Acylated flavonoids and phenol glycosides from Veronica thymoides subsp. pseudocinerea

A new acylated flavone glucoside, 3'-hydroxyscutellarein 7-O-(6'-O-protocatechuoyl)-beta-glucopyranoside (1), and a new phenol glucoside, 3,5-dihydroxyphenethyl alcohol 3-O-beta-glucopyranoside (6) were isolated from Veronica thymoides subsp. pseudocinerea together with seven known flavone, phenol and lignan glycosides; 3'-hydroxyscutellarein 7-O-(6'-O-trans-feruloyl)-beta-glucopyranoside (2), 3'-hydroxy, 6-O-methylscutellarein 7-O-beta-glucopyranoside (3), luteolin 7-O-beta-glucopyranoside (4), isoscutellarein 7-O-(6'-O-acetyl)-beta-allopyranosyl (1' --> 2')-beta-glucopyranoside (5), 3,4-dihydroxyphenethyl alcohol 8-O-beta-glucopyranoside (7), benzyl alcohol 7-O-beta-xylopyranosyl (1" --> 2')-beta-glucopyranoside (8), and (+)-syringaresinol 4'-O-beta-glucopyranoside (9). Compounds 2, 3 and 7-9 were reported for the first time in the genus Veronica. The structures of the isolates were determined by means of spectroscopic (UV, IR, 1D and 2D NMR, HR ESI-MS) methods. Isolated compounds (1-7) exhibited potent radical scavenging activity against the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical.     

Composition and antimicrobial activity of essential oils from Centaurea sessilis and Centaurea armena

The essential oils of air-dried Centaurea sessilis and Centaurea armena obtained by hydrodistillation were analyzed by gas chromatography-mass spectrometry (GC-MS). Forty and twenty components were identified in the essential oils and the main component of these taxons was beta-eudesmol in the ratios of 12.4% and 19.3% from C. sessilis and C. armena, respectively. The antimicrobial activity of the isolated essential oil of the plants was also investigated. They showed moderate antibacterial activity against Gram-positive and Gram-negative bacteria, but no antifungal activity was observed against two yeastlike fungi.     

Phenolic metabolites from Pyruscalleryana and evaluation of its free radical scavenging activity

Investigation of the aqueous alcoholic extract of Pyruscalleryana Decne. leaves led to the isolation of two new phenolic acids glycosides, namely protocatechuoylcalleryanin-3-O-β-glucopyranoside (1) and 3′-hydroxybenzyl-4-hydroxybenzoate-4′-O-β-glucopyranoside (2), together with nine known compounds among them lanceoloside A and methylgallate, which have been isolated for the first time from the genus Pyrus. Structures of the isolated compounds were established by spectroscopic analysis, including UV, IR, HRESI-MS, and 1D/2D NMR. The total extract and some isolated compounds were determined against DPPH (2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazinyl radical, for their free radical scavenging activity, the total alcoholic extract showed strong antioxidant activity while the two new compounds showed weak antioxidant activity.     

A new quinoline derivative with cytotoxic activity from Streptomyces sp. neau50

A new quinoline derivative, methyl 8-(3-methoxy-3-methylbutyl)-2-methylquinoline-4-carboxylate (1), was isolated from the endophytic strain Streptomyces sp. neau50, and the structure was elucidated by extensive spectroscopic analysis. Compound 1 showed cytotoxicity against human lung adenocarcinoma cell line A549 with an IC₅₀ value of 29.3 μg mL⁻¹.     

Phenolic glycosides and ionone glycoside from the stem of Sargentodoxa cuneata

Four phenolic glycosides, cuneatasides A-D (1-4), and one ionone glycoside cuneataside E (5), together with seven known phenolic compounds (6-12) were isolated from the water-soluble constituents of the stem of Sargentodoxa cuneata (Sargentodoxaceae). Their structures were elucidated by spectroscopic analysis. In vitro tests for antimicrobial activity showed compounds 1 and 2 to possess significant activity against two Gram-positive organisms, Staphylococcus aureus and Micrococcus epidermidis.     

Tetrahydroisoquinoline-monoterpene glycosides from Cephaelis acuminata.

From the dried roots of Cephaelis acuminata, five tetrahydroisoquinoline-monoterpene glycosides, 2-O-beta-D-glucopyranosyldemethylalangiside, demethylisoalangiside, 6"-O-beta-D-glucopyranosylipecoside, 6"-O-alpha-D-glucopyranosylipecoside and (4R)-4-hydroxyipecoside, were isolated. The structures of these glycosides were determined by spectroscopic and chemical means.     

Flavonoid glycosides from Centaurea pseudoscabiosa subsp. pseudoscabiosa from Turkey

Three flavonoid glycosides were isolated and characterized, together with a further 13 substances belonging to various classes of compounds, in particular two phenolic acids, a coumarin, a sugar and nine flavonoids from the flowered aerial parts of Centaurea pseudoscabiosa subsp. pseudoscabiosa Boiss. et Buhse (Asteraceae). Some considerations about their evolutionary meaning are provided.     

Phenolic glucosides from Hasseltia floribunda

The leaves of Hasseltia floribunda were examined for their chemical constituents. Twelve phenolic glucosides, namely three hydroxycyclohexenyl acyl glucosides, four acylated salicortin derivatives, and five coumaroyl salicin derivatives, were isolated along with eight known phenolic glycosides, six known flavones, and two known sesquiterpenoid cyclohexenone derivatives. The structures of the isolated compounds were elucidated by NMR spectroscopic and HRMS spectrometric methods and by comparing analytical data with those of related structures.     

Phenolic compounds and their anti-oxidative properties and protein kinase inhibition from the Chinese mangrove plant Laguncularia racemosa

Phenolic compounds, named integracin D (1), (7′R, 8′S, 8S)-8-hydroxyisoguaiacin (3), (2R, 3R) pinobanksin-3-caffeoylate (5) and threo-8S-7-methoxysyringylglycerol (6), respectively, were isolated from the Chinese mangrove plant Laguncularia racemosa (L) Gaertn. f. (Combretaceae), together with 23 known phenolic metabolites. Their structures were elucidated on the basis of extensive spectroscopic analyses including that of IR, UV, MS, CD, 1D and 2D NMR spectra as well as by comparison with literature data. Compound 5 showed significant anti-oxidative activity in the DPPH and TEAC free-radical-scavenging assays, while several of the phenolic compounds were tested for protein kinase inhibitory activity in an assay involving 24 different human tumor related protein kinases. Compounds 5, 7, and 23 showed potential inhibition with IC₅₀ values between 2.2 and 3.6 μg/mL toward individual kinases. The ellagic acid derivatives were tested for insecticidal activity.     

Phenolic glycosides from Kaempferia parviflora

Three phenolic glycosides were isolated together with two known flavonol glycosides from the H2O-soluble fraction of rhizomes of Kaempferia parviflora. Their structures were determined to be rel-(5aS,10bS)-5a,10b-dihydro-1,3,5a,9-tetrahydroxy-8-methoxy-6H-benz[b]indeno[1,2-d]furan-6-one 5a-O-[alpha-L-rhamnopyranosyl-(1-->6)-beta-d-glucopyranoside] (1), its rel-5aS,10bR isomer (2), and (2R,3S,4S)-3-O-[alpha-L-rhamnopyranosyl-(1-->6)-beta-d-glucopyranosyl]-3'-O-methyl-ent-epicatechin-(2alpha-->O-->3,4alpha-->4)-(5aS,10bS)-5a,10b-dihydro-1,3,5a,9-tetrahydroxy-8-methoxy-6H-benz[b]indeno[1,2-d]furan-6-one 5a-O-[alpha-L-rhamnopyranosyl-(1-->6)-beta-D-glucopyranoside] (3). The structures were elucidated on the basis of analyses of chemical and spectroscopic evidence.     

Phenolic and iridoid glycosides from Strychnos axillaris

Five phenolic glycosides 1-5 and an iridoid glucoside 6 were isolated, together with 22 known compounds, from the dried barks and woods of Strychnosaxillaris. Their structures were determined by application of spectroscopic (NMR, MS) and chemical methodologies.     

Secondary metabolites from Centaurea ensiformis P.H. Davis

Centaurea ensiformis P.H. Davis was evaluated for its secondary metabolites. 20 different compounds have been isolated and identified; four phenolic compounds, one aminoacid, two acetophenone glycosides, three phenylpropanoide glycosides, one coumarin glucoside, four flavon glycosides, two neolignan glycosides, two megastigmane glycosides and schikimic acid methyl ester.     

Sesquiterpenes from Centaurea aspera

The aerial parts of two subspecies of Centaurea aspera L. (Asteraceae) yielded the germacranolides 1a-h, 2, 3, 4 and 5, the elemane derivatives 6d and 6f, the lignan matairesinol, the degraded terpene loliolide, and the onopordopicrin-valine dimeric adduct 7. From these, compounds 1e, 3 and 6d are natural products. The chemical composition of the two subspecies is very similar, a circumstance which does not support a taxonomic subdivision of the species.     

Steroidal glycosides from the marine sponge Pandaros acanthifolium

The chemical composition of the Caribbean sponge Pandaros acanthifolium was investigated and led to the isolation of seven new steroidal glycosides namely pandarosides A-D (1, 3, 4 and 6) along with the three methyl esters of pandarosides A, C, and D (2, 5 and 7). Their structures were characterized as 3β-[β-glucopyranosyl-(1→2)-β-glucopyranosyloxyuronic acid]-16-hydroxy-5α,14β-poriferast-16-ene-15,23-dione (1) and its methyl ester (2), 3β-[β-glucopyranosyloxyuronic acid]-16-hydroxy-5α,14β-poriferast-16-ene-15,23-dione (3), 3β-[β-glucopyranosyl-(1→2)-β-glucopyranosyloxyuronic acid]-16-hydroxy-5α,14β-cholest-16-ene-15,23-dione (4) and its methyl ester (5), 3β-(β-glucopyranosyloxyuronic acid)-16-hydroxy-5α,14β-cholest-16-ene-15,23-dione (6) and its methyl ester (7) on the basis of detailed spectroscopic analyses, including 2D NMR and HRESIMS studies. Pandarosides A-D and their methyl esters (1-7) are all characterized by a rare 2-hydroxycyclopentenone D-ring with a 14β configuration. The absolute configuration of the aglycon part of pandaroside A (1) was assigned by comparison between experimental and TDDFT calculated circular dichroism spectra on the more stable conformer.