New cytotoxic halogenated sesquiterpenes from the Egyptian sea hare, Aplysia oculifera

Two new sesquiterpenes, oculiferane (1) and epi-obtusane (2) have been isolated and identified from an acetone extract of the digestive gland of the sea hare, Aplysia oculifera. The structures were elucidated by spectroscopic analysis including HREIMS, ¹H, ¹³C, DEPT, ¹H–¹H COSY, HMQC, and HMBC NMR; the relative configuration was confirmed by X-ray analysis. Compounds 1 and 2 exhibited cytotoxic activity in vitro against several human cancer cell lines with IC₅₀ values in the low μg/ml range.     

Antiplasmodial and cytotoxic activities of drimane sesquiterpenes from Canella winterana

The hexane extract from the leaves of Canella winterana exhibited strong activity against the chloroquine sensitive (CQS) strain of Plasmodium falciparum (D10) in vitro (IC50 2.53 microg/mL). Bioassay guided fractionation of this extract has led to the isolation of 5 drimane-type sesquiterpenoids: 9-epideoxymuzigadial, 9-deoxymuzigadial, muzigadial, 3-beta-acetoxypolygodial and the newly isolated hemiacetal, named muzigodiol, with IC50-values of 1.01, 2.19, 0.31, 2.77 and 7.43 microg/mL, respectively. The first four compounds were tested for their cytotoxicity using Chinese Hamster Ovarian (CHO) cells, where they showed IC50-values of 1.82, 33.69, 1.18, and 58.31 microg/mL, respectively. A structure-activity relationship is discussed.     

New cytotoxic sesquiterpenes from the red algae Laurencia obtusa and Laurencia microcladia

Three new sesquiterpenes (1-3), along with five known (5-9), were isolated from the organic extract of the red alga Laurencia obtusa, collected from the coastal rocks of Serifos in the Aegean Sea. A new dimeric sesquiterpene of the cyclolaurane-type (4) along with four previously reported (7, 10-12) metabolites, were isolated from the extract of Laurencia microcladia, collected at Chios island in the North Aegean Sea. The structures and the relative stereochemistry of the compounds are proposed on the basis of their spectral data. The cytotoxicity of the isolated metabolites was evaluated against several cell lines including human tumor cell lines.     

New calamenene sesquiterpenes from Tarenna madagascariensis

Four calamenene sequiterpenes, (+)-(7R,10S)-15-hydroxycalamenene (3), (+)-(7R,10S)-2,15-dihydroxycalamenene (4), (+)-(7R,10S)-2-hydroxy-15-calamenal (5), (+)-(7R,10S)-15-calamenal (6), along with the amorphane sesquiterpene (+)-(1S,6R,7R,10S)-1-hydroxy-3-oxo-amorph-4-ene (16), have been isolated from the Madagascan shrub Tarenna madagascariensis (Rubiaceae) and their structures determined by spectroscopic methods and chemical correlations. Furthermore, five known related sesquiterpenes [(+)-(7R,10S)-2-hydroxycalamenene (1), (+)-(7R,10S)-3-hydroxycalamenene (2), (-)-alpha-cadinol (13), cadinenal (14), 6-epicadinenal (15)], and three known lignans [(-)-hinokinin, (-)-dihydrocubebin, (-)-cubebin] were also isolated from the same plant. This is the first report of compounds 3, 4, 5, 6, and 16 from a natural source.     

New germacrane sesquiterpenes from Salvia chinensis

Two new germacrane sesquiterpenes, called salviadienol A (1) and salviadienol B (2), together with five known compounds, methyl-ent-4-epi-agath-18-oate (3), angelicoidenol (4), clovane-2beta,9alpha-diol (5), dehydrovomifoliol (6) and blumenol A (7), were isolated from Salvia chinensis. Their structures were identified on the basis of spectral characteristics.     

New sesquiterpenes and calebin derivatives from Curcuma longa

One novel sesquiterpene with new skeleton, (6S)-2-methyl-6-(4-hydroxyphenyl-3-methyl)-2-hepten-4-one (1), two new bisabolane sesquiterpenes, (6S)-2-methyl-6-(4-hydroxyphenyl)-2-hepten-4-one (2), (6S)-2-methyl-6-(4-formylphenyl)-2-hepten-4-one (3), and two calebin derivatives, 4'-(4'-hydroxyphenyl-3'-methoxy)-2'-oxo-3'-butenyl-3-(4'-hydroxyphenyl)-propenoate (4) and 4'-(4'-hydroxyphenyl)-2'-oxo-3'-butenyl-3-(4'-hydroxyphenyl-3'-methoxy)-propenoate (5) were isolated along with five known bisabolane sesquiterpenes from Curcuma longa. 1-4 were new compounds and 5 was a new natural product. Their structures were established by spectral methods.     

New acetylenic glucosides from Carthamus tinctorius

Two new acetylenic glucosides, 4',6'-acetonide-8Z-decaene-4,6-diyne-1-O-beta-D-glucopyranoside named carthamoside A(1) (1) and 4,6-decadiyne-1-O-beta-D-glucopyranoside named carthamoside A(2) (2), along with one known acetylenic glucoside, 8Z-decaene-4,6-diyne-1-O-beta-D-glucopyranoside (3), have been isolated from the air-dried flower of Carthamus tinctorius, these structures have been identified on the basis of spectroscopic methods.     

Three New Illudalane Sequiterpenoids from Pteris semipinnata

The chemical investigation of the aerial parts of Pteris semipinnata resulted in the isolation of three illudalane sesquiterpenoids, namely (2R)‐norpterosin B ( 1 ), (2R)‐12‐O‐β‐D ‐glucopyranosylnorpterosin B ( 2 ), and semipterosin A ( 3 ), along with three known compounds. The structures of 1 – 3 were established by spectroscopic methods, including extensive 2D‐NMR and CD analyses.     

New diterpenoid glucosides from Siegesbeckia pubescens

Plants of the genus Siegesbeckia are annual herbs widely distributed in tropical and temperate zones and they are used as a traditional medicine to treat rheumatic arthritis, hypertension, malaria, neurasthenia and snake-bite in China. In previous papers, we reported on five new ent-kaurane and ent-pimarane diterpenoids, siegesbeckioside, siegesbeckiol and siegesbeckic acid1, orientalin A and B, and eight know compounds2,3. The present paper describes the isolation and structural elucidation …     

New sesquiterpenes from Euonymus europaeus (Celastraceae)

A new sesquiterpene evoninate alkaloid (1), and two sesquiterpenes (2, 3) with a dihydro-beta-agarofuran skeleton, along with three known sesquiterpenes (4-6), were isolated from the seeds of Euonymus europaeus. Their structures were elucidated by high resolution mass analysis, and one- and two-dimensional (1D and 2D) NMR spectroscopy, including homonuclear and heteronuclear correlation [correlation spectroscopy (COSY), rotating frame Overhauser enhancement spectroscopy (ROESY), heteronuclear single quantum coherence (HSQC), and heteronuclear multiple bond correlation (HMBC)] experiments.     

New sesquiterpenes from the roots of Coriaria nepalensis

Six new trace sesquiterpenes, corialactones A–D (1–4), coriantone (5), corianol (6), together with nine known ones (7–15), were isolated from the roots of Coriaria nepalensis. The structures of 1–6 were elucidated through a combination of extensive NMR spectroscopic analysis, HRESIMS, CD, Rh₂(OCOCF₃)₄-induced CD, Snatzke's method, and X-ray crystallography. Compounds 2–4, and 6 possess characteristic structural units compared with the previously reported sesquiterpenes from this family. In vivo system, compounds 5, 6 and 10 showed anti-convulsant activity by 20%, 60%, and 20% at the dose of 5 mg/kg, respectively.     

New acetylenic glucosides from Bidens bipinnata LINNE

Two new acetylenic glucosides, 8Z-decaene-4,6-diyn-1-O-beta-D-glucopyranoside named bidenoside C, and 8E-decaene-4,6-diyn-3,10-dihydroxy-1-O-beta-D-glucopyranoside named bidenoside D, have been isolated from the aerial parts of Bidens bipinnata LINNE (Asterceae). These structures have been elucidated on the basis of spectroscopic methods.     

New sesquiterpenes from the red alga Laurencia microcladia

Three new aromatic sesquiterpenes (1, 2, and 4), one new dimeric sesquiterpene of the cyclolaurane-type (3), one sesquiterpene alcohol of bisabolene type (8) along with three previously reported metabolites (5-7), were isolated from the organic extracts of Laurencia microcladia, collected from the Chios island in the North Aegean Sea. The structures of the new natural products, as well as their relative stereochemistries, were established by means of spectral data analyses, including 2D experiments. The cytotoxicity of the isolated metabolites was evaluated against five human tumor cell lines.     

New lignan glucosides from the stems of Tinospora sinensis

Two new lignan glucosides, tinosposides A and B (1 and 2), were isolated from the stems of Tinospora sinensis collected in Hainan Island, China. Their structures were elucidated on the basis of spectroscopic analysis and chemical evidence.     

New alpha-tetralonyl glucosides from the fruit of Juglans mandshurica

Five new alpha-tetralonyl glucosides, juglanosides A-E (1-5) were isolated from the fresh rejuvenated fruit of Juglans mandshurica. Their structures were elucidated as (4S)-4-hydroxy-alpha-tetralone 4-O-beta-D-glucopyranoside (1), (4S)-4,5-dihydroxy-alpha-tetralone 4-O-beta-D-glucopyranoside (2), (4S)-4,6-dihydroxy-alpha-tetralone 4-O-beta-D-glucopyranoside (3), (4S)-4,5,8-trihydroxy-alpha-tetralone 4-O-beta-D-glucopyranoside (4), and (4S)-4,5,8-trihydroxy-alpha-tetralone 5-O-beta-D-glucopyranoside (5) on the basis of spectroscopic analysis and chemical evidence.     

New iridoid glucosides from the aerial parts of Verbena brasiliensis

Two new iridoid glucosides, verbenabraside A (1) and verbenabraside B (2), were isolated from the aerial parts of Verbena brasiliensis VELL., along with six known iridoid glucosides, gelsemiol 3-O-beta-D-glucoside (3), verbraside (4), 9-hydroxysemperoside (5), griselinoside (6), aralidioside (7), and 6alpha-hydroxyforsythide dimethyl ester (8), three known phenylethanoid glycosides, 2-phenylethyl O-beta-D-xylopyranosyl-(1-->2)-beta-D-glucopyranoside (9), acteoside (10), and leucosceptoside A (11), two known lignan glucosides, dihydroxymethyl-bis(3,5-dimethoxy-4-hydroxyphenyl) tetrahydrofuran-9 (or 9')-O-beta-glucopyranoside (12) and (+)-lyoniresinol 3alpha-O-beta-D-glucopyranoside (13), a known methyl salicylate glucoside, methyl 2-O-beta-D-glucopyranosylbenzoate (14), and two known sterols, beta-sitosterol 3-O-beta-D-glucopyranoside (15) and beta-sitosterol (16). Their chemical structures were determined on the basis of spectroscopic data. Compound 1 exhibited stronger scavenging effect on the stable free radical 1,1-diphenyl-2-picrylhydrazyl than that of alpha-tocopherol.     

New cytotoxic cerebroside from Gynura divaricata

A new cerebroside,gynuraoside(1),was isolated from the aerial parts of Gynura divaricata DC.It was determined to be 1-O-β- D-glucopyranosyl-(2S,3S,4R,10E)-2-[(2′R)-2′-hydroxyldocosanoyl-amino]-10-octadecene-1,3,4-triol on the basis of chemical and spectroscopic evidence.This compound showed strong cytotoxicity against L1210 leukemia cell line in vitro.     

New spirocyclic sesquiterpenes from the marine sponge Geodia exigua

Three new spirocyclic sesquiterpenes designated exiguamide (1), exicarbamate (2) and exigurin (3), together with (−)-10-epi-axisonitrile-3 (4), have been isolated from the marine sponge Geodia exigua. All four compounds possess the spiro[4.5]decene skeleton and their structures were determined on the basis of spectroscopic data. The structure of 1 was confirmed by X-ray crystallographic analysis and the absolute configuration was determined by applying the modified Mosher's method on its amine derivative. Exiguamide (1) inhibited cell fate specification during sea urchin embryogenesis at a minimum inhibitory concentration of 0.4 μM.     

Lignans and sesquiterpenes from Magnolia praecocissima

A new lignan 1 was isolated together with the five known lignans 2-6 and four sesquiterpenes 7-10 from the seeds of Magnolia praecocissima. The structure of 1 was elucidated by analysis of spectroscopic data and chemical reaction. Furthermore, the absolute configurations of 1, 2, and 3 were determined by the modified Mosher's method.     

New triterpene glucosides from the roots of Rosa laevigata Michx

Two new ursane-type triterpene glucosides, 2alpha,3alpha,24-trihydroxyurs-12,18-dien-28-oic acid beta-D-glucopyranosyl ester (1) and 2alpha,3alpha,23-trihydroxyurs-12,19(29)-dien-28-oic acid beta-D-glucopyranosyl ester (2), were isolated from the roots of Rosa laevigata, together with three known compounds: 2alpha,3beta,19alpha-trihydroxyurs-12-en-28-oic acid beta-Dglucopyranosyl ester (3), 2alpha,3alpha,19alpha-trihydroxyurs-12-en-28-oic acid beta-D-glucopyranosyl ester (4) and 2alpha,3beta,19alpha,23-tetrahydroxyurs-12-en-28-oic acid beta-D-glucopyranosyl ester (5). The structures of new compounds were established on the basis of detailed 1D and 2D NMR spectroscopic analyses. Compounds 2 and 5 exhibited modest in vitro antifungal activities against Candida albicans and C. krusei.