Twenty-two new lignans and neolignans (1-22), together with 14 known analogues, have been isolated from an ethanolic extract of the stem (with skin removed) of Sinocalamus affinis. Their structures were elucidated by spectroscopic and chemical methods. On the basis of systematic NMR and circular dichroism (CD) data analysis, the validity of J7,8 and ΔδC8-C7 values to distinguish threo and erythro aryl glycerol units in different neolignans and the CD data [particularly the Rh2(OCOCF3)4-induced CD data (the E band)] to determine the absolute configurations at C-8 (C-7) of the aryl glycerol units are discussed. At a concentration of 10 μM, compounds 20 and 22 inhibited NO production in mouse peritoneal macrophages 84.2±5.9% and 71.7±1.0%, respectively. Compounds 19, 20, and 22 showed activity against serum deprivation induced PC12 cell damage by increasing the cell viability from 80.7±2.8% to 91.6±6.4%, 107.2±8.0%, and 97.6±8.5%, respectively.

Five triterpenoids with a new 25-norfern carbon skeleton (1-5), a lupane triterpenoid (6), and four 20-hydroxyprogesterone acyl esters (7-10), together with 23 known compounds, were isolated from the stem (with skin removed) of Sinocalamus affinis. The absolute configuration of compound 1 was confirmed by single-crystal X-ray crystallographic analysis using anomalous scattering of Cu Kα radiation. Compounds 1-5 exhibited inhibitory activity against protein tyrosine phosphatase 1B.