents and XO inhibitory activity. The in vivo XO inhibitory activity and anti‑hyperuricemic effects of the extract were evaluated in mice with potassium oxonate‑induced hyperuricemia. To clarify the marker compounds that are responsible for the anti‑hyperuricemic effects, several key constituents were identified using gas chromatography‑mass spectrometry (GC‑MS) and and liquid chromatography-mass spectrometry (LC-MS). ECJL was found to have strong antioxidant activities, and in vitro XO inhibitory activity. The results of the in vivo experiments using mice demonstrated that ECJL at the doses of 100 and 300 mg/kg inhibited hepatic XO activity and significantly attenuated hyperuricemia. To the best of our knowledge, the present study is the first report on the XO inhibitory and anti-hyperuricemic effects of ECJL, which can be therapeutically applied in the treatment of hyperuricemia and gout.