Two New Flavanone Glycosides of Jasminum lanceolarium and Their Anti-oxidant Activities

Jia-Ming Sun, Jun-Shan Yang, Hui Zhang
2007 Chemical and pharmaceutical bulletin  
Jasminum is a genus of about 200 species, several members of which are known for their medicinal application in Chinese folklore. About 47 species of Jasminum have been reported to occur in China. 1,2) Jasminum lanceolarium is a climbing shrub distributed over thickets at low altitudes from south-eastern China to India. 3) Its steams and roots are used in Chinese medicine for the treatment of fever and rheumatic pain. The leaves are also used as an antiinflammatory agent for the release of pain
more » ... in the eyes. 4) Previous phytochemical investigation resulted in the isolation of several secoiridoid glycosides. 4,5) This paper reports the isolation and structural elucidation of two new flavanone glucosides, (2S)-5,7,3Ј,5Јtetrahydroxy-flavanone 7-O-b-D-allopyranoside (1) and (2S)-5,7,3Ј,5Ј-tetrahydroxy-flavanone 7-O-b-D-glucopyranosie (2), along with five known compounds obtained from the stems and leaves of this plant and their DPPH radical scavenging activities. Results and Discussion The ethanolic extract of the shade-dried stems and leaves of J. lanceolarium was evaporated in vacuo, then the residue was suspended in H 2 O and successively partitioned with petroleum (60-90°C), CHCl 3 , EtOAc and n-BuOH. Compound 3 was isolated from the petroleum (60-90°C)-soluble fraction and compounds 4 and 5 were obtained from the CHCl 3 -soluble fraction, while compounds 1, 2, 6 and 7 were isolated from the EtOAc-soluble fraction of J. lanceolarium by successive use of column chromatography. Of the seven compounds elucidated, the five known compounds were subsequently identified as Betulinaldehyde (3), 6) betulinic acid (4), 7) betulin (5), 7) syringin (6) 8) and Liriodendrin (7) 9) by comparisons of their spectral data (UV, IR, NMR and MS) with those reported previously. All of these known compounds were isolated from J. lanceolarium for the first time. Compound 1 Compound 1 was obtained as a pale yellow powder. Its molecular formula was established as C 21 H 22 O 11 by HR-FAB-MS at m/z 451.1220 [MϩH] ϩ (Calcd 451.1240). The IR absorption bands at 3383, 1643, 1578 and 1068 cm Ϫ1 were consistent with the presence of hydroxyl, carboxyl, aromatic ring, and ether groups respectively. The characteristic UV absorption bands (225, 283, 322 nm) showed compound 1 to be a flavanone. That was confirmed by the ABX system protons at d H 2.75 (1H, dd, Jϭ17.2, 3.6 Hz), 3.23 (1H, m), and 5.44 (1H, dd, Jϭ12.8, 3.6 Hz) in its 1 H-NMR spectrum and at d C 78.9 and 42.3 in its 13 C-NMR spectrum (Table 1) . 10) The 1 H-NMR spectrum showed three phenolic hydroxyl group at d H 12.05 , 9.06 and 9.02 (D 2 O exchangeable). The 13 C-NMR spectrum (Table 1) resolved 21 carbon signals, corresponding to a flavanone skeleton bearing three hydroxyl group and one sugar moiety. These signal patterns were similar to those of 5,7,3Ј,5Ј-tetrahydroxy-flavanone except for the sugar moiety. 11) In the aromatic region of the 1 H-NMR spectrum, the remaining five protons occurred as a set of meta coupled doublets at d H 6.13 (1H, d, Jϭ2.0 Hz) and 6.11 (1H, d, Jϭ2.0 Hz) for the A-ring protons, and three singlets d H 6.89 (1H, br s), 6.76 (1H, br s) Two new flavanone glucosides, (2S)-5,7,3,5-tetrahydroxy-flavanone 7-O-b b-D-allopyranoside (1) and (2S)-5,7,3,5-tetrahydroxy-flavanone 7-O-b b-D-glucopyranosie (2) were isolated from the stems and leaves of Jasminum lanceolarium, along with five known compounds: Betulinaldehyde (3), betulinic acid (4), betulin (5), syringin (6) and Liriodendrin (7). Their structures were determined on the basis of spectroscopic and chemical methods. The isolated compounds were screened for their in vitro antioxidant activity through DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging assay. Compounds 2 demonstrated significant radical scavenging activity.
doi:10.1248/cpb.55.474 pmid:17329896 fatcat:ipm5usjqwvaihjohrsqcktutim