Dammarane triterpenes of Commiphora confusa resin

Fractionation of a steam distilled residue of Commiphora confusa resin has yielded four novel dammarane triterpenes characterised as (20S)-3beta-acetoxy-12beta,16beta-trihydroxydammar-24-ene, (20S)-12beta,16beta-trihydroxydammar-24-ene-3beta-O-beta-glucopyranoside, (20S)-3beta-acetoxy-12beta,16beta,25-tetrahydroxydammar-23-ene, and (20S)-3beta,12beta,16beta,25-pentahydroxydammar-23-ene. The known compounds beta-amyrin, 3beta-amyrinacetate, 2-methoxyfuranodienone, 2-acetoxyfuranodienone, (20R)-3beta-acetoxy-16beta-dihydroxydammar-24-ene, (20R)-3beta,16beta-trihydroxydammar-24-ene, 3beta-acetoxy-16beta-hydroxydammar-24-ene, 3beta-hydroxydammar-24-ene, 3beta-acetoxydammar-24-ene, and beta-sistosterol were also isolated from the same extract. The structures of the compounds were determined using spectroscopic, physical, and chemical methods.     

Studies on the constituents of Cimicifuga species. XXVIII. Cycloart-7-enol glycosides from the underground parts of Cimicifuga simplex Wormsk

Four new cycloart-7-ene triterpenol arabinosides, bugbanosides C-F, were isolated from the underground parts of Cimicifuga simplex Wormsk. (Ranunculaceae). The structures were elucidated as 12beta-acetoxy-3beta,15alpha,-24R,25-tetrahydroxy-16,23-dione-cycloart-7-ene 3-O-alpha-arabinopyranoside, 12beta-acetoxy-24R,25-epoxy-3beta,15alpha-dihydroxy-16,23-dione-cycloart-7-ene 3-O-alpha-L-arabinopyranoside, 12beta-acetoxy-24R,25-epoxy-3beta-hydroxy-16,23-dione-cycloart-7-ene 3-O-alpha-L-arabinopyranoside, and 16,23R:16,24S-diepoxy-3beta,12beta,15alpha,25-tetrahydroxy-cycloart-7-ene 3-O-alpha-L-arabinopyranoside on the basis of spectral and chemical evidence. The circular dichroism (CD) of bugbanosides C-F showed strong negative maxima at 214-217 nm due to a cycloart-7-ene system, as well as other cycloart-7-ene triterpenes. The CD data showed to be useful in determining basic skeletons, including absolute stereostructures of cycloart-7-ene triterpenes.     

Three new pentacyclic triterpenes and some flavonoids from the fruits of an Indian Ayurvedic plant Dendrophthoe falcata and their estrogen receptor binding activity

Extensive chromatographic screening of extracts of the fruits of the Indian Ayurvedic plant, Dendrophthoe falcata, resulted in the isolation of three new triterpenes, 3beta-acetoxy-1beta-(2-hydroxy-2-propoxy)-11alpha-hydroxy-olean-12-ene (1), 3beta-acetoxy-11alpha-ethoxy-1beta-hydroxy-olean-12-ene (2) and 3beta-acetoxy-1beta-hydroxy-11alpha-methoxy-olean-12-ene (3) along with nine known compounds, 3beta-acetoxy-1beta,11alpha-dihydroxy-olean-12-ene (4), 3beta-acetoxy-1beta,11alpha-dihydroxy-urs-12-ene (5), 3beta-acetoxy-urs-12-ene-11-one (6), 3beta-acetoxy-lup-20(29)-ene (7), 30-nor-lup-3beta-acetoxy-20-one (8), (20S)-3beta-acetoxy-lupan-29-oic acid (9), kaempferol-3-O-alpha-L-rhamnopyranoside (10), quercetin-3-O-alpha-L-rhamnopyranoside (11), and gallic acid (12). The structures of these compounds were determined using 1D and 2D NMR and high resolution electrospray mass spectrometry. These compounds were assayed for binding to estrogen receptors-alpha and beta and kaempferol-3-O-alpha-L-rhamnopyranoside (10) was found to be a ligand for both receptors with greater affinity for beta. The triterpenes (1-9) are reported for the first time in the genus Dendrophthoe and assumes taxonomic significance.     

1H and 13C assignments of two new triterpenes from Cladocolea grahami

The structure elucidation and 1H and 13C assignments of the new triterpenes 3beta-palmitoxy-7beta-hydroxyolean-12-ene (1) and its hydrolysis product 3beta,7beta-dihydroxyolean-12-ene (2) and 3beta-sn-glyceroyl-(1'-palmitoxy)urs-12-ene (3), isolated from the aerial parts of Cladocolea grahami (Loranthaceae), are reported.     

Sesquiterpenes, nortriterpenes and other constituents from Ligularia tongolensis

Two new eremophilane-type sesquiterpenes, 3beta-(2'-methylbutanoyloxy)-8betaH-eremophil-7(11)-ene-12,8alpha-(14,6alpha)-diolide (1) and 8betaH-eremophil-3,7(11)-diene-12,8alpha(14,6alpha)-diolide (2), and two new norursane-type triterpenes, 2alpha,3beta,19alpha-trihydroxy-28-norurs-12-ene (7) and 2alpha,3alpha,19alpha-trihydroxy-28-norurs-12-ene (8), were isolated from the roots of Ligularia tongolensis, together with nine known compounds. The structures of the new compounds were elucidated by spectroscopic methods.     

Six new dammarane-type triterpene saponins from the leaves of Panax ginseng

Six new minor saponins, together with known ginsenosides, were isolated from the leaves of Panax ginseng. The new saponins were named as ginsenoside-Rh5, -Rh6, -Rh7 -Rh8, -Rh9 and -Rg7, and their structures were elucidated on the basis of chemical and physicochemical evidence to be as follows: ginsenoside-Rh5: 3beta,6alpha,12beta,24zeta-tetrahydroxy-dammar-20(22),25-diene 6-O-beta-D-glucopyranoside (1), -Rh6: 3beta,6alpha12beta,20(S)-tetrahydroxy-25-hydroperoxy-dammar-23-ene 20-O-beta-D-glucopyranoside (2), -Rh7: 3beta,7beta,12beta,20(S)-tetrahydroxy-dammar-5,24-diene 20-O-beta-D-glucopyranoside (3), -Rh8: 3beta,6alpha,20(S)-trihydroxy-dammar-24-ene-12-one 20-O-beta-D-glucopyranoside (4), -Rh9: 3beta,6alpha,20(S)-trihydroxy-12beta,23-epoxy-dammar-24-ene 20-O-beta-D-glucopyranoside (5) and -Rg7: 3-O-beta-D-glucopyranosyl 3beta,12beta,20(S),24(R)-tetrahydroxy-dammar-25-ene 20-O-beta-D-glucopyranoside (6).     

Antiproliferative constituents from Umbelliferae plants VI. New ursane-type saikosaponin analogs from the fruits of Bupleurum rotundifolium

The MeOH extract of the fruits of Bupleurum rotundifolium showed inhibitory activity against human gastric adenocarcinoma (MK-1) cell growth (GI(50): 6.25 microg/ml). From this extract, 10 new ursane-type triterpene glycosides viz. three 3-O-triosides (called rotundifoliosides A, I, and J) of 13beta,28-epoxy-3beta,16alpha-dihydroxyurs-11-ene, two (G and H) of 13beta,28-epoxy-3beta,16alpha,23-trihydroxyurs-11-ene, two (E and F) of 13beta,28-epoxy-3beta,16alpha,21beta-trihydroxyurs-11-ene, two (B and C) of 3beta,11alpha,16alpha,28-tetrahydroxyurs-12-ene, and one (D) of 3beta,11alpha,28-trihydroxy-15alpha,16alpha-epoxyurs-12-ene were isolated in addition to 16 new oleanane-type triterpene glycosides (rotundiosides J-Y), echinocystic acid 3-O-sulfate and 3 known oleanane-type triterpene glycosides (rotundiosides A, F and G). The isolation, structures and antiproliferative activity of the new ursane-type triterpene glycosides against MK-1, human uterus carcinoma (HeLa), and murine melanoma (B16F10) cell lines are described with some comments on the structural requirements for their activity.     

New triterpenoids from the stem barks of Drypetes tessmanniana

The MeOH extract of the stem barks of Drypetes tessmanniana (Euphorbiaceae) afforded two new triterpene derivatives characterized as 3beta-O-(E)-3,5-dihydroxycinnamoyl-11-oxo-olean-12-ene and 3beta,6alpha-dihydroxylup-20(29)-ene together with seven known compounds. Their structures were established on the basis of spectral analysis.     

Acid catalyzed isomerization of large ring bicyclic alkenes: a reevaluation of some betweenanene synthetic strategy

Acid treatment of $\text{cis}$-bicyclo[10.10.0]docos-1(12)-ene (Ib) affords bicyclo[10.10.0]docos-1-ene ($\text{11}$) as the sole product. Contrary to a previous report, [10.10]betwwenanene (IIb) is not produced under acidic conditions. Attempts to convert cycloalkylidenecycloalkanes and spiro systems to fused ring alkenes by acid treatment were also unsuccessful.     

Synthesis of Enantiomerically Pure Bis(hydroxymethyl)-Branched Cyclohexenyl and Cyclohexyl Purines as Potential Inhibitors of HIV

The synthesis of the enantiomerically pure bis(hydroxymethyl)-branched cyclohexenyl and cyclohexyl purines is described. Racemic trans-4,5-bis(methoxycarbonyl)cyclohexene [(+/-)-6] was reduced with lithium aluminum hydride to give the racemic diol (+/-)-7. Resolution of (+/-)-7 via a transesterification process using lipase from Pseudomonas sp. (SAM-II) gave both diols in enantiomerically pure form. The enantiomerically pure diol (S,S)-7was benzoylated and epoxidized to give the epoxide 9. Treatment of the epoxide 9 with trimethylsilyl trifluoromethanesulfonate and 1,5-diazabicyclo[5.4.0]undec-5-ene followed by dilute hydrochloric acid gave (1R,4S,5R)-4,5-bis[(benzoyloxy)methyl]-1-hydroxycyclohex-2-ene (10). Acetylation of 10 gave (1R,4S,5R)-1-acetoxy-4,5-bis[(benzoyloxy)methyl]cyclohex-2-ene (11). (1R,4S,5R)-1-Acetoxy-4,5-bis[(benzoyloxy)methyl]cyclohex-2-ene (11) was converted to the adenine derivative 12 and guanine derivative 13 via palladium(0)-catalyzed coupling with adenine and 2-amino-6-chloropurine, respectively. Hydrogenation of 12 and 13 gave the correspondning saturated adenine derivative 14 and guanine derivative 15. (1R,4S,5R)-4,5-Bis[(benzoyloxy)methyl]-1-hydroxycyclohex-2-ene (10) was converted to the adenine derivative 16 and guanine derivative 17 via coupling with 6-chloropurine and 2-amino-6-chloropurine, respectively, using a modified Mitsunobu procedure. Hydrogenation of 16 and 17 gave the corresponding saturated adenine derivative 18 and guanine derivative 19. Compounds 12-19 were evaluated for activity against human immunodeficiency virus (HIV), but were found to be inactive. Further biological testings are underway.     

Application of the taraxerane–oleanane rearrangement to the synthesis of seco-oleanane triterpenoids from taraxerone

Synthetic oleananes and seco-oleananes form a group of promising anti-inflammatory and cancer chemopreventive agents with an excellent safety profile. These compounds are usually prepared by semi-synthesis from natural oleanane triterpenoids. Since a taraxer-14-ene was reported to be rearranged into an olean-12-ene under mild reaction conditions, a rapid synthesis of seco-oleananes from taraxerone, which is a readily available starting material, was explored by us. Treatment of taraxerone with m-chloroperoxybenzoic acid gave 14,15-epoxy lactones, which underwent the taraxerane–oleanane rearrangement leading to new seco-oleanane triterpenoids.     

The Synthesis and Chemistry of 8-Substituted Bicyclo[5.1.0]oct-1(8)-ene

8-Bromobicyclo[5.1.0]oct-1(8)-cne (7), an intermediate for the preparation of 8-substituted bicyclo[5.1.0]oct-1(8)-enes, was synthesized by denomination of 1,8,8-tribromobicyclo[5.1.0]octane (6). Compound 7 underwent bromo-lithium exchange followed by nucleophilic substitution reactions to generate bicyclo[5.1.0]oct-1(8)-ene (5), 8-methylbicyclo[5.1.0]oct-1(8)-ene (10), and 8-trimethylsilylbicyclo[5.1.0]oct-1(8)-ene (11). The bicyclic cyclopropenes 7, 5, 10, and 11 reacted with cyclopentadiene to form adducts 12, 13, 14, and 15, respectively. All of these Diels-Alder adducts are endo-exo isomers (endo-addition from the view of the cyclopropene and exo-addition from the view of the cyclooctene).     

Chemo-enzymatic syntheses of drimane-type sesquiterpenes and the fundamental core of hongoquercin meroterpenoid by recombinant squalene-hopene cyclase

Squalene-hopene cyclase (SHC) converts squalene (C(30)) into pentacyclic triterpenes of hopene and hopanol. A linear sesquiterpene, (6E,10E)-2,6,10-trimethyldodeca-2,6,10-triene, underwent cyclization catalyzed by SHC, affording the following six bicyclic sesquiterpenes (drimane skeleton) in relatively high yield (68%): drim-7(8)-ene, drim-8(12)-ene, drim-8(9)-ene, driman-8α-ol, driman-8β-ol, and the novel sesquiterpene, named quasiclerodane, the skeleton of which is analogous to that of clerodane diterpene. To extend the scope of the enzymatic syntheses, acyclic sesquiterpenes to which a phenol moiety was appended were subjected to the enzymatic reaction catalyzed by SHC. The cyclic meroterpene core present in hongoquercins A and B was successfully prepared. The formation mechanisms of drimane-type sesquiterpenes and the cyclic meroterpene core of hongoquercins A and B are discussed.     

Antimicrobial triterpenes from Debregeasia salicifolia

New triterpene, 3beta-(trans-cinnamoyloxy)-19alpha-hydroxy-urs-12-ene (1) has been isolated from the methanolic fraction of Debregeasia salicifolia, along with uvaol (2), 3beta,19alpha-dihydroxy-urs-12-ene (3), ursolic acid (4), pomolic acid (5), pomolic acid methyl ester (6) and tormentic acid (7) reported for the first time from this species. The compounds (1), (3) and (6) showed significant antimicrobial activity. The structure elucidation was made with the help of extensive 2D NMR spectroscopic techniques.     

Double bond isomerization of 5-vinylbicyclo[2.2.1]hept-2-ene to 5-ethylidenebicyclo[2.2.1]hept-2-ene over alkaline earth oxides

All the alkaline earth oxides exhibit activities for double, bond isomerization of 5-vinylbicyclo[2.2.1]hept-2-ene (VBH) to 5-ethylidenebicyclo[2.2.1]hept-2-ene (EBH) at a reaction temperature of 273 K. The order of the activity on the basis of unit weight of catalyst was CaO>MgO>SrO>BaO when compared under optimum pretreatment conditions. The E/Z ratio in the products is determined by the reaction temperature regardless of the type of catalyst; the ratios were 82/18 and 88/12 for the reaction temperatures of 323 and 273 K, respectively.     

Anti-androgenic triterpenoids from the Brazilian medicinal plant, Cordia multispicata

Compounds 1-6 were isolated from the AcOEt soluble fraction of leaves of the Brazilian medicinal plant, Cordia multispicata, and their structures were elucidated to be 3beta,25-epoxy-21beta-acetoxy-3alpha,22beta-dihydroxyurs-12-en-28-al (1), 3beta,25-epoxy-28-acetoxy-3alpha,21beta,22beta-trihydroxyurs-12-ene (2), 21beta-acetoxy-22beta-hydroxy-3-oxours-12-en-28-al (3), 28-acetoxy-6beta, 21beta,22beta-trihydroxy-3-oxours-12-ene (4), 21beta,22beta-dihydroxy-3-oxours-1 2-en-28-al (5) and 3beta,21beta,22beta-trihydroxyurs-I2-en-28-al (6), respectively, by means of spectral data, especially two dimensional NMR techniques. Triterpenes having the hemiketal structure at the A-ring, an acyloxy group at C-22 and/or ketone at C-3 showed potent anti-androgenic activity.     

Gas-phase rate coefficients for the reactions of nitrate radicals with (Z)-pent-2-ene, (E)-pent-2-ene, (Z)-hex-2-ene, (E)-hex-2-ene, (Z)-hex-3-ene, (E)-hex-3-ene and (E)-3-methylpent-2-ene at room temperature

Rate coefficients for reactions of nitrate radicals (NO3) with (Z)-pent-2-ene, (E)-pent-2-ene, (Z)-hex-2-ene, (E)-hex-2-ene, (Z)-hex-3-ene, (E)-hex-3-ene and (E)-3-methylpent-2-ene were determined to be (6.55 +/- 0.78)x 10(-13) cm3 molecule(-1) s(-1), (3.78 +/- 0.45)x 10(-13) cm3 molecule(-1) s(-1), (5.30 +/- 0.73)x 10(-13) cm(3) molecule(-1) s(-1), (3.83 +/- 0.47)x 10(-13) cm(3) molecule(-1) s(-1), (4.37 +/- 0.49)x 10(-13) cm(3) molecule(-1) s(-1), (3.61 +/- 0.40)x 10(-13) cm3 molecule(-1) s(-1) and (8.9 +/- 1.5)x 10(-12) cm3 molecule(-1) s(-1), respectively. We performed kinetic experiments at room temperature and atmospheric pressure using a relative-rate technique with GC-FID analysis. The experimental results demonstrate a surprisingly large cis-trans(Z-E) effect, particularly in the case of the pent-2-enes, where the ratio of rate coefficients is ca. 1.7. Rate coefficients are discussed in terms of electronic and steric influences, and our results give some insight into the effects of chain length and position of the double bond on the reaction of NO3 with unsaturated hydrocarbons. Atmospheric lifetimes were calculated with respect to important oxidants in the troposphere for the alkenes studied, and NO3-initiated oxidation is found to be the dominant degradation route for (Z)-pent-2-ene, (Z)-hex-3-ene and (E)-3-methylpent-2-ene.     

A new eremophilanolide from Senecio sinuatus Gilib

From the hexane extracts of Senecio sinuatus roots, the new 3beta-angeloyloxy-6beta-hydroxyeremophil-1(10)-en-8beta,12-olide (3), along with the known compounds 3beta-angeloyloxy-6beta-hydroxyeremophil-1(10)-ene (1), 3beta-senecioyloxy-6beta-hydroxyeremophil-1(10)-ene (2), and 3beta-angeloyloxy-6beta,8alpha-dihydroxyeremophil-1(10)-en-8beta,12-olide (4), were isolated. Complete 1H and 13C NMR chemical shift assignments of 1-4 were achieved using one- and two-dimensional NMR techniques, including gHMQC and gHMBC experiments. A Monte Carlo search, followed by B3LYP/6-31G*DFT calculation, provided the theoretical conformations of the eremophilane rings, which were in agreement with results derived from 1H-1H NMR coupling constant analysis, and confirmed by NOESY experiments.     

1,3-Dipolar Cycloadditions to Strained Olefins

The Bredt olefins bicyclo [3.3.1]non-1-ene (2) , bicyclo [4.2.1]non-1 (8)-ene (3) , and bicyclo [4.2.1]non-1 (2)-ene (4) react rapidly with 1,3-dipoles such as diazomethane, phenyl azide, and mesitonitrile oxide to yield mixtures of two regioisomeric cycloadducts 10, 11 and 12 , respectively. On the contrary, cycloaddition to the comparable monocyclic 1-methyl-(E)-cyclooctene (5) is fairly regioselective. 2-Methylnorborn-2-ene (6) gives one isomer with mesitonitrile oxide (as do less strained olefins), but mixtures with diazomethane and phenyl azide. ¹H-NMR. and ¹³C-NMR. spectra of the cycloadducts are reported. The results are discussed in the light of frontier molecular orbital theory.     

Reactive collisions in quadrupole cells. Part I. Reaction of [CH3NH2]+˙ with the isomeric butenes and pentenes

The reactions of mass-selected [CH₃NH₂]⁺˙ ions with the isomeric butenes and pentenes were studied at low collision energies in the radiofrequency-only quadrupole collision cell of a hybrid BEqQ tandem mass spectrometer. Characteristic iminium ions arising by addition of the methylamine to the olefin followed by fragmentation are observed for but-1-ene pent-1-ene and 3-methylbut-1-ene. However, for but-2-ene pent-2-ene 2-methylpropene 2-methylbut-1-ene and 2-methylbut-2-ene the major reaction channel of [CH₃NH₂]⁺˙ is charge exchange to form the olefinic molecular ion. The isomeric olefins are characterized to a considerable extent by the characteristic ion–molecule reactions that these molecular ions undergo with the neutral olefin.