Chemistry of Natural Compounds

, Volume 48, Issue 5, pp 889–890

Constituents of Scutellaria holosericea

Authors

  • Kh. Sh. Kamoldinov
    • S. Yu. Yunusov Institute of the Chemistry of Plant Substances, Academy of Sciences
    • S. Yu. Yunusov Institute of the Chemistry of Plant Substances, Academy of Sciences
  • Kh. M. Bobakulov
    • S. Yu. Yunusov Institute of the Chemistry of Plant Substances, Academy of Sciences
Article

DOI: 10.1007/s10600-012-0413-z

Cite this article as:
Kamoldinov, K.S., Eshbakova, K.A. & Bobakulov, K.M. Chem Nat Compd (2012) 48: 889. doi:10.1007/s10600-012-0413-z
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Plants of the genus Scutellaria L. (Lamiaceae) are one source of flavonoids in the flora of Uzbekistan. Flavonoids represent the most numerous class of natural phenolic compounds and typically have varied structures, high and multi-faceted activities, and low toxicities.

Scutellaria holosericea Gontsch ex Juz [1] is a perennial endemic plant that flowers in June-July, bears fruit in July-August, and grows on slopes in the upper mountain zone. We studied the aerial part of S. holosericea collected during flowering in Surkhandar′ya Region, Republic of Uzbekistan. Ground and air-dried raw material (300 g) was extracted exhaustively (5×) by EtOH (70%) at room temperature. The combined extracts were distilled in vacuo. The condensed residue was diluted with H2O and worked up successively by hydrocarbons, CHCl3, EtOAc, and n-BuOH.

The EtOAc (12 g) and n-BuOH (14 g) fractions were chromatographed over a column of silica gel using gradients of hydrocarbons:CHCl3 (1) and CHCl3:MeOH (2). The chromatographic separation isolated from the EtOAc fraction (system 1, 9:1→2;1) compounds 1-5; from the n-BuOH fraction (system 2, 15:1→4:1), compounds 6–7.

The isolated compounds were identified using UV, IR, PMR, and 13C NMR spectral data, which were compared with the literature and also with authentic samples, as β-sitosterol (1), chrysin (2), 5-hydroxy-7-methoxyflavone (3), 3,5-dihydroxy-7-methoxyflavone (4), 5,7,4′-trihydroxyflavone (apigenin) (5), 7-ketologanin (6), and chrysin-7-O-β-glucoside (7).

β-Sitosterol was identified by direct comparison with an authentic sample.

Chrysin (2), yellow crystals, C15H14O4, mp 289–282°C. UV spectrum (EtOH, λmax, nm): 271, 320. IR spectrum (KBr, ν, cm–1): 3480–3290 (OH), 1685 (C=O), 1605, 1510 (C=C) [2].

5-Hydroxy-7-methoxyflavone (3), C16H16O4, mp 165–166°C. UV spectrum (EtOH, λ-max, nm): 271.5, 321. IR spectrum (KBr, ν, cm–1): 3485 (OH), 1687 (C=O), 1607, 1511 (C=C). PMR spectrum (400 MHz, CCl4 + DMSO-d6, δ, ppm, J/Hz, 0 = HMDS): 3.72 (3H, s, OCH3), 6.44 (1H, s, H-6), 6.64 (1H, s, H-8), 7.22 (1H, s, H-3), 7.43 (3H, m, H-3′,4′,5′), 7.86 (2H, dd, J = 7.65, 2.16, H-2′,6′), 12.75 (1H, s, 5-OH) [3].

3,5-Dihydroxy-7-methoxyflavone (4), C16H12O5, mp 230–231°C. UV spectrum (EtOH, λmax, nm): 279.1, 308, 327; +CH3COONa: 279, 307.3, 326. IR spectrum (KBr, ν, cm–1): 3462–3221 (OH), 2914 (OCH3), 1662 (C=O), 1606, 1505 (C=C). PMR spectrum (400 MHz, CCl4 + DMSO-d6, δ, ppm, J/Hz, 0 = HMDS): 3.77 (3H, s, OCH3), 6.44 (1H, s, H-6), 6.63 (1H, s, H-8), 7.42 (3H, m, H-3′,4′,5′), 7.87 (2H, d, J = 8.0, H-2′,6′), 10.24 (1H, s, 3-OH), 12.76 (1H, s, 5-OH) [4].

5,7,4-Trihydroxyflavone (5), C15H10O5, mp >340°C. UV spectrum (EtOH, λmax, nm): 294.2, 348.7. IR spectrum (KBr, ν, cm–1): 3217 (OH), 1668 (C=O), 1607, 1507 (C=C) [2].

7-Ketologanin (6), C17H24O10, mp 195°C. UV spectrum (MeOH, λmax, nm): 231.17. IR spectrum (KBr, ν, cm–1): 3373, 2921, 1749, 1683, 1645, 1447, 1299, 1075, 889, 845. PMR spectrum (400 MHz, CDCl3 + CD3OD, δ, ppm, J/Hz, 0 = HMDS): 1.11 (3H, d, J = 6.4, H-10), 2.10 (1H, d, J = 7.1, H-8), 2.28 (1H, ddd, J = 10.7, 7.1, 1.45, H-9), 2.50 (1H, dd, J = 14.0, 1.4, H-6α), 2.56 (1H, dd, J = 3.16, 1.4, H-6β), 3.24 (1H, m, H-5), 3.65 (3H, s, OCH3), 5.43 (1H, d, J = 3.6, H-1), 7.40 (1H, d, J = 1.47, H-3), 3.30 (1H, t, J = 8.0, H-2′), 3.36 (1H, t, J = 8.8, H-4′), 3.42 (2H, m, H-3′,5′), 3.70 (1H, dd, J = 11.7, 6.3, H-6′α), 3.82 (1H, dd, J = 11.9, 3.6, H-6′β), 4.63 (1H, d, J = 8.0, H-1′). 13C NMR spectrum (100 MHz, CDCl3 + CD3OD, δ, ppm): 94.08 (C-1), 151.87 (C-3), 109.79 (C-4), 26.99 (C-5), 42.48 (C-6), 218.78 (C-7), 43.52 (C-8), 45.15 (C-9), 13.30 (C-10), 167.50 (C-11), 98.78 (C-1′), 73.06 (C-2′), 76.36 (C-3′), 69.93 (C-4′), 77.55 (C-5′), 61.52 (C-6′), 51.36 (OCH3) [5].

Chrysin-7-O-β-glucoside (7), C21H20O9, mp 190–192°C. UV spectrum (MeOH, λmax, nm): 270.18, 307.11. IR spectrum (KBr, ν, cm–1): 3510–3285 (OH), 1668 (γ-pyrone C=O), 1615, 1560, 1507 (aromatic C=C), 1085, 1065, 1003 (glycoside C–O). Acid hydrolysis produced chrysin and D-glucose [6].

β-Sitosterol; chrysin; 3,5-dihydroxy-7-methoxyflavone; 5,7,4′-trihydroxyflavone; and chrysin-7-O-β-glucoside were isolated for the first time from this species; 5-hydroxy-7-methoxyflavone and 7-ketologanin, from the genus Scutellaria.

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© Springer Science+Business Media New York 2012