Isolation and identification of flavonoids from Coreopsis lanceolata L. petals

Article abstract of DOI:10.1080/14786419.2013.856905

The methanol extract of Coreopsis lanceolata L. petals was acid-hydrolysed, and 7,3′,4′-trihydroxy-8-methoxyflavanone (1) and 6,3′,4′-trihydroxy-7-methoxyaurone (leptosidin) (2) were successfully isolated. The structure of compound 1 is designated to flav

Full text of DOI:10.1080/14786419.2013.856905

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Isolation and identification of
flavonoids from Coreopsis lanceolata L.
petals
Yoshiharu Okadaa, Mari Okitaa, Yoshihiro Muraib, Yuka Okanoa &
Masato Nomuraa
a Graduate School of Systems Engineering, Kinki University,
Umenobe 1, Takaya, Higashi-Hiroshima 739-2116, Japan
b Kinki University Joint Research Center, 3-4-1 Kowakae, Higashi-
Osaka 577-8502, Japan
Published online: 18 Nov 2013.
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To cite this article: Yoshiharu Okada, Mari Okita, Yoshihiro Murai, Yuka Okano & Masato
Nomura (2014) Isolation and identification of flavonoids from Coreopsis lanceolata L.
petals, Natural Product Research: Formerly Natural Product Letters, 28:3, 201-204, DOI:
10.1080/14786419.2013.856905
To link to this article: http://dx.doi.org/10.1080/14786419.2013.856905
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Natural Product Research, 2014
Vol. 28, No. 3, 201–204, http://dx.doi.org/10.1080/14786419.2013.856905
SHORT COMMUNICATION
Isolation and identification of flavonoids from Coreopsis lanceolata L. petals
Yoshiharu Okadaa*, Mari Okitaa, Yoshihiro Muraib, Yuka Okanoa and Masato Nomuraa
aGraduate School of Systems Engineering, Kinki University, Umenobe 1, Takaya, Higashi-Hiroshima 739-
2116, Japan; bKinki University Joint Research Center, 3-4-1 Kowakae, Higashi-Osaka 577-8502, Japan
(Received 16 May 2013; final version received 13 October 2013)
The methanol extract of Coreopsis lanceolata L. petals was acid-hydrolysed, and
7,30,40-trihydroxy-8-methoxyflavanone (1) and 6,30,40-trihydroxy-7-methoxyaurone
(leptosidin) (2) were successfully isolated. The structure of compound 1 is designated
to flavanone based on X-ray crystallographic analysis and NMR spectroscopic analysis.
Compound 1 showed high-antioxidant effects based on diphenylpicrylhydrazyl radical
scavenging assay (94.3% scavenging rate) and superoxide dismutase-like activity assay
(23.9% inhibition rate).
Keywords: Coreopsis lanceolata L; 7,30,40-trihydroxy-8-methoxyflavanone; leptosidin
1. Introduction
Coreopsis lanceolata L. is a denizen native of North America and makes a yellow flower bloom
from May to June in Japan. Now, it has been appointed to a specified foreign organism in
February 2006 because of its strength of propagative power, in Japan. Therefore, C. lanceolata
L. was gathered and burned off. So, we became interested in the utilisation of C. lanceolata L.
and their ingredients. We have already reported the isolation and physiological activities of
3,4,20,40-tetrahydroxy-30-methoxychalcone-40-glucoside from C. lanceolata L. petals (Tanimoto
et al. 2009). In this paper, we wish to report the isolation and physiological activities of the
unknown flavonoids of C. lanceolata L. petals.
2. Results and discussion
The dried petals of C. lanceolata L. were extracted with methanol by soxhlet apparatus. The
methanol extract was hydrolysed with 6M hydrochloric acid and column-chromatographed on
silica gel with chloroform–methanol (9:1) as elution to give three fractions. The physiological
activities of the three fractions were assessed on the basis of diphenylpicrylhydrazyl (DPPH)
free radical scavenging assay (Tominaga et al. 2005) and superoxide dismutase (SOD)-like
activity assay (Tada et al. 1996). The results are shown in Table 1. The second fraction showed
highest antioxidant effect (96.3% scavenging rate) among the three fractions based on DPPH
radical scavenging assay. In case of SOD-like activity assay also, the second fraction exhibited
highest antioxidant effect (94.1% inhibition rate). Next, attempt to characterise antioxidant
compounds in the second fraction was made. The second fraction was re-fractionated with
preparative thin layer chromatography (chloroform–methanol, 9:1) to give yellowish orange
solid 1 (Rf ¼ 0.41) and orange solid 2 (Rf ¼ 0.28). . Recrystallisation of solid 1 from methanol
was successful and gave citrine needle crystals, while recrystallisation of solid 2 could not be
*Corresponding author. Email: okadasan@hiro.kindai.ac.jp
q 2013 Taylor & Francis

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Y. Okada et al.
Table 1. Antioxidant activities of fractions 1–3.
DPPH radical scavenging assaya
SOD-like activity assayc
Inhibition rate (%)
Fraction
Scavenging rate (%)b
1
2
3
85.5
96.3
94.3
93.5
–
48.5
94.1
83.9
–
a-Tocopherold
Ascorbic acide
10.8
a Sample concentration: 1 mg/ml.
b Final concentration: 0.4 mg/ml.
c Sample concentration: 1 mg/ml.
d Concentration: 1 mM.
e Concentration: 0.1 mg/ml.
done. Structures of 1 and 2 were assigned on the basis of their 1H NMR, 13C NMR, H-C COSY
1
NMR and mass spectral data. H NMR spectrum of 1 shows a signal for methine proton (dd,
J ¼ 2.9 and 12.5 Hz) at d 5.40, two methylene protons (dd, J ¼ 2.9 and 16.9 Hz) at d 2.65 and
(dd, J ¼ 12.6 and 16.9 Hz) at d 3.04, respectively. These coupling constants of 2.9 Hz and
12.5 Hz were assigned vicinal coupling constants between two methylene protons and methine
proton. The coupling constant between B-ring aromatic protons at d 6.78 (d, J ¼ 1.5 Hz) and d
6.94 (d, J ¼ 1.5 Hz) was assigned para-coupling. Therefore, B-ring was decided as the 3,4-
dihydroxyphenyl group, and coupling constant between A-ring aromatic protons at d 6.59
(d, J ¼ 8.8 Hz) and d 7.42 (d, J ¼ 8.8 Hz) was assigned vicinal coupling constant. Additional
X-ray analysis of 1 was assigned 7,30,40-trihydroxy-8-methoxyflavanone (1) (Figures 1 and 2).
On the other hand, the 1H NMR spectrum of 2 shows signals for three B-ring aromatic protons at
d 6.84 (d, J ¼ 8.3 Hz), 7.24 (dd, J ¼ 2.0 and 8.3 Hz) and 7.42 (d, J ¼ 2.0 Hz), respectively.
Therefore, B-ring of 2 was also assigned 3,4-dihydroxyphenyl group. The two A-ring aromatic
protons were observed at d 6.76 (d, J ¼ 8.3 Hz) and 7.32 (d, J ¼ 8.3 Hz), respectively.
Therefore, A-ring of 2 was similar to that of 1. Two A-ring aromatic carbons were observed at d
157.73 and 157.83. Moreover, the olefinic proton was observed at d 6.63 (s). These results
1
indicated that the structure of 2 was not flavone or isoflavone. The H NMR and 13C NMR
spectra of 2 were compared with that of 6,7,30,40-tetrahydroxyaurone (Sashida et al. 1991) and
the synthesised 6,30,40-trihydroxy-7-methoxyaurone (for the isolation of leptosin and leptosidin,
´
see: Geissman & Heaton 1943; Seikel & Geissman 1950; Geissman & Moje 1951;
Shimokoriyama & Hattori 1953), which was prepared from 7-methoxy-6-hydroxy-3(2H)-
benzofuranone and 3,4-di(methoxymethoxy)benzaldehyde using aluminium oxide (Bolek &
Gutschow 2005). The 13C NMR spectrum of 2 shows a signal for olefinic carbon at d 112.30.
According to 13C NMR study of aurones (Pelter et al. 1979), a signal for olefinic carbon of Z-
isomer has been observed at about 110 ppm, whereas that of E-isomer shows at about 120 ppm.
Therefore, the structure of 2 was assigned as (Z)-6,30,40-trihydroxy-7-methoxyaurone.
OH
OMe
OMe
OH
OH
HO
O
HO
OH
O
O
O
1
2
Figure 1. Structures of the isolated compounds of 1 and 2 from C. lanceolata L.

Natural Product Research
203
Figure 2. Ortep diagram of compound 1.
Table 2. Antioxidant activities of compound 1.
DPPH radical scavenging assaya
Scavenging rate (%)b SC50c
SOD-like activity assayd
Inhibition rate (%)
Compound
1
94.3
94.7
–
6.3
6.8
23.9
–
10.8
a-Tocopherol
Ascorbic acid
a Sample concentration: 0.1 mM.
b Final concentration: 0.04 mM.
c 50% scavenging concentration (mM).
d Sample concentration: 0.1 mg/ml.
DPPH radical scavenging rate and active oxygen inhibition rate of 1 were 94.3% and 23.9%,
respectively (Table 2). High DPPH radical scavenging activity of fraction 2 seemed to be
strongly contributed by compound 1.
3. Conclusions
Thus, 7,30,40-trihydroxy-8-methoxyflavanone and (Z)-6,30,40-trihydroxy-7-methoxyaurone were
newly isolated from C. lanceolata L. petals. The structures of 1 and 2 were successfully clarified
on the basis of NMR spectroscopy. Compound 1 showed antioxidant effect (94.3% scavenging
rate) equal to or higher than that of a-tocopherol based on DPPH radical scavenging assay.
In case of SOD-like activity assay also, compound 1 exhibited higher antioxidant effect (23.9%
inhibition rate) than ascorbic acid.

204
Y. Okada et al.
4. Supplementary material
Experimental details relating to this paper are available online. Crystallographic data for the
structure of 1 as reported in this paper are deposited with the Cambridge Crystallographic Data
Centre, under reference number CCDC 935091. Copies of the data can be obtained, free of
charge, on application to the Director, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK.
Acknowledgement
We thank Ms. K. Hasegawa (Rigaku Co.) for X-ray analysis.
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