Rhodococcus erythropolis DCL14 contains a novel degradation pathway for limonene

Strain DCL14, which is able to grow on limonene as a sole source of carbon and energy, was isolated from a freshwater sediment sample. This organism was identified as a strain of Rhodococcus erythropolis by chemotaxonomic and genetic studies. R. erythropolis DCL14 also assimilated the terpenes limonene-1,2-epoxide, limonene-1,2-diol, carveol, carvone, and (-)-menthol, while perillyl alcohol was not utilized as a carbon and energy source. Induction tests with cells grown on limonene revealed that the oxygen consumption rates with limonene-1,2-epoxide, limonene-1,2-diol, 1-hydroxy-2-oxolimonene, and carveol were high. Limonene-induced cells of R. erythropolis DCL14 contained the following four novel enzymatic activities involved in the limonene degradation pathway of this microorganism: a flavin adenine dinucleotide- and NADH-dependent limonene 1, 2-monooxygenase activity, a cofactor-independent limonene-1, 2-epoxide hydrolase activity, a dichlorophenolindophenol-dependent limonene-1,2-diol dehydrogenase activity, and an NADPH-dependent 1-hydroxy-2-oxolimonene 1,2-monooxygenase activity. Product accumulation studies showed that (1S,2S,4R)-limonene-1,2-diol, (1S, 4R)-1-hydroxy-2-oxolimonene, and (3R)-3-isopropenyl-6-oxoheptanoate were intermediates in the (4R)-limonene degradation pathway. The opposite enantiomers [(1R,2R,4S)-limonene-1,2-diol, (1R, 4S)-1-hydroxy-2-oxolimonene, and (3S)-3-isopropenyl-6-oxoheptanoate] were found in the (4S)-limonene degradation pathway, while accumulation of (1R,2S,4S)-limonene-1,2-diol from (4S)-limonene was also observed. These results show that R. erythropolis DCL14 metabolizes both enantiomers of limonene via a novel degradation pathway that starts with epoxidation at the 1,2 double bond forming limonene-1,2-epoxide. This epoxide is subsequently converted to limonene-1,2-diol, 1-hydroxy-2-oxolimonene, and 7-hydroxy-4-isopropenyl-7-methyl-2-oxo-oxepanone. This lactone spontaneously rearranges to form 3-isopropenyl-6-oxoheptanoate. In the presence of coenzyme A and ATP this acid is converted further, and this finding, together with the high levels of isocitrate lyase activity in extracts of limonene-grown cells, suggests that further degradation takes place via the beta-oxidation pathway.     

Substrate specificity and stereospecificity of limonene-1,2-epoxide hydrolase from Rhodococcus erythropolis DCL14; an enzyme showing sequential and enantioconvergent substrate conversion

Limonene-1,2-epoxide hydrolase (LEH) from Rhodococcus erythropolis DCL14, an enzyme involved in the limonene degradation pathway of this microlorganism, has a narrow substrate specificity. Of the compounds tested, the natural substrate, limonene-1,2-epoxide, and several alicyclic and 2-methyl-1,2-epoxides (e.g. 1-methylcyclohexene oxide and indene oxide), were substrates for the enzyme. When LEH was incubated with a diastereomeric mixture of limonene-1,2-epoxide, the sequential hydrolysis of first the (1R,2S)- and then the (1S,2R)-isomer was observed. The hydrolysis of (4R)- and (4S)-limonene-1,2-epoxide resulted in, respectively, (1S,2S,4R)- and (1R,2R,4S)-limonene-1,2-diol as the sole product with a diastereomeric excess of over 98%. With all other substrates, LEH showed moderate to low enantioselectivities (E ratios between 34 and 3).     

Xanthobacter sp. C20 contains a novel bioconversion pathway for limonene

Xanthobacter sp. C20 was isolated from sediment of the river Rhine using cyclohexane as sole source of carbon and energy. Xanthobacter sp. C20 converted both enantiomers of limonene quantitatively into limonene-8,9-epoxide, a not previously described bioconversion product of limonene. With (4R)-limonene, (4R,8R)-limonene-8, 9-epoxide was formed as the only reaction product, while (4S)-limonene was converted into a (78:22) mixture of (4S,8R)- and (4S,8S)-limonene-8,9-epoxide. Cytochrome P-450 was shown to be induced concomitantly with limonene bioconversion activity following growth of Xanthobacter sp. C20 on cyclohexane. Maximal limonene bioconversion rate was observed at an initial substrate concentration of 12 mM. The amount of limonene-8,9-epoxide formed, up to 0.8 g l(-1), was limited by a strong product inhibition.     

Monoterpene biotransformation by <Emphasis Type="Italic">Colletotrichum</Emphasis> species

Objective

To investigate the biocatalytic potential of Colletotrichum acutatum and Colletotrichum nymphaeae for monoterpene biotransformation.

Results

C. acutatum and C. nymphaeae used limonene, α-pinene, β-pinene, farnesene, citronellol, linalool, geraniol, perillyl alcohol, and carveol as sole carbon and energy sources. Both species biotransformed limonene and linalool, accumulating limonene-1,2-diol and linalool oxides, respectively. α-Pinene was only biotransformed by C. nymphaeae producing campholenic aldehyde, pinanone and verbenone. The biotransformation of limonene by C. nymphaeae yielded 3.34–4.01 g limonene-1,2-diol l^?1, depending on the substrate (R-(+)-limonene, S-(?)-limonene or citrus terpene (an agro-industrial by-product). This is among the highest concentrations already reported for this product.

Conclusions

This is the first report on the biotransformation of these terpenes by Colletotrichum spp. and the biotransformation of limonene to limonene-1,2-diol possibly involves enzymes similar to those found in Grosmannia clavigera.

     

Limonene-1,2-Epoxide Hydrolase from Rhodococcus erythropolis DCL14 Belongs to a Novel Class of Epoxide Hydrolases

An epoxide hydrolase from Rhodococcus erythropolis DCL14 catalyzes the hydrolysis of limonene-1,2-epoxide to limonene-1,2-diol. The enzyme is induced when R. erythropolis is grown on monoterpenes, reflecting its role in the limonene degradation pathway of this microorganism. Limonene-1,2-epoxide hydrolase was purified to homogeneity. It is a monomeric cytoplasmic enzyme of 17 kDa, and its N-terminal amino acid sequence was determined. No cofactor was required for activity of this colorless enzyme. Maximal enzyme activity was measured at pH 7 and 50°C. None of the tested inhibitors or metal ions inhibited limonene-1,2-epoxide hydrolase activity. Limonene-1,2-epoxide hydrolase has a narrow substrate range. Of the compounds tested, only limonene-1,2-epoxide, 1-methylcyclohexene oxide, cyclohexene oxide, and indene oxide were substrates. This report shows that limonene-1,2-epoxide hydrolase belongs to a new class of epoxide hydrolases based on (i) its low molecular mass, (ii) the absence of any significant homology between the partial amino acid sequence of limonene-1,2-epoxide hydrolase and amino acid sequences of known epoxide hydrolases, (iii) its pH profile, and (iv) the inability of 2-bromo-4′-nitroacetophenone, diethylpyrocarbonate, 4-fluorochalcone oxide, and 1,10-phenanthroline to inhibit limonene-1,2-epoxide hydrolase activity.Epoxides are highly reactive compounds which readily react with numerous biological compounds, including proteins and nucleic acids. Consequently, epoxides are cytotoxic, mutagenic, and potentially carcinogenic, and there is considerable interest in biological degradation mechanisms for these compounds.In bacteria, epoxides are formed during the metabolism of alkenes (23) and halohydrins (15, 26, 34, 49). Enzymes belonging to a large number of enzyme classes, including dehydrogenases (17), lyases (21), carboxylases (1, 43), glutathione S-transferases (6, 8), isomerases (24), and hydrolases (7, 19, 44), are involved in the microbial degradation of epoxides.Epoxide hydrolases are enzymes catalyzing the addition of water to epoxides forming the corresponding diol. This group of enzymes has been extensively studied in mammals, while only limited information is available on bacterial epoxide hydrolases. Three functions for epoxide hydrolases are recognized (42). In bacteria, epoxide hydrolases are involved in the degradation of several hydrocarbons, including 1,3-dihalo-2-propanol (34), 2,3-dihalo-1-propanol (15, 26), epichlorohydrin (46), propylene oxide (16), 9,10-epoxy fatty acids (30, 36), trans-2,3-epoxysuccinate (2), and cyclohexene oxide (14). Other epoxide hydrolases, such as microsomal and cytosolic epoxide hydrolase from mammals (for reviews, see references 4, 8, and 44), are involved in the detoxification of epoxides formed due to the action of P-450-dependent monooxygenases (8). Epoxide hydrolases are also involved in biosynthesis of hormones, such as leukotrienes and juvenile hormone (40, 45), and plant cuticular elements (11). Remarkably, the bacterial and eukaryotic epoxide hydrolases described so far form a homogeneous group of enzymes belonging to the α/β-hydrolase fold superfamily (10, 38).Rhodococcus erythropolis DCL14, a gram-positive bacterium, is able to grow on both (+)- and (−)-limonene as the sole source of carbon and energy (47). Cells grown on limonene contained a novel epoxide hydrolase that does not belong to the α/β-hydrolase fold superfamily. This limonene-1,2-epoxide hydrolase converts limonene-1,2-epoxide to limonene-1,2-diol (p-menth-8-ene-1,2-diol [Fig. 1]). In this report, we describe the purification and characterization of this enzyme and show that limonene-1,2-epoxide hydrolase belongs to a novel class of epoxide hydrolases. Open in a separate windowFIG. 1Reaction catalyzed by limonene-1,2-epoxide hydrolase.     

Genetic and Biochemical Characterization of a Novel Monoterpene ɛ-Lactone Hydrolase from Rhodococcus erythropolis DCL14

A monoterpene -lactone hydrolase (MLH) from Rhodococcus erythropolis DCL14, catalyzing the ring opening of lactones which are formed during degradation of several monocyclic monoterpenes, including carvone and menthol, was purified to apparent homogeneity. It is a monomeric enzyme of 31 kDa that is active with (4R)-4-isopropenyl-7-methyl-2-oxo-oxepanone and (6R)-6-isopropenyl-3-methyl-2-oxo-oxepanone, lactones derived from (4R)-dihydrocarvone, and 7-isopropyl-4-methyl-2-oxo-oxepanone, the lactone derived from menthone. Both enantiomers of 4-, 5-, 6-, and 7-methyl-2-oxo-oxepanone were converted at equal rates, suggesting that the enzyme is not stereoselective. Maximal enzyme activity was measured at pH 9.5 and 30°C. Determination of the N-terminal amino acid sequence of purified MLH enabled cloning of the corresponding gene by a combination of PCR and colony screening. The gene, designated mlhB (monoterpene lactone hydrolysis), showed up to 43% similarity to members of the GDXG family of lipolytic enzymes. Sequencing of the adjacent regions revealed two other open reading frames, one encoding a protein with similarity to the short-chain dehydrogenase reductase family and the second encoding a protein with similarity to acyl coenzyme A dehydrogenases. Both enzymes are possibly also involved in the monoterpene degradation pathways of this microorganism.     

Squarate-based carbocyclic nucleosides: Syntheses,computational analyses and anticancer/antiviral evaluation

Squaric acid and its derivatives are versatile synthons and have demonstrated applications in medicinal chemistry, notably as non-classical bioisosteric replacements for functional groups such as carboxylic acids, alpha-amino acids, urea, guanidine, peptide bonds and phosphate/pyrophosphate linkages. Surprisingly, no reports have appeared concerning its possible application as a nucleobase substitute in nucleosides. A preliminary investigation of such an application is reported herein. 3-Amino-4-((1R,4S)-4-(hydroxymethyl)cyclopent-2-en-1-yl)amino-cyclobut-3-ene-1,2-dione, 3-((1R,4S)-4-(hydroxymethyl)cyclopent-2-en-1-yl)amino-4-methoxycyclobut-3-ene-1,2-dione, and 3-hydroxy-4-((1R,4S)-4-(hydroxymethyl)cyclopent-2-en-1-yl)amino-cyclobut-3-ene-1,2-dione sodium salt were synthesized. Computational analyses of their structures and preliminary antitumor and antiviral screening results are reported.     

Biotransformation of (R)-(+)- and (S)-(-)-limonene by fungi and the use of solid phase microextraction for screening

The biotransformation of (R)-(-)- and (S)-(-)-limonene by fungi was investigated. More than 60 fungal cultures were screened for their ability to bioconvert the substrate, using solid phase microextraction as the monitoring technique. After screening, the best fungal strains were selected for further study and were grown as sporulated surface cultures in conical flasks and as submerged liquid cultures. It was found that (+)- and (-)-limonene were converted by Penicillium digitatum to alpha-terpineol (main metabolite), cis- and trans-p-menth-2-en-1-ol, neodihydrocarveol and limonene oxide (minor metabolites) using liquid cultures. The bioconversion of (R)-(-)- and (S)-(-)-limonene by Corwespora cassiicola yielded (1S,2S,4R)- and (1R,2R,4S)-limonene-1,2-diol respectively. The bioconversions by liquid cultures were also monitored by solid phase microextraction as a function of time. The optimum conversion of limonene to alpha-terpineol by Penicillium digitatum was obtained after 8 hours (yield up to 100%). Since an important pH-decrease was noticed in some liquid broths, the stability of limonene under acidic conditions was investigated. No acid catalysed conversion products were recovered after 8 days from control flasks at pH 3.5 containing limonene.     

Estrogenic and anti-estrogenic compounds from the Thai medicinal plant, Smilax corbularia (Smilacaceae)

From the rhizomes of Smilax corbularia Kunth. (Smilacaceae), 11 compounds, (2R,3R)-2″-acetyl astilbin, (2R,3R)-3″-acetyl astilbin, (2R,3R)-4″-acetyl astilbin, (2R,3R)-3″-acetyl engeletin, (2R,3S)-4″-acetyl isoastilbin, 2-(4-hydroxyphenyl)-3,4,9,10-tetrahydro-3,5-dihydroxy-10-(3,4-dihydroxyphenyl)-(2R,3R,10R)-2H,8H-benzo [1,2-b:3,4-b′] dipyran-8-one, 2-(4-hydroxyphenyl)-3,4,9,10-tetrahydro-3,5-dihydroxy-10-(3,4-dihydroxyphenyl)-(2R,3R,10S)-2H, 8H-benzo [1,2-b:3,4-b′] dipyran-8-one, 3,4-dihydro-7-hydroxy-4-(3,4-dihydroxyphenyl)-5-[(1E)-2-(4-hydroxyphenyl) ethenyl]-2H-1-benzopyran-2-one, 3,4-dihydro-7-hydroxy-4-(3,4-dihydroxy-phenyl)-5-[(1E)-2-(3,4-dihydroxyphenyl) ethenyl]-2H-1-benzopyran-2-one, 3,4-dihydro-7-hydroxy-4-(4-hydroxy-3-methoxyphenyl)-5-[(1E)-2-(4-hydroxyphenyl) ethenyl]-2H-1-benzopyran-2-one, and 5,7,3′,4′-tetrahydroxy-3-phenylcoumarin along with 34 known compounds were isolated and characterized as 19 flavonoids, 14 catechin derivatives, 6 stilbene derivatives, and 6 miscellaneous substances. All isolates had their estrogenic and anti-estrogenic activities determined using the estrogen-responsive human breast cancer cell lines MCF-7 and T47D. The major constituents were recognized as flavanonol rhamnosides by the suppressive effect on estradiol induced cell proliferation at a concentration of 1 μM. Meanwhile, flavanonol rhamnoside acetates demonstrated estrogenic activity in both MCF-7 and T47D cells at a concentration of 100 μM, and they enhanced the effects of co-treated E2 on T47D cell proliferation at concentrations of more than 0.1 μM.     

Novel 2-[(benzylamino)methyl]pyrrolidine-3,4-diol derivatives as α-mannosidase inhibitors and with antitumor activities against hematological and solid malignancies

Novel α-mannosidase inhibitors of the type (2R,3R,4S)-2-({[(1R)-2-hydroxy-1-arylethyl]amino}methyl)pyrrolidine-3,4-diol have been prepared and assayed for their anticancer activities. Compound 30 with the aryl group = 4-trifluoromethylbiphenyl inhibits the proliferation of primary cells and cell lines of different origins, irrespective of Bcl-2 expression levels, inducing a G2/Mcell cycle arrest and by modification of genes involved in cell cycle progression and survival.     

Absolute stereochemistry of (+)-trans-1,2-dihydroxyacenaphthene,a mammalian metabolite of acenaphthylene

A sample of (+)-trans-1,2-dihydroxyacenaphthene, a mammalian metabolite of acenaphthylene, was prepared by stereoselective partial hydrolysis of the corresponding synthetic racemic diacetate using the mold, Rhizopus nigricans. The absolute stereochemistry of the trans-diol was established as (1R,2R) by conversion to the known dimethyl (2S,3S)diacetoxysuccinate.     

Polyhydroxylated azetidine iminosugars: Synthesis,glycosidase inhibitory activity and molecular docking studies

An efficient and practical strategy for the synthesis of unknown azetidine iminosugars (2S,3R,4S)-2-((R)-1,2-dihydroxyethyl)-3-hydroxy-4-(hydroxymethyl)azetidine 2, (2S,3r,4R)-3-hydroxy-2,4-bis(hydroxymethyl)azetidine 3 and (2S,3R,4S)-3-hydroxy-4-(hydroxymethyl)-N-methylazetidine-2-carboxylic acid 4, starting from the d-glucose has been reported. The methodology involves preparation of the 3-amino-N-benzyloxycarbonyl-3-deoxy-6-O-tert-butyldimethylsillyl-1,2-O-isopropylidene-α-d-glucofuranose 9, which was converted to the C-5-OMs derivative 11. Intramolecular nucleophilic displacement of the C-5-OMs group with in situ generated 3-amino functionality provided the required key azetidine ring skeletons 10 with additional hydroxymethyl group. Removal of 1,2-acetonide protection, followed by reduction and hydrogenolysis afforded azetidine iminosugar 2. Alternatively, removal of 1,2-acetonide group and chopping of C1-anomeric carbon gave C2-aldehyde that on reduction or oxidation followed by hydrogenolysis gave 2,4-bis(hydroxymethyl) azetidine iminosugars 3 and N-methylazetidine-2-carboxylic acid 4 respectively. The glycosidase inhibitory activity of 2–4 iminosugars was screened against various glycosidase enzymes and compared with a standard miglitol. Amongst synthesized targets, the compound 2 was found to be more potent amyloglucosidase inhibitor than miglitol. These results were supported by molecular docking studies.     

Neolignans from an Aniba species

A benzene extract of the trunk of an Aniba species (Lauraceae) contained benzyl benzoate, benzyl salicylate, sitosterol and the neolignans (2S,3S,3aR)-3a-allyl-5-methoxy-3-methyl-2-piperonyl-2,3,3a,6-tetrahydro-6-oxobenzofuran (burchellin); (2S,3S,3aR)-3a-allyl-5-methoxy-3-methyl-2-veratryl-2,3,3a,6-tetrahydro-6-oxobenzofuran; (2S,3S,3aR)-3a-allyl-5,7-dimethoxy-3-methyl-2-veratryl-2,3,3a,6-tetrahydro-6-oxobenzofuran; (2S,3S,5S)-5-allyl-5-methoxy-3-methyl-2-veratryl-2,3,5,6-tetrahydro-6-oxo-benzofuran; (2R,3R)-7-methoxy-3-methyl-5-propenyl-2-veratryl-2,3-dihydrobenzofuran; rel-(1R,5R,6R,7R,8S)-1-allyl-8-hydroxy-3-methoxy-7-methyl-4-oxo-6-piperonylbicyclo[3,2,1]oct-2-ene (guianin); rel-(1S,5S,6S,7R,8R)-1-allyl-8-hydroxy-3,5-dimethoxy-7-methyl-4-oxo-6-piperonylbicyclo[3,2,1]oct-2-ene; rel-(1S,5S,6S,7R,8R)-8-acetoxy-1-allyl-3-hydroxy-5-methoxy-7-methyl-4-oxo-6-piperonyl-bicyclo[3,2,1]oct-2-ene; rel-1S,5S,6S,7R,8R)-8-acetoxy-3,5-dimethoxy-7-methyl-4-oxo-6-piperonylbicyclo[3,2,1]oct-2-ene; rel-(1R,5S,6R,7R)-1-allyl-3-methoxy-7-methyl-4,8-dioxo-6-piperonylbicyclo[3,2,1]oct-2-ene.     

Dolabellane diterpenoids from Aglaia odorata

Dolabellane diterpenoids, (1R,3E,7E,10S,11S,12R)-dolabella-3,7-dien-10,18-diol (1), (1R,3S,7E,11S,12R)-dolabella-4(16),7-dien-3,18-diol (2), (1R,7E,11S,12R)-18-hydroxydolabella-4(16),7-dien-3-one (3), (1R,3S,4S,7E,11S,12R)-3,4-epoxydolabella-7-en-18-ol (4), and (1R,3R,7E,11S,12R)-dolabella-4(16),7,18-trien-3-ol (5), were obtained from the ornamental plant Aglaia odorata. Their structures were characterized on the basis of spectroscopic analyses and further confirmed by X-ray diffraction. Compounds 1 and 5 showed weak cytotoxicity against the human myeloid leukemia HL-60, hepatocellular carcinoma SMMC-7721, and lung cancer A-549 cells.     

Determination of the Absolute Configuration of Quercivorol, (1S,4R)-p-Menth-2-en-1-ol,an Aggregation Pheromone of the Ambrosia Beetle Platypus quercivorus (Coleoptera: Platypodidae)

A pair of enantiomers of trans-p-menth-2-en-1-ol, an aggregation pheromone of Platypus quercivorus, was synthesized from (S)- and (R)-limonene. The retention time of the aggregation pheromone from the insect coincided with that of (1S,4R)-p-menth-2-en-1-ol synthesized from (S)-limonene from GC analyses with a chiral column, enabling the absolute configuration of the aggregation pheromone to be determined as (1S,4R).     

Steroid sapogenins from Tristagma uniflorum

From bulbs of Tristagma uniflorum the known sapogenins tigogenin, neotigogenin and (20S,22R,25S)-5α-spirostan-3β,25-diol, as well as the new (20S,22R,25R)-5α-spirostan-3β,25-diol, (20S,22S,25S)-5α-furostan-22,25-epoxy-3β,26-diol and (20S,22S,25R) -5α-furostan-22,25-epoxy-3β,26-diol, were isolated and characterized by spectroscopic (IR, ¹H NMR, ¹³C NMR, MS) methods.     

Three new neolignan glucosides from the stems of Dendrobium aurantiacum var. denneanum

Three new neolignan glucosides (1–3), together with four known analogs (4–7), have been isolated from the stems of Dendrobium aurantiacum var. denneanum. Structures of the new compounds including the absolute configurations were determined by spectroscopic and chemical methods as (−)-(8R,7′E)-4-hydroxy-3,3′,5,5′-tetramethoxy-8,4′-oxyneolign-7′-ene-9,9′-diol 4,9-bis-O-β-d-glucopyranoside (1), (−)-(8S,7′E)-4-hydroxy-3,3′,5,5′-tetramethoxy-8,4′-oxyneolign-7′-ene-9,9′-diol 4,9-bis-O-β-d-glucopyranoside (2), and (−)-(8R,7′E)-4-hydroxy-3,3′,5,5′,9′-pentamethoxy-8,4′-oxyneolign-7′-ene-9-ol 4,9-bis-O-β-d-glucopyranoside (3), respectively.     

Configurational studies on red algae carotenoids

The configurations of (6′R)-β,ε-carotene, (3′R,6′R)-β,ε-caroten-3′-ol (α-cryptoxanthin), (3R,3′R,6′R)-β,ε-carotene-3,3′-diol (lutein), (3R)-β,β-caroten-3-ol (β-cryptoxanthin), (3R,3′R)-β,β-carotene-3,3′-diol (zeaxanthin) and all-trans (3S,5R,6S,3′R)-5,6-epoxy-5,6-dihydro-β,β-carotene-3,3′-diol (antheraxanthin) were established by CD and ¹H NMR studies. The red algal carotenoids consequently possessed chiralities at each chiral center (C-3, C-5, C-6, C-3′, C-6′), corresponding to the chiralities established for the same carotenoids in higher plants. Two post mortem artifacts from Erythrotrichia carnea were assigned the chiral structures (3S,5R,8R,3′R)-5,8-epoxy-5,8-dihydro-β,β-carotene-3,3′-diol [(8R)-mutatoxanthin] and (3S,5R,8S,3′R)-5,8-epoxy-5,8-dihydro-β,β-carotene-3,3′-diol [(8S)-mutatoxanthin]. This is the first well documented report of a naturally occurring β,ε-caroten-3′-ol (¹H NMR, CD, chemical derivatization).     

Sesquiterpenes and diterpenes from Ambrosia arborescens

Six compounds, eudesm-11(13)-en-4β,9β-diol, 15R,16-dihydroxy-3-oxoisopimar-9(11)-ene, 15S,16-dihydroxy-3-oxoisopimar-9(11)-ene, 1α-hydroxy-7-oxo-iso-anhydrooplopanone, 10α-hydroxy-11,13-dihydro-5-epi-psilostachyin, and 4β-hydroxypseudoguaian-12,6-olide 4-O-β-d-glucopyranoside, together with 12 known sesquiterpenes, were isolated from the leaves of Ambrosia arborescens. Structures were elucidated by 1D and 2D NMR spectroscopy including 1D-TOCSY, DQF-COSY, 2D-ROESY, HSQC, and HMBC experiments, as well as by ESI mass spectrometry. The absolute configuration of the 15,16-diol moiety in 15R,16-dihydroxy-3-oxoisopimar-9(11)-ene and 15S,16-dihydroxy-3-oxoisopimar-9(11)-ene was determined using Snatzke’s method. All compounds were evaluated for antiproliferative activity.