Cytotoxic Oleanane‐Type Saponins from the Leaves of Albizia anthelmintica Brongn.

Two new oleanane‐type saponins: β‐d ‐xylopyranosyl‐(1 → 4)‐6‐deoxy‐α‐l ‐mannopyranosyl‐(1 → 2)‐1‐O‐{(3β)‐28‐oxo‐3‐[(2‐O‐β‐d ‐xylopyranosyl‐β‐d ‐glucopyranosyl)oxy]olean‐12‐en‐28‐yl}‐β‐d ‐glucopyranose ( 1 ) and 1‐O‐[(3β)‐28‐oxo‐3‐{[β‐d ‐xylopyranosyl‐(1 → 2)‐α‐l ‐arabinopyranosyl‐(1 → 6)‐2‐acetamido‐2‐deoxy‐β‐d ‐glucopyranosyl]oxy}olean‐12‐en‐28‐yl]β‐d ‐glucopyranose ( 2 ), along with two known saponins: (3β)‐3‐[(β‐d ‐Glucopyranosyl‐(1 → 2)‐β‐d ‐glucopyranosyl)oxy]olean‐12‐en‐28‐oic acid ( 3 ) and (3β)‐3‐{[α‐l ‐arabinopyranosyl‐(1 → 6)‐[β‐d ‐glucopyranosyl‐(1 → 2)]‐β‐d ‐glucopyranosyl]oxy}olean‐12‐en‐28‐oic acid ( 4 ) were isolated from the acetone‐insoluble fraction obtained from the 80% aqueous MeOH extract of Albizia anthelmintica Brongn . leaves. Their structures were identified using different NMR experiments including: ¹H‐ and ¹³C‐NMR, HSQC, HMBC and ¹H,¹H‐COSY, together with HR‐ESI‐MS/MS, as well as by acid hydrolysis. The four isolated saponins and the fractions of the extract exhibited cytotoxic activity against HepG‐2 and HCT‐116 cell lines. Compound 2 showed the most potent cytotoxic activity among the other tested compounds against the HepG2 cell line with an IC₅₀ value of 3.60μm . Whereas, compound 1 showed the most potent cytotoxic effect with an IC₅₀ value of 4.75μm on HCT‐116 cells.     

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.     

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.     

Imidazole dipeptides can quench toxic 4‐oxo‐2(E)‐nonenal: Molecular mechanism and mass spectrometric characterization of the reaction products

Imidazole dipeptides, such as carnosine (β‐alanyl‐l ‐histidine) and anserine (β‐alanyl‐N^π‐methyl‐l ‐histidine), are highly localized in excitable tissues, including skeletal muscle and nervous tissue, and play important roles such as scavenging reactive oxygen species and quenching reactive aldehydes. We have demonstrated several reactions between imidazole dipeptides (namely, carnosine, and anserine) and a lipid peroxide‐derived reactive aldehyde 4‐oxo‐2(E)‐nonenal. Seven carnosine adducts and two anserine adducts were characterized using liquid chromatography/electrospray ionization‐multiple‐stage mass spectrometry. Adduct formation occurred between imidazole dipeptides and 4‐oxo‐2(E)‐nonenal mainly through Michael addition, Schiff base formation, and/or Paal‐Knorr reaction. The reactions were much more complicated than the reaction with a similar lipid peroxide‐derived reactive aldehyde, 4‐hydroxy‐2(E)‐nonenal.     

Cytotoxic Steroidal Saponins from the Rhizomes of Tacca integrifolia

Three new steroid saponins (3β,25R)‐spirost‐5‐en‐3‐yl 6‐deoxy‐α‐L ‐mannopyranosyl‐(1→2)‐[β‐D ‐glucopyranosyl‐(1→4)‐6‐deoxy‐α‐L ‐mannopyranosyl‐(1→3)]‐β‐D ‐glucopyranoside ( 1 ), (3β,22R,25R)‐26‐(β‐D ‐glucopyranosyloxy)‐22‐hydroxyfurost‐5‐en‐3‐yl 6‐deoxy‐α‐L ‐mannopyranosyl‐(1→2)‐[6‐deoxy‐α‐L ‐mannopyranosyl‐(1→3)]‐β‐D ‐glucopyranoside ( 3 ), and (3β,22R,25R)‐26‐(β‐D ‐glucopyranosyloxy)‐22‐hydroxyfurost‐5‐en‐3‐yl 6‐deoxy‐α‐L ‐mannopyranosyl‐(1→2)‐[β‐D ‐glucopyranosyl‐(1→4)‐6‐deoxy‐α‐L ‐mannopyranosyl‐(1→3)]‐β‐D ‐glucopyranoside ( 5 ), as well as the new pregnane glycoside (3β,16β)‐3‐{[6‐deoxy‐α‐L ‐mannopyranosyl‐(1→2)‐[6‐deoxy‐α‐L ‐mannopyranosyl‐(1→3)]‐β‐D ‐glucopyranosyl]oxy}‐20‐oxopregn‐5‐en‐16‐yl (4R)‐5‐(β‐D ‐glucopyranosyloxy)‐4‐methylpentanoate ( 6 ), were isolated from the rhizomes of Tacca integrifolia together with two known (25R) configurated steroid saponins (3β,25R)‐spirost‐5‐en‐3‐yl 6‐deoxy‐α‐L ‐mannopyranosyl‐(1→2)‐[6‐deoxy‐α‐L ‐mannopyranosyl‐(1→3)]‐β‐D ‐glucopyranoside ( 2 ) and (3β,22R,25R)‐26‐(β‐D ‐glucopyranosyloxy)‐22‐methoxyfurost‐5‐en‐3‐yl 6‐deoxy‐α‐L ‐mannopyranosyl‐(1→2)‐[6‐deoxy‐α‐L ‐mannopyranosyl‐(1→3)]‐β‐D ‐glucopyranoside ( 4 ). The cytotoxic activity of the isolated compounds was evaluated in HeLa cells and showed the highest cytotoxicity value for compound 2 with an IC₅₀ of 1.2±0.4 μM . Intriguingly, while compounds 1 – 5 exhibited similar cytotoxic properties between 1.2±0.4 ( 2 ) and 4.0±0.6 μM ( 5 ), only compound 2 showed a significant microtubule‐stabilizing activity in vitro.     

Difference in the structures of alanine tri‐ and tetra‐peptides with antiparallel β‐sheet assessed by X‐ray diffraction,solid‐state NMR and chemical shift calculations by GIPAW

Alanine oligomers provide a key structure for silk fibers from spider and wild silkworms.We report on structural analysis of l ‐alanyl‐l ‐alanyl‐l ‐alanyl‐l ‐alanine (Ala)₄ with anti‐parallel (AP) β‐structures using X‐ray and solid‐state NMR. All of the Ala residues in the (Ala)₄ are in equivalent positions, whereas for alanine trimer (Ala)₃ there are two alternative locations in a unit cell as reported previously (Fawcett and Camerman, Acta Cryst., 1975, 31, 658–665). (Ala)₄ with AP β‐structure is more stable than AP‐(Ala)₃ due to formation of the stronger hydrogen bonds. The intermolecular structure of (Ala)₄ is also different from polyalanine fiber structure, indicating that the interchain arrangement of AP β‐structure changes with increasing alanine sequencelength. Furthermore the precise ¹H positions, which are usually inaccesible by X‐ray diffraction method, are determined by high resolution ¹H solid state NMR combined with the chemical shift calculations by the gauge‐including projector augmented wave method. © 2013 Wiley Periodicals, Inc. Biopolymers 101: 13–20, 2014.     

Effects of supplementation with free glutamine and the dipeptide alanyl‐glutamine on parameters of muscle damage and inflammation in rats submitted to prolonged exercise

In this study, we investigated the effect of the supplementation with the dipeptide L ‐alanyl‐L ‐glutamine (DIP) and a solution containing L ‐glutamine and L ‐alanine on plasma levels markers of muscle damage and levels of pro‐inflammatory cytokines and glutamine metabolism in rats submitted to prolonged exercise. Rats were submitted to sessions of swim training for 6 weeks. Twenty‐one days prior to euthanasia, the animals were supplemented with DIP (n = 8) (1.5 g.kg^?1), a solution of free L ‐glutamine (1 g.kg^?1) and free L ‐alanine (0.61 g.kg^?1) (G&A, n = 8) or water (control (CON), n = 8). Animals were killed at rest before (R), after prolonged exercise (PE—2 h of exercise). Plasma concentrations of glutamine, glutamate, tumour necrosis factor‐α (TNF‐α), prostaglandin E2 (PGE2) and activity of creatine kinase (CK), lactate dehydrogenase (LDH) and muscle concentrations of glutamine and glutamate were measured. The concentrations of plasma TNF‐α, PGE2 and the activity of CK were lower in the G&A‐R and DIP‐R groups, compared to the CON‐R. Glutamine in plasma (p < 0.04) and soleus muscle (p < 0.001) was higher in the DIP‐R and G&A‐R groups relative to the CON‐R group. G&A‐PE and DIP‐PE groups exhibited lower concentrations of plasma PGE2 (p < 0.05) and TNF‐α (p < 0.05), and higher concentrations of glutamine and glutamate in soleus (p < 0.001) and gastrocnemius muscles (p < 0.05) relative to the CON‐PE group. We concluded that supplementation with free L ‐glutamine and the dipeptide LL ‐alanyl‐LL ‐glutamine represents an effective source of glutamine, which may attenuate inflammation biomarkers after periods of training and plasma levels of CK and the inflammatory response induced by prolonged exercise. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis of Lanostane‐Type Triterpenoid N‐Glycosides and Their Cytotoxicity against Human Cancer Cell Lines

Seventeen lanostane‐type triterpenoid derivatives ( 2 – 18 ), including 11N‐glycosides ( 8 – 18 ), were synthesized from the natural triterpenoid, lanosterol ( 1 ), and were evaluated for their cytotoxicity against the human cancer cell lines, HL‐60, A549, and MKN45, as well as the normal human lung cells, WI‐38. Among them, N‐β‐d ‐2‐acetamido‐2‐deoxyglucoside ( 10 ) showed cytotoxicity against HL‐60, A549, MKN45, and WI‐38 cells (IC₅₀ 0.0078 – 2.8 μm ). However, N‐β‐d ‐galactoside ( 12 ) showed cytotoxicity against HL‐60 and MKN45 cells (IC₅₀ 0.0021 – 4.0 μm ), but not the normal WI‐38 cells. Furthermore, Western blot analysis suggested that 12 induces apoptosis by activation of caspases‐3, 8, and 9. These results will be useful for the synthesis of other tetracyclic triterpenoids or steroid N‐glycosides to increase their cytotoxicity and apoptosis‐inducing activities.     

Anti‐HSV‐1 and HSV‐2 Flavonoids and a New Kaempferol Triglycoside from the Medicinal Plant Kalanchoe daigremontiana

Kalanchoe daigremontiana (Crassulaceae) is a medicinal plant native to Madagascar. The aim of this study was to investigate the flavonoid content of an aqueous leaf extract from K. daigremontiana (Kd), and assess its antiherpetic potential. The major flavonoid, kaempferol 3‐O‐β‐d ‐xylopyranosyl‐(1 → 2)‐α‐l ‐rhamnopyranoside ( 1 ), was isolated from the AcOEt fraction (Kd‐AC). The BuOH‐soluble fraction afforded quercetin 3‐O‐β‐d ‐xylopyranosyl‐(1 → 2)‐α‐l ‐rhamnopyranoside ( 2 ) and the new kaempferol 3‐O‐β‐d ‐xylopyranosyl‐(1 → 2)‐α‐l ‐rhamnopyranoside‐7‐O‐β‐d ‐glucopyranoside ( 3 ), named daigremontrioside. The crude extract, Kd‐AC fraction, flavonoids 1 and 2 were evaluated using acyclovir‐sensitive strains of HSV‐1 and HSV‐2. Kd‐AC was highly active against HSV‐1 (EC₅₀ = 0.97 μg/ml, SI > 206.1) and HSV‐2 (EC₅₀ = 0.72 μg/ml, SI > 277.7). Flavonoids 1 and 2 showed anti‐HSV‐1 (EC₅₀ = 7.4 μg/ml; SI > 27 and EC₅₀ = 5.8 μg/ml; SI > 8.6, respectively) and anti‐HSV‐2 (EC₅₀ = 9.0 μg/ml; SI > 22.2 and EC₅₀ = 36.2 μg/ml; SI > 5.5, respectively) activities, suggesting the contribution of additional substances to the antiviral activity.     

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.     

Three New Polyacetylene Glycosides from the Roots of Heracleum dissectum and Their Triglyceride Accumulating Activities in 3T3‐L1 Cells

Continually phytochemical study of the roots of Heracleum dissectum had led to the isolation of three previously undescribed polyacetylene glycosides ( 1 – 3 ), together with seven known compounds, including one polyacetylene ( 8 ) and six coumarins ( 4 – 7 and 9 – 10 ) using diverse chromatographic methods. The structures of these three new compounds were characterized and identified as deca‐4,6‐diyn‐1‐yl β‐d ‐glucopyranosyl‐(1→6)‐β‐d ‐glucopyranosyl‐(1→2)‐β‐d ‐glucopyranoside ( 1 ), (8Z)‐dec‐8‐ene‐4,6‐diyn‐1‐yl β‐d ‐glucopyranosyl‐(1→6)‐β‐d ‐glucopyranosyl‐(1→2)‐β‐d ‐glucopyranoside ( 2 ), and (8E)‐dec‐8‐ene‐4,6‐diyn‐1‐yl β‐d ‐glucopyranosyl‐(1→6)‐β‐d ‐glucopyranosyl‐(1→2)‐β‐d ‐glucopyranoside ( 3 ) based on their physicochemical properties and extensive analyses of various spectroscopic data. Their triglycerides accumulating activities were assayed and the results showed that the three new polyacetylene glycosides ( 1 – 3 ) exhibited triglyceride accumulating activities in 3T3‐L1 adipocytes.     

Dodecyl α‐L‐Rhamnopyranosyl‐(1→2)‐β‐D‐fucopyranoside Derivatives from the Glandular Trichome Exudate of Erodium pelargoniflorum

Chemical investigation of the glandular trichome exudate of Erodium pelargoniflorum (Geraniaceae) led to the isolation of two dodecyl disaccharide derivatives, named pelargoside A1 and pelargoside B1 ( 1 and 2 , resp.). The structures of 1 and 2 were determined as dodecyl 4‐O‐acetyl‐α‐L ‐rhamnopyranosyl‐(1→2)‐4‐O‐acetyl‐β‐D ‐fucopyranoside and dodecyl 3,4‐di‐O‐acetyl‐α‐L ‐rhamnopyranosyl‐(1→2)‐4‐O‐acetyl‐β‐D ‐fucopyranoside, respectively, by spectroscopic studies, including 2D‐NMR, and chemical transformations. In addition, undecyl, tridecyl, and tetradecyl homologs of 1 and 2 , named pelargosides A2–A4 and pelargosides B2–B4, were also characterized as minor constituents of the exudate.     

Simenoside A,a New Triterpenoid Saponin from Gypsophila simonii Hub.‐Mor.

Saponins are amphiphilic glycoconjugates which give soap‐like foams in H₂O. A new triterpenoid saponin, simenoside A ( 1 ), based on gypsogenin aglycone, and the known saponin 2 were isolated from Gypsophila simonii Hub.‐Mor. The structure of the new saponin was elucidated as 3‐O‐β‐D ‐galactopyranosyl‐(1→2)‐[β‐D ‐xylopyranosyl‐(1→3)]‐β‐D ‐glucuronopyranosylgypsogenin 28‐O‐β‐D ‐glucopyranosyl‐(1→3)‐[β‐D ‐glucopyranosyl‐(1→2)‐β‐D ‐xylopyranosyl‐(1→4)]‐α‐L ‐rhamnopyranosyl‐(1→2)‐β‐D ‐fucopyranosyl ester on the basis of extensive spectral analyses and chemical evidence. Saponins 1 and 2 were isolated from G. simonii for the first time.     

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 .     

Chiral Recognition of N‐Phthaloyl,N‐Tetrachlorophthaloyl,and N‐Naphthaloyl α‐Amino Acids and Their Esters on Polysaccharide‐Derived Chiral Stationary Phases

Enantiomeric separations of N‐phthaloyl (N‐PHT), N‐tetrachlorophthaloyl (N‐TCPHT), and N‐naphthaloyl (N‐NPHT) α‐amino acids and their esters were examined on several kinds of polysaccharide‐derived chiral stationary phases (CSPs). Resolution capability of CSPs was greater Chiralcel OF than the others for N‐PHT and N‐NPHT α‐amino acids and their esters. In N‐TCPHT α‐amino acids and their esters, good enantioselectivities showed Chiralcel OG for N‐TCPHT α‐amino acids, Chiralpak AD for N‐TCPHT α‐amino acid methyl esters, and Chiralcel OD for N‐TCPHT α‐amino acid ethyl esters, respectively. From the results of liquid chromatography and computational chemistry, it is concluded that l ‐form is preferred and more retained with electrostatic interaction in case of interaction between N‐PHT α‐amino acid derivatives and Chiralcel OF, N‐TCPHT α‐amino acid derivatives and Chiralcel OD, and N‐NPHT α‐amino acid derivatives and Chiracel OF. On the other hand, d ‐form is preferred and more retained with van der Waals interaction in case of interaction between N‐TCPHT α‐amino acid ester derivatives and Chiralcel OG and Chiralpak AD. Chirality 24:1037–1046, 2012. © 2012 Wiley Periodicals, Inc.     

Purification and molecular characterization of a novel mannose‐specific lectin from Dioclea reflexa hook seeds with inflammatory activity

A novel lectin present in Dioclea reflexa seeds (DrfL) was discovered and described in this study. DrfL was purified in a single step by affinity chromatography in a Sephadex G‐50 column. The lectin strongly agglutinated rabbit erythrocytes and was inhibited by α‐methyl‐d ‐mannoside, d ‐mannose, and d ‐glucose. The hemagglutinating activity of DrfL is optimum at pH 5.0–7.0, stable up to 50 °C, and dependent on divalent cations. Similar to other lectins of the subtribe Diocleinae, the analysis by mass spectrometry indicated that DrfL has three chains (α, β, and γ) with masses of 25 562, 12 874, and 12 706 Da, respectively, with no disulfide bonds or glycosylation. DrfL showed inflammatory activity in the paw edema model and exhibited low cytotoxicity against Artemia sp. Copyright © 2015 John Wiley & Sons, Ltd.     

The Mycobacterium tuberculosis complex has a pathway for the biosynthesis of 4‐formamido‐4,6‐dideoxy‐d‐glucose

Recent studies have demonstrated that the O‐antigens of some pathogenic bacteria such as Brucella abortus, Francisella tularensis, and Campylobacter jejuni contain quite unusual N‐formylated sugars (3‐formamido‐3,6‐dideoxy‐d ‐glucose or 4‐formamido‐4,6‐dideoxy‐d ‐glucose). Typically, four enzymes are required for the formation of such sugars: a thymidylyltransferase, a 4,6‐dehydratase, a pyridoxal 5'‐phosphate or PLP‐dependent aminotransferase, and an N‐formyltransferase. To date, there have been no published reports of N‐formylated sugars associated with Mycobacterium tuberculosis. A recent investigation from our laboratories, however, has demonstrated that one gene product from M. tuberculosis, Rv3404c, functions as a sugar N‐formyltransferase. Given that M. tuberculosis produces l ‐rhamnose, both a thymidylyltransferase (Rv0334) and a 4,6‐dehydratase (Rv3464) required for its formation have been identified. Thus, there is one remaining enzyme needed for the production of an N‐formylated sugar in M. tuberculosis, namely a PLP‐dependent aminotransferase. Here we demonstrate that the M. tuberculosis rv3402c gene encodes such an enzyme. Our data prove that M. tuberculosis contains all of the enzymatic activities required for the formation of dTDP‐4‐formamido‐4,6‐dideoxy‐d ‐glucose. Indeed, the rv3402c gene product likely contributes to virulence or persistence during infection, though its temporal expression and location remain to be determined.     

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.     

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.).