Isolation And Structure Elucidation Of Triterpenoids From Branch Barks Of Davidia Involucrata

Davidia involucrata Baill., an ornamental tree known as the Chinese dovetree or hankerchief tree, is the only species in the family Davidiaceae. Davidia involucrata Baill. is a relic deciduous tree species of the Tertiary period and has been listed as a protected species. Populations are often found in evergreen broad-leaved trees at altitudes of between 700 and 2400 m, and its distribution is limited to Yunnan, Guizhou, Sichuan, Hunan, Hubei, Shanxi and Gansu provinces of China.The phytochemical study of the aerial parts of the plant revealed the presence of alkaloids, sterols, flavonoids, triterpenes, lignans and neogligans, phenols. We introduced here in this paper the present status of the phytochemical study of Davidia involucrata Baill., in addition to our recent work of the continue study on the triterpenes constituents of this plant. All the 24 triterpenes out of 34 compounds, which were obtained from the MeOH extract of the aerial parts of Davidia involucrata Baill., were identified by ¹³C- and ¹H NMR analysis, and in some case, by IR and 2D-NMR spectroscopy including HSQC, HMBC, and ROESY analysis.The identified pentacyclic triterpenes included fifteen ursanes, five oleananes, and three lupanes, which were listed and figured as below.a) Fifteen ursanes including: 3β-hydroxyurs-12-en-28-oic acid (ursolic acid, T-9), 2α-hydroxyursolic acid (corosolic acid, TQ-9), 2α,3α-dihydroxyursolic acid (T-50), 2α,3β,23-trihydroxyurs-12-en-28-oic acid (asiatic acid, TQ-15), 2α,3α,23-trihydroxyurs-12-en-28-oic acid (T-26), 3β,28-dihydroxyurs- 12-en-27-oic acid (T-81), 3β-hydroxyurs-12-en-28-aldehyde-27-oic acid (T-15), 2α,3α,19α-trihydroxyurs-12-en-28-oic acid (euscaphic acid, T-37), 2α,3α,19α,23-tetrahydroxyurs-12-en-28-oic acid (myrianthic acid, T-40), 2α,3α-dihydroxyursa-12,20(30)-dien-28-oic acid (T-18), 2α,3α,23- trihydroxyursa-12,20(30)-dien-28-oic acid (TQ-5), 3β-Z-feruloyl corosolic acid (T-64), 3β-E-feruloyl corosolic acid (T-65), 3β-Z-coumaroylcorosolic acid (T-29), and 3β-p-E-coumaroylcorosolic acid (T-27).b) Five oleananes including: 2α,3β-dihydroxyolean-12-en-28-oic acid (maslinic acid, TQ-2), 2α,3β,23-trihydroxyolean-12-en-28-oic acid (arjunolic acid, TQ-18), 2α,3α,23-trihydroxyolean-12-en-28-oic acid (TQ-6), myricadiol (T-63), and 3β-p-E-coumaroylmaslinic acid (T-28).c) Four lupanes including: lupeol (T-49), betulin (T-61), 3β-hydroxy-20(29)- lupene-28-oic acid (betulinic acid, T-55), 3β-hydroxy-20-oxo-30-norlupan- 28-oic acid (platanic acid, T-3).All the 24 identified triterpenoids were isolated from this plant for the first time, among which five triterpenoids including 3β-hydroxyurs-12-en-28-aldehyde-27- oic acid (T-15), 3β-Z-coumaroylcorosolic acid (T-29), and 3β-p-E-coumaroyl- corosolic acid (T-27), 3β-Z-feruloyl corosolic acid (T-64), 3β-E-feruloyl corosolic acid (T-65) were identified as new compounds.