Anti-inflammatory and anti-viral labdane diterpenoids from the fruits of Forsythia suspensa
Eight labdane diterpenoids, including two new labdane diterpenoids, named forsyshiyanins A-B (2–3), along with six known ones (1, 4–8), were isolated from the fruits of Forsythia suspensa. The new structures including their absolute configurations were elucidated by extensive spectroscopic analyses, X-ray diffraction and computational calculation. In vitro, eight labdane diterpenoids showed anti-inflammatory activities, with the inhibition rates of release of β-glucuronidase from polymorphonuclear leukocytes of rats being in the range 46.8–51.0% at concentrations of 10 µM, as well as anti-viral activities against influenza A (H1N1) virus and respiratory syncytial virus (RSV), with the IC50 values in the range 18.4–26.2 μM and EC50 values in the range 10.5–14.4 μM, respectively.
Circular dichroism, Absolute configuration, Natural products, Medicinal