Bozhanka Mikhova

SYNTHESIS AND SPECTROSCOPIC INVESTIGATION OF SOME DIMERIC COUMARIN AND FURANOCOUMARIN MODELS

SummaryThe synthesis of some dimeric coumarin and furanocoumarin models and their structure elucidation by1H NMR,13C NMR, and mass spectroscopy is presented. In the presence of moisture some aldehydes are accompanied by their hydrates. Methoxy signal doubling in the presence of a chiral lanthanide shift reagent proves the dimeric nature of compound8. In the mass spectra, heterolytic cleavage of the O-C linkage was noticed which is a rare fragmentation in the case of aromatic ethers.ZusammenfassungDie Synthese einiger dimerer Cumarin- und Furanocumarin-Modellverbindungen und ihre Strukturaufklärung mit1H- und13C-NMR- sowie Massenspektrometrie werden beschrieben. In Gegenwart von Feuchtigkeit werden einige der Aldehyde von ihren Hydraten begleitet. Verdoppelungen der Methoxy-1H-Signale von8 in Anwesenheit eines chiralen Lanthanoid-Verschiebungsreagenzes beweisen, daß8 ein Dimer ist. In den Massenspektren finden sich Hinweise für heterolytische Spaltungen der O-C-Bindungen. Solche Fragmentierungen sind bei aromatischen Ethern ungewöhnlich.

Bioactive Phenolics from Carthamus lanatus L.

Abstract Two flavonoid aglycons, eight flavonoid glycosides, chlorogenic acid and syringin were isolated from aerial parts of Carthamus lanatus. Isorhamnetin 3-O-β-ᴅ-glucoside and chlorogenic acid were found for the first time in the genus Carthamus and respectively, quercimeritrin, astragalin, kaempferol 3-O-β-ᴅ-sophoroside and syringin in the species. The ethyl acetate fraction of the methanol extract exhibited a higher antioxidant activity than the butanol fraction measured by the α,α-diphenyl-β-picrazylhydrazyl (DPPH) free radical scavenging assay. Cytotoxicity and antioxidant activities of the main constituent, luteolin 7-O-β-D-glucoside, were evaluated.

New furostanol saponins from Smilax aspera L. and their in vitro cytotoxicity

The occurrence of the two new cis-fused A/B rings furostanol saponins (25S)-26-O-β-D-glucopyranosyl-5β-furostan-1β,3β,22α,26-tetraol-1-O-β-D-glucopyranoside and (25S)-26-O-β-D-glucopyranosyl-5β-furostan-1β,2β,3β,5β,22α,26-hexaol and the known compounds (25S)-26-O-β-D-glucopyranosyl-5β-furostan-3β,22α,26-triol-3-O-α-L-rhamnopyranosyl-(1 → 2)-O-β-D-glucopyranosyl-(1 → 2)-O-β-D-glucopyranoside and (25S)-26-O-β-D-glucopyranosyl-5β-furostan-3β,22α,26-triol-3-O-β-D-glucopyranosyl-(1 → 2)-O-β-D-glucopyranoside, trans-resveratrol, (+) catechin and (-) epicatechin in the rhizomes of Smilax aspera is reported. All saponins have been isolated as their 22-OMe derivatives, which were further subjected to extensive spectroscopic analysis. The isolated furostanol saponins were evaluated for cytotoxic activity against human normal amniotic and human lung carcinoma cell lines using neutral red and MTT assays. In vitro experiments showed significant cytotoxicity in a dose dependent manner with IC(50) values in the range of 32.98-94.53 µM.

Anthraquinone, naphthalene, and naphthoquinone components of Asphodeline lutea

The genus Asphodeline belongs to the family Asphodelaceae, subfamily Asphodeloideae. The 1,8-dihydroxyanthraquinones based on a chrysophanol unit are characteristic compounds of this subfamily. Anthraquinones, flavonoids, oxepines, and sesquiterpene lactones have been reported to occur in the genus Asphodeline [1–4]. Asphodeline lutea is a perennial plant growing in the Mediterranian region. The only report found on this plant species reveals the presence of 1,8-dihydroxyanthraquinones, flavonoids, and a chlorogenic acid [5]. Data on the biological activity and the medicinal use of A. lutea are not available. However, the edible use of its roots, shoots, and flowers has been reported [6]. The ancient Greeks roasted the roots like potatoes and ate them with salt and oil or mashed them with figs. The raw fresh flowers are very decorative and a tasty addition to salad, while the young shoots are eaten cooked. The roots of A. lutea were collected in June 2005 near the town of Pernik, Bulgaria. The dried roots (0.70 kg) of A. lutea were extracted with methanol (3 times 24 h 2.7 L) at room temperature, then concentrated in vacuum to give a crude methanol extract (22.0 g). Solvent-solvent partition of this extract using petroleum ether, chloroform, and ethylacetate afforded the corresponding petroleum ether (4.3 g), chloroform (5.2 g), and ethylacetate (0.5 g) extracts and an aqueous residue (15.2 g). The petroleum ether extract was subjected to liquid vacuum chromatography (LVC) on silica gel using PE, PE–CHCl3 (3:1 1:3), CHCl3, CHCl3–EtOAc (1:1), and EtOAc to give fractions F1-F6. Silica gel CC and repeated pTLC of F6 afforded compounds 1 (2 mg), 2 (6 mg), 3 (7 mg), 4 (3 mg), and 5 (1 mg). LVC of the chloroform extract with PE–CHCl3 (20:1 1:1) and CHCl3 gave fractions F1-F4. From F4 after silica gel CC and pTLC separation components 6 (4 mg), 7 (2 mg), 5 (5 mg), and 8 (6 mg) were isolated. The chemical structures of the isolated compounds were determined by a combination of spectral methods (UV, IR, 1D and 2D NMR, and MS) and comparison with literature data as chrysophanol (1) [7], 1,5,8-trihydroxy-3-methylanthraquinone (2) [8], 2-acetyl-1,8-dimethoxy-3-methylnaphthalene (3) [9, 10], 1-hydroxy-8-methoxy-3-methylanthraquinone (4) [11], asphodeline (5) [12], 2-acetyl-1-hydroxy-8-methoxy-3-methylnaphthalene (6) [9, 10], 2-acetyl-8-methoxy-3methylnaphthoquinone (7) [13], and 1,1 ,8,8 ,10-pentahydroxy-3,3 -dimethyl-10,7 -bianthracene-9,9 ,10 -trione (8) [14]. Of them only chrysophanol (1) and asphodeline (5) have been reported to occur in A. lutea [5]. The anthraquinones 2 and 4 and the naphthalene compounds 3 and 6 are new for the genus Asphodeline. The naphthoquinone 7 is a known synthetic compound [13]. However, this is the first report on its natural occurrence and on the presence of naphthoquinones in Asphodeline species. A full assignment of all protons and carbons in the molecule of 3 was undertaken by detailed 1D and 2D NMR measurements because of the discrepancy between the assignments of C signals in previous reports [9, 10]. Our data are presented in Table 1. The 13C NMR data of 7 have been reported by Piggot and Wege without any assignment [13]. Our results from the complete assignment of all protons and carbons achieved by 1D and 2D NMR experiments are presented in Table 1. 2-Acetyl-1,8-dimethoxy-3-methylnaphthalene (3). UV (EtOH, max, nm): 225, 299, 313 sh, 329; IR (KBr, max, cm–1): 2924, 2839, 1700, 1623, 1568, 1460; EI-MS (m/z, Irel.,%): 244 (M+, 70.9), 229 (100), 214 (8.1), 201 (1.5), 186 (25.8), 158 (4.8), 128 (19.3), 127 (9.7), 115 (20.9), 43 (5.6). For 1H and 13C NMR data, see Table 1.

Steroidal saponins from Smilax excelsa rhizomes

From the n-butanol soluble fraction of the methanol extract of the rhizomes of Smilax excelsa, three new furostanol saponins 3-O-[4-O-acetyl-α-L-rhamnopyranosyl-(1 → 2)-{α-L-rhamnopyranosyl-(1 → 4)}-β-D-glucopyranosyl]-26-O-[β-D-glucopyranosyl]-22α-hydroxy-(25R)-furost-5-ene-3β,26-diol (1), 3-O-[2-O-acetyl-α-L-rhamnopyranosyl-(1 → 2)-{α-L-rhamnopyranosyl-(1 → 4)}-β-D-glucopyranosyl]-26-O-[β-D-glucopyranosyl]-22α-hydroxy-(25R)-furost-5-ene-3β,26-diol (2), 3-O-[3-O-acetyl-α-L-rhamnopyranosyl-(1 → 2)-{α-L-rhamnopyranosyl-(1 → 4)}-β-D-glucopyranosyl]-26-O-[β-D-glucopyranosyl]-22α-hydroxy-(25R)-furost-5-ene-3β,26-diol (3), and three known saponins: protodioscin (4), pseudoprotodioscin (5) and dioscin (6) were isolated.

Antiinflammatory and analgesic effects of Carthamus lanatus aerial parts

Fractions of methanol, dichloromethane, water extracts and volatiles of Carthamus lanatus aerial parts given by oral route at a dose of 2 mg/kg showed significant antiinflammatory activities in rats. On the contrary, only the water fraction of MeOH extract possesses a significant analgesic activity.

Alkaloids from the roots of Senecio macedonicus Griseb.

The new alkaloids 7-,9-diangeloylplatynecine (1) and 8-episarracine N-oxide (2), were isolated and identified from the roots of Senecio macedonicus. Another one, 8-epineosarracine was detected by GC/MS analyses of the crude alkaloid mixture. The cytotoxicity and biological activity of the alkaloids were tested on normal murine spleen lymphocytes and P3U1 mouse myeloma.

(-)-Veranigrine, a new steroidal alkaloid from Veratrum nigrum L.

A new steroidal alkaloid, (-)-veranigrine (1) was isolated from the roots and rhizomes of Veratrum nigrum L. By means of spectroscopic methods its structure was established as (20S, 25S)-iminocholesta-5,22(N)-diene-1beta,3beta-diol.

Oxygenated Bisabolane Fucosides from Carthamus lanatus L.

The aerial parts of Carthamus lanatus (Asteraceae) afforded four new oxygenated bisabolane fucosides, 10-hydroperoxy-bisabola-2,11-diene 7-O-β-ᴅ-fucopyranoside, 11-hydroperoxy- bisabola-2,9-diene 7-O-β-ᴅ-fucopyranoside, 10-hydroxy-bisabola-2,11-diene 7-O-β-ᴅ-fucopyranoside and 11-hydroxy-bisabola-2,9-diene 7-O-β-ᴅ-fucopyranoside together with the known compounds α-bisabolol β-ᴅ-fucopyranoside, asperuloside, sitosterol 3-O-β-ᴅ-glucoside and stigmasterol 3-O-β-ᴅ-glucoside. Asperuloside appears to be the second representative of the iridoid monoterpene group found in the plant family Asteraceae, which until recently was considered to lack iridoids. The main constituent α-bisabolol fucoside exhibited noticeable antibacterial and cytotoxic activities.

Alkaloids from Senecio aquaticus.

Erucifoline (1) and 9-angeloylhastanecine (2) were isolated from the aerial parts of Senecio aquaticus. Five other pyrrolizidine alkaloids were tentatively identified by GC/MS analysis: jacobine; seneciphylline; spartioidine; jacozine; and senecionine.