Chemistry of Natural Compounds, Vol. 40, No. 3, 2004
ANTIOXIDANT STUDY AND ASSIGNMENTS OF NMR SPECTRAL DATA
FOR 3 ,4 ,7-TRIHYDROXYFLAVANONE 3 ,7-DI-O-
′ ′ β-D-GLUCOPYRANOSIDE
′
(BUTRIN) AND ITS HYDROLYZED PRODUCT
Amir Reza Jassbi1, Pahup Singh2, Vivek Krishna2,
Pradeep K. Gupta2, and Satoshi Tahara3
UDC 547.972:66.094
The NMR spectral dataincludinghighresolution1H, 13C and 2D NMR for butrin, 3′,4′,7-trihydroxyflavanone
3′,7-di-O-β-D-glucopyranoside, isolated from flowers of Butea monosperma, are reported here for the first
time. Butrin was hydrolyzed using b-glucosidase to butin in high yield. They were subjected to free radical
scavenging test using 2,2-diphenyl-1-picrylhydrazyl (DPPH) spectrophotometric assay. At a dose of 4 × 10-8
mol of tested compounds, the percentage of reduced DPPH for butin was 14.5% while no reduction was
observed for butrin (0%).
Key words: Butrin, butin, antioxidant, 3′,4′,7-trihydroxyflavanone3′,7-di-O-β-D-glucopyranoside, Buteamonosperma,
NMR spectra.
Butrin, 3′,4′,7-trihydroxyflavanone 3′,7-di-O-β-D-glucopyranoside (1), is a major flavonoid found in Butea
monosperma [1, 2], B. frondosa [3, 4], and B. superba [5]. Butea monosperma is used in India as a medicinal plant to cure
hepatic disorders and viral hepatitis [2]. Isobutrin and butrin (1) were reported as the antihepatotoxic components in a butanolic
fraction of methanolic extracts of the flower of B. monosperma [2]. Despite the early identification of this compound [3], to the
best of our knowledge there is no report on its 13C NMR and high resolution 2D NMR in the literature. In this paper we report
the detailed NMRassignment ofbutrin. Butrin ishydrolyzedcompletelytobutin (2) and their antioxidant activities were assayed
by radical scavenging test using DPPH.
OH
H
H
O
HO
O
1' ' '
O
HO
OH
H
H
5'
3'
H
OH
OH
H
OH
O
OH
H
1'
H
HO
HO
O
O
9
O
9
5'
7
3'
HO
1'
7
1' '
H
OH
3
3
H
5
5
1
2
O
Butrin was separated as yellowneedles from the flowers ofButea monosperma. The UV and FABnegative mass spectra
1
were similar to those reported previously [2]. The high resolution H NMR spectrum recorded on a 500 MHz instrument is
presented in Table 1. The 13C NMR spectral data are assigned with the help of 2D NMR spectra including HMQC and HMBC
spectra. In the 1H NMR spectrum (in DMSO-d6) the signals at δ 5.45 (2H, bdd, J = 2.2, 12.5 Hz, H-2, OH-3″ or OH-3′″), 2.67
(1H, dd, J = 2.2, 14.5 H-3β), and 3.2 (m, H-3α) represented the C ring proton signals for a flavanone structure and the signals
at δ 7.70 (1H, d, J = 8.6 Hz, H-5), 6.70 (1H, bd, J = 8.6 Hz, H-6), and 6.66 (1H, bs, H-8) are assigned for the A ring. The signals
at δ 7.28 (1H, bs, H-2′), 6.83 (1H, d, J = 8.3 Hz, H-5′), and 7.02 (1H, bd, J = 8.3 Hz, H-6′) represent the 3′, 4′ di-substituted B
ring. The anomeric protons at 4.97 (1H, d, J = 7.4 Hz) and 4.71 (1H, d, J = 7.1 Hz) represent two β-glycosidic bonds.
1)Department ofPhytochemistry, Medicinal PlantsResearch Institute, ShahidBeheshti University, Evin, Tehran, Iran,
fax: (+9821) 241 86 79, e-mail: a-jassbi@cc.sbu.ac.ir; 2) Department of Chemistry, University of Rajasthan, Jaipur, India;
3) Laboratoryof Ecological Chemistry, Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University,
Kita-ku, Sapporo 060-8589, Japan. Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 212-214, May-June, 2004.
Original article submitted April 16, 2004.
0009-3130/04/4003-0250 ©2004 Plenum Publishing Corporation
250