Flavone Glucosides from the Aerial Part of Scutellaria comosa

Full text of DOI:10.1007/s10600-019-02737-0

DOI 10.1007/s10600-019-02737-0
Chemistry of Natural Compounds, Vol. 55, No. 3, May, 2019
FLAVONE GLUCOSIDES FROM THE AERIAL
PART OF Scutellaria comosa
A. M. Karimov,1,2 Yu. V. Ostroushko,
and E. Kh. Botirov
3
3
*
The phytochemistry of available species of Scutellaria is being systematically investigated because of the wide use of
S. baicalensis in folk and official medicine and the limited raw-material resources. Flavonoids from plants of the genus
Scutellaria L. were studied by us to discover new biologically active compounds and their available resources. The aerial part
and roots of S. comosa Juz. (skullcap) contained 18 flavonoids, mainly flavone and flavanone derivatives [1–3]. In continuation
of this research, flavonoids from the aerial part of S. comosa collected during full flowering (May 1, 2015) in the foothills
town of Gov, Chustski District, Namangan Region, Republic of Uzbekistan, were studied.
Milled air-dried plant raw material was extracted (6×) at 65–70°C with EtOH (93%). The combined extracts were
evacuated in vacuo, diluted with H O, and washed with CHCl to remove lipophilic compounds. The precipitate that formed
2
3
upon cooling the purified extract was rinsed with H O and dried. Part (10 mL) of the mother liquor was filtered off, evaporated
2
in vacuo, and analyzed by reversed-phase HPLC on a Shimadzu LC10VP using a diode-array detector at 254 and 360 nm.
Flavonoids were determined using a linear gradient ofAcOH–MeCN over a C18 column (4.6 × 250 mm, 5 μm). The flavonoids
chrysin, wogonin, norwogonin, oroxylin, and scutellarein were detected using authentic standards [4–6].
The precipitate was chromatographed over a column of Sephadex LH-20 using EtOH (96%). Separate eluates afforded
flavonoids 1 (53 mg), 2 (97 mg), 3 (186 mg), and 4 (201 mg).
Spots of flavonoids 2–4 on Silufol plates turned brown during storage. Their EtOH solutions gave a positive gossypetin
reaction with p-benzoquinone, indicating the presence of C-5 and C-8 hydroxyls in their molecules.
Flavonoid 1, C H O , mp 193–195°C. UV spectrum (EtOH, λmax, nm): 288, 337; +NaOAc, 290, 340. PMR
2
1 20 11
spectra and production of scutellarein and D-glucose by acid hydrolysis of 1 identified it as scutellarein 7-O-β-D-glucopyranoside
5–7].
[
Flavonoid 2, C H O , mp >275°C (dec.). UV spectrum (MeOH, λmax, nm): 279, 350 (sh). Enzymatic hydrolysis
2
1 20 10
of 2 by β-glycosidase produced norwogonin and D-glucose. PMR spectra and direct comparison with an authentic sample
identified 2 as norwogonin 7-O-β-D-glucopyranoside [5–7].
Flavonoid 3, Ñ Í Î , mp 263–265°C, [α] –63.4° (c 0.2, Me CO). UV spectrum (MeOH, λ , nm): 257 (sh),
2
1
20 12
D
2
max
–
1
2
3
78, 306, 337; +NaOAc 258, 277, 337; +NaOAc+H BO 267, 380; +NaOMe 267, 344, 392. IR spectrum (KBr, ν , cm ):
389, 3361, 3285 (ÎÍ), 1656 (γ-pyrone Ñ=Î), 1618 (arom. Ñ=Ñ), 1097, 1082, 1049 (glycoside Ñ–Î). H NMR spectrum
3 3 max
1
(
400 MHz, DMSO-d , δ, ppm, J/Hz): 3.09–3.47 (4H, m, Í-2′′–5′′), 3.67 (2H, m, 2Í-6′′), 4.64 (1H, br.s, 6′′-ÎÍ), 4.88 (1Í, d,
6
J = 7.6, Í-1′′), 5.09 (1H, br.s, 2′′-ÎÍ), 6.68 (1H, s, Í-6), 6.58 (1H, s, Í-3), 6,85 (1H, d, J = 8.4, Í-5′), 7.42 (1H, dd, J = 2.3,
8
.4, Í-6′), 7.44 (1H, d, J = 2.3, Í-2′), 12.34 (1Í, s, 5-ÎÍ).
Enzymatic hydrolysis of 3 by β-glycosidase produced hypolaetin (5,7,8,3′,4′-pentahydroxyflavone), C H O ,
1
5 10 7
1
3
mp 286–290°C. UV spectrum (λmax, nm): 256, 284, 344 [6, 8] and D-glucose. C NMR spectrum (100 MHz, DMSO-d , δ,
6
ppm): 182.32 (C-4), 164.26 (C-2), 152.35 (C-5), 151.13 (C-7), 149.88 (C-4′), 145.72 (C-9), 144.32 (C-3′), 126.95 (C-8),
1
21.62 (C-1′), 119.25 (C-6′), 116.04 (C-5′), 113.55 (C-2′), 105.19 (C-10), 102.69 (C-3), 101.30 (C-1′′), 98.60 (C-6), 77.31
1
3
(
[
C-5′′), 75.70 (C-3′′), 73.23 (C-2′′), 69.70 (C-4′′), 60.67 (C-6′′). A comparison of C NMR spectra of hypolaetin glucosides
9, 10] and 3 found that the last was hypolaetin 7-O-β-D-glucopyranoside. This flavonoid was isolated earlier from the plants
1
) S. Yu. Yunusov Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan,
Tashkent, Uzbekistan; 2) Namangan State University, 316 Uichi St., Namangan, 716001, Uzbekistan; 3) Surgut State University,
Lenina St., Surgut, 628412, Russia; e-mail: botirov-nepi@mail.ru; translated from Khimiya Prirodnykh Soedinenii, No. 3,
May–June, 2019, pp. 469–470, original article submitted November 14, 2018.
1
0
009-3130/19/5503-0545 ©2019 Springer Science+Business Media, LLC
545

Juniperus macropoda and Caryopteris mongolica [8]. The 13C NMR spectrum of 3 is published for the first time.
Hypolaetin glycosides possessed anti-inflammatory, antioxidant, and antiulcer properties [11].
Flavonoid 4, Ñ Í Î , mp > 300°Ñ (dec.), [α] –19.2° (c 0.10, 60% EtOH). UV spectrum (MeOH, λmax, nm):
79, 309, 329 (sh), 363 (sh). Enzymatic hydrolysis of 4 by β-glycosidase produced isoscutellarein (5,7,8,4′-tetrahydroxyflavone)
2
1
20 11
D
2
and D-glucose. These results and a comparison with an authentic sample identified 4 as isoscutellarein 7-O-β-D-glucopyranoside
1
3
[
8, 12]. PMR and C NMR spectra of 4 agreed with those published before [12].
Flavonoids 1, 2, and 4 were isolated for the first time from S. comosa. Flavonoid 3 was not previously observed in
plants of the genus Scutellaria.
REFERENCES
1
.
B. Yusupova, R. Atazhanov, I. Toshmatov, Sh. Abdullaev, and V. Litvinenko, Chem. Nat. Compd., 31, 144 (1995).
M. P. Yuldashev, E. Kh. Botirov, and V. M. Malikov, Chem. Nat. Compd., 32, 592 (1996).
M. P. Yuldashev, Chem. Nat. Compd., 35, 212 (1999).
2
.
3.
4
5.
.
X. Shang, X. He, X. He, M. Li, R. Zhang, P. Fan, Q. Zhang, and Z. Jia, J. Ethnopharmacol., 128, 279 (2010).
A. M. Karimov, E. Kh. Botirov, A. U. Mamatkhanov, and Sh. Sh. Sagdullaev, Flavonoids from Plants of the Genus
Scutellaria L., Fan va Texnologiya, Tashkent, 2016, 180 pp.
6.
A. M. Karimov and E. Kh. Botirov, Russ. J. Bioorg. Chem., 43 (7), 691 (2017).
7.
M. P. Yuldashev, Chem. Nat. Compd., 37, 428 (2001).
8.
J. Buckingham, V. Ranjit, and N. Munasinghe, Dictionary of Flavonoids, CRC Press, Taylor & Francis Group,
Boca Raton, 2015, pp. 623–624.
9
.
J. H. Ko, Y. H. Nam, S. W. Joo, H. G. Kim, Y. G. Lee, T. H. Kang, and N. I. Baek, Molecules, 23, 833 (2018).
J. Sendker, I. Boker, I. Lengers, S. Brandt, J. Jose, T. Stark, T. Hofmann, C. Fink, H. Abdel-Aziz, and A. Hensel,
J. Nat. Prod., 80, 290 (2017).
10.
1
1.
A. Villar, M. A. Gasco, and M. J. Alcaraz, J. Pharm. Pharmacol., 36 (12), 820 (1984).
A. M. Karimov and E. Kh. Botirov, Chem. Nat. Compd., 52, 907 (2016).
12.
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