Sh. V. Abdullaev

Flavonoids of the roots of Scutellaria squarrosa

The phenolic compounds from the comminuted roots were extracted with aqueous acetone and were separated by a known method [2]. Six flavonoids (I-VI) were isolated and were identified with the aid of chemical and physicochemical methods: (I) baicalein, mp 260262°C, ~max MeOH 325, 275 nm; (II) baicalin (baicalein 7-O-B-D-glucopyranoside), mp 226228°C, [~]D 2° -145.0 ° , kmax MeOH 315, 280 nm; (III) oroxylin, mp 195-197 C, kmax MeOH 315, 280 nm; (IV) oroxyloside (oroxylin 7-O-8-D-glucopyranoside), amorphous compounds, laid 2° -15.0 ° , kmax MeOH 315, 280 nm; (V) wogonin, mp 201-203°C, kmax MeuH 316, 275, 245 nm; (VI) chrysin, mp 288-290°C, kmax MeOH 270, 310 nm.

Flavonoids from Scutellaria cordifrons and S. phyllostachya roots

Plants of the genus Scutellaria L. (Lamiaceae) are rich sources of flavonoids, terpenoids, phenylpropanoids, and other biologically active compounds [1]. In continuation of research on flavonoids from plants of this genus, we studied roots of S. cordifrons Juz. and S. phyllostachya Juz. [2]. Baikalein, 5,7-dihydroxy-2 ′-methoxyflavone, and chrysin have previously been isolated from roots of S. phyllostachya [3]. The flavonoid composition of S. cordifrons has not previously been studied. Ground air-dried roots (1 kg) of S. cordifrons were collected at the end of vegetation (November 2000) near the village Chodak of Namangan District of the Republic of Uzbekistan and were exhaustively extracted with ethanol. The ethanol extract was condensed in vacuo, diluted with water, and extracted successively with hexane, chloroform, and ethylacetate. Chromatography of the CHCl 3 fraction (20.0 g) over a silica-gel column with gradient elution by CHCl 3:propan-2-ol isolated 1 and 2, which were also isolated from the CHCl 3 extract of the alcohol extract of S. phyllostachya (raw material collected in November 2000 near the village Mamai of Yangikurgan Region of Namangan District). Flavonoid 1, C18H18O7, mp 220-221°C (dec.). The UV spectrum (EtOH, λmax, 242 sh, 290, 346 nm) was characteristic of flavanone derivatives [4]. The IR spectrum of 1 contained absorption bands for hydroxyl (3200, 3450 cm -1), ethoxyls (2930), pyrone carbonyl (1650), and aromatic C=C (1615, 1590). The mass spectrum exhibited peaks for ions with m/z 346 [M] +, 328 [M H2O], 313 (100) [M H2O CH3], 285, 197, 196, 181, 168, 153. The PMR spectrum (DMSO-d 6, ppm, J/Hz) had signals for protons at 2.52 (1H, dd, J = 17.5, 3.2, H-3 eq), .65, 3.76, 3.83 (each 3H, s, 3 × OCH 3), 3.95 (1H, dd, J = 17.5, 13.5, H-3ax), 5.96 (1H, dd, J = 13.5, 3.2, H-2), 6.22 (1H, s, H-8), 6.51 (2H, br. d, J = 8.5, H-3 ′, H-5′), 7.20 (1H, br. t, J = 8.5, H-4′), 9.90 (1H, s, 2-OH), 12.10 (1H, s, 5-OH). Based on PMR and mass spectral data, 1 contains three methoxyls and two hydroxyls. The mass spectral fragmentation is consistent with two methoxyls and one hydroxyl on ring A [5]. Comparison of the spectral data with those of an authentic sample of 1 identified it as (+)-5,2 ′-dihydroxy-6,7,6′-trimethoxyflavanone [6, 7]. Flavonoid 2, C19H20O8, mp 148-149°C, was a flavanone derivative according to its UV spectrum ( λmax 289, 359 nm) [4]. The IR spectrum contained absorption bands at 3450-3250, 2950, 1660, 1617, and 1578 cm -1. The ass spectrum of 2 had peaks for ions with m/z 376 [M] +, 358, 343, 315, 226, 211, 183, 131, 119, 83, and 69 (100). The PMR spectrum (DMSO-d6, J/Hz): 2.75 (1H, dd, J = 3.1, 17.5, H-3 eq), 3.16, 3.30, 3.43, 3.55 (each 3H, s, 4 × OCH 3), 3.75 (1H, dd, J = 3.1, 17.5, H-3ax), 5.95 (1H, dd, J = 13.5, 3.1, H-2), 6.52 (2H, br. d, J = 8.5, H-3 ′ 5′), 7.19 (1H, br. t, J = 8.5, H-4 ′), 11.90 (1H, s, 5-OH). The PMR and mass spectrum indicated that 2 differed from 1 by the presence of an additional methoxyl in the 8-position of the flavanone nucleus. Based on the data and a direct comparison with an authentic sample, 2 was identified as (-)-5,2 ′-dihydroxy6,7,8,6′-tetramethoxyflavanone [7, 8]. Flavonoids 1 and 2 were isolated for the first time from these Scutellaria species.

Structures of two new flavanones fromVexibia alopecuroides

Two new flavanones — vexibinol and vexibidin — have been isolated from the chloroform fraction of an ethanolic extract of the roots ofVexibia alopecuroides by column chromatography on silica gel. Their structures have been established on the basis of chemical and spectral characteristics. Their IR, UV,1H, and13C NMR, and mass spectra are given.

Flavonoids fromAmmothamnus lehmannii

We have previously isolated phenolic acids from the plant A~ot~nu8 ~e~z~anni Bge [1]. Continuing our investigation, from an ethyl acetate fraction of an alcoholic extract of the epigeal part of the plant collected in the flowering period in the Kenimekh region of Navoi province (close to the village of Kokcha), we have isolated another five flavonoids by column chromatography on silica gel with elutlon by chloroform-ethanol in various ratios.

Structure of a new chalcone ammothamnidin fromAmmothamnus lehmanni

A new chalcone ammothamnidin with the composition C25H28O4, mp 112–114°C [α]D20 + 4.5° (methanol) has been isolated from the epigeal part and roots ofAmmothamnus lehmanni Bge. On the basis of chemical transformations and IR, UV,1H and13C NMR, and mass spectra it has been shown that ammothamnidin has the structure of 2,2′,4′-trihydroxy-3′-(2″-isopropenyl-5″-methylhex-4″-enyl)chalcone.

Method of quantitative HPLC analysis in investigation of cyclocondensation of 2-pyrrolidone with anthranilic acid

The products of the cyclocondensation of 2-pyrrolidonewith anthranilic acid in the presence of condensing agents have been investigated by high-performance liquid chromatography (HPLC). The main product of this reaction is the alkaloid deoxyvasicinone (DOV) [I]. To analyze the starting materials and the reaction products we used reversed-phase HPLC with the UV detection of the separated substances at a wavelength of 254 nm [2]. The HPLC method has not previously been used for studying the products of this reaction.

Flavonoids ofGoebelia pachycarpa

The following substances were isolated and were identified on the basis of chemical and spectral characteristics: kaempferol, quercetin, and genistein. A fourth compound C26H2sO14 (I), mp 125-128°C, [a]~ 2 --34.4 ± 2 ° (c 1.05 MeOH) was an isoflavone derivative according to its UV spectrum (%maxethanol, nm: 263, 328 sh; log g 4.56, 3.73) [i]. Its IR spectrum contained absorption bands at (cm -I) 3527-3295 (OH groups), 1660 (C=O of a a-pyrone), 1622, 1589 (aromatic ~ bonds), and 1098-1040 (C O vibrations of glycosides).

Organic acids ofAmmothamnus lehmannii

To isolate the phenolic acids, concentrated ethanolic extracts of various organs were diluted with distilled water (i:i) and extracted exhaustively with ether. The ethereal extracts were washed with 5% sodium carbonate solution and then the aqueous solution was acidified with 5% sulfuric acid and re-extracted with ether. The combined phenolic acids so obtained were separated by column chromatography on silica gel and cellulose in a gradient hexane--acetone system. In this way, four substances of phenolic nature were obtained which gave positive reaction with a number of reagents for phenolcarboxylic acids [2]. These acids were identified on the basis of their UV and IR spectra, and also by direct comparison with authentic samples.