Triterpene Glycosides and Glucosyl Esters, and a Triterpene from the Leaves of Schefflera actinophylla (original) (raw)

2010, CHEMICAL & PHARMACEUTICAL BULLETIN

The Araliaceae family is one of the most medicinally important plant families, which include about 55 genera and 700 species of trees, shrubs, lianas and perennial herbaceous plants. Chemical and pharmacological investigations have indicated that triterpenoid saponins are important bioactive components existing in the plants of Araliaceae family. 1) Schefflera actinophylla (ENDLICHER) HARMS, (synonym: Brassaia actinophylla ENDLICHER) is an evergreen tree in the Araliaceae family and native to tropical rainforests and gallery forests in Australia, New Guinea and Java. This distinctive ornamental plant is easily recognized by the several trunks mostly unbranched, a few very large palmately compound leaves with 7-12 leaflets as in an umbrella, and the large showy clusters of many dark red or crimson flowers on 10-20 widely spreading dark purple axes, suggesting arms of an octopus. Hence, common names include umbrella tree and octopus tree. Up till now, there have been no phytochemical and bioactivities reports on this species. In this manuscript, we described the isolation and structure elucidation of three new ursane-type triterpene glycosides (1-3), two new lupane-type triterpene glucosides (4, 6), one new lupane-type triterpene (5) and one new lupane-type triterpene glucosyl ester (7), along with nine known lupanetype triterpene glycosides (8-16) that were identified by comparing their spectroscopic data with the previously reported ones. Results and Discussion The air-dried and powdered leaves of Schefflera actinophylla were extracted with 70% MeOH till exhaustion and then concentrated under reduced pressure to yield a viscous gummy material. The concentrated methanol extract was washed with n-hexane. The methanolic layer was evaporated, suspended in water and then extracted with EtOAc and 1-BuOH, successively. The 1-BuOH-soluble fraction as well as the EtOAc-soluble fraction was subjected to Diaion HP-20, silica gel, octadecylsilanized (ODS) silica gel column chromatographies (CC), droplet counter-current chromatography (DCCC), and high-performance liquid column chromatography (HPLC) to afford seven new compounds (1-7), along with nine known triterpene compounds, 3a-hydroxylup-20(29)-ene-23,28-dioic acid (8), 2) 3a-hydroxylup-20(29)ene-23,28-dioic acid 28-O-[4Љ-O-a-L-rhamnopyranosyl-6Ј-O-b-D-glucopyranosyl]-b-D-glucopyranosyl ester (9), 3) 3a,23-dihydroxylup-20(29)-en-28-oic acid 28-O-[4Љ-O-a-Lrhamnopyranosyl-6Ј-O-b-D-glucopyranosyl]-b-D-glucopyranosyl ester (10), 4) 3-epi-betulinic acid 3-O-sulfate (11), 5) 3epi-betulinic acid 3-O-b-D-glucopyranoside (12), 6) 3-epi-betulinic acid 3-O-sulphate, 28-O-[4Љ-O-a-L-rhamnopyranosyl-6Ј-O-b-D-glucopyranosyl]-b-D-glucopyranosyl ester (13), 7) 3-epi-betulinic acid 28-O-[4Љ-O-a-L-rhamnopyranosyl-6Ј-Ob-D-glucopyranosyl]-b-D-glucopyranosyl ester (14), 8) 3-epibetulinic acid 3-O-b-D-glucopyranoside, 28-O-[4Љ-O-a-Lrhamnopyranosyl-6Љ-O-b-D-glucopyranosyl]-b-D-glucopyranosyl ester (15), 9) 3-epi-betulinic acid 3-O-b-D-6Ј-acetylglucopyranoside, 28-O-[4Љ-O-a-L-rhamnopyranosyl-6Љ-O-b-Dglucopyranosyl]-b-D-glucopyranosyl ester (16) 10) (Fig. 1).