Flavonoids from Iryanthera laevis

Trunk wood of Iryanthera laevis Markgr. (Myristicaceae) contains 2′,4′-dihydroxy- 4,6′dimethoxydihydrochalcone, three 2′-hydroxy-4′,5′-methylenedioxyflavans with differently substituted A-rings (7-OH-6,8-diMe; 7-OH-5,8-diMe; 5-OH-7-OMe-6,8-diMe) and 1-(2′-hydroxy-4′-methoxy-5′-methylphenyl)-3(2″-hydroxy-4″,5″-methylenedioxphenyl)- propane, as well as three additional known diarylpropanes.     

Phenolic compounds from Selaginella moellendorfii

Chemical investigation of the leaves and roots of Selaginella moellendorfii Hieron has resulted in the isolation and characterization of two new flavone glucosides, 7‐O‐(β‐glucopyranosyl(1→2)‐[β‐glucopyranosyl(1→6)]‐β‐glucopyranosyl)flavone‐3′,4′,5,7‐tetraol ( 1 ) and 7‐O‐(β‐glucopyranosyl(1→2)‐[β‐glucopyranosyl(1→6)]‐β‐glucopyranosyl)flavone‐4′,5,7‐triol ( 2 ), two new biflavonoids, 2,3‐dihydroflavone‐5,7,4′‐triol‐(3′→8″)‐flavone‐5″,6″,7″,4′′′‐tetraol ( 3 ) and 6‐methylflavone‐5,7,4′‐triol‐(3′→O→4′′′)‐6″‐methylflavone‐5″,7″‐diol ( 4 ), two new lignans, (7′E)‐3,5,3′,5′‐tetramethoxy‐8 : 4′‐oxyneolign‐7′‐ene‐4,9,9′‐triol ( 5 ) and 3,3′‐dimethoxylign‐8′‐ene‐4,4′,9‐triol ( 6 ), together with two known monolignans, four known lignans, and four known biflavonoids. Their structures were established by spectroscopic means and by comparison with literature values.     

Flavonoids from the ferns Blechnum regnellianum and Pityrogramma ebenea

From the leaves of the fern Pityrogramma ebenea a new compound 2′,6′-dihydroxy-4,3′-dimethoxy-4′,5′-methylenedioxydihydrochalcone was characterized. (2S)-5,7-Dihydroxy-4′-methoxy-6,8-dimethylflavanone was identified in another fern, Blechnum regnellianum     

Flavonoid glucosides from licorice

Two new flavanone glycosides, liquiritigenin 4′-apiosyl(1 → 2)-glucoside and liquiritigenin 7,4′-diglucoside together with a known flavone, apigenin 6,8-di-C-glucoside, have been isolated from licorice.     

A flavone dimer from Ouratea hexasperma

From the leaves of Ouratea hexasperma, the flavone dimer 4′,5,7-trihydroxyflavone-(6→8″)-4‴,5″-dihydroxy-7″-methoxyflavone was isolated in addition to methyl myoinositol. The structures were established by various analyses including 2D-NMR spectroscopy.     

Lipophilic C-methylflavonoids with no B-ring oxygenation in Metrosideros species (Myrtaceae)

Five unusual C-methylflavonoids lacking B-ring oxygenation (2′,4′-dihydroxy-3′,5′-dimethyl-6′-methoxychalcone, 2′,4′-dihydroxy-3′-methyl-6′-methoxychalcone, 2′,6′-dihydroxy-3′-methyl-4′-methoxychalcone, 2′-hydroxy-3′-methyl-4′,6′-dimethoxychalcone and 5,7-dihydroxy-6,8-dimethylflavanone) were found for the first time in Metrosideros excelsa. The flavanone was the major constituent in leaves, whereas 2′,6′-dihydroxy-3′-methyl-4′-methoxychalcone dominated all other aerial plant parts studied. Other Metrosideros species were investigated for these five flavonoids. C₁₉–C₃₆ aldehydes and C₂₂–C₃₂ alcohols were also identified from the dried seed capsules of M. excelsa.     

Flavonoids from Gutierrezia grandis

Thirteen flavonoids, including three new compounds, were isolated from Gutierrezia grandis. The structures of the new compounds were 3,5,7,3′,4′-pentahydroxy-6,8-dimethoxyflavone, 5,7,3′-trihydroxy-3,6,8,4′,5′-pentamethoxyflavone and 5,7,3′,5′-tetrahydroxy-3,6,8,4′-tetramethoxyflavone 3′-O-glucoside.     

New prenylated isoflavones and a prenylated dihydroflavonol from Millettia pachycarpa

Extraction of Millettia pachycarpa Benth. gave 5,7,4′-trihydroxy-6,8-diprenylisoflavone (1a), 5,7,4′-trihydroxy-6,3′-diprenylisoflavone (2a), 5,7,3′,4′-tetrahydroxy-6,8-diprenylisoflavone (3a) and (2R, 3R)-5,4′-dihydroxy-8-prenyl-6″,6″-dimethylpyrano[2″,3″: 7,6]-dihydroflavonol (4a) whose structures were established by chemical transformations and spectroscopic means. Pectolinarigenin and salvigenin were isolated from Buddleia macrostachya Benth.     

Antiproliferative constituents from Aphananthe aspera leaves

Extensive screening for the antiproliferative activity of different compounds found in trees was performed by extracting the leaves of Aphananthe aspera (Thunb.) Planch and then using chromatographic separation to afford 2 new compounds, (2S,4R)-2-carboxy-4-(E)-p-caffeoyl-1-methyl-hydroxyproline (1) and 5-O-caffeoyl quinic acid-(7′R,8′S,7′′E)-3′,4′,3′′-dihydroxy-4′′,7′-epoxy-8′,5′′-neolign-7′-ene-9- carboxyl (2). In addition, 6 known compounds were discovered from the leaves of this plant. The structural determination of all compounds, including their absolute configurations, was established by UV, IR, HRESIMS, 1D and 2D NMR, and CD spectroscopy. The novel compound 1 showed strong antiproliferative activity against human breast adenocarcinoma cells MCF-7 and MDA-MB-231.     

Flavonoids from Wyethia glabra

Ten flavonoid compounds, including three new natural products, were isolated from a dichloromethane extract of Wyethia glabra. The known compounds are: orobol 7-methyl ether, orobol 3′-methyl ether, naringenin 7-methyl ether, eriodictyol, 8-C-prenyleriodictyol, 6-C-prenyleriodictyol and 8-C-prenylnaringenin. Eriodictyol 7-methyl ether, 2′,4′,6′-trihydroxy-4-methoxychalcone and 6-C-prenylnaringenin are new natural products. An additional prenylated flavanone was isolated and partially characterized.     

Chemistry of toxic range plants. Highly oxygenated flavonol methyl ethers from Gutierrezia microcephala

The perennial American desert shrub, Gutierrezia microcephala, contains 20 flavonol methyl ethers displaying nine different oxygenation patterns. These include 11 new flavonols: 5,7-dihydroxy-3,6,8,3′,4′,5′-hexamethoxyflavone, 5,7,4′-trihydroxy-3,6,8,3′,5′-pentamethoxyflavone, 5,7,3′-trihydroxy-3,6,8,4′,5′-pentamethoxyflavone, 5,7,2′,4′-tetrahydroxy-3,6,8,5′-tetramethoxyflavone, 5,7,3′,4′-tetrahydroxy-3,6,8-trimethoxyflavone, 5,7,8,3′,4′-pentahydroxy-3,6-dimethoxyflavone, 3,5,7,3′,4′-pentahydroxy-6,8-dimethoxyflavone, 5,7,4′-trihydroxy-3,6,8-trimethoxyflavone, 5,7,8,4′-tetrahydroxy-3,3′-dimethoxyflavone, 5,7,8,3′,4′-pentahydroxy-3-methoxyflavone and 5,7,8,4′-tetrahydroxy-3-methoxyflavone. In addition, the following known flavonols were isolated: 5,7-dihydroxy-3,8,3′,4′,5′-pentamethoxyflavone, 5,7,4′-trihydroxy-3,8-dimethoxyflavone, 5,7,4′-trihydroxy-3,8,3′-trimethoxyflavone, 5,7,3′,4′-tetrahydroxy-3,8-dimethoxyflavone, 5,7,4′-trihydroxy-3,6,3′-trimethoxyflavone, 5,7,3′,4′-tetrahydroxy-3-methoxyflavone, 5,4′-dihydroxy-3,6,7,8,3′-pentamethoxyflavone, 5,7,4′-trihydroxy-3,6,8,3′-tetramethoxyflavone and 3,5,7,4′-tetrahydroxy-6,8,3′-trimethoxyflavone.     

Studies on the Constituents of Murraya paniculata (L.) jack Grown in Yunnan

Two flavonoids were isolated from the leaves of Murraya paniculata (L.) Jack. (Rutaceae) grown in Yunnan. On the basis of spectroscopy (UV, IR, NMR and MS) analysis compound A and B were identified as 3,3′,4′,5,5′,7, 8-heptamethoxyflavone (Ⅰ), 3′, 4′ 5, 5′, 7, 8-hexamethoxyflavone (Ⅱ), respectively. The latter, named bannamu- rpanisin, is new natural product. In addition, three known coumarins, meranzin hydrate (Ⅲ), murragatin (Ⅳ) and murpanidin (Ⅴ) were obtained.     

Neolignans from mezilaurus itauba

The wood bark of Mezilaurus itauba afforded in addition to seven known neolignans, three new compounds rel-(7R,8R,1′S,3′S)-Δ^5′,8′-5′-methoxy-3,4-methylenedioxy-1′,2′,3′,4′-tetrahydro-2′,4′-dioxo-7.3′,8.1′-neolignan, rel-(7S,8S,1′S, 2′S, 3′R, 4′S)-Δ^8′-2′,4′-dihydroxy-3,4-methylenedioxy-1′,2′,3′,4′,5′,6′-hexahydro-5′-oxo-7.3′,8.1′-neolignan and rel-(7S,8S)-Δ^8′-6′-hydroxy 5′-methoxy-3,4-methylenedioxy-7·O·2′,8.3′-neolignan. The latter compound has been detected previously in Aniba terminalis. The structures were elucidated by spectroscopic methods and comparison with related compounds.     

Two polymethoxyflavones from Ageratum houstonianum

Besides agecorynin C, eupalestin and lucidin dimethyl ether, two new highly oxygenated flavones were isolated from Ageratum houstonianum. Their structures were established by spectroscopic and degradative evidence as 5, 6, 7, 8, 2′, 3′, 4′, 5′-octamethoxyflavone and 5, 6, 7, 2′, 3′, 4′, 5′-heptamethoxyflavone.     

La 5′-méthoxybilobétine,une biflavone extraite du Ginkgo biloba

A new biflavone, I-5′-methoxybilobetin has been isolated from Ginkgo biloba leaves. ¹H and ¹³C NMR spectral data show that it is a II-4′, I-5, II-5, I-7, II-7-pentahydroxy-I-4′, I-5′-dimethoxy- [I-3′, II-8] biflavone.     

Secondary metabolites from the leaves of the medicinal plant goldenseal (Hydrastis canadensis)

The study presented herein constitutes an extensive investigation of constituents in Hydrastis canadensis L. (Ranunculaceae) leaves. It describes the isolation and identification of two previously unknown compounds, 3,4-dimethoxy-2-(methoxycarbonyl)benzoic acid (1) and 3,5,3′-trihydroxy-7,4′-dimethoxy-6,8-C-dimethyl-flavone (2), along with the known compounds (±)-chilenine (3), (2R)-5,4′-dihydroxy-6-C-methyl-7-methoxy-flavanone (4), 5,4′-dihydroxy-6,8-di-C-methyl-7-methoxy-flavanone (5), noroxyhydrastinine (6), oxyhydrastinine (7) and 4′,5′-dimethoxy-4-methyl-3′-oxo-(1,2,5,6-tetrahydro-4H-1,3-dioxolo-[4′,5′:4,5]-benzo[1,2-e]-1,2-oxazocin)-2-spiro-1′-phtalan (8). Compounds 3–8 have been reported from other sources, but this is the first report of their presence in H. canadensis extracts. A mass spectrometry based assay was employed to demonstrate bacterial efflux pump inhibitory activity against Staphylococcus aureus for 2, with an IC₅₀ value of 180 ± 6 μM. This activity in addition to that of other bioactive compounds such as flavonoids and alkaloids, may explain the purported efficacy of H. canadensis for treatment of bacterial infections. Finally, this report includes high mass accuracy fragmentation spectra for all compounds investigated herein which were uploaded into the Global Natural Products Social molecular networking library and can be used to facilitate their future identification in H. canadensis or other botanicals.     

Three new neolignan glucosides from the stems of Dendrobium aurantiacum var. denneanum

Three new neolignan glucosides (1–3), together with four known analogs (4–7), have been isolated from the stems of Dendrobium aurantiacum var. denneanum. Structures of the new compounds including the absolute configurations were determined by spectroscopic and chemical methods as (−)-(8R,7′E)-4-hydroxy-3,3′,5,5′-tetramethoxy-8,4′-oxyneolign-7′-ene-9,9′-diol 4,9-bis-O-β-d-glucopyranoside (1), (−)-(8S,7′E)-4-hydroxy-3,3′,5,5′-tetramethoxy-8,4′-oxyneolign-7′-ene-9,9′-diol 4,9-bis-O-β-d-glucopyranoside (2), and (−)-(8R,7′E)-4-hydroxy-3,3′,5,5′,9′-pentamethoxy-8,4′-oxyneolign-7′-ene-9-ol 4,9-bis-O-β-d-glucopyranoside (3), respectively.     

Highly oxygenated flavones from Mentha piperita

Six highly oxygenated flavones have been isolated from the leaves of Mentha piperita. Five known compounds, 5-hydroxy-6,7,8,4′-tetramethoxyflavone, 5,4′-dihydroxy-6,7,8-trimethoxyflavone, 5,3′-dihydroxy-6,7,8,4′-tetramethoxyflavone, 5-hydroxy-6,7,8,3′,4′-pentamethoxyflavone and 5,3′,4′-trihydroxy-6,7,8-trimethoxyflavone, are reported for the first time in the genus Mentha. The sixth compound has been identified as 5,6-dihydroxy-7,8,3′,4′-tetramethoxyflavone by UV, NMR and mass spectra.     

Benzofuranoid Neolignans from Piper kadsura

In a continuing research for neolignans from Piper kadsura (Choisy) Ohwi, six benzofuranoid neolignans were isolated from the aerial part of the plant. Their structure determination were based on the spectroscopic analysis (UV, IR, MS, NMR and CD) and derivative synthesis. Three of the isolated compounds were identified as new structures: 7R, 8R, 1′S-△8′-3, 4-methylenedioxy-5′-methoxy-l′, 4′-dihydro-4′-oxo-7, 0, 2′, 8. l′-neolignan ( Ⅰ ), 7 R, 8 R, 1 ′ R- △8′ - 3,4- methylenedioxy- 1 ′- methoxy - 1′,6′- dihydro- 6′- oxo- 7.0.4′,8. 3′-neolignan (Ⅳ) and 7R, 8R, 1′S-△8′-3, 4-methylenedioxy-l′-methoxy-1′,6′-dihydro-6′-oxo-7.0.4′,8.3′-neolignan (Ⅴ). Known compounds among them are 7R, 8S,1′S-△8′-3, 4-methylenedioxy-5′-methoxy-1′, 4′-dihydro-4′-oxo-7. 0. 2′, 8. 1′-neolignan(Ⅱ), 7S, 8S, 1′R-△8′-3, 4, 5′-trimethoxy-1′, 4′-dihydro-4′-oxo-7.0. 2′, 8. 1′-neolignan (Ⅲ) and 75, 85, 1′S-△8′-3, 4, l′-trimethoxy-l′, 6′-dihydro-6′-oxo-7. 0. 4′, 8. 3′-neolignans (Ⅵ). All of them were isolated from the plant for the first time.     

Two new dihydrobenzofuran-type neolignans from Breynia fruticosa

(7S,8R,7′S)-9,7′,9′-Trihydroxy-3,4-methylenedioxy-3′-methoxy [7-O-4′,8-5′] neolignan (1) and (7S,8R,7′S)-9,9′-dihydroxy-3,4-methylenedioxy-3′,7′-dimethoxy [7-O-4′,8-5′] neolignan (2), two new natural dihydrobenzofuran-type neolignans, along with 9,9′-dihydroxy-3,4-methylenedioxy-3′-methoxy [7-O-4′,8-5′] neolignan (3) and (-)-machicendiol (4), were isolated from the whole plants of Breynia fruticosa. The structures of 1 and 2, including the absolute configurations, were determined by spectroscopic methods and circular dichroism (CD) techniques. The absolute configuration of 4 was confirmed by calculations of the OR spectrum, together with OR and ECD spectra of its p-bromobenzoate ester (4a).