Active Chemical Constituents From Cortex Fraxini And Litchi (Litchi Chinensis Sonn.)

The chemical constituents from dichlormethane fraction of 95% ethanol extract of Cortex Fraxini were studied. Their structures were mainly elucidated on the basis of NMR, MS, IR and UV spectral evidences. Twenty compounds including a new secoiridoid were separated and identified. They were chinensisol (1), medioresinol (2), pinoresinol (3), syringaresinol (4),8-hydroxypinoresinol (5), balanophonin (6), dehyd-drodiconiferyl alcohol (7), lariciresinol (8),2-(4-hydroxy-3-methoxyphenyl)-3-(2-hy-droxy-5-methoxyphenyl)-3-oxo-l-propanol (9), ficusal (10), tyrosol (11),2-(4-hydro-xyphenyl) ethanol (12), coniferyl aldehyde (13), coniferyl alcohol (14), scopoletin (15), esculetin (16), fraxetin (17), floribin (18), esculin (19) and linolenic acid (20). The quinone reductase (QR) inducing activities of the compounds were evaluated and the results showed that compounds 1,9 and 14 had moderate QR inducing activities with CD values (concentration required to double the specific activity of QR) of 72.4±7.7,34.3±3.3 and 42.0±0.4μM respectively.Litchi (Litchi chinensis Sonn.) is widely accepted as a delicious fruit in China and its seeds have been commonly used in traditional Chinese medicine to relieve neuralgic pain. In the present study, chemical investigation of the 95%ethanol extract of L. sinensis seeds led to the isolation of four new compounds,2α,3α-epoxy-5,7,3', 4'-tetrahydroxyflavan-(4β-8)-catechin (24),2β,3β-epoxy-5,7,3',4'-tetrahydroxyflav-an-(4α8)-epicatechin (26), litchiol A (28) and litchiol B (31), together with eleven known ones,2,5-dihydroxy-hexanoic acid (21), scopoletin (15), p-coumaric acid (22), protocatechuic acid (23), 2α,3α-epoxy-5,7,3',4'-tetrahydroxyflavan-(4β-8)-epicatec -hin (25), pterodontriol 6-O-β-D-glucopyranoside (27), narirutin (29), naringin (30), dihydrocharcone 7-O-β-D-glucopyranoside (32), pinocembrin 7-rutinoside (33), pinocembrin 7-neohesperidoside (34). Their structures were mainly elucidated on the basis of NMR, MS, IR, CD and UV spectral evidences. Antioxidant activities of fourteen compounds were determined by DPPH radical-scavenging assay and Trolox Equivalent antioxidant capacity assay, and the results showed that four compounds, protocatechuic acid (23),2α,3α-epoxy-5,7,3',4'-tetrahydroxyflavan-(4β-8)-catechin (24),2α,3α-epoxy-5,7,3',4'-tetrahydroxyflavan-(4β-8)-epicatechin (25),2β,2β,3βepoxy-5,7,3',4'-tetrahydroxyflavan-(4α-8)-epicatechin (26) exhibited moderate antioxidant activities.