Rare sesquiterpenes from South African Pteronia species

The genus Pteronia consists of approximately 80 species which are widely distributed in southern Africa. The essential oils isolated from the aerial parts of eleven species, analyzed by GC-MS varied both qualitatively and quantitatively. In Pteronia pallens, Pteronia empetrifolia and Pteronia flexicaulis uncommon sesquiterpenes such as presilphiperfolol-7-ene, 7-α-(H)-silphiperfol-5-ene, 7-β-(H)-silphiperfol-5-ene, α-campholene aldehyde, silphiperfol-5-ene, cameroonan-7-α-ol, silphiperfol-7-β-ol, presilphiperfolan-9-α-ol and presilphiperfolan-8-ol (a major compound in P. pallens) were identified. Cluster analysis based of the chemical composition of the oils revealed that individual plants of Pteronia camphorata collected in the same population had similar oil profiles with a high correlation coefficient (S_corr ≈ 0.98). Similarly, the essential oil composition of P. pallens collected from two distinct localities also showed high levels of congruency (S_corr ≈ 0.99).     

Lipase-catalyzed kinetic resolution of 2-methylene-substituted cycloalkanols in batch and continuous-flow modes

Kinetic resolutions of cyclic racemic secondary alcohols (2-methylenecyclopentan-1-ol rac-1a, 2-methylenecyclohexan-1-ol rac-1b, 2-methylenecycloheptan-1-ol rac-1c, 6-methylene-[1,3]dioxepan-5-ol rac-1d, 2,2-dimethyl-6-methylene-[1,3]dioxepan-5-ol rac-1e and trans-2-bromocyclohexan-1-ol rac-3) catalyzed by different (commercial and in-house-made) lipases were performed using vinyl acetate in THF-hexane. In the most typical cases (rac-1b, rac-1d and rac-3), the immobilized Candida antarctica lipase B (CaLB, for rac-1b and rac-3)- or sol–gel immobilized Pseudomonas fluorescens lipase (sol–gel LAK, for rac-1d)-catalyzed batch mode reactions were compared to the continuous mode reactions carried out in an enzyme-filled stainless steel bioreactor. The effect of temperature (20–60 °C) and flow rate (0.1–0.3 ml min⁻¹) on the continuous-flow acetylation of rac-1b, rac-1d and rac-3 were investigated. In the kinetic resolutions of rac-1b, rac-1d and rac-3, the enantiomeric selectivities (E) were similar in the continuous-flow and batch (shake flask) modes. However, the productivities (specific reaction rate: r), were significantly higher in the continuous-flow mode biotransformations of rac-1b, rac-1d and rac-3.     

New C9-polyacetylenes from the essential oil of the highly endangered species Baccharis palustris Heering (Asteraceae)

The essential oil composition of the aerial parts from Baccharis palustris Heering (Asteraceae), a highly endangered species, was analyzed by GC/qMS, GC/HRMS-TOF, FT-IR, UV–vis and NMR spectroscopy using 1D and 2D techniques. To our knowledge, this is the first report on the essential oil composition of B. palustris, as well as the first phytochemical study on this plant species. The volatile extracts were obtained from different phenologicals stages of plant, at flowering stage (FS) and vegetative stage (VS), where 51 components were identified accounting for 96.3 % and 99.0 % of the oil, respectively. The oil was rich in polyacetylene compounds (> 75 %), being the main components identified the new natural C₉-polyacetylenes 1-nonene-3,5-diyne (1, here named as baccharisdiyne) (52.7–65.0 %), 1,7(Z)-nonadiene-3,5-diyne [2, 7(Z)-dehydro-baccharisdiyne] (14.4–17.8 %), and 1,7(E)-nonadiene-3,5-diyne [3, 7(E)-dehydro-baccharisdiyne] (1.5–2.4 %). In addition, the known polyacetylenic compounds (Z)-lachnophyllum acid methyl ester (4) (4.3–5.3 %) and (E)-lachnophyllum acid methyl ester (5) (0.2 %) were also identified. Moreover, GC/qMS analysis allowed the identification of other 46 components in the essential oil samples, mainly mono- and sesquiterpenoids. In B. palustris, C₉-polyacetylenes probably derive biogenetically from a C₁₀ precursor: baccharisdiyne (1) would be derived from either or both lachnophyllum methyl ester geometric isomers (4 or 5), by enzymatic hydrolysis followed by decarboxylation. Dehydro-baccharisdiynes (2 and 3) could be produced by a similar pathway starting from the corresponding matricaria acid methyl ester isomers, one of which was tentatively identified at trace-level in B. palustris essential oil.     

Capitula essential oil composition of seven Centaurea species (sect. Acrocentron,Asteraceae) – Taxonomic implication and ecological significance

In this paper, we analyzed the capitula essential oil composition of seven Centaurea species, six of which belong to Centaurea calocephala complex, and the related species Centaurea melanocephala Pančić (subgenus Acrocentron, tribus Cardueae, subtribus Centaureinae) which inhabit Balkans Peninsula. The volatile organic compounds were extracted by simultaneous distillation extraction, using Likens-Nickerson type apparatus and the oils were analyzed by GC-FID and GC-MS. In total, 146 compounds were identified (95.5–99.4% of the total oil composition). The essential oils were dominated by sesquiterpenes (39.1–81.7%). The most abundant components were β-caryophyllene (3.1–28.3%), caryophyllene oxide (4.7–31.2%), germacrene D (2.9–22.2%), followed by n-hexacosane, [2Z,6E]-farnesol, eudesma-4(15),7-dien-1-β-ol, α-cadinole, germacrene B, trans-verbenol, and hexanal that were present in some samples in relatively high abundances. The geographic region and the color of capitula were analyzed in correlation with essential oil composition. Also, all investigated species are characterized by the different amount of most dominant components, which leads to the hypothesis that they “choose” different strategies: different combination and amounts of attractants for pollinators. Ecological correlations and taxonomical implications are further discussed.     

Two antibacterial biphenyls from rhynchosia suaveolens

Two new biphenyls characterized as 4-(3-methyl-but-2-enyl)-5-methoxy-[1,1′-biphenyl]-3-ol 1 and 2-carboxy-4-(3-methyl-but-2-enyl)-5-methoxy- [1,1′-biphenyl]-3-ol 5 have been isolated from Rhynchosia suaveolens. Both compounds displayed antibacterial activity.     

Inhibition of cholesteryl ester synthesis by polyacetylenes from Atractylodes rhizome

Using activity guided purification, four known compounds, sesquiterpene atractylenolide III (1), and the polyacetylenes 14-acetoxy-12-senecioyloxytetradeca-2E,8E,10E-trien-4,6-diyn-1-ol (2), 14-acetoxy-12-α-methylbutyl-2E,8E,10E-trien-4,6-diyn-1-ol (3), and 14-acetoxy-12-β -methylbutyl-2E,8E,10E-trien-4,6-diyn-1-ol (4), were isolated from a traditional herbal medicine, Atractylodes rhizome. Structurally similar 3 and 4 (3/4 mixture) were obtained as a mixture. In intact Chinese hamster ovary (CHO) K1 cell assays, 1, 2, and a 3/4 mixture selectively inhibited cholesterol [¹⁴C]oleate synthesis from [¹⁴C]oleate with IC₅₀ values of 73.5 µM, 35.4 µM, and 10.2 µM, respectively, without any effects on cytotoxicity. As a potential target of these inhibitors involved in cholesteryl ester (CE) synthesis, effects on sterol O-acyltransferase (SOAT) activity were investigated using microsomes prepared from CHO-K1 cells as an enzyme source. Hence, these compounds inhibit SOAT activity with IC₅₀ values (211 µM for 1, 29.0 µM for 2, and 11.8 µM for 3/4 mixture) that correlate well with those measured from intact cell assays. Our results strongly suggest that these compounds inhibit CE synthesis by blocking SOAT activity in CHO-K1 cells.     

Polymorphism of essential oils in thyme species growing in European part of North-East Russia and Ural

Essential oils of thyme species growing in the European part of North-East Russia and Ural were shown to contain azulene, trans-isopropyl-1-methyl-2-cyclohexene-1-ol, trans-4,5-epoxycarane, 1,3,5-tri-methylene cycloheptane, eudesm-7(11)-en-4-ol, and isoaromadendrene epoxide. Detection in the plants of the genus Thymes of uncharacteristic compounds could be accounted for by the beginning of investigation of earlier unexplored species or by the biosynthesis of these compounds induced by environmental conditions. All species of the genus Thymus growing in the European part of North-East Russia and Ural (T. hirticaulis, T. talijevii, T. paucifolius, T. guberlinensis, and T. punctulosus) belong to nonphenolic chemotype characteristic of the way of their adaptation to low temperatures. In three species (T. talijevii, T. paucifolius, and T. punctulosus), essential oils were rich in bicyclic sesquiterpenes.     

Synthesis and structures of zinc complexes with new binucleating ligands containing alkoxide bridges, and their activities in the hydrolysis of tris(p-nitrophenyl)phosphate

Four new binucleating ligands featuring a hydroxytrimethylene linker between two coordination sites (1,3-bis{N-[3-(dimethylamino)propyl]-N-methylamino}propan-2-ol, HL¹; 1,3-bis{N-[2-(dimethylamino)ethyl]-N-methylamino}propan-2-ol, HL²; 1,3-bis[bis(2-methoxyethyl)amino]propan-2-ol, HL³; and 1-bis[(2-methoxyethyl)amino]-3-{N-[2-(dimethylamino)ethyl]-N-methylamino}propan-2-ol, HL⁴) were synthesized, along with the corresponding zinc complexes. The structures of three dinuclear zinc complexes ([Zn₂L¹(μ-CH₃COO)₂]BPh₄ (1), [Zn₂L³(μ-CH₃COO)₂]BPh₄ (3), and [Zn₂L⁴(μ-CH₃COO)(CH₃COO)(EtOH)]BPh₄ (4)) and a tetranuclear zinc complex ({[Zn₂L²(μ-CH₃COO)]₂(μ-OH)₂}(BPh₄)₂ (2)) were revealed by X-ray crystallography. Hydrolysis of tris(p-nitrophenyl)phosphate (TNP) by these zinc complexes in an acetonitrile solution containing 5% Tris buffer (pH 8.0) at 30 °C was investigated spectrophotometrically and by ³¹P NMR. Although zinc complexes 1, 3, and 4 did not show hydrolysis activity, the tetranuclear zinc complex 2, containing μ-hydroxo bridges, was capable of hydrolyzing TNP. This suggests that the hydroxide moiety in the complex may have an important role in the hydrolysis reaction.     

Synthesis and SAR study of a novel series of dopamine receptor agonists

The synthesis of a novel series of dopamine receptor agonists are described as well as their in vitro potency and efficacy on dopamine D₁ and D₂ receptors. This series was designed from pergolide and (4aR,10aR)-1-propyl-1,2,3,4,4a,5,10,10a-octahydro-benzo[g]quinolin-6-ol (PHBQ) and resulted in the synthesis of (2R,4aR,10aR)-2-methylsulfanylmethyl-4-propyl-3,4,4a,5,10,10a-hexahydro-2H-naphtho[2,3-b][1,4]oxazin-9-ol (compound 27), which has a D₁ and D₂ receptor profile similar to that of the most recently approved drug for Parkinson’s disease, rotigotine.     

Microbial oxygenation of dialkylbenzenes (I)

The use of the microorganism Sporotrichum sulfurescens (ATCC 7159) to oxygenate organic molecules has been extended to several dialkylbenzenes. Oxygenation of 1,4-di-t-butylbenzene (1) gave 4-t-butyl(1-hydroxy-2-methyl)isopropylbenzene (2) and 1,4-di-(1-hydroxy-2-methyl)isopropylbenzene (3); of 1,4-diisopropylbenzene (4) gave (R,R)-1,4-di-(1-hydroxy)isopropylbenzene (5); of 1,3-diisopropylbenzene (6) gave 1,3-di-(2-hydroxy)isopropylbenzene (7), 3-(1-hydroxy)isopropyl-(2-hydroxy)isopropylbenzene (8), and 1,3-di-(1-hydroxy)isopropylbenzene (9); and of p-isobutylisopropylbenzene (20) gave 1-(p-2-hydroxyisopropylphenyl)-2-methylpropan-2-ol (15) and 1-(p-1-hydroxyisopropylphenyl)-2-methylpropan-2-ol (16). Monohydroxydialkylbenzenes also served as useful substrates in this reaction as suggested by the fact that 2 is an intermediate in the formation of 3 from 1. Oxygenation of 1-(p-isopropylphenyl)-2-methylpropan-2-ol (14), conveniently prepared from 2-(p-isopropylphenyl)propene (12) via oxygenative isomerization with thallium trinitrate to 13 followed by addition of methyl magnesium bromide, gave 15 and 16. Oxygenation of 2-(p-isobutylphenyl)propan-2-ol (18) gave 15, 2-(p-isobutylphenyl)-propan-1,2-diol (21), and 1-(p-2-hydroxyisopropylphenyl)-2-methylpropan-3-ol (22). Compound 16, obtained from substrate 14, was converted to (2R)-2-[4-(2-hydroxy-2-methylpropyl)phenyl]propionic acid (11), the enantiomer of a metabolite of the antiinflammatory agent, 2-(4-i-butyl)phenylpropionic acid (10).     

The discovery of potent,orally bioavailable pyrazolo and triazolopyrimidine CXCR2 receptor antagonists

A hit-to-lead optimisation programme was carried out on the Novartis archive screening hit, pyrazolopyrimidine 2-methyl-5-((phenylthio)methyl)pyrazolo[1,5-a]pyrimidin-7-ol 1, resulting in the discovery of CXCR2 receptor antagonist 2-benzyl-5-(((2,3-difluorophenyl)thio)methyl)-[1,2,4]triazolo[1,5-a]pyrimidin-7-ol 14. The SAR was investigated by systematic variation of the pendant thiol, alkyl and pyrimidinol groups. Replacement of the pyrazolopyrimidine core with a triazolo alternative led to a dual series of antagonists with favourable biological and pharmacokinetic properties.     

Antimicrobial activity and chemical composition of essential oil from Helichrysum microphyllum Cambess. subsp. tyrrhenicum Bacch., Brullo & Giusso collected in South-West Sardinia

The aim of this study was to evaluate the chemical composition and the antimicrobial activity of essential oils of Helichrysum microphyllum subsp. tyrrhenicum collected in four different stations in South-Western Sardinia.The composition of the essential oils was determined by gas chromatography and gas chromatography/mass spectrometry. The oil samples showed different chromatographic profiles. The oil of the station 4 revealed the presence of significant amount of neryl acetate (33.6%); in oils from stations 1 and 2 we found γ-curcumene (28%) and in station 3 γ-curcumene (12%) and linalool (11%), while there was no trace of neryl acetate. Standard microbiological assays demonstrated that essential oils obtained by plants collected in station 1 and 2, very rich in curcumene, showed an interesting anticandidal activity, dose- and time-dependent, which is enhanced by sub-inhibitory concentrations of chitosan.Our results suggest that the essential oil of Helichrysum microphyllum subsp. tyrrhenicum, associated with chitosan in innovative formulations, could be considered as a therapeutic alternative in the treatment of Candida opportunistic infections. The results of this study shows that the chemotypization of the species examined could lead to their targeted clinical use, in a concept of a rational scientific aromatherapy.     

Chemotaxonomy of Hypericum genus from Portugal: Geographical distribution and essential oils composition of Hypericum perfoliatum, Hypericum humifusum, Hypericum linarifolium and Hypericum pulchrum

The geographical distribution and analysis of the essential oils of species from three sections of Hypericum L. (Guttiferae/Clusiaceae/Hypericaceae) from Portugal are presented. Hypericum perfoliatum (section Drosocarpium) grows wild in the centre and south of Portugal; Hypericum humifusum and Hypericum linarifolium are both from section Oligostema, the former occurring throughout the country, while the second is distributed mainly in the north and centre; Hypericum pulchrum (section Taeniocarpium) is confined to the littoral north of Portugal. The essential oils were obtained by distillation–extraction, hydrodistillation and distillation in a modified Marcusson apparatus from the dried aerial parts of the different populations and were analysed by GC and GC–MS. Monoterpene hydrocarbons constituted the main fraction in all oils (43–69%, 53–85%, 28–45% and 48–65% for H. perfoliatum, H. humifusum, H. linarifolium and H. pulchrum, respectively). Sesquiterpene hydrocarbons (2–13%, 6–18%, 21–27% and 16–18%, respectively) and a third fraction of non-terpenic compounds (20–29%, 3–16%, 2–14% and 5–11%, respectively) from the four species attained relatively high amounts in all oils. Within each species, no major differences were detected in the essential oil composition, despite the fact that different locations, phenological phases and extraction methodologies were used. Notwithstanding the dominance of α-pinene in all four species' oils, cluster and principal components analysis on the identified components showed that the range of α-pinene, β-pinene and n-nonane supported a separation of the four species. The essential oil composition of the four species showed some qualitative resemblances, which correlate well with the taxonomical classification based on morphological characters.     

Synthesis and evaluation of N-alkyl-S-[3-(piperidin-1-yl)propyl]isothioureas: High affinity and human/rat species-selective histamine H3 receptor antagonists

S-Alkyl-N-alkylisothiourea compounds containing various cyclic amines were synthesized in the search for novel nonimidazole histamine H₃ receptor (H₃R) antagonists. Among them, four N-alkyl S-[3-(piperidin-1-yl)propyl]isothioureas 18, 19, 22, and 23 were found to exhibit potent and selective H₃R antagonistic activities against in vitro human H₃R, but were inactive against in vitro human H₄R. Furthermore, three alkyl homologs 18–20 showed inactivity for histamine release in in vivo rat brain microdialysis, suggesting differences in antagonist affinities between species. In addition, in silico docking studies of N-[4-(4-chlorophenyl)butyl]-S-[3-piperidin-1-yl)propyl]isothiourea 19 and a shorter homolog 17 with human/rat H₃Rs revealed that structural differences between the antagonist-docking cavities of rat and human H₃Rs were likely caused by the Ala122/Val122 mutation.     

Essential oil composition of Hypericum L. species from Southeastern Serbia and their chemotaxonomy

The essential oils of the aerial parts of nine species of Hypericum (Hypericum barbatum, Hypericum hirsutum, Hypericum linarioides, Hypericum maculatum, Hypericum olympicum, Hypericum perforatum, Hypericum richeri, Hypericum rumeliacum and Hypericum tetrapterum), collected from different locations in Southeast Serbia, were obtained by steam distillation and analyzed by GC and GC–MS. The essential oils investigated were characterized by a high content of non-terpene compounds and a low content of monoterpenes. The contents of non-terpenes, monoterpenes and sesquiterpenes in oils of the species H. barbatum, H. richeri and H. rumeliacum (section Drosocaprium) were similar and these oils were characterized by high contents of fatty acids. The oils of H. hirsutum and H. linarioides (section Taeniocarpium) contained a high percentage of n-nonane. There were similarities in contents of non-terpenes and sesquiterpenes in oils of species that belong to the section Hypericum (H. maculatum, H. perforatum and H. tetrapterum). The oil of H. olympicum differed from others by higher terpene content. A comparison was also carried out of the chemical composition of the essential oils from flower, leaf and stem of H. perforatum and it revealed that the highest concentration of non-terpene compounds was found in the flower and stem oil, while a high concentration of sesquiterpenes was characteristic for leaf oil. There were significant differences in the concentrations of the same compounds in the essential oils of H. maculatum, H. olympicum and H. perforatum, collected in different years from the same location which could be explained by seasonal differences. All data were statistically processed with principal component analysis and cluster analysis. The main conclusion from the above data is that genetic and environmental factors both play a role in determining the composition of essential oils of the Hypericum species studied.     

Synthesis,antimicrobial activity,structure-activity relationship and cytotoxic studies of a new series of functionalized (Z)-3-(2-oxo-2-substituted ethylidene)-3,4-dihydro-2H-benzo[b][1,4]oxazin-2-ones

A new series of functionalized (Z)-3-(2-oxo-2-substituted ethylidene)-3,4-dihydro-2H-benzo[b][1,4]oxazin-2-ones 23–26, incorporating pharmaceutically privileged substructures such as cyclopropyl, naphthyl, biphenyl and cyclohexylphenyl were synthesized in excellent yields. All the synthesized compounds were screened for their in vitro antibacterial activity against gram-(+)ve and gram-(?)ve bacterial species i.e. S. griseus, S. aureus, B. subtillis and E. coli as well as in vitro antifungal activity against fungal species i.e. F. oxysporium, A. niger, P. funiculosum and T. reesei, respectively. In this study, compounds containing cyclopropyl and cyclohexylphenyl substructures were identified as promising antimicrobial agents than standard drugs, ampicillin and chloramphenicol as well as ketoconazole. SAR study illustrates that electron-withdrawing groups increases the antibacterial as well as antifungal activity of 2-oxo-benzo[1,4]oxazines and vice versa. Compounds 23e and 26e, the most active compounds of the series, displayed promising antibacterial activity than Ampicillin and Chloramphenicol. Moreover, compound 26d showed promising antifungal potency as compared to Ketoconazole. Cytotoxic studies of the active compounds i.e. 23c–e, 24e, 25d and 26d–e found to be non-toxic in nature in 3T₃ fibroblast cell lines using MTT assay.     

Fumigant Toxicity of Plant Essential Oils to Plutella xylostella (Lepidoptera: Yponomeutidae) and Cotesia glomerata (Hymenoptera: Braconidae)

The fumigant toxicity of 66 plant essential oils to Plutella xylostella (L.) larvae and Cotesia glomerata (L.) adults was examined using a vapor-phase toxicity bioassay and compared with that of dichlorvos. Responses varied according to oil and insect species used. Based on 24 h LD₅₀ values, pennyroyal oil [10.77 mg/filter paper (4.25 cm diameter)] was the most toxic fumigant, followed by rosemary and sage (Dalmatin) oils (15.15 mg/paper). Potent fumigant toxicity was also produced from armoise, buchu leaf, cedarleaf, coriander, eucalyptus, howood, lavender, myrtle, niaouli, peppermint, and rosewood oils (LD₅₀, 21.29–27.31 mg/paper). All essential oils were less effective than dichlorvos (LD₅₀, 0.52 mg/paper). Against adult C. glomerata, dichlorvos (LD₅₀, 0.03 mg/paper) was the most toxic fumigant, whereas the LD₅₀ values of the 14 essential oils ranged from 1.59 to 8.51 mg/paper. Based on selective toxicity ratio (STR, P. xylostella LD₅₀/C. glomerata LD₅₀), the 14 essential oils (STR, 2.5–14.5) are more selective than dichlorvos (STR, 17.3). The essential oils tested merit further study as potential fumigants for the control of P. xylostella in greenhouses because of their selective toxicity to adult C. glomerata and their much greater activity as a fumigant.     

Tropane alkaloid metabolism by Pseudomonas AT3 cell cultures: Interchange between the nortropine and norpseudotropine catabolic pathways

Selected strains of Pseudomonas bacteria can degrade tropane alkaloids to obtain both nitrogen and carbon for growth. In order to probe the mechanisms of the catabolic enzymes involved, the metabolic process responsible for the opening of the 8-azabicyclo[3.2.1]octan-3-ol ring of nortropane alkaloids has been explored. It is found that the bacteria contain considerable flexibility in their enzyme complement and can convert (3-endo)-8-azabicyclo[3.2.1]octan-3-ol) (nortropine (2) to (3-exo)-8-azabicyclo[3.2.1]octan-3-ol) (norpseudotropine). Both of these compounds can serve as substrates for the catalytic cascade. In order to establish the proportionation between direct and indirect pathways, metabolism has been probed by competitive substrate availability and by incorporation of stable heavy labels into substrate pools. The results indicate that, while norpseudotropine is almost entirely metabolized directly, nortropine is partitioned c. 4:1 between direct and indirect catabolism.     

Cooperative effect of the camphor imine ligand in alkynols activation by trans-[MCl2(YNC10H14O)2] (M = Pd or Pt)

The cooperative effect of the camphor imine ligand (YNC₁₀H₁₄O) in the cyclization of 5-hexyn-1-ol and 4-pentyn-1-ol promoted by complexes trans-[MCl₂(YNC₁₀H₁₄O)₂] (M = Pd, Y = NH₂, NHMe, NMe₂, OH, Ph; Pt, Y = NH₂, NHMe, NMe₂) is established from a direct relation between the constants calculated for conversion of 5-hexyn-1-ol (A) into 2-methyl-2-pent-4-ynyloxy-tetrahydropyran (B) and 4-pentyn-1-ol (C) into 2-methyl-2-pent-4-ynyloxy-tetrahydrofuran (D) and the basic character of the camphor imine substituent (Y). In the catalytic process acid-base interactions between the alkynol and the coordinated camphor imine are supported by the structural characterization of [PdCl₄][Me₂NHNC₁₀H₁₄O]₂.     

Phenolic compounds with radical scavenging and cyclooxygenase-2 (COX-2) inhibitory activities from Dioscorea opposita

Phytochemical studies of the chloroform soluble fraction of Dioscorea opposita resulted in the isolation of four new compounds, 3,5-dihydroxy-4-methoxybibenzyl (1), 3,3′,5-trihydroxy-2′-methoxybibenzyl (2), 10,11-dihydro-dibenz[b,f]oxepin-2,4-diol (3), and 10,11-dihydro-4-methoxy-dibenz[b,f]oxepin-2-ol (4), together with an additional fifteen known compounds. The structures of 1–4 were elucidated by spectroscopic methods including 2D NMR. All of the nineteen isolated compounds were tested in the DPPH, superoxide anion radical scavenging assays and cyclooxygenases (COXs) inhibition assay. Of those, compounds 7, 9, 11, 12, 13, 15 and 18 exhibited radical scavenging activities and compounds 2, 3, 8, 13, 15 and 16 showed selective inhibitory activities against COX-2.