Two New Chromone Glycosides from the Roots of Saposhnikovia divaricata

Five chromone glycosides were isolated from the water‐soluble portions of 70% EtOH extract of the roots of Saposhnikovia divaricata, including two new chromone glycosides 1 and 2 . The structures of the chromone glycosides were identified as (3′S)‐3′‐O‐β‐d ‐apiofuranosyl‐(1 → 6)‐β‐d ‐glucopyranosylhamaudol ( 1 ), (2′S)‐4′‐O‐β‐d ‐apiofuranosyl‐(1 → 6)‐β‐d ‐glucopyranosylvisamminol ( 2 ), 3′‐O‐glucopyranosylhamaudol ( 3 ), 4′‐O‐β‐d ‐glucopyranosylvisamminol ( 4 ), and 4′‐O‐β‐d ‐glucopyranosyl‐5‐O‐methylvisamminol ( 5 ) on the basis of extensive spectroscopic methods, and the absolute configurations of the new compounds were elucidated by the electronic circular dichroism (ECD) calculation and acid hydrolysis. The cytotoxic activities of the glycosides 1 – 5 against three human cancer cell lines (PC‐3, SK‐OV‐3, and H460) were evaluated. The result showed that compounds 1 – 5 had weak cytotoxic activities against the human cancer cell lines with IC₅₀ values in the range of 48.54 ± 0.80 – 94.25 ± 1.45 μm .     

Oleanane‐type Saponins from Glochidion hirsutum and Their Cytotoxic Activities

Five new oleanane‐type saponins, hirsutosides A – E, were isolated from the leaves of Glochidion hirsutum (Roxb .) Voigt . Their structures were elucidated as 21β‐benzoyloxy‐3β,16β,23,28‐tetrahydroxyolean‐12‐ene 3‐O‐β‐d ‐glucopyranoside ( 1 ), 21β‐benzoyloxy‐3β,16β,23,28‐tetrahydroxyolean‐12‐ene 3‐O‐β‐d ‐glucopyranosyl‐(1 → 3)‐β‐d ‐glucopyranoside ( 2 ), 21β‐benzoyloxy‐3β,16β,23,28‐tetrahydroxyolean‐12‐ene 3‐O‐6‐acetyl‐[β‐d ‐glucopyranosyl‐(1 → 3)]‐β‐d ‐glucopyranoside ( 3 ), 21β‐benzoyloxy‐3β,16β,23,28‐tetrahydroxyolean‐12‐ene 3‐O‐β‐d ‐glucopyranosyl‐(1 → 3)‐〈‐l ‐arabinopyranoside ( 4 ), and 21β‐benzoyloxy‐3β,16β,23‐trihydroxyolean‐12‐ene‐28‐al 3‐O‐β‐d ‐glucopyranosyl‐(1 → 3)‐α‐l ‐arabinopyranoside ( 5 ). All isolated compounds were evaluated for cytotoxic activities on four human cancer cell lines, HepG‐2, A‐549, MCF‐7, and SW‐626 using the SRB assay. Compounds 1 , 2 , 4 , and 5 showed significant cytotoxic activities against all human cancer cell lines with IC₅₀ values ranging from 3.4 to 10.2 μm . Compound 3 containing acetyl group at glc C(6″) exhibited weak cytotoxic activity with IC₅₀ values ranging from 47.0 to 54.4 μm .     

Preparative isolation and purification of four flavonoids from the petals of nelumbo nucifera by high‐speed counter‐current chromatography

Introduction – Flavonoids, the primary constituents of the petals of Nelumbo nucifera, are known to have antioxidant properties and antibacterial bioactivities. However, efficient methods for the preparative isolation and purification of flavonoids from this plant are not currently available. Objective – To develop an efficient method for the preparative isolation and purification of flavonoids from the petals of N. nucifera by high‐speed counter‐current chromatography (HSCCC). Methodology – Following an initial clean‐up step on a polyamide column, HSCCC was utilised to separate and purify flavonoids. Purities and identities of the isolated compounds were established by HPLC‐PAD, ESI‐MS, ¹H‐NMR and ¹³C‐NMR. Results – The separation was performed using a two‐phase solvent system composed of ethyl acetate–methanol–water–acetic acid (4 : 1 : 5 : 0.1, by volume), in which the upper phase was used as the stationary phase and the lower phase was used as the mobile phase at a flow‐rate of 1.0 mL/min in the head‐to‐tail elution mode. Ultimately, 5.0 mg syringetin‐3‐O‐β‐d‐glucoside, 6.5 mg quercetin‐3‐O‐β‐d‐glucoside, 12.8 mg isorhamnetin‐3‐O‐β‐d‐glucoside and 32.5 mg kaempferol‐3‐O‐β‐d‐glucoside were obtained from 125 mg crude sample. Conclusion – The combination of HSCCC with a polyamide column is an efficient method for the preparative separation and purification of flavonoids from the petals of N. nucifera. Copyright © 2009 John Wiley & Sons, Ltd.     

Flavanone glycosides from viscum coloratum and their inhibitory effects on osteoclast formation

Two novel flavanone glycosides, homoeriodictyol 7‐O‐β‐D ‐[6‐(3‐hydroxybutanoyl)glucopyranoside] (viscumneoside IX; 1 ) and homoeriodictyol 7‐O‐β‐D ‐[6‐(3‐hydroxybutanoyl)glucopyranosyl](1→2)‐β‐D ‐glucopyranoside (viscumneoside X; 2 ), together with four known flavanoids, 2‐homoeriodictyol 7‐O‐β‐D ‐glucopyranoside ( 3 ), viscumneoside I ( 4 ), viscumneoside III ( 5 ), and 4′,5‐dihydroxy‐3′‐methoxy‐7‐(2‐O‐α‐L ‐rhamnopyranosyl‐β‐D ‐glucopyranosyloxy)flavanone ( 6 ) were isolated from stems and leaves of Viscum coloratum. Their structures were elucidated on the basis of their NMR spectra, HR‐FAB‐MS data, and acid hydrolysis. Inhibitory effects of the four compounds 1 – 4 on the formation of osteoclast‐like multinucleated cells were investigated. As a result, all the four flavanoids showed significant inhibitory effects on the formation of osteoclast‐like multinuclear cells even at a low concentration of 2 μg/ml. The activities of 1 – 4 at such a concentration exceeded or approximated to that of elcitonin, the positive control drug at a concentration of 2 U/ml, suggesting that they may be of interest for the development of new anti‐osteoporosis drugs.     

Who Is the King? The α‐Hydroxy‐β‐oxo‐α,β‐enone Moiety or the Catechol B Ring: Relationship between the Structure of Quercetin Derivatives and Their Pro‐Oxidative Abilities

Quercetin and other flavonoids have been reported to exhibit both antioxidant and pro‐oxidant properties. Most studies about the pro‐oxidative ability were conducted in the presence of metal ions, and the essential functional moiety of quercetin responsible for the pro‐oxidative effect is still unclear. In this study, we evaluated the pro‐oxidative abilities in the absence of metal ions of two quercetin derivatives, i.e., quercetin‐3′‐O‐β‐D ‐glucoside ( 1 ) and quercetin‐3‐O‐β‐D ‐glucoside ( 2 ), by assessing DNA cleavage and HO^.‐radical production. The binding mode between these compounds and DNA was studied by fluorescence and viscometric titrations. The results showed that 1 can efficiently induce oxidative damage to plasmid DNA, while 2 shows poor activity. Both 1 and 2 bind to DNA via groove‐binding. These results proved that the α‐hydroxy‐β‐oxo‐α,β‐enone moiety contributes to the pro‐oxidative activity of quercetin.     

New Flavonoid Glucuronate Esters with Anti‐inflammatory Activities from Scutellaria regeliana

Two new flavonoid glucuronate esters, named scuregeliosides A and B ( 1 and 2 ), as well as three known ones, chrysin‐7‐O‐β‐d ‐glucuronic acid methyl ester ( 3 ), 5,7,4′‐trihydroxyflavone‐8‐O‐β‐d ‐glucuronic acid methyl ester ( 4 ) and apigenin‐7‐O‐β‐d ‐glucuronic acid ethyl ester ( 5 ), were isolated from the ethanolic extract of the whole plant of Scutellaria regeliana. Their chemical structures were elucidated on the basis of comprehensive spectroscopic analyses. Five compounds were screened for anti‐inflammatory activity in vitro. As the results, the inhibition rates of release of β‐glucuronidase from rat polymorphonuclear leukocytes were in the range of 42.2 – 47.1% at a concentration of 10 μm .     

Triterpenoids and Flavonoids from the Leaves of Astragalus membranaceus and Their Inhibitory Effects on Nitric Oxide Production

Four new cycloartane triterpenes, named huangqiyegenins V and VI and huangqiyenins K and L ( 1 – 4 , resp.), together with nine known triterpenoids, 5 – 13 , and eight flavonoids, 14 – 21 , were isolated from a 70%‐EtOH extract of Astragalus membranaceus leaves. The structures of the new compounds were elucidated by detailed spectroscopic analyses, and the compounds were identified as (9β,11α,16β,20R,24S)‐11,16,25‐trihydroxy‐20,24‐epoxy‐9,19‐cyclolanostane‐3,6‐dione ( 1 ), (9β,16β,24S)‐16,24,25‐trihydroxy‐9,19‐cyclolanostane‐3,6‐dione ( 2 ), (3β,6α,9β,16β,20R,24R)‐16,25‐dihydroxy‐3‐(β‐D ‐xylopyranosyloxy)‐20,24‐epoxy‐9,19‐cyclolanostan‐6‐yl acetate ( 3 ), and (3β,6α,9β,16β,24E)‐26‐(β‐D ‐glucopyranosyloxy)‐16‐hydroxy‐3‐(β‐D ‐xylopyranosyloxy)‐9,19‐cyclolanost‐24‐en‐6‐yl acetate ( 4 ). All isolated compounds were evaluated for their inhibitory activities against LPS‐induced NO production in RAW264.7 macrophage cells. Compounds 1 – 3, 14, 15 , and 18 exhibited strong inhibition on LPS‐induced NO release by macrophages with IC₅₀ values of 14.4–27.1 μM .     

Triterpene Saponins from the Roots of Ilex asprella

Six new triterpene saponins, ilexasprellanosides A–F ( 1 – 6 , resp.), together with eleven known compounds were isolated from the roots of Ilex asprella. The new saponins were characterized as ursa‐12,18‐dien‐28‐oic acid 3‐O‐β‐D ‐xylopyranoside ( 1 ), 19α‐hydroxyursolic acid 3‐O‐β‐D ‐(2′‐O‐acetylxylopyranoside) ( 2 ), 19α‐hydroxyursolic acid 3‐O‐β‐D ‐glucuronopyranoside ( 3 ), 3β,19α‐dihydroxyolean‐12‐en‐23,28‐dioic acid 28‐O‐β‐D ‐glucopyranoside ( 4 ), 19α‐hydroxyoleanolic acid 3‐O‐β‐D ‐(2′‐O‐acetylxylopyranoside) ( 5 ), 19α‐hydroxyoleanolic acid 3‐O‐β‐D ‐glucuronopyranoside ( 6 ). The structures of the new compounds were elucidated by analysis of their spectroscopic data and chemical degradation. Compounds 2, 4 , oleanolic acid 3‐O‐β‐D ‐glucuronopyranoside, 3‐β‐acetoxy‐28‐hydroxyurs‐12‐ene, and pomolic acid showed significant cytotoxic activities against human tumor cell line A549 (IC₅₀ values of 1.87, 2.51, 1.41, 3.24, and 5.63 μM , resp.).     

Unusual Secondary Metabolites from Astragalus halicacabus Lam.

From the whole plant of Astragalus halicacabus (Sect. Halicacabus), a new cycloartane‐type glycoside, (20R,24S)‐3‐O‐[α‐L ‐arabinopyranosyl‐(1→2)‐β‐D ‐xylopyranosyl]‐20,24‐epoxy‐16‐O‐β‐D ‐glucopyranosyl‐3β,6α,16β,25‐tetrahydroxycycloartane, and a new glycoside, 3‐O‐[β‐D ‐apiofuranosyl‐(1→2)‐β‐D ‐glucopyranosyl]maltol were isolated together with seven known cycloartane‐type glycosides, i.e., cyclocanthoside D, askendosides D, F, and G, cyclosieversioside G, cyclostipuloside A, elongatoside, and a known maltol glucoside, 3‐O‐β‐D ‐glucopyranosylmaltol. The structures were elucidated by means of high‐resolution mass spectrometry, and extensive 1D‐ and 2D‐NMR spectroscopic analysis. This is the first phytochemical work on A. halicacabus, and a maltol glycoside was encountered for the first time in the Leguminosae family.     

Carbonic Anhydrase and Urease Inhibitory Potential of Various Plant Phenolics Using in vitro and in silico Methods

Plant phenolics are known to display many pharmacological activities. In the current study, eight phenolic compounds, e.g., luteolin 5‐O‐β‐glucoside ( 1 ), methyl rosmarinate ( 2 ), apigenin ( 3 ), vicenin 2 ( 4 ), lithospermic acid ( 5 ), soyasaponin II ( 6 ), rubiadin 3‐O‐β‐primeveroside ( 7 ), and 4‐(β‐d ‐glucopyranosyloxy)benzyl 3,4‐dihydroxybenzoate ( 8 ), isolated from various plant species were tested at 0.2 mm against carbonic anhydrase‐II (CA‐II) and urease using microtiter assays. Urease inhibition rate for compounds 1  –  8 ranged between 5.0 – 41.7%, while only compounds 1 , 2 , and 4 showed a considerable inhibition over 50% against CA‐II with the IC₅₀ values of 73.5 ± 1.05, 39.5 ± 1.14, and 104.5 ± 2.50 μm , respectively, where IC₅₀ of the reference (acetazolamide) was 21.0 ± 0.12 μm . In silico experiments were also performed through two docking softwares (Autodock Vina and i‐GEMDOCK) in order to find out interactions between the compounds and CA‐II. Actually, compounds 6 (30.0%) and 7 (42.0%) possessed a better binding capability toward the active site of CA‐II. According to our results obtained in this study, among the phenolic compounds screened, particularly 1 , 2 , and 4 appear to be the promising inhibitors of CA‐II and may be further investigated as possible leads for diuretic, anti‐glaucoma, and antiepileptic agents.     

Inhibition of NO Production by Grindelia argentina and Isolation of Three New Cytotoxic Saponins

A bioassay‐guided phytochemical analysis of the ethanolic extract of Grindelia argentina Deble & Oliveira ‐Deble (Asteraceae) allowed the isolation of a known flavone, hispidulin, and three new oleanane‐type saponins, 3‐O‐β‐D ‐xylopyranosyl‐(1→3)‐β‐D ‐glucopyranosyl‐2β,3β,16α,23‐tetrahydroxyolean‐12‐en‐28‐oic acid 28‐O‐β‐D ‐xylopyranosyl‐(1→2)‐β‐D ‐apiofuranosyl‐(1→3)‐β‐D ‐xylopyranosyl‐(1→3)‐α‐L ‐rhamnopyranosyl‐(1→2)‐α‐L ‐arabinopyranosyl ester ( 2 ), 3‐O‐β‐D ‐glucopyranosyl‐2β,3β,23‐trihydroxyolean‐12‐en‐28‐oic acid 28‐O‐β‐D ‐xylopyranosyl‐(1→2)‐β‐D ‐apiofuranosyl‐(1→3)‐β‐D ‐xylopyranosyl‐(1→3)‐α‐L ‐rhamnopyranosyl‐(1→2)‐α‐L ‐arabinopyranosyl ester, ( 3 ) and 3‐O‐β‐D ‐xylopyranosyl‐(1→3)‐β‐D ‐glucopyranosyl‐2β,3β,23‐trihydroxyolean‐12‐en‐28‐oic acid 28‐O‐β‐D ‐xylopyranosyl‐(1→2)‐β‐D ‐apiofuranosyl‐(1→3)‐β‐D ‐xylopyranosyl‐(1→3)‐α‐L ‐rhamnopyranosyl‐(1→2)‐α‐L ‐arabinopyranosyl ester ( 4 ), named grindeliosides A–C, respectively. Their structures were determined by extensive 1D‐ and 2D‐NMR experiments along with mass spectrometry and chemical evidence. The isolated compounds were evaluated for their inhibitory activities against LPS/IFN‐γ‐induced NO production in RAW 264.7 macrophages and for their cytotoxic activities against the human leukemic cell line CCRF‐CEM and MRC‐5 lung fibroblasts. Hispidulin markedly reduced LPS/IFN‐γ‐induced NO production (IC₅₀ 51.4 μM ), while grindeliosides A–C were found to be cytotoxic, with grindelioside C being the most active against both CCRF‐CEM (IC₅₀ 4.2±0.1 μM ) and MRC‐5 (IC₅₀ 4.5±0.1 μM ) cell lines.     

New Thymoquinol Glycosides and Neuroprotective Dibenzocyclooctane Lignans from the Rattan Stems of Schisandra chinensis

Three new lignans ( 1 – 3 ), together with four new thymoquinol glycosides ( 4 – 7 ), were isolated from 70%‐EtOH extract of the rattan stems of Schisandra chinensis. The structures of 1 – 7 were elucidated by detailed spectroscopic analyses, and these new compounds were identified as pinobatol‐9‐O‐β‐d ‐glucopyranoside ( 1 ), 1,2,13,14‐tetramethoxydibenzocyclooctadiene 3,12‐O‐β‐d ‐diglucopyranoside ( 2 ), 3,7‐dihydroxy‐1,2,13,14‐tetramethoxydibenzocyclooctadiene 12‐O‐β‐d ‐glucopyranoside ( 3 ), thymoquinol 2‐O‐β‐d ‐apiofuranosyl‐(1→6)‐β‐d ‐glucopyranoside ( 4 ), thymoquinol 2‐O‐α‐d ‐arabinofuranosyl‐(1→6)‐β‐d ‐glucopyranoside ( 5 ), thymoquinol 5‐O‐β‐d ‐apiofuranosyl‐(1→6)‐β‐d ‐glucopyranoside ( 6 ), and thymoquinol 5‐O‐α‐d ‐arabinofuranosyl‐(1→6)‐β‐d ‐glucopyranoside ( 7 ). The neuroprotective activity of 1 – 7 was evaluated on PC12 cells with neurotoxicity induced by amyloid‐beta 1 – 42 (Aβ_{1 – 42}). Compounds 2 and 3 showed protecting activity against Aβ‐induced toxicity in PC12 cells.     

Effect of one D‐Leu residue on right‐handed helical ‐L‐Leu‐Aib‐ peptides in the crystal state

Four diastereomeric‐Leu‐Leu‐Aib‐Leu‐Leu‐Aib‐peptides, Boc‐D ‐Leu‐L ‐Leu‐Aib‐L ‐Leu‐L ‐Leu‐Aib‐OMe (1), Boc‐L ‐Leu‐D ‐Leu‐Aib‐L ‐Leu‐L ‐Leu‐Aib‐OMe (2), Boc‐L ‐Leu‐L ‐Leu‐Aib‐D ‐Leu‐L ‐Leu‐Aib‐OMe (3), and Boc‐L ‐Leu‐L ‐Leu‐Aib‐L ‐Leu‐D ‐Leu‐Aib‐OMe (4), were synthesized. The crystals of the four hexapeptides were characterized by X‐ray crystallographic analysis. Two diastereomeric hexapeptides 1 and 2 having D ‐Leu(1) or D ‐Leu(2) were folded into right‐handed (P) 3 ₁₀ ‐helical structures, while peptide 3 having D ‐Leu(4) was folded into a turn structure nucleated by type III′ and I$' \bf{\beta}$ ‐turns, and peptide 4 having D ‐Leu(5) was folded into a left‐handed (M) 3 ₁₀ ‐helical structure. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.     

Naphtho‐γ‐pyrones from Endophyte Aspergillus niger Occurring in the Liverwort Heteroscyphus tener (Steph.) Schiffn.

Bioactivity‐guided fractionation of the cytotoxic extract of Aspergillus niger, an endophytic fungus from the Chinese liverwort Heteroscyphus tener (Steph .) Schiffn ., afforded five new naphtho‐γ‐pyrones, rubrofusarin‐6‐O‐α‐D ‐ribofuranoside ( 1 ), (R)‐10‐(3‐succinimidyl)‐TMC‐256A1 ( 2 ), asperpyrone E ( 3 ), isoaurasperone A ( 4 ), and isoaurasperone F ( 5 ), as well as four known ones, dianhydroaurasperone C ( 6 ), aurasperone D ( 7 ), asperpyrone D ( 8 ), and asperpyrone A ( 9 ), together with a cytotoxic cyclic pentapeptide, malformin A₁ ( 10 ). Their structures were determined by extensive spectroscopic analysis. The absolute configurations of dimeric naphtho‐γ‐pyrones 3 – 9 were also determined by analysis of their respective CD spectra.     

Four New Steroidal Glycosides,Protolinckiosides A – D,from the Starfish Protoreaster lincki

Four new steroidal glycosides, protolinckiosides A – D ( 1 – 4 , resp.), were isolated along with four previously known glycosides, 5 – 8 , from the MeOH/EtOH extract of the starfish Protoreaster lincki. The structures of 1 – 4 were elucidated by extensive NMR and ESI‐MS techniques as (3β,4β,5α,6β,7α,15α,16β,25S)‐4,6,7,8,15,16,26‐heptahydroxycholestan‐3‐yl 2‐O‐methyl‐β‐d ‐xylopyranoside ( 1 ), (3β,5α,6β,15α,24S)‐3,5,6,8,15‐pentahydroxycholestan‐24‐yl α‐l ‐arabinofuranoside ( 2 ), sodium (3β,6β,15α,16β,24R)‐29‐(β‐d ‐galactofuranosyloxy)‐6,8,16‐trihydroxy‐3‐[(2‐O‐methyl‐β‐d ‐xylopyranosyl)oxy]stigmast‐4‐en‐15‐yl sulfate ( 3 ), and sodium (3β,6β,15α,16β,22E,24R)‐28‐(β‐d ‐galactofuranosyloxy)‐6,8,16‐trihydroxy‐3‐[(2‐O‐methyl‐β‐d ‐xylopyranosyl)oxy]ergosta‐4,22‐dien‐15‐yl sulfate ( 4 ). The unsubstituted β‐d ‐galactofuranose residue at C(28) or C(29) of the side chains was found in starfish steroidal glycosides for the first time. Compounds 1 – 4 significantly decreased the intracellular reactive oxygen species (ROS) content in RAW 264.7 murine macrophages at induction by proinflammatory endotoxic lipopolysaccharide (LPS) from E. coli.     

Piptadenin,a Novel 3,4‐Secooleanane Triterpene and Piptadenamide,a New Ceramide from the Stem Bark of Piptadeniastrum africanum (Hook.f.) Brenan

Piptadenin ( 1 ), a new triterpene along with piptadenamide ( 10 ), a new ceramide, have been isolated from the AcOEt‐soluble fraction of the MeOH extract of the stem bark of Piptadeniastrum africanum along with nine known compounds, 1‐O‐[(3β,22β)‐3,22‐dihydroxy‐28‐oxoolean‐12‐en‐28‐yl]‐β‐d ‐glucopyranose ( 2 ), 22β‐hydroxyoleanic acid ( 3 ), oleanic acid ( 4 ), lupeol ( 5 ), betulinic acid ( 6 ), 5α‐stigmasta‐7,22‐dien‐3β‐ol ( 7 ), 5α‐stigmasta‐7,22‐dien‐3‐one ( 8 ), (3β)‐stigmast‐5‐en‐3‐yl β‐d ‐glucopyranoside ( 9 ) and 2,3‐dihydroxypropyl hexacosanoate ( 11 ). Except for compound 11 , all the isolated compounds are reported for the first time from this plant. The structures of the isolated compounds were elucidated by spectroscopic data including 1D and 2D NMR. The pure compounds 1 – 11 were subjected to the pharmacological screening and compounds 2 , 5 – 7 and 9 exhibited potent urease inhibitory activity with IC₅₀ value of 25.8, 28.9, 30.1, 31.8 and 32.7 μm , respectively, whereas compound 1 showed moderate activity (IC₅₀ = 98.7 μm ). The potent urease inhibitory activity supplemented the previous literature reports and medicinal uses of this plant.     

High glucose regulates cyclin D1/E of human mesenchymal stem cells through TGF‐β1 expression via Ca2+/PKC/MAPKs and PI3K/Akt/mTOR signal pathways

The elucidation of factors that support human mesenchymal stem cells (hMSCs) growth has remained unresolved partly because of the reliance of many researchers on ill‐defined, proprietary medium formulation. Thus, we investigated the effects of high glucose (D ‐glucose, 25 mM) on hMSCs proliferation. High glucose significantly increased [³H]‐thymidine incorporation and cell‐cycle regulatory protein expression levels compared with 5 mM D ‐glucose or 25 mM L ‐glucose. In addition, high glucose increased transforming growth factor‐β1 (TGF‐β₁) mRNA and protein expression levels. High glucose‐induced cell‐cycle regulatory protein expression levels and [³H]‐thymidine incorporation, which were inhibited by TGF‐β₁ siRNA transfection and TGF‐β₁ neutralizing antibody treatment. High glucose‐induced phosphorylation of protein kinase C (PKC), p44/42 mitogen‐activated protein kinases (MAPKs), p38 MAPK, Akt, and mammalian target of rapamycin (mTOR) in a time‐dependent manner. Pretreatment of PKC inhibitors (staurosporine, 10^?6 M; bisindolylmaleimide I, 10^?6 M), LY 294002 (PI3 kinase inhibitor, 10^?6 M), Akt inhibitor (10^?5 M), PD 98059 (p44/42 MAPKs inhibitor, 10^?5 M), SB 203580 (p38 MAPK inhibitor, 10^?6 M), and rapamycin (mTOR inhibitor, 10^?8 M) blocked the high glucose‐induced cellular proliferation and TGF‐β₁ protein expression. In conclusion, high glucose stimulated hMSCs proliferation through TGF‐β₁ expression via Ca²⁺/PKC/MAPKs as well as PI3K/Akt/mTOR signal pathways. J. Cell. Physiol. 224:59–70, 2010 © 2010 Wiley‐Liss, Inc.     

Melanogenesis‐Inhibitory and Cytotoxic Activities of Diarylheptanoids from Acer nikoense Bark and Their Derivatives

Nine cyclic diarylheptanoids, 1 – 9 , including two new compounds, i.e., 9‐oxoacerogenin A ( 8 ) and 9‐O‐β‐D ‐glucopyranosylacerogenin K ( 9 ), along with three acyclic diarylheptanoids, 10 – 12 , and four phenolic compounds, 13 – 16 , were isolated from a MeOH extract of the bark of Acer nikoense (Aceraceae). Acid hydrolysis of 9 yielded acerogenin K ( 17 ) and D ‐glucose. Two of the cyclic diarylheptanoids, acerogenin A ( 1 ) and (R)‐acerogenin B ( 5 ), were converted to their ether and ester derivatives, 18 – 24 and 27 – 33 , respectively, and to the dehydrated derivatives, 25, 26, 34 , and 35 . Upon evaluation of compounds 1 – 16 and 18 – 35 for their inhibitory activities against melanogenesis in B16 melanoma cells, induced with α‐melanocyte‐stimulating hormone (α‐MSH), eight natural glycosides, i.e., six diarylheptanoid glycosides, 2 – 4, 6, 9 , and 12 , and two phenolic glycosides, 15 and 16 , exhibited inhibitory activities with 24–61% reduction of melanin content at 100 μM concentration with no or almost no toxicity to the cells (88–106% of cell viability at 100 μM ). In addition, when compounds 1 – 16 and 18 – 35 were evaluated for cytotoxic activity against human cancer cell lines, two natural acyclic diarylheptanoids, 10 and 11 , ten ether and ester derivatives, 18 – 22 and 27 – 31 , and two dehydrated derivatives, 34 and 35 , exhibited potent cytotoxicities against HL60 human leukemia cell line (IC₅₀ 8.1–19.3 μM ), and five compounds, 10, 11, 20, 29 , and 30 , against CRL1579 human melanoma cell line (IC₅₀ 10.1–18.4 μM ).     

Phenolic compounds from the whole plants of Gentiana rhodantha (Gentianaceae)

Gentiana rhodantha Franch. ex Hemsl. (Gentianaceae), an annual herb widely distributed in the southwest of China, has been medicinally used for the treatment of inflammation, cholecystitis, and tuberculosis by the local people of its growing areas. Chemical investigation on the whole plants led to the identification of eight new phenolic compounds, rhodanthenones A–D ( 1 – 4 , resp.), apigenin 7‐O‐glucopyranosyl‐(1→3)‐glucopyranosyl‐(1→3)‐glucopyranoside ( 5 ), 1,2‐dihydroxy‐4‐methoxybenzene 1‐O‐α‐L ‐rhamnopyranosyl‐(1→6)‐β‐D ‐glucopyranoside ( 6 ), 1,2‐dihydroxy‐4,6‐dimethoxybenzene 1‐O‐α‐L ‐rhamnopyranosyl‐(1→6)‐β‐D ‐glucopyranoside ( 7 ), and methyl 2‐O‐β‐D ‐glucopyranosyl‐2,4,6‐trihydroxybenzoate ( 8 ), together with eleven known compounds, 9 – 19 . Their structures were determined on the basis of detailed spectroscopic analyses and chemical methods. Acetylcholinesterase (AChE) inhibition and cytotoxicity tests against five human cancer cell lines showed that only rhodanthenone D ( 4 ) and mangiferin ( 12 ) exhibited 18.4 and 13.4% of AChE inhibitory effects at a concentration of 10⁻⁴ M , respectively, while compounds 1 – 5 and the known xanthones lancerin ( 11 ), mangiferin ( 12 ), and neomangiferin ( 13 ) displayed no cytotoxicity at a concentration of 40 μM .