Two new dihydrofuranoisoflavanones from the leaves of <Emphasis Type="Italic">Lespedeza maximowiczi</Emphasis> and their inhibitory effect on the formation of advanced glycation end products

Two new dihydrofuranoisoflavanones, 2′,4′,5-trihydroxy-[5″-(1,2-dihydroxy-1-methylethyl)-dihydrofurano(2″,3″:7,8)]-(3S)-isoflavanone (1) and 2′, 4′, 5-trihydroxy-[5″-(1,2-dihydroxy-1-methylethyl)-dihydrofurano(2″,3″:7,8)]-(3R)-isoflavanone (2) as well as one already-known compound, (+)-catechin (3), were isolated from an n-BuOH soluble fraction from the leaves of Lespedeza maximowiczi. Spectroscopic data was used to elucidate the structures of compounds 1 and 2. All of the isolates were evaluated in vitro for their inhibitory activity on the formation of advanced glycation end products (AGEs). Among these, compounds 1, 2, and 3 exhibited inhibitory activity against AGEs formation with IC₅₀ values of 20.6, 18.4, and 5.6 μM, respectively.     

Homoisoflavanones from <Emphasis Type="Italic">Polygonatum odoratum</Emphasis> rhizomes inhibit advanced glycation end product formation

Protein glycation inhibitors from Polygonatum odoratum rhizomes were investigated using a bioassay-guided procedure to characterize active compounds for preventing and treating diabetic complications. The EtOH extract and soluble fractions were evaluated using an in vivo model of renal advanced glycation end-product (AGE) accumulation in streptozotocin-induced diabetic rats and an in vitro bovine serum albumin-glucose assay. Three homoisoflavanones 3-(4′-hydroxybenzyl)-5,7-dihydroxy-6-methyl-8-methoxychroman-4-one (1), 3-(4′-hydroxybenzyl)-5,7-dihydroxy-6,8-dimethylchroman-4-one (2), and 3-(4′-methoxybenzyl)-5,7-dihydroxy-6-methyl-8-methoxychroman-4-one (3), isolated from the active CHCl3-soluble fraction of the EtOH extract, were subjected to in vitro bioassays to evaluate their inhibitory activities against AGE formation. All the isolates inhibited AGE formation more effectively than the positive control, aminoguanidine. These results indicate that pending further study these compounds could be used as novel natural product drug for mitigating diabetic complications.     

A new prenylated dihydrochalcone from the leaves of <Emphasis Type="Italic">Artocarpus lowii</Emphasis>

A new prenylated dihydrochalcone, 2′,4′-dihydroxy-4-methoxy-3′-prenyldihydrochalcone (1), along with two known compounds, 2′,4′,4-trihydroxy-3′-prenylchalcone (2) and 2′,4-dihydroxy-3′,4′-(2,2-dimethylchromene)chalcone (3) were isolated from the leaves of Artocarpus lowii. The structures of 1–3 were elucidated by spectroscopic methods and by comparison with data reported in the literature. Compounds 1–3 showed strong free radical scavenging activity towards 2,2-diphenyl-1-picrylhydrazyl (DPPH) measured by electron spin resonance (ESR) spectrometry.     

A new flavonol glycoside from <Emphasis Type="Italic">Hylomecon vernalis</Emphasis>

Purification of a MeOH extract from the aerial parts of Hylomecon vernalis Maxim. (Papaveraceae) using column chromatography furnished a new acetylated flavonol glycoside (1), together with twenty known phenolic compounds (2–21). Structural elucidation of 1 was based on 1D- and 2D-NMR spectroscopy data analysis to be quercetin 3-O-[4‴-O-acetyl-α-L-arabinopyranosyl]-(1‴→6″)-β-D-galactopyranoside (1). The structures of compounds 2–21 were elucidated by spectroscopy and confirmed by comparison with reported data; quercetin 3-O-[2‴-O-acetyl-α-L-arabinopyranosyl]-(1‴→6″)-β -D-galactopyranoside (2), quercetin 3-O-α-L-arabinopyranosyl-(1‴→6″)-β-D-galactopyranoside (3), quercetin 3-O-β -D-galactopyranoside (4), kaempferol 3,7-O-α-L-dirhamnopyranoside (5), diosmetin 7-O-β -D-glucopyranoside (6), diosmetin 7-O-β -D-xylopyranosyl-(1‴→6″)-β-D-glucopyranoside (7), p-hydroxybenzoic acid (8), protocatechuic acid (9), caffeic acid (10), 6-hydroxy-3,4-dihydro-1-oxo-β -carboline (11), (Z)-3-hexenyl-β -D-glucopyranoside (12), (E)-2-hexenyl-β -D-glucopyranoside (13), (Z)-3-hexenyl-α-Larabinopyranosyl-(1″→6′)-β-D-glucopyranoside (14), oct-1-en-3-yl-α-L-arabinopyranosyl-(1″→6′)-β-D-glucopyranoside (15), benzyl-β-D-apiofuranosyl-(1″→6′)-β-D-glucopyranoside (16), benzyl-α-L-arabinopyranosyl-(1″→6′)-β-D-glucopyranoside (17), benzyl-β-D-xylopyranosyl-(1″→6′)-β-Dglucopyranoside (18), 2-phenylethyl-α-L-arabinopyranosyl-(1″→6′)-β-D-glucopyranoside (19), 2-phenylethyl-β-D-apiofuranosyl-(1″→6′)-β-D-glucopyranoside (20), and aryl-β-D-glucopyranoside (21). Compounds 2-21 were isolated for the first time from this plant. The isolated compounds were tested for cytotoxicity against four human tumor cell lines in vitro using a Sulforhodamin B bioassay.     

Monoterpene glycoside and flavonoids from <Emphasis Type="Italic">Blumea lacera</Emphasis>

The dichloromethane extract of air-dried leaves of Blumea lacera (Asteraceae) afforded α-pinene-7β-O-β-d-2,6-diacetylglucopyranoside (1), 5,4′-dihydroxy-6,7,3′-trimethoxyflavone (2), and 3,5,4′-trihydroxy-6,7,3′-trimethoxyflavone (3). Compounds 1–3 showed moderate activity against Candida albicans, low activity against Trichophyton mentagrophytes, and were inactive against Aspergillus niger. Compounds 1 and 3 indicated low activity against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus and were inactive against Bacillus subtilis, while 2 was inactive against all four bacteria tested.     

Phenylpropanoid glycosides from <Emphasis Type="Italic">Heterosmilax erythrantha</Emphasis> and their antioxidant activity

By various chromatographic methods, one new phenylpropanoid glycoside, heterosmilaside (1), two known phenylpropanoid glycosides, helonioside B (2), and 2′,6′-diacetyl-3,6-diferuloyl sucrose (3), and three known flavonoids, isoquercetin (4), quercetin-3-O-β-D-glucuronopyranoside (5), and quercetin-3-O-(2″-α-L-rhamnopyranosyl)-β-D-glucuronopyranoside (6) were isolated from the methanolic extract of the aerial part of Heterosmilax erythrantha Baill. Their structures were elucidated on the basis of spectroscopic analyses. All the isolated compounds were tested for antioxidant activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay. Among them, compounds 5 and 6 showed significant antioxidant activity with SC₅₀ values of 3.7 and 6.5 μg/mL, respectively.     

New flavonoids with 2BS cell proliferation promoting effect from the seeds of <Emphasis Type="Italic">Trigonella foenum</Emphasis>-<Emphasis Type="Italic">graecum</Emphasis> L.

Ten flavonoids were isolated from the ethyl acetate-soluble fraction of the ethanolic extract of the seeds of Trigonella foenum-graecum and their structures were elucidated on the basis of spectroscopic methods to be 5,7,3′-trihydroxy-5′-methoxylisoflavone (1), biochanin A (2), formononetin (3), irilone (4), tricin (5), daidzein (6), calycosin (7), orientin-2″-O-p-trans-coumarate (8), vitexin-2″-O-p-trans-coumarate (9), and tricin-7-O-β-d-glucopyranoside (10). Compounds 1 and 8 are new flavonoids, and 8 and 9 strongly promoted 2BS cell proliferation induced by H₂O₂.     

New glycosides from <Emphasis Type="Italic">Dracocephalum tanguticum</Emphasis> maxim

Four new glycosides, luteolin-7-methoxy-3′-O-(3″-O-acetyl)-β-D-gluco pyranuronic acid-6″-methyl ester (1), benzyl-6-[(2E)-2-butenoate]-β-D-glucopyranoside (2), 2-methoxy-4-(2-propen-1-yl)penyl-6-acetate-β-D-glucopyranoside (3), and 2-methoxy-4-(2-propen-1-yl)penyl-6-[(2E)-2-butenoate]-β-D-glucopyranoside (4), along with benzyl-β-D-glucopyranoside (5), 2-methoxy-4-(2-propen-1-yl)penyl-β-D-glucopyranoside (6), and pectolarigenin (7), were isolated from the whole plant of Dracocephalum tanguticum Maxim. The structures of 1-4 were elucidated by detailed spectroscopic analyses, including HR-ESI-MS and 2D NMR spectroscopic data. The inhibitory effects against nitric oxide production in LPS-stimulated RAW264.7 cells of all seven compounds were also evaluated.     

Phenolic constituents of <Emphasis Type="Italic">Acorus gramineus</Emphasis>

The purification of a MeOH extract from the rhizome of Acorus gramineus (Araceae) using column chromatography furnished two new stereoisomers of phenylpropanoid, acoraminol A (1) and acoraimol B (2). It also furnished 17 known phenolic compounds, β-asarone (3), asaraldehyde (4), isoacoramone (5), propioveratrone (6), (1′R,2′S)-1′,2′-dihydroxyasarone (7), (1′S,2′S)-1′,2′-dihydroxyasarone (8), 3′,4′-dimethoxycinnamyl alcohol (9), 3′,4′,5′-trimethoxycinnamyl alcohol (10), kaempferol 3-methyl ether (11), 2-[4-(3-hydroxypropyl)-2-methoxyphenoxy]-1,3-propanediol (12), hydroxytyrosol (13), tyrosol (14), (2S,5S)-diveratryl-(3R,4S)-dimethyltetrahydrofuran (15), (7S,8R)-dihydrodehydrodiconiferyl alcohol (16), 7S,8S-threo-4,7,9,9′-tetrahydroxy-3,3′-dimethoxy-8-O-4′-neolignan (17), 7S,8R-erythro-4,7,9,9′-tetrahydroxy-3,3′-dimethoxy-8-O-4′-neolignan (18), and dihydroyashsbushiketol (19). The structures of the new compounds were elucidated by analysis of spectroscopic data including 1D and 2D NMR data. The absolute configurations of 1 and 2 were determined using the convenient Mosher ester procedure. Compounds 5–19 were isolated for the first time from this plant source. The isolated compounds were tested for cytotoxicity against four human tumor cell lines in vitro using a Sulforhodamine B (SRB) bioassay.     

Anthraquinones from the Roots of <Emphasis Type="Italic">Knoxia valerianoides</Emphasis> inhibit the formation of advanced glycation end products and rat lens aldose reductase <Emphasis Type="Italic">in vitro</Emphasis>

Eight known compounds, lucidin (1), lucidin-ω-methyl ether (2), rubiadin (3), damnacanthol (4), 1,3,6-trihydroxy-2-methoxymethylanthraquinone (5), 3,6-dihydroxy-2-hydroxymethyl-9,10-anthraquinone (6), 1,3,6-trihydroxy-2-hydroxymethyl-9,10-anthraquinone 3-O-β-primeveroside (7), and vanillic acid (8), were isolated from EtOAc- and n-BuOH-soluble fractions of the roots of Knoxia valerianoides. The structures of 1–8 were identified by analysis of spectroscopic data as well as by comparison with published values. All the isolates were subjected to in vitro bioassays to evaluate advanced glycation end products (AGEs) formation and rat lens aldose reductase (RLAR) inhibitory activity. Compound 5 showed the most potent inhibitory activity (IC₅₀ = 52.72 μM) against AGEs formation. Compounds 1, 2, and 8 also showed potent inhibitory activity on AGEs formation with IC₅₀ values of 79.28, 62.79, and 93.93 μM, respectively, compared with positive control, aminoguanidine (IC₅₀ = 962 μM). While, compounds 1 and 5–7 showed strong inhibitory activity against RLAR with IC₅₀ values of 3.35, 3.04, 6.39, and 2.05 μM, respectively.     

Deuteromycols A and B,two benzofuranoids from a Red Sea marine-derived <Emphasis Type="Italic">Deuteromycete</Emphasis> sp.

Two benzofuranoids, deuteromycol A, 6,7-dihydroxy-2-[1′-hydroxy-(1′→5″)-2″,3″,4″-trihydroxy-2″,3″-dihydropyran]benzofuran and deuteromycol B, 1-(6,7-dihydroxy benzofuran-2-yl)methyl acetate have been isolated from the ethanol extract of the marine-derived fungal strain MF 003 (Deuteromycete) obtained from Red Sea mangrove drift wood. Deuteromycols A and B contain a catecholic nucleus that to the best of our knowledge is unusual in association with marine fungi secondary metabolites. Structures were established on the basis of extensive 1D-and 2D-NMR spectroscopic studies as well as on mass spectrometric analysis. Besides, the extracts exhibited in vitro antibacterial activity.     

Five new glycosides from <Emphasis Type="Italic">Hypericum erectum</Emphasis> Thunb.

Five new glycosides, quercetin 3′-O-β-d-galactopyranoside (1), quercetin 3-O-(2″-acetyl)-β-d-glucopyranoside (2), 4,6-dihydroxy-2-methoxyphenyl 1-O-β-d-glucopyranoside (3), 4-hydroxy-2,6-dimethoxyphenyl 1-O-α-l-rhamnopyranosyl (1 → 6)-β-d-glucopyranoside (4) and 3-methyl-but-2-en-1-yl β-d-glucopyranosyl (1 → 6)-β-d-glucopyranoside (5), were isolated from Hypericum erectum Thunb. Their structures were established on the basis of spectral and chemical data.     

Iridoid glucoside, (3<Emphasis Type="Italic">R</Emphasis>)-oct-1-en-3-ol glycosides,and phenylethanoid from the aerial parts of <Emphasis Type="Italic">Caryopteris incana</Emphasis>

Eleven compounds of interest were isolated from the aerial parts of Caryopteris incana, specifically a new acyl derivative (3) of 8-O-acetylharpagide, two new (3R)-oct-1-en-3-ol glycosides (5, 6), and 6-O-caffeoylphlinoside A (11) along with seven known compounds, 8-O-acetylharpagide (1), 6′-O-p-coumaroyl-8-O-acetylharpagide (2), (3R)-oct-1-en-3-ol (matsutake alcohol) O-α-l-arabinopyranosyl-(1″ → 6′)-O-β-d-glucopyranoside (4), apigenin 7-O-neohesperidinoside (7), 6′-O-caffeoylarbutin (8), and two phenylethanoids, leucosceptoside A (9) and phlinoside A (10). This paper deals with structural elucidation of the new compounds.     

New isoflavone glycosides from <Emphasis Type="Italic">Iris spuria</Emphasis> L. (Calizona) cultivated in Egypt

Two new isoflavone glycosides, tectorigenin 7-O-β-d-glucopyranoside-4′-O-[β-d-glucopyranosyl-(1″″ → 6′′′)-β-d-glucopyranoside] (1) and iristectorigenin B 4′-O-[β-d-glucopyranosyl-(1′′′ → 6″)-β-d-glucopyranoside] (2), together with 11 known compounds, including six isoflavones, tectorigenin 7-O-β-d-glucopyranoside-4′-O-β-d-glucopyranoside (3), tectorigenin 4′-O-[β-d-glucopyranosyl-(1′′′ → 6″)-β-d-glucopyranoside] (4), tectorigenin 7-O-β-d-glucopyranoside (5), genistein 7-O-β-d-glucopyranoside (6), tectorigenin 4′-O-β-d-glucopyranoside (7), and tectorigenin (8); two phenolic acid glycosides, vanillic acid 4-O-β-d-glucopyranoside (9) and glucosyringic acid (10); a phenylpropanoid glycoside, E-coniferin (11); an auronol derivative, maesopsin 6-O-β-d-glucopyranoside (12); and a pyrrole derivative, 4-(2-formyl-5-hydroxymethylpyrrol-1-yl) butyric acid (13), were isolated from fresh Iris spuria (Calizona) rhizomes. The structures of these compounds were established on the basis of spectroscopic and chemical evidence. Inhibitory effects on the activation of Epstein–Barr virus early antigen were examined for compounds 1–8 and 12.     

Studies on the constituents from the fruits of <Emphasis Type="Italic">Phaleria macrocarpa</Emphasis>

From the fruits of Phaleria macrocarpa, icariside C₃ (1), phalerin (2), and mangiferin (3) were isolated and their structures were identified on the basis of spectroscopic data. Icariside C₃ (1) showed a slow vasorelaxant activity against noradrenaline-induced contraction of isolated rat aorta. The structure of phalerin (2) was revised as 2,4′,6-trihydroxy-4-methoxybenzophenone-2-O-β-d-glucoside.     

Prenylated flavones from <Emphasis Type="Italic">Artocarpus altilis</Emphasis>

Six prenylated flavones, including one new compound, were isolated and identified from the stem bark extracts of Artocarpus altilis. The new prenylated flavone hydroxyartocarpin (1) was characterized as 3-(γ,γ-dimethylallyl)-6-isopentenyl-5,8,2′,4′-tetrahydroxy-7-methoxyflavone and the known compounds were artocarpin (2), morusin (3), cycloartobiloxanthone (4), cycloartocarpin A (5) and artoindonesianin V (6). The structures of the compounds were determined by spectroscopic methods (IR, MS, ¹H-NMR and ¹³C-NMR) and comparison with published data for the known compounds.     

A new phenylpropane glycoside from the rhizome of <Emphasis Type="Italic">Sparganium stoloniferum</Emphasis>

The purification of the MeOH extract from the rhizome of Sparganium stoloniferum Buch.-Hamil. (Sparganiaceae) using column chromatography furnished one new phenylpropanoid glycoside (7) and known phenolic compounds (1–6, and 8–13). The structural elucidation of 7 was based on 1D- and 2D-NMR spectroscopic data analysis to be β-d-(6-O-trans-feruloyl) fructofuranosyl-α-d-O-glucopyranoside. Compounds 1–6, and 8–13 were elucidated by spectroscopy and confirmed by comparison with reported data; 24-methylenecycloartanol (1), p-hydroxybenzaldehyde (2), ferulic acid (3), p-coumaric acid (4), vanillic acid (5), β-d-(1-O-acetyl-3-O-trans-feruloyl)fructofuranosy-α-d-2′,4′,6′.-O-triacetyglucopyranoisde (6), β-d-(1-O-acetyl-3,6-O-trans-diferuloyl)fructofuranosyl-β-d-2′,4′,6′.-O-triacetylglucopyranoisde (8), hydroxytyrosol acetate (9), hydroxytyrosol (10), isorhamnetin-3-O-rutinoside (11), n-butyl-α-d-fructofuranoside (12), and n-butyl-β-d-fructopyranoside (13). Compounds 3 and 9–13 were isolated for the first time from this plant. The isolated compounds were tested for cytotoxicity against four human tumor cell lines in vitro using a Sulforhodamin B bioassay.     

Prenylated xanthones from <Emphasis Type="Italic">Hypericum ascyron</Emphasis>

Three new prenylated xanthones, 1,3,5-trihydroxy-6,7-[2′-(1-methylethenyl)-dihydrofurano]-xanthone (1), 1,3,5-trihydroxy-6,7-[2′-(1-hydroxy-1-methylethyl)-dihydrofurano]-xanthone (2), and 1,3,5-trihydroxy-6-O-prenyl-xanthone (3), together with eight known compounds were isolated from the leaves of Hypericum ascyron. Compound 3 has an O-prenyl moiety, and therefore represents the first reported xanthone to have an O-prenyl moiety from genus Hypericum. The structures of the isolated compounds were established based on spectroscopic data and on a comparison with values for previously identified analogues.     

Lignans from the flowers of <Emphasis Type="Italic">Osmanthus fragrans</Emphasis> var. <Emphasis Type="Italic">aurantiacus</Emphasis> and their inhibition effect on NO production

A new lignan, (7R,7′R,8R,8′R)-8-hydroxypinoresinol 8-O-β-D-glucopyranoside 4′-methyl ether (7), was isolated from the flowers of Osmanthus fragrans var. aurantiacus along with six known lignans: (+)-phillygenin (1), phillyrin (2), (−)-phillygenin (3), (−)-epipinoresinol-β-D-glucoside (4), taxiresinol (5), and (−)-olivil (6). The structure of the new compound was elucidated on the basis of 1D- and 2D-NMR spectroscopic analysis and specific rotation data. The compounds isolated from the flowers of O. fragrans var. aurantiacus were evaluated for inhibitory activities on nitric oxide production in lipopolysaccharide-stimulated macrophage RAW 264.7 cells. (+)-Phillygenin (1), phillyrin (2), and (−)-phillygenin (3) exerted the strongest inhibitory activities on NO production with IC₅₀ values of 25.5, 18.9, and 25.5 μM, respectively. These compounds may prove beneficial in the development of natural agents for prevention and treatment of inflammatory diseases.     

Cholinesterase inhibitors from <Emphasis Type="Italic">Cleistocalyx operculatus</Emphasis> buds

Five flavonoids, myricetin-3′-methylether 3-O-β-d-galactopyranoside (1), myricetin-3′,5′-dimethylether 3-O-β-d-galactopyranoside (2), quercetin (3), kaempferol (4), and tamarixetin (5) were isolated from the buds of Cleistocalyx operculatus (Myrtaceae). The chemical structures of these compounds were determined on the basis of spectroscopic analyses, including 2D NMR. Their anti-Alzheimer effects were evaluated via acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activity assays. All five compounds 1–5 showed potential inhibitory activities against AChE with IC₅₀ values of 19.9, 37.8, 25.9, 30.4 and 22.3 μM, respectively, while compounds 1, 3, 4 and 5 also possessed BChE inhibitory activity with IC₅₀ values of 152.5, 177.8, 62.5, and 160.6 μM, respectively.