Chemical Constituents of the Roots and Rhizomes of Rubia yunnanensis and Their Neuroprotective Activity.
Twelve previously undescribed compounds, including 10 naphthalene derivatives (1, 3-11), one benzo[b]oxepine derivative (2) and one anthraquinone analogue (12) were isolated from the CH2Cl2 extract of the roots and rhizomes of Rubia yunnanensis, together with 27 known ones (13-39). Their structures were elucidated on the basis of extensive spectroscopic analyses, electronic circular dichroism (ECD) calculations, and single-crystal X-ray diffraction analysis. Angeloylgomisin O (31) exhibited anti-neuroinflammatory activity by inhibiting lipopolysaccharide (LPS)-induced overproduction of nitric oxide (NO) in BV-2 microglial cells. Furthermore, angeloylgomisin O (31) exhibited notable neuroprotective effects against oxygen-glucose deprivation/reoxygenation (OGD/R)-induced injuries in SH-SY5Y cells. These investigation results suggested that angeloylgomisin O (31) may contribute to the anti-inflammatory effects of Rubia yunnanensis and may provide valuable insights into the discovery of novel protective agents against ischemic neuronal or microglial injuries.