Antiviral triterpenoids from the medicinal plant Schefflera heptaphylla.

Schefflera heptaphylla (L.) Frodin is a principal ingredient of an herbal tea formulation widely used for the treatment of common cold in southern China. An extract of the long leafstalk of the compound leaf of S. heptaphylla exhibited the most potent antiviral activity against respiratory syncytial virus (RSV). Further antiviral-guided fractionation and isolation of the leafstalk extract of S. heptaphylla led to obtain two highly active pure triterpenoids, namely 3alpha-hydroxylup-20(29)-ene-23,28-dioic acid and 3-epi-betulinic acid 3-O-sulfate, together with an inactive saponin, 3alpha-hydroxylup-20(29)-ene-23,28-dioic acid 28-O-alpha-l-rhamnopyranosyl-(1-->4)-O-beta-d-glucopyranosyl-(1-->6)-beta-d-glucopyranoside. An antiviral assay using a cytopathic effect (CPE) reduction method showed that the two triterpenoids possessed broader antiviral activity against respiratory syncytial virus (RSV) with a similar 50% inhibition concentration (IC(50)) value of 6.25 microg/mL, influenza A (H1N1) virus with IC(50) values of 25 and 31.3 microg/mL, Coxsackie B3 (Cox B3) virus with IC(50) values of 12.5 and 20 microg/mL and herpes simplex virus type 1 (HSV-1) with IC(50) values of 18.8 and 25 microg/mL, respectively, whereas the saponin did not have antiviral activity against these four viruses at a concentration of 100 microg/mL.