Hyrtiosins A–E,Five New Scalarane Sesterterpenes from the South China Sea Sponge Hyrtios erecta

Five new scalarane sesterterpenes, hyrtiosins A–E ( 1 – 5 ), together with three previously reported sesterterpenes, 25‐dehydroxy‐12‐epi‐scalarin ( 6 ), 12‐epi‐scalarin ( 7 ) and heteronemin ( 9 ), were isolated from the South China Sea sponge Hyrtios erecta. Their structures were determined on the basis of extensive NMR studies and high‐resolution MS measurements.     

A New ent‐Kaurane Diterpene from Stems of Alibertia macrophylla K. Schum. (Rubiaceae)

Phytochemical investigations of the stems of a specimen of Alibertia macrophylla led to the isolation and characterization of the new diterpene ent‐kaurane‐2β,3α,16α‐triol ( 1 ), along with triterpenes 2 – 8 , iridoids 9 – 12 , and phenolic acids 13 – 15 . The structure of 1 was established based on spectroscopic studies (¹H‐ and ¹³C‐NMR, IR, and HR‐ESI‐MS). This is the first report of the isolation of a diterpene from the Alibertia genus in Rubiaceae.     

Two New Labdane‐Type Diterpene Acids from the Wood of Cunninghamia konishii

Two new labdane‐type diterpene acids, (12S)‐12‐hydroxylabda‐8(17),13(16),14‐trien‐18‐oic acid ( 1 ) and (12R)‐12‐hydroxy‐15,16‐epoxylabda‐8(17),13‐dien‐18‐oic acid ( 2 ), along with a known labdane‐type diterpene, (11E)‐15,16‐bisnor‐13‐oxolabda‐8(17),11‐dien‐19‐oic acid ( 3 ), were isolated from the MeOH extract of the wood of Cunninghamia konishii. Their structures were determined by analysis of spectroscopic data and comparison with the data of known analogs.     

Diketopiperazine Alkaloids Produced by the Endophytic Fungus Aspergillus fumigatus from the Stem of Erythrophloeum fordii Oliv.

Four new diketopiperazine alkaloids, rel‐(8R)‐9‐hydroxy‐8‐methoxy‐18‐epi‐fumitremorgin C ( 1 ), rel‐(8S)‐19,20‐dihydro‐9,20‐dihydroxy‐8‐methoxy‐9,18‐di‐epi‐fumitremorgin C ( 2 ), rel‐(8S,19S)‐19,20‐dihydro‐9,19,20‐trihydroxy‐8‐methoxy‐9‐epi‐fumitremorgin C ( 3 ), and (3S,8S,9S,18S)‐8,9‐dihydroxyspirotryprostatin A ( 4 ), together with the eight known compounds 5 – 12 , were isolated from the endophytic fungus Aspergillus fumigatus. The structures of the new compounds were determined by extensive spectroscopic methods including HR‐ESI‐MS, NMR, and CD experiments. Compound 12 showed weak inhibitory activity in vitro against the release of β‐glucuronidase in rat polymorphonuclear leukocytes induced by the platelet‐activating factor. None of the twelve compounds exhibited detectable cytotoxic activities toward five human tumor cell lines (HCT‐8, Bel‐7402, BGC‐823, A549, and A2780) in the MTT assay.     

Two New, 1‐Oxygenated ent‐Kaurane‐Type Diterpenes from Croton kongensis

One new ent‐8,9‐secokaurane diterpene, kongensin D ( 1 ), and one new ent‐kaurane diterpene, kongensin E ( 2 ), along with one known compound, (7α)‐7,18‐dihydroxy‐ent‐kaur‐16‐en‐15‐one 18‐acetate ( 3 ), were isolated from the aerial parts of Croton kongensis. The structures of the new compounds were elucidated by means of HR‐MS and in‐depth NMR experiments, and by comparison with literature data. Compounds 1 and 2 showed an unusual oxygenation pattern with an OH or AcO group at C(1).     

Stereo‐ and Regioselective Phyllobilane Oxidation in Leaf Homogenates of the Peace Lily (Spathiphyllum wallisii): Hypothetical Endogenous Path to Yellow Chlorophyll Catabolites

In senescent leaves, chlorophyll typically is broken down to colorless and essentially photo‐inactive phyllobilanes, which are linear tetrapyrroles classified as “nonfluorescent” chlorophyll catabolites (NCCs) and dioxobilane‐type NCCs (DNCCs). In homogenates of senescent leaves of the tropical evergreen Spathiphyllum wallisii, when left at room temperature and extracted with methanol, the major endogenous, naturally formed NCC was regio‐ and stereoselectively oxidized (in part) to a mixture of its 15‐hydroxy and 15‐methoxy derivative. In the absence of methanol in the extract, only the 15‐OH‐NCC was observed. The endogenous oxidation process depended upon molecular oxygen. It was inhibited by carbon monoxide, as well as by keeping the leaf homogenate and extract at low temperatures. The remarkable “oxidative activity” was inactivated by heating the homogenate for 10 min at 70 °C. Upon addition of a natural epimeric NCC (epiNCC) to the homogenate of senescent or green Sp. wallisii leaves at room temperature, the exogenous epiNCC was oxidized regio‐ and stereoselectively to 15‐OH‐epiNCC and 15‐OMe‐epiNCC. The identical two oxidized epiNCCs were also obtained as products of the oxidation of epiNCC with dicyanodichlorobenzoquinone (DDQ). Water elimination from 15‐OH‐epiNCC occurred readily and gave a known “yellow” chlorophyll catabolite (YCC). The endogenous oxidation process, described here, may represent the elusive natural path from the colorless NCCs to yellow and pink coloured phyllobilins, which were found in (extracts of) some senescent leaves.     

Structure elucidation of new fusarielins from Fusarium sp. and their antimicrobial activity

Three new fusarielins, 3‐epi‐fusarielin H ( 1 ), 3‐O‐methyl‐fusarielin H ( 2 ), and 3‐O‐methyl‐epi‐fusarielin H ( 3 ), were isolated from the fungus Fusarium sp. together with the known analogues, fusarielins F ( 4 ) and G ( 5 ). The structures of these compounds were elucidated by analysis of their ESI‐HRTOFMS, 1D and 2D NMR spectroscopic data. The new compounds exhibited weak antibacterial effect against Staphylococcus aureus.     

Labdane Diterpenes and Flavonoids from Leonurus japonicus

Chemical investigation of the aerial part of Leonurus japonicus led to the isolation and characterization of a new labdane‐type diterpene, named 3α‐acetoxy‐15‐O‐methylleopersin C ( 3 ), and a new acylated rutin derivative, named 2′′′‐syringylrutin ( 9 ), along with seven known compounds, including a labdane‐type diterpene and six flavonoids. The structures of the new compounds were established by spectroscopic methods.     

Three New ent‐Kaurane Diterpenoids from Siegesbeckia pubescens

Three new ent‐kaurane glucopyranosides, 2‐O‐[β‐D ‐apiofuranosyl‐(1→3)‐2‐O‐isovaleryl‐β‐D ‐glucopyranosyl]‐4‐epi‐atractyligenin ( 1 ), 2‐O‐[β‐D ‐apiofuranosyl‐(1→3)‐2‐O‐isovaleryl‐β‐D ‐glucopyranosyl]atractyligenin ( 2 ), and 2‐O‐[β‐D ‐apiofuranosyl‐(1→3)‐2‐O‐(3‐methylpentanoyl)‐β‐D ‐glucopyranosyl]‐4‐epi‐atractyligenin ( 3 ), along with 2‐O‐(2‐O‐isovaleryl‐β‐D ‐glucopyranosyl)‐4‐epi‐atractyligenin ( 4 ), were isolated for the first time from the aerial parts of Siegesbeckia pubescens. The structures were established by extensive spectroscopic analyses including 1D ‐ and 2D ‐NMR (HSQC, HMBC, and ROESY), and HR‐ESI‐MS, and by comparison with published data.     

Three New Cadinene Derivatives from Xenia Puerto‐Galerae

Chromatographic investigation of an acetone extract of the octocoral Xenia puerto‐galerae afforded three new cadinene sesquiterpenes; 8‐epi‐xenitorin A ( 1 ), 10‐epi‐xenitorin C ( 2 ), and 7‐isopropenyl‐4,10‐dimethyl‐2,3,4,5‐tetrahydronaphthalene ( 3 ), in addition to four known cadinene analogs ( 4 , 11–13 ) and six xenicanes ( 5–10 ). The structures were elucidated through spectroscopic analysis, especially 2D NMR. A biogenetic pathway of 1–3 and analogs was proposed.     

gem‐Dihalocyclopropanes as Building Blocks in Natural‐Product Synthesis: Enantioselective Total Syntheses of ent‐Erythramine and 3‐epi‐Erythramine

ent‐Erythramine ((?)‐ 1 ), the enantiomer of the alkaloid erythramine, was prepared in 15 steps from known compounds. The first of three pivotal bond‐forming steps in the synthesis was a Suzuki–Miyaura cross‐coupling reaction of the starting materials to give a bis‐silyl ether. The second involved silver(I)‐induced electrocyclic ring opening of the gem‐dichlorocyclopropane formed in the next step and trapping of the ensuing π‐allyl cation by the tethered nitrogen atom to give, following cleavage of the allyloxycarbonyl protecting group, an approximately 5:6 mixture of the chromatographically separable diastereoisomeric spirocyclic products. In the third critical bond‐forming reaction, the iodide formed from one of the diastereoisomers underwent a radical‐addition/elimination reaction sequence that led to (?)‐ 1 in 89 % yield. The application of the same sequence of transformations to the other diastereoisomer afforded 3‐epi‐(+)‐erythramine (3‐epi‐(+)‐ 1 ).     

Chemical Constituents of the Aerial Part of Celastrus Hypoleucus

Fourteen compounds including eight triterpenoids, 12‐oleanaen‐3β‐ol (β‐amyrin) ( 1 ), 12‐oleanaen‐3β‐caffeate ( 2 ), 9(11),12‐oleanadien‐3β‐ol ( 3 ), 9(11),12‐oleanadien‐3‐one ( 4 ), 9(11),12‐oleanadien‐3 β‐caffeate ( 5 ), friedela‐3‐one (friedelin) ( 6 ), friedela‐3‐one‐29‐ol ( 7 ), and 12‐gammateraen‐3 β‐ol (tetrehymanol) ( 8 ); one steroid, β‐sitosterol ( 9 ); one long‐chain acid, octadecadienoic acid ( 10 ); two esters, ester of n‐octaolecyl‐4‐hydroxy‐cinnamate ( 11 ), and ester of n‐octadecyl‐caffeic acid ( 12 ); one diterpene, 8β,19‐dihydroxy‐3‐oxopimar‐15‐ene ( 13 ); one sesquiterpene, 1β,2β,9α‐trihydroxy‐β‐dihydroagarofuran ( 14 ) were isolated from the aerial part of Celastrus hypoleucus. These compounds were characterized and identified by physical and spectral methods. All compounds were isolated for the first time from this plant. Among them 12‐oleanaen‐3β‐caffeate ( 2 ) and 9(11),12‐oleanadien‐3β‐caffeate ( 5 ) are two new compounds, and ester of n‐octadecyl‐caffeic acid (12) possessed antilipoperoxidative effect by specifically scavenging the hydroxyl free radical (?OH) in vitro.     

Two New Acidic Diterpenoids from the Heartwood of Pinus massoniana Lamb.

A new abietane diterpene, named abietopinoic acid, and a new podocarpane diterpene, named podopinoic acid, were isolated from the acetone extract of the heartwood of Pinus massoniana. Their structures were established as 12‐hydroxy‐7‐oxoabieta‐8,11,13‐trien‐18‐oic acid ( 1 ) and 13‐hydroxy‐7‐oxopodocarpane ( 2 ) by means of spectroscopic analyses including 2D‐NMR. To the best of our knowledge, this is the second report of a podocarpa‐8,11,13‐trien‐18‐oic acid diterpene, isolated from the genus Pinus.     

Terpenoids from the Chinese Liverwort Chiloscyphus polyanthus

A new diterpene, (7α,11β,14β,16R)‐7,11,14‐trihydroxy‐ent‐kaur‐15‐one ( 1 ), and a new sesquiterpene, polyanthuslide ( 2 ), were isolated from the Chinese liverwort Chiloscyphus polyanthus. Their structures were determined on the basis of extensive spectroscopic analyses, and the configuration of 2 was established by X‐ray crystallographic analysis.     

Structure elucidation and 13C NMR spectral assignments of 3α‐hydroxyolean‐12‐en‐30‐oic acid,a new triterpene from Bocconia arborea

The structure and ¹³C NMR assignments of 3α‐hydroxyolean‐12‐en‐30‐oic acid (20‐epi‐katonic acid), a novel pentacyclic triterpene isolated from the aerial parts of Bocconia arborea (Papaveraceae), are reported. Copyright © 2003 John Wiley & Sons, Ltd.     

Chemical Constituents from the Roots of Schnabelia tetradonta

The new rearranged‐abietane diterpene 1 , the four new triterpenoids 2 – 5 , and the new aminoethylphenyl oligoglycoside 6 , besides 19 known compounds, were isolated from the roots of Schnabelia tetradonta, a Chinese endemic herb. The structures of the new compounds were elucidated on the basis of spectroscopic evidence as 12,17‐epoxy‐11,14,16‐trihydroxy‐17(15→16)‐abeo‐abieta‐8,11,13,15‐tetraen‐7‐one ( 1 ), 21β‐(β‐D ‐glucopyranosyloxy)‐2α,3α‐dihydroxyolean‐12‐en‐28‐oic acid ( 2 ), 2β,3β,16β‐trihydroxy‐15‐oxo‐28‐norolean‐12‐en‐23‐oic acid ( 3 ), 3β‐[(4‐O‐acetyl‐β‐D ‐glucopyranuronosyl)oxy]‐2β,16β‐dihydroxy‐28‐norolean‐15‐oxo‐12‐en‐23‐oic acid ( 4 ), 3β‐[(4‐O‐acetyl‐6‐O‐methyl‐β‐D ‐glucopyranuronosyl)oxy]‐2β,16β‐dihydroxy‐15‐oxo‐28‐norolean‐12‐en‐23‐oic acid ( 5 ), and 4‐[2‐(acetylamino)ethyl]phenyl O‐6‐O‐[(Z)‐p‐methoxycinnamoyl]‐β‐D ‐glucopyranosyl‐(1→2)]‐O‐[β‐D ‐glucopyranosyl‐(1→3)]‐4‐O‐acetyl‐α‐L ‐rhamnopyranoside ( 6 ), respectively.     

Comparison of racemic epi‐inosose and (−)‐epi‐inosose

The conversion of myo‐inositol to epi‐inositol can be achieved by the hydride reduction of an intermediate epi‐inosose derived from myo‐inositol. (−)‐epi‐Inosose, (I), crystallized in the monoclinic space group P2₁, with two independent molecules in the asymmetric unit [Hosomi et al. (2000). Acta Cryst. C 56 , e584–e585]. On the other hand, (2RS,3SR,5SR,6SR)‐epi‐inosose, C₆H₁₀O₆, (II), crystallized in the orthorhombic space group Pca2₁. Interestingly, the conformation of the molecules in the two structures is nearly the same, the only difference being the orientation of the C‐3 and C‐4 hydroxy H atoms. As a result, the molecular organization achieved mainly through strong O—H...O hydrogen bonding in the racemic and homochiral lattices is similar. The compound also follows Wallach's rule, in that the racemic crystals are denser than the optically active form.     

A New Tetracyclic Diterpene from Jatropha curcas

Jatrophodione A ( 1 ), a new diterpene with four rings, together with nine known compounds, caniojane ( 2 ), jatropholone A ( 3 ), jatropholone B ( 4 ), jatrogrossidione ( 5 ), 2‐epijatrogrossidione ( 6 ), heudelotinone ( 7 ), gossweilone ( 8 ), (3α)‐3‐hydroxy‐ent‐pimara‐8(14),15‐dien‐12‐one ( 9 ), and 12‐hydroxy‐13‐methylpodocarpa‐8,11,13‐trien‐3‐one ( 10 ), was isolated from the aerial parts of Jatropha curcas. Compounds 5, 6, 9 , and 10 were found for the first time in this plant. Their structures were established by spectroscopic analysis, including 2D‐NMR spectroscopic techniques. Cytotoxicities of compounds 1, 2, 7, 8 , and 9 were tested on the three cancer cell lines A549, Hela, and SMMC‐7721. Results showed that 7 exhibited cytotoxicity against SMMC‐7721 with an IC₅₀ value of 21.68 μM , whereas 7 and 8 were active against A549 with the IC₅₀ values of 16.04 and 20.47 μM , and against Hela with the IC₅₀ values of 10.67 and 22.83 μM , respectively.     

Identification of Intermediates in the Biosynthesis of PR Toxin by Penicillium roqueforti

The sesquiterpenoid 7‐epi‐neopetasone was synthesized via the Wieland–Miescher ketone. The compound was identical to a previously tentatively identified headspace constituent of Penicillium roqueforti. Feeding experiments with ¹³C‐labeled mevalonolactone isotopomers demonstrated that oxidation at C12 and an isomerization of the C11?C12 to a C7?C11 double bond must occur independently and not via a C7‐C11‐C12 allyl radical in one step. Feeding with (11,12,13‐¹³C₃)‐7‐epi‐neopetasone resulted in labelling of the PR toxin, thus establishing this compound as a newly identified pathway intermediate.     

New Diterpene Alkaloids from Aconitum sungpanense var. leucanthum

Five new C₁₉ diterpene alkaloids, leucanthumsines A ( 1 ), B ( 2 ), C ( 3 ), D ( 4 ), and E ( 5 ), were isolated from the Chinese medicinal herb Aconitum sungpanense var. leucanthum, together with the known C₁₉ diterpene alkaloids pseudaconine, neoline, 1‐O‐methyldelphisine, crassicaudine, chasmanine, talatisamine, indaconitine, ezochansmanine, and leueantine D. The structures of these new alkaloids were elucidated by HR‐MS and advanced NMR methods, including ¹H‐ and ¹³C‐NMR (DEPT), ¹H,¹H‐COSY, HMQC, and HMBC experiments.