Studies on the chemical constituents of Eucalyptus robusta Sm.: Isolation and identification of robustaol B and other constituents

Nine known compounds, 5-hydroxy-4′,7-dimethoxy-6,8-dimethylflavone, 4′,5-dihydroxy-7-methoxy-6,8-dimethylflavone, 3β-hydroxy-urs-11-ene-28-oic-13(28)-lactone, 3β-acetoxy-urs-11-ene-28-oic-13(28)-lactone, uvaol, β-sitosterol, 7β-O-glucoside of 5,7-dihydroxy-2-methylchromone, 1-triacontanol and 1-triacontanoic acid, and a new acylphloroglucinol named robustaol B 6 were isolated from the leaves of Eucalyptus robusta Sm. 6 was shown to be 4,6-dihydroxy-2-methoxy isobutyrophenone by spectral analyses and was confirmed by synthesis. 6 showed inhibition against Staphylococcus aureus 209P and Bacillus subtilis 6633 in vitro.     

Carbon-13 n.m.r. studies of flavanone 5,3′,4′-trihydroxy-7β-glucoside from Juelia subterranea (Balanophoraceae)

The complete structure and stereochemical elucidation of flavanone 5,3′,4′-trihydroxy-7β-glucoside has been achieved by the aid of ¹³C n.m.r.     

Separation of nine compounds from Salvia plebeia R.Br. using two‐step high‐speed counter‐current chromatography with different elution modes

Nine compounds were successfully separated from Salvia plebeia R.Br. using two‐step high‐speed counter‐current chromatography with three elution modes. Elution–extrusion counter‐current chromatography was applied in the first step, while classical counter‐current chromatography and recycling counter‐current chromatography were used in the second step. Three solvent systems, n‐hexane/ethyl acetate/ethanol/water (4:6.5:3:7, v/v), methyl tert‐butyl ether/ethyl acetate/n‐butanol/methanol/water (6:4:1:2:8, v/v) and n‐hexane/ethyl acetate/methanol/water (5:5.5:5:5, v/v) were screened and optimized for the two‐step separation. The separation yielded nine compounds, including caffeic acid ( 1 ), 6‐hydroxyluteuolin‐7‐glucoside ( 2 ), 5,7,3′,4′‐tetrahydroxy‐6‐methoxyflavanone‐7‐glucoside ( 3 ), nepitrin ( 4 ), rosmarinic acid ( 5 ), homoplantaginin ( 6 ), nepetin ( 7 ), hispidulin ( 8 ), and 5,6,7,4′‐tertrahydroxyflavone ( 9 ). To the best of our knowledge, 5,7,3′,4′‐tetrahydroxy‐6‐methoxyflavanone‐7‐glucoside and 5,6,7,4′‐tertrahydroxyflavone have been separated from Salvia plebeia R.Br. for the first time. The purities and structures of these compounds were identified by high‐performance liquid chromatography, electrospray ionization mass spectrometry, ¹H and ¹³C NMR spectroscopy. This study demonstrates that high‐speed counter‐current chromatography is a useful and flexible tool for the separation of components from a complex sample.     

Studies on the constituents of Anaxagorea luzonensis A. GRAY

Five new xanthones, 1,3,6-trihydroxy-5-methoxy-4-prenylxanthone (1), 1,3,5-trihydroxy-6-methoxy-2-prenylxanthone (2), 1,3,5-trihydroxy-4-(3-hydroxy-3-methylbutyl) xanthone (3), 1,3,6-trihydroxy-4-prenylxanthone (4), 3,6-dihydroxy-1,5-dimethoxyxanthone (5) and one new flavonoid, 3,5,7,4'-tetrahydroxy-2'-methoxyflavone (6) along with seven known xanthones and seven known flavonoids were isolated from the bark of Anaxagorea luzonensis A. GRAY and their chemical structures were determined by means of chemical and spectral studies. Almost all flavonoids and one xanthone (13) showed antioxidant activity.     

Protogenkwanin 4′-glucoside,a new type of natural flavonoid with a non aromatic B-ring

From fertile sprouts of $\text{Equisetum arvense}$ L. (Equisetaceae) a flavonoid has been isolated and called protogenkwanin 4′-glucoside (2-(4-β-D-glucosyloxy-1-hydroxy-2,5-cyclohexadienyl)-5-hydroxy-7-methoxy chromone). Its structure has been established on the basis of chemical and spectroscopical evidences.     

Identification de xanthones et de nouveaux arabinosides de C-glucosides flavoniques dans Swertia perennisL.

Identification of xanthones and new arabinosides of flavone C-glucosides from Swertia perennis L. – Seven tetraoxygenated xanthones [1,3,7,8-tetrahydroxy-xanthone ( 1 ); 1,8-dihydroxy-3,7-dimethoxy-xanthone ( 2 ); 1,7-dihydroxy-3,8-dimethoxy-xanthone ( 3 ); 1-hydroxy-3,7,8-trimethoxy-xanthone ( 4 ); 3,7,8-trihydroxy-xanthone-xanthone-1-0-β-glucoside ( 5 ); 3,7,8-trimethoxy-xanthone-1-0-primeveroside ( 6 ); 8-hydroxy-3,7-dimethoxy-xanthone-1-0-primeveroside ( 7 )] have been isolated chromatographically, using polyamide columns, from roots of Swertia perennis L . From leaves and stems of the same plant, six xanthones [1,5,8-trihydroxy-3-methoxy-xanthone ( 8 ); 1,5-dihydroxy-3-methoxy-xanthone-8-0-β-glucoside ( 9 ); mangiferin ( 10 ); 1 ; 4 ; 5 ] and four flavone C-glycosides [iso-orientin ( 11 ); isovitexin ( 12 ); iso-orientin-6″-arabinoside ( 13 ); isovitexin-6″-arabinoside ( 14 )] have also been isolated. Among these compounds, 7 , 13 and 14 were not encountered before in nature. In the last two compounds, the position of arabinose on the C-glucoside moiety of the flavone was established by ¹³C-NMR. spectroscopy.     

Flavonoids of the rhizomes ofRhodiola rosea. I. Tricin glucosides

Gallic acid and the flavonoid tricin (4′,5,7-trihydroxy-3′,5′-dimethoxyflavone) and its 7- and 5-O glucosides have been isolated for the first time from the rhizomes ofRhodiola rosea L. Identification was made on the basis of UV, IR, PMR, and mass spectra of the initial substances and the products of their acid hydrolysis and acetylation. The physicochemical constants, not previously given in the literature, of the 5-O-β-D-glucopyranoside have been determined.     

新疆雪莲化学成分的研究(Ⅰ)

从新疆雪莲中首次得到五种结晶,经鉴定晶Ⅰ为槲皮素,晶Ⅱ为4′,5,7,-三羟基-3′,6-二甲氧基黄酮,晶Ⅲ为高车前素,晶Ⅳ结构待定,晶Ⅴ为芦丁。     

Synthesis of a New Naturally Occurring 3-Phenyl-4H-1-Benzopyran-4-One

7-Hydroxy-8-methoxy-3-(3,4-methylenedioxyphenyl)-4H-1-benzopyran-4-one (1), a new isoflavone reported to occur in the aerial parts and roots of Tephrosia maxima has been synthesized by the oxidative rearrangement of 2′-hydroxy-3′-methoxy-4′-benzyloxy-3,4-methylenedioxychalcone (4) with thallium (III) nitrate (TTN) in trimethyl orthoformate (TMOF), followed by acid catalysed cyclization and debenzylation. It has also been synthesized by another method from 2,3,4-trihydroxy-3,4′-methylenedioxydeoxybenzoin; the hitherto unknown biisoflavone, 7,7′-dimethoxy-3′,4″,3″,4″-dimethylenedioxy-8,8′-biisoflavonyl ether was also formed during this method.     

Two new xanthones from the pericarp of Garcinia mangostana

Two new xanthones, designated garcimangosxanthone F (1) and garcimangosxanthone G (2), were isolated from the EtOAc-soluble fraction of ethanolic extract from the pericarp of Garcinia mangostana. Their structures were established as 1,6,7-trihydroxy-5-(3-methylbut-2-enyl)-8-(3-hydroxy-3-methylbutyl)-6′,6′-dimethylpyrano[2′,3′:3,2]xanthone and 1,6,7-trihydroxy-5-(3-methylbut-2-enyl)-8-(3-hydroxy-3-methylbutyl)-6′,6′-dimethyl-4′,5′-dihydropyrano[2′,3′:3,2]xanthone, respectively, on the basis of their 1D, 2D NMR and MS data interpretation.     

Synthetic transformations of isoquinoline alkaloids. Synthesis of 1-halo derivatives of <Emphasis Type="Italic">endo</Emphasis>-ethenotetrahydrothebaine and their behavior in the heck reaction

Bromination of endo-ethenotetrahydrothebaine derivatives having a pyrrolidine ring fused at the C⁷-C⁸ bond, namely 1′-substituted 4,5α-epoxy-6α,14-etheno-3,6-dimethoxy-17-methyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]morphinan-2′,5′-diones, 1′-aryl-4,5α-epoxy-6α,14-etheno-3,6-dimethoxy-17-methyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]morphinans, and 4,5α-epoxy-6α,14-etheno-2′α-hydroxy-3,6-dimethoxy-17-methyl-1′-phenyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]morpphinan-5′-one, with molecular bromine in formic acid smoothly afforded the corresponding 1-bromo derivatives. Iodination of 4,5α-epoxy-6α,14-etheno-3,6-dimethoxy-17-methyl-1′-phenyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]-4,5α-epoxy-6α,14-etheno-3,6-dimethoxy-17-methyl-1′-phenyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]-morphinan-2′,5′-dione with iodine(I) chloride gave 4,5α-epoxy-6α,14-etheno-1-iodo-3,6-dimethoxy-17-methyl-1′-phenyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]morphinan-2′,5′-dione. The resulting 1-halo derivatives were brought into the Heck reaction with acrylic acid esters to obtain 1-[(E)-2-(alkoxycarbonyl)ethenyl]-substituted compounds. Demethylation of the 6-methoxy group in 1-bromo-endo-ethenotetrahydrothebaines was accomplished using boron(III) bromide in chloroform.     

A new flavonoid from Cudrania cochinchinensis

Chemical investigation of the ethanol extract of the roots of Cudrania cochinchinensis led to the isolation of a new flavonoid, (6S,12S,13R)-1-methoxy cyanomaclurin (1), together with seven known compounds, 1,3,5-trihydroxy-4-(3′-hydroxy-3′-methylbutyl)xanthone (2), 1,3,6-trihydroxy-4-prenylxanthone (3), 1,3,6,7-tetrahydroxyxanthone (4), 1,3,5,6-tetrahydroxyxanthone (5), 1,3,6-trihydroxy-5-methoxyxanthone (6), resveratrol (7) and oxyresveratrol (8). The structure of compound 1 was elucidated on the basis of 1D and 2D NMR spectra and the HR-ESI-MS data. The absolute stereochemistry was deduced via Rh₂(OCOCF₃)₄-induced CD and NOESY spectra.     

Five-membered 2,3-dioxo heterocycles: LXII. Reaction of 3-aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones with N,N′-dihydroxycyclohexane-1,2-diamine. Unusual rearrangement in the spiro[quinoxaline-2,2′-pyrrole] system

3-Aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones reacted with N,N′-dihydroxycyclohexane-1,2-diamine to give 3-aroyl-1′,4,4′-trihydroxy-1-(2-hydroxyphenyl)-4a′,5′,6′,7′,8′,8a′-hexahydro-1′H-spiro[pyrrole-2,2′-quinoxaline]-3′,5(1H,4′H)-diones which underwent rearrangement into 1′-aroyloxy-4,4′-dihydroxy-1-(2-hydroxyphenyl)-4a′,5′,6′,7′,8′,8a′-hexahydro-1′H-spiro[pyrrolidine-2,2′-quinoxaline]3′,4,5(4′H)-triones via [1,4]-migration of the aroyl group. The product structure was proved by X-ray analysis.     

New Flavone C-Glycosides from Scleranthus perennis and Their Anti-Collagenase Activity

Three new flavone glycosides, one known flavone glycoside, and the phenolic derivative apiopaenonside were isolated and identified from the ethyl acetate fraction of the aerial parts of Scleranthus perennis. The planar structures were elucidated through extensive analysis of UV-Vis, IR, and ¹H NMR and ¹³C NMR spectral data, including the 2D techniques COSY, HSQC, and HMBC, as well as ESI mass spectrometry. The isolated compounds were established as 5,7,3′-trihydroxy-4′-acetoxyflavone-8-C-β-d-xylopyranoside-2′′-O-glucoside (1), 5,7,3′-trihydroxy-4′-methoxyflavone-8-C-β-d-xylopyranoside-2′′-O-glucoside (2), 5,7-dihydroxy-3′-methoxy-4′-acetoxyflavone-8-C-β-d-xylopyranoside-2′′-O-glucoside (3), 5,7-dihydroxy-3′-methoxy-4′-acetoxyflavone-8-C-β-d-xylopyranoside-2′′-O-(4′′′-acetoxy)-glucoside (4), and apiopaenonside (5). Moreover, all isolated compounds were evaluated for anti-collagenase activity. All compounds exhibited moderate inhibitory activity with IC₅₀ values ranging from 36.06 to 70.24 µM.     

Phytochemical investigation on Myristica fragrans stem bark

Myristica fragrans Houtt., the source of very important spice ‘nutmeg’ used world over is native to India, Indonesia, Sri Lanka, South Africa and Southeast Asia. Phytochemical investigation of M. fragrans stem bark led to the isolation of bis-aryl dimethyl tetrahydrofuran lignans, such as grandisin [(7S,8S,7′S,8′S)-3,3′,4,4′,5,5′-hexamethoxy-7,7′,8,8′-lignan] and (7S,8S,7′R,8′R)-3,3′,4,4′,5,5′-hexamethoxy-7,7′,8,8′-lignan along with important lignans and neolignans, licarinA, licarin B, odoratisol A, (2S, 3R)-7-methoxy-3-methyl-5-((E)-prop-1-enyl)-2-(5-methoxy,3,4-methylenedioxyphenyl)-2,3-dihydrobenzofuran, elemicin, fragransin B₁, raphidecursinol B, erythro-(7S,8R)-Δ^8′-4,7-dihydroxy-3,5,3′-trimethoxy-8-O-4′-neolignan, erythro-(7S,8R)-Δ⁸′-7-hydroxy-3,4,3′,5′-tetramethoxy-8-O-4′-neolignan, surinamensin.and β-sitosterol. Structures of the 12 compounds isolated were unambiguously identified by various spectroscopic methods. The former two compounds were isolated from M. fragrans for the first time. Furthermore, the X-ray crystal structure of odoratisol A is reported in this paper for the first time.     

Preparative separation of six coumarins from the pummelo (Citrus maxima (Burm.) Merr. Cv. Shatian Yu) peel by high-speed countercurrent chromatography

In this work, six coumarins, including two new ones, 8-(3-hydroxy-2,2-dimethylpropyl)-7-methoxy-2H-chromen-2-one (2) and 5-[(7′,8′-dihydroxy-3′,8′-dimethyl-2-nonadienyl)oxy] psoralen (4), as well as four known ones, 5-[(6′,7′-dihydroxy-3′,7′-dimethyl-2-octenyl) oxy] psoralen (1), marmin (3), epoxybergamottin (5), and aurapten (6) were successfully separated from the crude extract of pummelo (Citrus maxima (Burm.) Merr. Cv. Shatian Yu) peel by high-speed countercurrent chromatography in a single run with petroleum-ether–ethyl acetate–methanol–water (4:6:6:4, v/v). The structures of these six coumarins were elucidated by ESI-MS, extensive 1D and 2D NMR spectroscopy.     

New Monoterpene-Substituted Dihydrochalcones from Piper aduncum

Five New unusual monoterpene-substituted dihydrochalcones, the adunctins A–E (1″S)-1-{2′-hydroxy-4′-methoxy-6′-[4″-methyl-1″-(1?-methylethyl)cyclohex-3″ -en-1″ -yloxy]phenyl}-3-phenylpropan-1-one ( 1 ), (5aR*,8R*,9aR*)-3-phenyl-1-[5′,8′,9′,9′a-tetrahydro-3′-hydroxy-1′-methoxy-8′-(1″-methylethyl)-5′-a-methyldibenzo-[b,d]furan-4′-yl]propan-1-one ( 2 ), (2′R*,4″S*)-1-{6′-hydroxy-4′-methoxy-4″-(1?-methylethyl)spiro[benzo[b]-furan-2′(3′H),1″ -cyclohex-2″ -en]-7′-yl}-3-phenylpropan-1-one ( 3 ), (2′R*,4″R*)-1-{6′-hydroxy-4′-methylethyl-4″-(1?-methylethyl)spiro[benzo[b]furan-2′(3′H),1″-cyclohex-2″-en]-7′-yl}-3-phenypropan-1-one ( 4 ), and (5′aR*,6′S*, 9′R*,9′aS*)-1-[5′a,6′,7′,8′,9′a-hexahydro-3′,6′-methoxy-6′-methyl-9′-(1″-methylethyl)dibenzo[b,d]-furan-4′-yl]-3-phenylpropan-1-one ( 5 ) were isolated from the leaves of Piper aduncum (Piperaceae) by preparative liquid chromatography. In addition, (?)-methyllindaretin ( 6 ), trans-phytol, and α-tocopherol ( = vitamin E) were also isolated and identified. The structures were elucidated by spectroscopic methods, including 1D- and 2D-NMR spectroscopy as well as single-crystal X-ray diffraction analysis. The antibacterial and cytotoxic potentials of the isolates were also investigated.     

Mass spectral fragmentation pattern of 2,2′-Bipyridyls. Part IX. 6-Alkoxy-2,2′-bipyridyls

The mass spectral fragmentation patterns of 6-methoxy-, 6-ethoxy- and 6-propoxy-2,2 ′-bipyridyls are reported. The base peaks in the spectra of both the 6-methoxy and 6-ethoxy compounds are due to the M-lion of 6-methoxy-2,2′-bipyridyl, while the base peak with 6-propoxy-2,2- bipyridyl is due to a species formed by loss of C₃H₆ from the molecular ion.     

Synthesis of uvaretin,an antitumour and antimicrobial flavonoid

The flavonoid uvaretin (1-(2,4-di-hydroxy-6-methoxy-3-((2-hydroxy phenyl)-methyl)-phenyl)-3-phenyl-1-propanone), known to be active against some tumours and several bacteria, has been synthesized in six steps from 2′,4′,6′-trimethoxyacetophenone, 2-hydroxybenzaldehyde and benzaldehyde.     

Physical and chemical properties of hydroxyflavones. IV. Infrared absorption spectra of dihydroxyflavones containing the 5-hydroxyl group

Solid state infrared curves (O-H and C-H stretching region) are given for 5, n-dihydroxyflavones, where n is 2′, 3′, 4′, 6, 7 and 8. In chloroform solution spectra of 3,5-dihydroxyflavone and 3-hydroxy-5-methoxyflavone, the 3-OH stretching band appears at 3400 and 3334 cm^?1, respectively, indicative of a stronger hydrogen bond in the latter substance. Solid state and solution carbonyl bands are presented for twenty-six flavone derivatives which contain a hydroxyl, methoxyl or acetoxyl group at the 5-position. The solution spectra (dioxane or carbon tetrachloride) of fourteen flavone derivatives containing a free 5-hydroxyl group show carbonyl bands at 1655±2 cm^?1. Eleven flavones in which the 5-hydroxyl is blocked (carbon tetrachloride solution) give spectra with flavone carbonyl bands at 1653±3 cm^?1. The high resolution chloroform solution spectrum of 3, 5-dihydroxyflavone possesses a multi-peaked carbonyl band with midpoint at 1641 cm^?1. The chloroform solution spectrum of 3-hydroxy-5-methoxyflavone has a very strong band at 1616 cm^?1, with shoulder at 1646 cm^?1. Spectral data of this and a previous paper support the postulate that in 4′-hydroxyflavone the flavone carbonyl oxygen is the donor atom in an intermolecular hydrogen bond. Certain details of synthesis, and analytical data, are given for 3, 5-dihydroxyflavone.