LAUSR

Rhus trichocarpa Miq. (Anacardiaceae) is an edible and medicinal plant distributed throughout China, Japan, and Korea. The sap of R. trichocarpa has traditionally been used as a cathartic, antirheumatic, sedative, anti-diabetes agent, and tonic. Additionally, the stem bark of R. trichocarpa is used as a stimulant as well as an ingredient in chicken soup, together with R. verniciflua Stokes. R. verniciflua, commonly known as the lacquer tree, has been used to treat various stomach diseases, including tumors in East Asia. In a number of studies investigating the biological activity of R. verniciflua, the extract was shown to exhibit anticancer, antiproliferative, neuroprotective, antiplatelet, and antiobesity effects. However, few studies have been conducted regarding the constituents and biological activity of R. trichocarpa. Previously, we reported the cytotoxic effects of alkyl phloroglucinol derivatives isolated from R. trichocarpa roots. In this study, we attempted to isolate other bioactive constituents from R. trichocarpa. Nitric oxide (NO) is a highly reactive free radical produced by NO synthases from L-arginine and it mediates numerous functions by acting on various cells through interaction with different molecular targets. There is increasing body of evidence showing that NO plays a key role in diverse neurodegenerative-associated processes such as neuronal death, necrosis, apoptosis, and autophagy. Thus, we tried to find compounds, which would modulate NO production from natural products, by using LPS-stimulated BV2 microglia. A methanolic extract of the roots of R. trichocarpa was found to significantly inhibit NO production in BV2 microglial cells (72.1 ± 1.0% at a concentration of 10 μg/ml; P < 0.05). The extract was then suspended in H2O and sequentially partitioned with n-hexane, EtOAc, and n-BuOH. The EtOAc fraction was subsequently subjected to both normal and reversed-phase column chromatography affording a new triterpene (1) together with three known compounds (2–4). In this study, we describe the isolation and structure elucidation of a new compound from the roots of R. trichocarpa as well as its inhibitory effects against NO production.