Monoterpenoids from the aerial parts of Aruncus dioicus var. kamtschaticus and their antioxidant and cytotoxic activities

The aerial parts of Aruncus dioicus var. kamtschaticus afforded five new monoterpenoids (1-5): 4-(erythro-6,7-dihydroxy-9-methylpent-8-enyl)furan-2(5H)-one (1, aruncin A), 2-(8-ethoxy-8-methylpropylidene)-5-hydroxy-3,6-dihydro-2H-pyran-4-carboxylic acid (2, aruncin B), 4-(hydroxymethyl)-6-(8-methylprop-7-enyl)-5,6-dihydro-2H-pyran-2-one-11-O-β-d-glucopyranoside (3, aruncide A), (3S,4S,5R,10R)-3-(10-ethoxy-11-hydroxyethyl)-4-(5-hydroxy-7-methylbut-6-enyl)oxetan-2-one-11-O-β-d-glucopyranoside (4, aruncide B), and (3S,4S,5R,7R)-5-(9-methylprop-8-enyl)-1,6-dioxabicyclo[3,2,0]heptan-2-one-7-(hydroxymethyl)-12-O-β-d-glucopyranoside (5, aruncide C). Compound 2 showed potent cytotoxicity against Jurkat T cells with an IC₅₀ value of 17.15 μg/mL. In addition, compounds 7 and 10 exhibited moderate antioxidant activity with IC₅₀ values of 46.3 and 11.7 μM, respectively.     

Rubrenolide and rubrynolide: An alkene-alkyne pair from Nectandra rubra

Structures are proposed for rubrenolide, (2S,4R)-2-[(2′S)-2′,3′-dihydroxypropyl]-4-(dec-9′'-enyl)-γ-lactone, and rubrynolide, (2S,4R)-2-[(2′S)-2′,3′-dihydroxypropyl]-4-(dec-9′'-ynyl)-γ-lactone, isolated from Nectandra rubra (Lauraceae).     

Chemical constituents of the root bark of Erythrina droogmansiana

Two new compounds namely 7,4′-dihydroxy-2′-methoxy-3′-(3-methylbut-2-enyl)isoflavanone (1) and 5,7,3′-trihydroxy-8-(3-methylbut-2-enyl)-[6′′,6′′-dimethylpyrano(2′′,3′′:4′,5′)]isoflavone (4) were isolated from the root bark of Erythrina droogmansiana together with eight known compounds. Their structures were elucidated on the basis of spectroscopic analyses (1D- and 2D-NMR and ESI-HRMS) and by comparison with literature data. In addition, the correct ¹³C NMR of 5,7,2′,4′-tertahydroxy-8,5′-di-(3-metylbut-2-enyl)isoflavone (6) was assigned. The DPPH free radical scavenging properties of the isolated compounds were evaluated. Compounds 4–7 showed weak to moderate DPPH free radical scavenging activities.     

Anthrasesamones from roots of Sesamum indicum

Three anthraquinones, named anthrasesamones A, B and C, were isolated from the roots of Sesamum indicum, and their respective structures were determined to be 1-hydroxy-2-(4-methylpent-3-enyl)anthraquinone, 1,4-dihydroxy-2-(4-methylpent-3-enyl)anthraquinone and 2-chloro-1,4-dihydroxy-3-(4-methylpent-3-enyl)anthraquinone on the basis of spectroscopic evidence. Two known anthraquinones were also isolated for the first time from S. indicum roots and characterized as 2-(4-methylpent-3-enyl)anthraquinone and (E)-2-(4-methylpenta-1,3-dienyl)anthraquinone. Anthrasesamone C is a rare chlorinated anthraquinone in higher plants.     

Phenolic derivatives from Artemisia campestris subsp. Glutinosa

From the hexane extract of Artemisia campestris subsp. glutinosa, sakuranetin, dihydroquercetin-7,3′-dimethyl ether and three acetophenone derivatives identified as 3-[4-acetoxyisopent-2(Z)-enyl]-4-hydroxyacetophenone, 3-[4-acetoxyisopent-2(E)-enyl]-4-hydroxyacetophenone and 3-(3-acetoxymethyl-2-hydroxybut-3-enyl)-4-hydroxyacetophenone, have been isolated.     

Minor phenolics from Angelica keiskei and their proliferative effects on Hep3B cells

A new coumarin, (?)-cis-(3′R,4′R)-4′-O-angeloylkhellactone-3′-O-β-d-glucopyranoside (1) and two new chalcones, 3′-[(2E)-5-carboxy-3-methyl-2-pentenyl]-4,2′,4′-trihydroxychalcone (4) and (±)-4,2′,4′-trihydroxy-3′-{2-hydroxy-2-[tetrahydro-2-methyl-5-(1-methylethenyl)-2-furanyl]ethyl}chalcone (5) were isolated from the aerial parts of Angelica keiskei (Umbelliferae), together with six known compounds: (R)-O-isobutyroyllomatin (2), 3′-O-methylvaginol (3), (?)-jejuchalcone F (6), isoliquiritigenin (7), davidigenin (8), and (±)-liquiritigenin (9). The structures of the new compounds were determined by interpretation of their spectroscopic data including 1D and 2D NMR data. All known compounds (2, 3, and 6–9) were isolated as constituents of A. keiskei for the first time. To identify novel hepatocyte proliferation inducer for liver regeneration, 1–9 were evaluated for their cell proliferative effects using a Hep3B human hepatoma cell line. All isolates exhibited cell proliferative effects compared to untreated control (DMSO). Cytoprotective effects against oxidative stress induced by glucose oxidase were also examined on Hep3B cells and mouse fibroblast NIH3T3 cells and all compounds showed significant dose-dependent protection against oxidative stress.     

(2S)-Prenylflavanones and taraxerane triterpenoids from Mallotus mollissimus

Three prenylflavanones, (2S)-5,7-dihydroxy-4′-methoxy-8-(3″,3″-dimethylallyl)flavanone (3), (2S)-5,4′-dihydroxy-7-methoxy-6-(3″,3″-dimethylallyl)flavanone (6), 8-prenylnaringenin (11), and a new epimeric pair (2″S/2″R)-(2S)-5,7-dihydroxy-4′-methoxy-6-(2″-hydroxy-3″-methylbut-3″-enyl)flavanones (4a/4b) were isolated together with taraxerone, taraxerol, epitaraxerol, β-sitosterol, oleanolic acid, 1-O-docosanoyl glycerol, apigenin, and apigenin 7-O-β-D-glucopyranoside from the MeOH extract of the leaves of Mallotus mollissimus. The structures of the isolated compounds were determined on the basis of 1D/2D NMR and HR-MS spectroscopic data; the 2S configuration of the prenylflavanones 3, 4, and 6 was deduced from CD spectroscopic data. The presence of three taraxerane triterpenoids reinforces the inclusion of M. mollissimus (syn. Croton mollissimus) in Mallotus genus. Among species of Mallotus the occurrence of the (2S)-prenylflavanones 3, 4, and 6 is confined to M. mollissimus.     

Dilignol glycosides from needles of Picea abies

(2R,3R)-2 3-Dihydro-2-(4′-hydroxy-3′-methoxyphenyl)-3-(hydroxymethyl)-7-methoxy-5-benzofuranpropanol 4′-O-β-d-glucopyranoside [dihydrodehydrodiconiferyl alcohol glucoside], (2R,3R)-2 3-dihydro-7-hydroxy-2-(4′-hydroxy-3′-methoxyphenyl)-3-(hydroxymethyl)-5-benzofuranpropanol 4′-O-β-d-glucopyranoside and 4′-O-α-l-rhamnopyranoside, 1-(4′-hydroxy-3′-methoxyphenyl)-2- [2″-hydroxy-4″-(3-hydroxypropyl)phenoxy]-1, 3-propanediol 1-O-β-d-glucopyranoside and 4′-O-β-d-xylopyranoside, 2,3-bis[(4′-hydroxy-3′-methoxyphenyl)-methyl]-1,4-butanediol 1-O-β-d-glucopyranoside [(?)-seco-isolariciresinol glucoside] and (1R,2S,3S)-1,2,3,4-tetrahydro-7-hydroxy-1-(4′-hydroxy-3′-methoxyphenyl)-6-methoxy-2 3-naphthalenedimethanol α²-O-β-d-xylopyranoside [(?)-isolariciresinol xyloside] have been isolated from needles of Picea abies and identified.     

Tirumalin,a new prenylated dihydroflavonol from Rhynchosia cyanosperma

A new dihydroflavonol has been isolated together with the known flavonol-O- glycosides, rutin and kaempferol-3-rutinoside, and (+)-pinitol from the leaves of R. cyanosperma Benth. The dihydroflavonol was identified as (+)-(2R, 3R)-8-C-prenyltaxifolin-7, 4′-dimethyl ether on the basis of spectroscopic studies and the compound given the trivial name tirumalin.     

Benzofuranoid neolignans from Aniba simulans

Forteen neolignans, isolated from the benzene extract of Aniba simulans (Lauraceae) trunk wood, included the hitherto undescribed (2S, 3S, 5R)-5-allyl-5,7-dimethoxy-2-(3′,4′,5′-trimethoxyphenyl)-3-methyl-2,3,5,6-tetra-hydro-6-oxobenzofuran, (2R,3S,5R) -5-allyl-5-methoxy-2-(3′-methoxy-4′,5′-methylenedioxyphenyl)-3-methy1-2,3,5, 6-tetrahydro-6-oxobenzofuran, (2S,3S)-6-O-allyl -5-methoxy-2-(3′-methoxy-4′-5′-methylenedioxyphenyl)-3-methyl-2,3-dihydrobenzofuran, (2R,3S)-6-O-allyl-5-methoxy-2- (3′-methoxy-4′,5′-methylenedioxyphenyl)-3-methyl-2,3-dihydrobenzofuran and 7-allyl-6-hydroxy-5-methoxy-2-(3′-methoxy-4,5′ -methylenedioxyphenyl)-3-methylbenzofuran.     

Cardiovascular protective flavonolignans and flavonoids from Calamus quiquesetinervius

Tricin-type flavonolignans, (2S)-dihydrotricin 4′-O-(erythro-β-guaiacylglyceryl) ether, (2S)-dihydrotricin 4′-O-(threo-β-guaiacylglyceryl) ether, (2S)-dihydrotricin 4′-O-(threo-β-4-hydroxyphenylglyceryl) ether, tricin 4′-O-(erythro-β-4-hydroxyphenylglyceryl) ether, tricin 4′-O-(threo-β-4-hydroxylphenylglyceryl) ether, and (2S)-dihydrotricin 4′-O-(β-6′′-methoxy-4′′-oxo-chroman-3′′-yloxy) ether namely calquiquelignan A–F, respectively, were isolated and characterized from the EtOAc extract of Calamus quiquesetinervius. Additionally, six known phenolic compounds, including dihydrotricin, tricin, salcolin A, p-hydroxybenzoic acid, (2S, 3S)-trans-dihydrokapempferol and (2S)-naringenin, were also obtained and identified from the extract. Structures of the flavonolignans were assigned based on spectroscopic analyses that included 1D and 2D NMR spectroscopic techniques, such as HMQC, HMBC, and NOESY. Bioassay results showed that calquiquelignan A, dihydrotricin and (2S)-naringenin exhibited significant vasodilatory potencies, as indicated by 60.3%, 80.3% and 60.9% relaxations, respectively, at 100 μM. Salcolin A showed potent platelet aggregation inhibition, compared with aspirin. Most of the tricin-type derivatives (calquiquelignan A–B, dihydrotricin and tricin) also exhibited more potent hydroxyl radical (OH) scavenging activity than trolox as characterized by the ultraweak chemiluminescence assay.     

Anthrasesamones D and E from Sesamum indicum Roots

Two anthraquinone derivatives, named anthrasesamones D and E, were isolated from the roots of Sesamum indicum. Their respective structures were determined to be 1,2,4-trihydroxy-3-(4-methylpent-3-enyl)anthraquinone and 1,2-dihydroxy-3-(4-methylpent-3-enyl)anthraquinone on the basis of spectroscopic evidence.     

Polyhydroxylated steroid compounds from the Far Eastern starfish <Emphasis Type="Italic">Distolasterias nipon</Emphasis>

Two new steroid glycosides: distolasteroside D₆, (24S)-24-O-(β-D-xylopyranosyl)-5α-cholestane-3β,6α,8,15β,16β,24-hexaol, and distolasteroside D₇, (22E,24R)-24-O-(β-D-xylopyranosyl)-5α-cholest-22-ene-3β,6α,8,15β,24-pentaol were isolated along with the previously known distolasterosides D₁, D₂, and D₃, echinasteroside C, and (25S)-5α-cholestane-3β4β,6α,7α,8,15α,16β,26-octaol from the Far Eastern starfish Distolasterias nipon. The structures of new compounds were elucidated by NMR spectroscopy and MALDI TOF mass spectrometry. Like neurotrophins, distolasterosides D₁, D₂, and D₃ were shown to induce neuroblast differentiation in a mouse neuroblastoma C1300 cell culture.     

New steroid glycosides from the starfish Fromia milleporella

Two new steroid glycosides from the starfish Fromia milleporella collected in the Seychelles were isolated and characterized: milleporoside A, (20R, 24R)-29-O-[3-O-methyl-β-D-xylopyranosyl-(1→4)-3-O-methyl-β-D-xylopyranosyl]-24-ethyl-5α-cholestane-3β,4β,6α,8,15β,16β,29-heptaol, and milleporoside B, (20R, 24R)-(22E)-28-O-[3-O-methyl-β-D-xylopyranosyl-(1→4)-3-O-methyl-β-D-xylopyranosyl]-24-methyl-5α-cholest-22-ene-3β,4β,6α,8,15β,16β,28-heptaol. The structures of the glycosides were determined from their spectra and a comparison with spectral characteristics of known compounds. These compounds exhibit a moderate cytostatic activity toward the embryos of the sea urchin Strongylocentrotus intermedius.     

CD correlation of C-2′substituted monocyclic carotenoids

The scope and limitation of circular dichroism (CD) correlations of several C-2′ substituted monocyclic monochiral, homodichiral and heterodichiral carotenoids have been investigated, aiming at the assignment of absolute configuration at C-2′ by using the diester and 2′-β-d-tetraacetylglucosyl derivative of (2′R)-plectaniaxanthin and a synthetic chiral C₄₅-carotene as key references. The correlations are based on the additivity hypothesis, the conformational rule and a comparison of CD spectra, preferably conservative ones. Quantitative aspects of the conformational rule are considered. Substituent effects at C-2′ and C-1′ have been studied. Absolute configurations are suggested for (2′)-phleixanthophyll (3S,2′S)-2′-hydroxyflexixanthin, (3R,2′S)-myxoxanthophyll, (3S,2′S-4-ketomyxoxanthophyll (3R,2′S)-myxol-2′-O-methyl methylpentoside and (2R,2′S)-Cp. 473 from relevant CD correlations. The chiralities of (2′S)-4-ketophleixanthophyll and (2R,6R,2′S)-A.g. 471 are suggested from biogenetic considerations. A chemosystematic consideration of chirality and source is included.     

Biosynthesis of vitamin E and of the plastoquinones in chloroplasts: Steric course of the decarboxylation

Samples of (3R)- and (3S)-4′hydroxyphenyl[3-²H₁, 3-³H]pyruvate were prepared by taking advantage of the known stereospecificity of phenylpyruvate keto-enol isomerase (tautomerase). 4′-Hydroxyphenyl[3-¹⁴C]pyruvate was obtained by the action of l-amino acid oxidase on dl-[3-¹⁴C]tyrosine, whereas a simple base-catalyzed exchange procedure yielded samples of 4′-hydroxyphenyl[3-³H]- and 4′-hydroxyphenyl[3-²H₂]pyruvate. All labeled samples were converted in situ into the corresponding homogentisic acids on 4′-hydroxyphenyl-pyruvate dioxygenase that is known to catalyze the migration of the acetate side chain with retention of configuration. The isolated doubly labeled homogentisic acids were incubated with chloroplasts from Raphanus sativus cv. saxa Treib, and from the lipophilic products a fraction containing inter alia tocopherol, tocoquinone, and plastoquinone was obtained by chromatographic procedures. The incorporation of radioactivity was between 0.5 and 11% based on homogentisate. Reductive acetylation of the quinones yielded crystalline diacetylhydroquinones, which were submitted to Kuhn-Roth degradation. The radioactive acetate samples thus obtained were analyzed for chirality by an enzymatic procedure previously published. (2R)-[2-²H₁, 2-³H]Homogentisate gave mainly (S)-acetate, whereas (2S)-[2-²H₁, 2-³H]homogentisate was converted mainly into (R)-acetate. It is concluded that the decarboxylation of the side chain occurred with stereochemical retention during the biosynthetic process.     

Chemical constituents of Trilepisium madagascariense (Moraceae) and their antimicrobial activity

The chemical study of Trilepisium madagascariense has led to the isolation of two previously undescribed compounds, (+)-(2S)-7-hydroxy-3′,4′-dimethoxyflavan (trilepisflavan) and (E)-4-[3-(3,4-dihydroxyphenyl)prop-2-enoyloxy]-3-hydroxybenzoic acid (trilepisuimic acid), together with ten known compounds caffeic acid, catechin, erythrodiol-3-O-palmitate, 8-C-glucopyranosylapigenin, dihydrokaempferol, protocatechuic acid, 3′,7-dihydroxy-4′-methoxyflavan, isoliquiritigenin, luteolin and 1,3-dimethoxybenzene. Their structures were elucidated on the basis of spectroscopic evidence. Crude extracts, trilepisflavan, dihydrokaempferol and 8-C-glucopyranosylapigenin showed significant antimicrobial activity.     

Sesquiterpenoids and lignans from the fruits of Illicium simonsii Maxim

Twenty-two known compounds were isolated from the 95% alcohol extract of the fruits of Illicium simonsii Maxim, including seven sesquiterpenoids (16–22) and fifteen lignans (1–15). In the present research, compounds 3 ((7S,8R,8′S)-3,3′-dimethoxy-4,4′,9-trihydroxy-7,9′-epoxylignan-7′-one), 4 ((−)-(7′S,8S,8′R)-4,4′-dihydroxy-3,3′,5,5′-tetramethoxy-7′,9-epoxylignan-9′-ol-7-one), 5 ((+)-8-hydroxypinoresinol), 6 ((+)-8-hydroxymedioresinol), 8 ((2R,3R)-2β-(4″-hydroxy-3″-methoxybenzyl)-3α-(4′-hydroxy-3′-methoxybenzyl)-γ-butyrolactone 2-O-(β-D-glucopyranoside), 12 ((+)-8-methoxyisolariciresinol), 13 (α-conidendrin), 14 (boehmenan) and 15 (7R,8R,7′E-7′,8′-didehydro-4,7,9,9′- tetrahydroxy-3-methoxy-8-O-4′-neolignan) were reported from the Illicium genus for the first time, and compounds 1 (simulanol), 7 ((+)-secoisolariciresinol monoglucoside), 10 ((+)-9-O-β-D-glucopyranosyl lyoniresinol), 11 ((+)-isolariciresinol), 18 (neoanisatin), 19 (veranisatin A), 20 (4,5-d₂-8′-oxo-dihydrophaseic acid) and 22 (Oligandrumin A) were firstly isolated from the plant. Their structures were elucidated on the basis of NMR spectroscopic and mass spectrometric data. Moreover, the chemotaxonomic significance of the isolated compounds is discussed.     

Chromones from the tubers of Eranthis cilicica and their antioxidant activity

Chemical studies on the constituents of Eranthis cilicica led to isolation of ten chromone derivatives, two of which were previously known. Comprehensive spectroscopic analysis, including extensive 1D and 2D NMR data, and the results of enzymatic hydrolysis allowed the chemical structures of the compounds to be assigned as 8,11-dihydro-5-hydroxy-2,9-dihydroxymethyl-4H-pyrano[2,3-g][1]benzoxepin-4-one, 5,7-dihydroxy-8-[(2E)-4-hydroxy-3-methylbut-2-enyl]-2-methyl-4H-1-benzopyran-4-one, 5,7-dihydroxy-2-hydroxymethyl-8-[(2E)-4-hydroxy-3-methylbut-2-enyl]-4H-1-benzopyran-4-one, 7-[(β-d-glucopyranosyl)oxy]-5-hydroxy-8-[(2E)-4-hydroxy-3-methylbut-2-enyl]-2-methyl-4H-1-benzopyran-4-one, 7-[(β-d-glucopyranosyl)oxy]-5-hydroxy-2-hydroxymethyl-8-[(2E)-4-hydroxy-3-methylbut-2-enyl]-4H-1-benzopyran-4-one, 9-[(O-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl)oxy]methyl-8,11-dihydro-5,9-dihydroxy-2-methyl-4H-pyrano[2,3-g][1]benzoxepin-4-one, 8,11-dihydro-5,9-dihydroxy-9-hydroxymethyl-2-methyl-4H-pyrano[2,3-g][1]benzoxepin-4-one, and 7-[(O-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl)oxy]methyl-4-hydroxy-5H-furo[3,2-g][1]benzopyran-5-one, respectively. The isolated compounds were evaluated for their antioxidant activity.     

Two new steroid glycosides from the Far East starfish <Emphasis Type="Italic">Hippasteria kurilensis</Emphasis>

Two new steroid glycosides were isolated from the Far East starfish Hippasteria kurilensis collected in the Sea of Okhotsk. They were characterized as (22E,24R)-3-O-(2-O-methyl-β-D-xylopyranosyl)-24-O-[2-O-methyl-β-D-xylopyranosyl-(1→5)-α-L-arabinofuranosyl]-5α-cholest-22-ene-3β,4β,6α,7α,8,15β,24-heptaol (kurilensoside I) and (24S)-3-O-(2-O-methyl-β-D-xylopyranosyl)-24-O-(α-L-arabinofuranosyl)-5α-cholestane-3β,4β,6β,15α,24-pentaol (kurilensoside J). In addition, the earlier known glycosides linkosides F and L1, leviusculoside G, forbeside L, desulfated echinasteroside, and granulatoside A were isolated and identified. The structures of the new compounds were established with the help of two-dimentional NMR spectroscopy and mass- spectrometry.