Cancer Chemopreventive Activity of Oleanane‐Type Triterpenoids from the Stem Bark of Betula ermanii

In search for cancer chemopreventive agents from natural sources, three oleanane‐ and four known lupane‐type triterpenoids, and sitosterol from the stem bark of Betula ermanii were tested for their inhibitory effects on Epstein–Barr virus early antigen (EBV‐EA) activation induced by 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA). Among them, 3β‐acetoxy‐12α‐hydroxyoleanan‐13β,28‐olide ( 1 ) and 3β‐acetoxy‐11α,12α‐epoxyoleanan‐13β,28‐olide ( 2 ) were investigated for the inhibitory effect in a two‐stage carcinogenesis test on mouse skin using 7,12‐dimethylbenz[a]anthracene (DMBA) as an initiator and TPA as a promoter. 3β‐Acetoxy‐11α,12α‐epoxyoleanan‐13β,28‐olide ( 2 ) was found to exhibit the potent antitumor promoting activity in the in vivo carcinogenesis test.     

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.     

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.     

Microbial Reactions on 7α‐Hydroxyfrullanolide and Evaluation of Biotransformed Products for Antibacterial Activity

7α‐Hydroxyfrullanolide ( 1 ), a known sesquiterpenoid, was isolated from Sphaeranthus indicus using an antibacterial‐activity‐directed fractionation method. This compound had exhibited a significant antibacterial activity against Gram‐positive bacteria. Chemical and microbial reactions were performed to prepare eight different analogues of compound 1 in order to evaluate these newly synthesized compounds for antibacterial activity. These compounds were 1β,7α‐dihydroxyfrullanolide ( 2 ), 7α‐hydroxy‐1‐oxofrullanolide ( 3 ), 4,5‐dihydro‐7α‐hydroxyfrullanolide ( 4 ), 11,13‐dihydro‐7α‐hydroxyfrullanolide ( 5 ), 13‐acetyl‐7α‐hydroxyfrullanolide ( 6 ), 2α,7α‐dihydroxysphaerantholide ( 7 ), 4α,5α‐epoxy‐7α‐hydroxyfrullanolide ( 8 ), and 4β,5β‐epoxy‐7α‐hydroxyfrullanolide ( 9 ). Microbial reactions on 1 using whole‐cell cultures of Cunninghamella echinulata and Curvularia lunata yielded compounds 2 – 4 . Incubation of compound 1 with the liquid cultures of Apsergillus niger and Rhizopus circinans yielded metabolites 5 – 7 , while 8 and 9 were prepared by carrying out an epoxidation reaction on 1 using meta‐chloroperbenzoic acid (mCPBA). Structures of compounds 2 – 9 were elucidated with the aid of extensive NMR spectral studies. Compounds 2 – 4 were found to be new metabolites. Compounds 1 – 9 were evaluated for antibacterial activity and found to exhibit a wide range of bioactivities. Antibacterial‐activity data of 1 – 9 suggested that the bioactivity of 1 is largely due to the presence of C(4)?C(5), C(11)?C(13), and a γ‐lactone moiety.     

Aldehyde oxidase carrying an unusual subunit structure from Pseudomonas sp. MX‐058

Pseudomonas sp. MX‐058 produces aldehyde oxidase catalysing glyoxal to glyoxylic acid. Two aldehyde oxidases (F10 and F13) were purified to homogeneity from Pseudomonas sp. MX‐058. F10 and F13 had subunit structures, a heterotetramer and heteropentamer respectively. The N‐terminal amino acid sequences of all subunits were highly homologous to amino acid sequences of the putative oxidoreductases of Pseudomonas strains. All of these homologous oxidoreductases have a heterotrimer structure consisting of 85‐88 (α), 37‐39 (β) and 18‐23 (γ) kDa subunits. However, the α‐subunits of F10 and F13 might have decomposed into two [80 (α¹) and 9 kDa (α²)] and three [58 (α^1′), 22 (α^1″) and 9 (α²) kDa] subunits, respectively, while the β‐ and γ‐subunits remained intact. Both F10 and F13 show high activity toward several aliphatic and aromatic aldehydes. The aldehyde oxidases of Pseudomonas sp. MX‐058 has unique protein structures, α¹α²βγ for F10 and α^1′α^1″α²βγ for F13, a heterotetramer and heteropentamer respectively. The enzymes exhibit significantly low activity toward glyoxylic acid compared with glyoxal, which is an advantageous property for glyoxylic acid production from glyoxal.     

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 .     

A new steroidal saponin from Allium ampeloprasum var. porrum with antiinflammatory and gastroprotective effects

A new steroidal saponin was isolated from the bulbs of Allium ampeloprasum var. porrum. On the basis of chemical conversions and detailed analyses of ¹H and ¹³C NMR spectra including 2D NMR spectroscopic techniques, its structure was established as 3-[(O-β-d-glucopyranosyl-(1 → 3)-β-d-glucopyranosyl-(1 → 2)-O-[O-β-d-glucopyranosyl-(1 → 3)]-O-β-d-glucopyranosyl-(1 → 4)-β-d-galactopyranosyl)oxy]-2,6-dihydroxy-(2α,3β,5α,6β,25R)-spirostane. Results of the present study indicated that the steroidal saponin showed haemolytic effects in the in vitro assays and demonstrated antiinflammatory activity and gastroprotective property using in vivo models.     

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.     

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.     

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.     

Six New Polyhydroxysteroidal Glycosides,Anthenosides S1 – S6, from the Starfish Anthenea sibogae

Six new polyhydroxysteroidal glycosides, anthenosides S1  –  S6 ( 1  –  6 ), along with a mixture of two previously known related glycosides, 7 and 8 , were isolated from the methanolic extract of the starfish Anthenea sibogae. The structures of 1  –  6 were established by NMR and HR‐ESI‐MS techniques as well as by chemical transformations. All new compounds have a 5α‐cholest‐8(14)‐ene‐3α,6β,7β,16α‐tetrahydroxysteroidal nucleus and differ from majority of starfish glycosides in positions of carbohydrate moieties at C(7) and C(16) ( 1  –  4 , 6 ) or only at C(16) ( 5 ). The 4‐O‐methyl‐β‐d ‐glucopyranose residue ( 2 ) and Δ²⁴‐cholestane side chain ( 3 ) have not been found earlier in the starfish steroidal glycosides. The mixture of 7 and 8 slightly inhibited the proliferation of human breast cancer T‐47D cells and decreased the colony size in the colony formation assay.     

New NF-κB Inhibitory Steroids from the Marine Sponge Dysidea avara Collected from the South China Sea

Chemical investigation of the marine sponge Dysidea avara, collected from the South China Sea, yielded 13 steroids, including nine new ( 1 – 9 ) and four known ( 10 – 13 ) ones. The new structures were elucidated as (3S,14R)-3,14-dihydroxycholesta-5,8-dien-7-one ( 1 ), (22E,24R)-7α-ethoxy-5α,6α-epoxyergosta-8(14),22-dien-3β-ol ( 2 ), 3β-hydroxy-7α-ethoxy-5α,6α-epoxy-8(14)-cholestene ( 3 ), 3β,5α-dihydroxy-6α-ethoxychofesta-7,9(11)-diene ( 4 ), 3β,5α-dihydroxy-6β-ethoxycholest-7-ene ( 5 ), (22E,24R)-24-ethoxy-3β,5α-dihydroxy-6β-ethoxyergosta-7,22-diene ( 6 ), (22E)-3β,5α-dihydroxy-6β-ethoxycholesta-7,22-diene ( 7 ), 24-ethoxy-3β,5α-dihydroxy-6β-ethoxycholest-7-ene ( 8 and 9 ), by extensive spectroscopic analyses, such as HR-ESI-MS, 1D and 2D NMR data. The absolute configuration of 1 was assigned by comparison the experimental ECD spectra with the calculated ones. Among the 13 metabolites, compounds 1 , 4 , 11 , 12 , and 13 showed NF-κB inhibitory activities in human HER-293 cells with IC₅₀ values of 6.4, 18.7, 8.1, 9.6, and 7.5 μM, respectively. Preliminary structure−activity relationship analysis unveiled that the conjugated ketones or unsaturated double bonds might be the functional groups for the five active steroids.     

Furanocembranoids from the Soft Corals Sinularia asterolobata and Litophyton arboreum

The new cembranoid diterpene danielid ( 1 ) along with 3α‐ethoxyfuranocembranoid 2 , pukalide ( 3 ), 13α‐acetoxypukalide ( 4 ), furanocembranoid 5 , and furanosesquiterpene 6 have been isolated from the soft coral Sinularia asterolobata. The furanocembranoid diterpene 11β,12β‐epoxypukalide ( 7 ) and the sesquiterpene (?)‐bicyclogermacrene ( 8 ) have been obtained from the soft coral Litophyton arboreum. The structures were elucidated primarily by NMR spectroscopy. The furanocembranoids 2, 4 , and 5 show good antiproliferative activities against the cell lines L‐929 and K‐562, and weak cytotoxic effects on HeLa cells.     

Volatile‐Oils Composition,and Bioactivity of the Essential Oils of Plectranthus barbatus,P. neochilus,and P. ornatus Grown in Portugal

Volatile‐oils chemical composition and bioactivity of the essentail oils from Plectranthus barbatus, P. neochilus, and P. ornatus (Lamiaceae) were assessed. Aerial parts from these three related Plectranthus species were collected from cultivated plants grown in Portugal, during vegetative and flowering phases. Volatiles, isolated by distillation? extraction, were analyzed by GC and GC/MS. Monoterpene hydrocarbons (12–74%) and sesquiterpene hydrocarbons (4–45%) constituted the main fractions in all volatiles. α‐Pinene ( 3 ; 12–67%), oct‐1‐en‐3‐ol ( 6 ; traces–28%), β‐pinene ( 7 ; 0.1–22%), and β‐caryophyllene ( 50 ; 7–12%) dominated P. barbatus volatiles. P. neochilus major volatile components were α‐terpenyl acetate ( 41 ; traces–48%), α‐thujone ( 2 ; 2–28%), β‐caryophyllene ( 50 ; 2–28%), β‐pinene ( 7 ; 1–25%), and α‐pinene ( 3 ; 1–19%). Oct‐1‐en‐3‐ol ( 6 ; 13–31%), β‐pinene ( 7 ; 11–24%), α‐pinene ( 3 ; 11–19%), and β‐caryophyllene ( 50 ; traces–11%) were the main constituents from P. ornatus volatiles. These chemical compositions were rather different from those previously found for specimens harvested in Africa and Brazil. Moreover, the volatiles from the flowers are herewith reported for the first time. Essential oils, isolated by hydrodistillation from leaves and stems, showed a yellowish color and unpleasant odor, with yields ranging from 0.08% to 0.84% (v/dry weight). Antioxidant and antimicrobial activities of the essential oils were evaluated by DPPH^. and TBARS assays, and agar disc‐diffusion method, respectively. Results showed low or moderate antioxidant capacity and significant antimicrobial activity against Gram‐positive bacteria.     

Microbial hydroxylation of 17β-estradiol by Penicillium brevicompactum

Microbial hydroxylation of 17β-estradiol (1) with Penicillium brevicompactum, a fungal species not used in biotransformation so far, yielded four metabolites: 1, 3, 5-estratriene-3, 15α-diol-17-one (2); 1, 3, 5-estratriene-3, 6α, 17β-triol (3); 1, 3, 5-estratriene-3, 15α, 17β-triol (4); and 1, 3, 5-estratriene-3, 6α, 15α-triol-17-one (5). All the products were determined by ¹H NMR, ¹³C NMR, two-dimensional NMR, and HRMS techniques. Compounds 3, 4, and 5 are reported for the first time via microbial transformation, and 5 is a new compound as far as we know. Possible metabolic pathway of 17β-estradiol via Penicillium brevicompactum was also proposed.     

Effects of altered α‐ and β‐branch carotenoid biosynthesis on photoprotection and whole‐plant acclimation of Arabidopsis to photo‐oxidative stress

Functions of α‐ and β‐branch carotenoids in whole‐plant acclimation to photo‐oxidative stress were studied in Arabidopsis thaliana wild‐type (wt) and carotenoid mutants, lut ein deficient (lut2, lut5), n on‐p hotochemical q uenching1 (npq1) and s uppressor of z eaxanthin‐l ess1 (szl1) npq1 double mutant. Photo‐oxidative stress was applied by exposing plants to sunflecks. The sunflecks caused reduction of chlorophyll content in all plants, but more severely in those having high α‐ to β‐branch carotenoid composition (α/β‐ratio) (lut5, szl1npq1). While this did not alter carotenoid composition in wt or lut2, which accumulates only β‐branch carotenoids, increased xanthophyll levels were found in the mutants with high α/β‐ratios (lut5, szl1npq1) or without xanthophyll‐cycle operation (npq1, szl1npq1). The PsbS protein content increased in all sunfleck plants but lut2. These changes were accompanied by no change (npq1, szl1npq1) or enhanced capacity (wt, lut5) of NPQ. Leaf mass per area increased in lut2, but decreased in wt and lut5 that showed increased NPQ. The sunflecks decelerated primary root growth in wt and npq1 having normal α/β‐ratios, but suppressed lateral root formation in lut5 and szl1npq1 having high α/β‐ratios. The results highlight the importance of proper regulation of the α‐ and β‐branch carotenoid pathways for whole‐plant acclimation, not only leaf photoprotection, under photo‐oxidative stress.     

Oplopane Sesquiterpenes from Ligularia knorringiana and Their Anti‐Complementary Activity

Three new oplopane sesquiterpenes, knorringianalarins D – F ( 1 – 3 , respectively), and five known analogues ( 4 – 8 , respectively), were isolated from the roots and rhizomes of Ligularia knorringiana. The structures of three new compounds were identified as 4‐acetoxy‐11α,12‐epoxy‐2β‐hydroxy‐3β‐(2‐methylbutyryloxy)‐9α‐(4‐methylsenecioyloxy)oplop‐10(14)‐ene ( 1 ), 3β,4‐diacetoxy‐9α‐(4‐acetoxy‐4‐methylsenecioyloxy)‐11α,12‐epoxy‐8α‐(2‐methylbutyryloxy)oplop‐10(14)‐ene ( 2 ), and (1R,5R,6R,7R,9R)‐5,9,11‐trihydroxy‐4,15‐dinoroplop‐10(14)‐en‐3‐one ( 3 ) based on spectroscopic methods including 1D‐ and 2D‐NMR, mass spectrometry, and CD spectroscopy techniques. All compounds were evaluated for their anti‐complementary activity on the classical pathway of the complement system in vitro. Among which, three oplopane sesquiterpenes ( 3 , 7 , and 8 ) exhibited better anti‐complementary effects with CH₅₀ values ranging from 0.33 to 0.89 mm , which are plausible candidates for developing potent anti‐complementary agents.     

Correlation of 2J couplings with protein secondary structure

Geminal two‐bond couplings (²J) in proteins were analyzed in terms of correlation with protein secondary structure. NMR coupling constants measured and evaluated for a total six proteins comprise 3999 values of ²J_CαN′, ²J_C′HN, ²J_HNCα, ²J_C′Cα, ²J_HαC′, ²J_HαCα, ²J_CβC′, ²J_N′Hα, ²J_N′Cβ, and ²J_N′C′, encompassing an aggregate 969 amino‐acid residues. A seamless chain of pattern comparisons across the spectrum datasets recorded allowed the absolute signs of all ²J coupling constants studied to be retrieved. Grouped by their mediating nucleus, C′, N′ or C^α, ²J couplings related to C′ and N′ depend significantly on ?,ψ torsion‐angle combinations. β turn types I, I′, II and II′, especially, can be distinguished on the basis of relative‐value patterns of ²J_CαN′, ²J_HNCα, ²J_C′HN, and ²J_HαC′. These coupling types also depend on planar or tetrahedral bond angles, whereas such dependences seem insignificant for other types. ²J_HαCβ appears to depend on amino‐acid type only, showing negligible correlation with torsion‐angle geometry. Owing to its unusual properties, ²J_CαN′ can be considered a “one‐bond” rather than two‐bond interaction, the allylic analog of ¹J_N′Cα, as it were. Of all protein J coupling types, ²J_CαN′ exhibits the strongest dependence on molecular conformation, and among the ²J types, ²J_HNCα comes second in terms of significance, yet was hitherto barely attended to in protein structure work. Proteins 2010. © 2009 Wiley‐Liss, Inc.     

Sesquiterpene Lactones from Centaurea zuccariniana and Their Antimicrobial Activity

Twenty‐nine compounds were isolated from the aerial parts of the Greek plant C. zuccariniana DC. The structures of the isolated compounds were established by means of NMR‐ (¹H,¹H‐COSY, ¹H,¹³C‐HSQC, HMBC, NOESY, and ROESY) and mass‐spectral analyses. These compounds comprise 13 sesquiterpene lactones, 14 flavonoids, two lignans, and one simple lactone. Among the isolated sesquiterpene lactones, three are new, namely one heliangolide, (1E,4Z)‐15‐hydroxy‐8α‐O‐(4′‐acetoxy‐3′‐hydroxy‐2′‐methylidenebutanoyl)‐6βH,7αH‐germacra‐1,4,11(13)‐trien‐6,12‐olide; and two eudesmanolides, 8α‐(4′,5′‐diacetoxyangeloyl)sonchucarpolide and one unusual eudesmanolide with an oxygenated bridge linking C(1) and C(4), named zuccarinin. The main sesquiterpene lactones were malacitenolide, cnicin, and 4′‐O‐acetylcnicin. These results are in agreement with those obtained from the previously studied Greek Centaurea sp. belonging to the section Acrolophus (Cass .) DC.; this finding could be of chemotaxonomic significance for the genus Centaurea. The in vitro antimicrobial activities of the isolated new sesquiterpene lactones were against eight bacteria and eight fungal species. A 96‐well microbioassay procedure for fast and easy evaluation of antibacterial and antifungal activities was applied to compare these compounds with commercial antibiotic and fungicide standards, and with previously isolated analogous sesquiterpene lactones tested by the same bioassay. All of the compounds tested showed moderate antibacterial, but significant antifungal activities; the present results corroborate with previous data, indicating that these types of compounds exhibit low or moderate antibacterial, but potent antifungal activities. The unusual eudesmanolide zuccarinin proved to be the most potent among the present tested sesquiterpene lactones, as well as among all previously tested eudesmanolides isolated from Greek Centaurea sp.     

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.