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1.
Sesquiterpene lactones are a major class of natural bitter compounds occurring in vegetables and culinary herbs as well as in aromatic and medicinal plants, where they often represent the main gustatory and pharmacologically active component. Investigations on sesquiterpene lactones have mainly focused on their bioactive potential rather than on their sensory properties. In the present study, we report about the stimulation of heterologously expressed human bitter taste receptors, hTAS2Rs, by the bitter sesquiterpene lactone herbolide D. A specific response to herbolide D was observed i.a. for hTAS2R46, a so far orphan bitter taste receptor without any known ligand. By further investigation of its agonist pattern, we characterized hTAS2R46 as a bitter receptor broadly tuned to sesquiterpene lactones and to clerodane and labdane diterpenoids as well as to the unrelated bitter substances strychnine and denatonium.  相似文献   

2.
Diterpenoids from Cascarilla (Croton eluteria Bennet)   总被引：1，自引：0，他引：1  
Cascarilla is a commercially available and cheap source of polyfunctionalized diterpenoids belonging to the clerodane structural type. In addition to the bitter triol cascarillin, 10 additional new diterpenoids (eluterins A-J) have been isolated and characterized by spectroscopic means. Structural diversity within cascarilla clerodanes involves mainly the linkage between the carbocyclic and the heterocyclic moieties and the functionalization of C-3, C-4, and C-6 of the decalin core. Cascarillin was shown to be a mixture of interconverting gamma-lactols and not a gamma-hydroxyaldehyde as previously reported.  相似文献   

3.
The antifungal activity on Botrytis cinerea of the diterpenoids 3beta-hydroxy-kaurenoic acid and kaurenoic acid, obtained from the resinous exudates of Pseudognaphalium vira vira, was determined. 3beta-Hydroxy-kaurenoic acid reduced the mycelial growth of B. cinerea in solid and liquid media. Additionally, the damage produced by the fungus on the surface of tomato leaves in the presence of the diterpenoids was evaluated. A higher protective effect was observed in the presence of the hydroxylated diterpene. On the other hand, the effect of the diterpenoids on the production of enzymes that participate in the plant infection by B. cinerea was analyzed. p-Nitrophenylbutyrate esterase production was induced by both diterpenoids, whereas laccase production was only induced by the hydroxylated diterpene. In the study of the mechanism of action of these compounds, it was determined that 3beta-hydroxy-kaurenoic acid would produce permeabilization of the cell membrane of B. cinerea.  相似文献   

4.
Three new diterpenoids belonging to the clerodane (2-3) and halimane (4) structural types have been isolated from the bark of Croton eluteria Bennet, commonly known as cascarilla. Their structures have been fully characterized by spectroscopic means. Cascarilla extract and its major component, cascarillin, were found to significantly increase histamine-induced gastric acid secretion in the mouse stomach. These preliminary results provide the first rationale for the use of cascarilla in bitter preparations aimed at improving digestion.  相似文献   

5.
A new abietane diterpenoid, 12-O-methyl carnosol (2), was isolated from the leaves of sage (Salvia officinalis L.), together with 11 abietane diterpenoids, 3 apianane terpenoids, 1 anthraquinone, and 8 flavonoids. Antioxidant activity of these compounds along with 4 flavonoids isolated from thyme (Thymus vulgaris L.) was evaluated by the oil stability index method using a model substrate oil including methyl linoleate in silicone oil at 90 degrees C. Carnosol, rosmanol, epirosmanol, isorosmanol, galdosol, and carnosic acid exhibited remarkably strong activity, which was comparable to that of alpha-tocopherol. The activity of miltirone, atuntzensin A, luteolin, 7-O-methyl luteolin, and eupafolin was comparable to that of butylated hydroxytoluene. The activity of these compounds was mainly due to the presence of ortho-dihydroxy groups. The 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity of these compounds showed the similar result.  相似文献   

6.
Several natural neo-clerodane diterpenoids isolated from Linaria saxatilis and some semisynthetic derivatives were tested against several insect species with different feeding adaptations. The antifeedant tests showed that the oliphagous Leptinotarsa decemlineata was the most sensitive insect, followed by the aphid Myzus persicae. The polyphagous Spodoptera littoralis was not deterred by these diterpenoids; however, following oral administration, some of these compounds did have postingestive antifeedant effects on this insect. In general terms, the antifeedant effects of these compounds were species-dependent and more selective than their toxic/postingestive effects. The study of their structure-activity relationships showed that both the decalin moiety and the chain at C-9 determined their bioactivity. Furthermore, the presence of a 4,18-epoxy/diol moiety was an important feature for both the antifeedant and the toxic/postingestive effects.  相似文献   

7.
To estimate the antimicrobial effect of p-hydroxyphenyl acrylate (H5) derivatives on the basis of their molecular structure, the hydroxy and acryl groups of p-hydroxyphenyl acrylate were modified. The antimicrobial activity of the resulting compounds was assessed against a Gram-positive bacterium (Staphylococcus aureus), a Gram-negative bacterium (Pseudomonas aeruginosa), and fungi (Aspergillus fumigatus and Penicillium pinphilum) by the halo zone and the shake flask test. The antimicrobial activity of H5 was ascribed mainly to the acryl group. Compounds with acryl or acryloxy groups bound to the phenyl moiety were found to exhibit particularly high antimicrobial activities. The activities of phenyl acrylate and phenyl vinyl ketone were excellent as compared to aliphatic acrylates such as cyclohexyl acrylate and hexyl acrylate, indicating that the stereoelectronic effect of the phenyl group was important to the antimicrobial activity.  相似文献   

8.
A structure-antifungal activity relationship (SAR) study of 22 related cinnamic acid derivatives was carried out. Attention was focused on the antifungal activities exhibited against Aspergillus flavus, Aspergillus terreus, and Aspergillus niger. (E)-3-(4-methoxy-3-(3-methylbut-2-enyl)phenyl)acrylic acid (16) exhibited antifungal activity against A. niger, comparable to that of miconazole and a significant antifungal effect against A. flavus and A. terreus as well. A structure-activity relationship (SAR) study of related cinnamic acid derivatives has allowed a model to be proposed for the recognition of the minimal structural requirements for the antifungal effect in this series.  相似文献   

9.
On the basis of our previous structure-activity relationship (SAR) and antiviral mechanism studies, a series of phenanthrene-based antofine derivatives (1-12 and 18-50) were designed targeting tobacco mosaic virus (TMV) RNA and synthesized and systematically evaluated for their antiviral activity against TMV. The bioassay results showed that most of these compounds exhibited good to excellent in vivo anti-TMV activity, of which compounds 19 and 27 displayed higher activity than commercial Ribavirin, thus emerging as potential inhibitors of plant virus. The novel concise structure provides another new template for antiviral studies.  相似文献   

10.
Vertisols in the Sudan occur under different climatic zones, ranging from arid in the north to tropical monsoon in the south, with rainfall varying from 150 mm to 1000 mm per annum. In this study, the exchangeable sodium percentage (ESP) was estimated from the sodium adsorption ratio (SAR); values of SAR and ESP for all identified soil series of Vertisols in the Sudan were extracted from the available data. These data were used to examine the variability in SAR and ESP in these soils using coefficient of variation (CV) as an index and then to regress ESP on SAR for the three master horizons (A, AC, C) and pooled data for all horizon. Curvilinear, linear, quadratic, and cubic equations were used to examine the relation between ESP and SAR. The significance of the F ratio and correlation coefficient was tested for individual equation. The soil series were then sorted out into saline and nonsaline, sodic and nonsodic, and the ESP was regressed on SAR once again. The equations used for the regression were curvilinear and first‐, second‐, and third‐degree polynomial equations. Then analysis of variance (ANOVA) was used to screen any significant difference between the estimated values of ESP (using these equations and USDA salinity laboratory equation) on one hand and the actual (measured) values of ESP. The results revealed that ESP and SAR are highly variable irrespective of depth despite slight decrease with depth. Furthermore, ESP is more variable than SAR in horizons A and AC but less variable in horizon C. The regression equations indicated that ESP might be reasonably estimated from SAR. However, different equations were appropriate for different horizons. Moreover, the result indicated that in most of the cases the relation between ESP and SAR better fits quadratic equations. But for simplicity, linear equations for all horizons could be used to estimate ESP from SAR.  相似文献   

11.
Edible yams are tropical crops that serve as important staple foods in many parts of the world. The rhizome of Dioscorea japonica , well-known as "Japanese yam", is a food and medicinal source known as "San Yak" in Korea. Bioassay-guided fractionation and chemical investigation of the extract of this yam resulted in the identification of two new withanolides, named dioscorolide A (1) and dioscorolide B (2). The structures of these new compounds were determined by spectroscopic methods, including 1D and 2D nuclear magnetic resonance (NMR) techniques, high-resolution mass spectrometry (HRMS), and chemical methods. The cytotoxic activities of the isolates (1 and 2) were evaluated by determining their inhibitory effects on four human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT15) and a human normal cell line (HUVEC) using a sulforhodamine B (SRB) bioassay. Compounds 1 and 2 showed cytotoxicity against tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT15) with IC(50) values ranging from 6.3 to 26.9 μM and exhibited lower activity against the normal cell line (HUVEC) with IC(50) values ranging from 27.1 to 28.8 μM, suggesting selective toxicity among tumor and normal cells.  相似文献   

12.
Biological effects on Ceratitis capitata were evaluated for several withanolides isolated from Salpichroa origanifolia (Solanaceae), (20S,22R,24S,25S,26R)-5alpha,6alpha:22,26:24,25-triepoxy-26-hydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide A, 1), (20S,22R,24S,25S,26R)-22,26:24,25-diepoxy-5alpha,6beta,26-trihydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide C, 2), (20S,22R,24S,25S,26R)-5alpha,6alpha;22,26:24,25-triepoxy-15,26-dihydroxy-17(13-->18)abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide G, 3), and (20S,22R,24S,25S,26R)-5alpha,6alpha:22,26:24,25-triepoxy-1,26-dihydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraene (salpichrolide B, 5), and for chemically modified analogues. Influence of chemical modifications on development delay was analyzed. The compounds were incorporated into the larval diet and the adults' drinking water. Significant development delays from larvae to puparia were observed in treatments with the natural withanolides salpichrolides A, C, and G (1-3) at a concentration of 500 ppm. Salpichrolide B (5) was the most toxic compound, the highest mortality (95%) being observed at the larval stage. Exposure of adults to drinking water containing natural withanolides 1-3 and 5 produced mortality in all cases.  相似文献   

13.
Two known neo-clerodane diterpenoids, scutecyprol A (1) and scutalbin C (2), have been isolated from the acetone extract of the aerial parts of Scutellaria sieberi. The antifeedant activity of scutecyprol A (1), of its 15-oxo derivative (3), and of several halohydrins (4-9), synthesized starting from compounds 1 and 3, against Spodoptera littoralis have been determined and structure-antifeedant relationships are discussed.  相似文献   

14.
Biological effects on Tribolium castaneum larvae were evaluated for three withanolides isolated from Salpichroa origanifolia (Solanaceae), (20S,22R,24S,25S,26R)-5alpha,6alpha:22,26:24,25-triepoxy-26-hydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide A, 1), (20S,22R,24S,25S,26R)-22,26:24,25-diepoxy-5alpha,6beta,26-trihydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide C, 2), and (20S,22R,24S,25S,26R)-5alpha,6alpha:22,26:24,25-triepoxy-15,26-dihydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide G, 3), and for several chemically modified analogues. The compounds were incorporated into the larval diet at concentrations of 500 and 2000 ppm. Salpichrolide C (2) produced a significant delay in the development of neonate larvae to adults at the highest concentration (2000 ppm); development delays and lethal effects were produced by salpichrolides A (1) and G (3) at both concentrations assayed. The size of surviving adults was used as a criterion for assessing feedant deterrent effects; the results suggest that these compounds act as feeding inhibitors. Influence of chemical modifications in development delay was analyzed.  相似文献   

15.
The antifeedant polymethylated flavones 5-hydroxy-3,6,7,8,4'-heptamethoxyflavone, 5-hydroxy-3,6,7,8-tetramethoxyflavone, and 5,6-dihydroxy-3,7-dimethoxyflavone have been isolated from the cudweed, Gnaphalium affine D. Don (Compositae). These flavonoids and authentic analogues showed insect antifeedant activity against the common cutworm (Spodoptera litura F.). In a previous paper, it was suggested that there was no substituent on the B-ring of the flavonoid for the beneficial antifeedant activity against the common cutworm. These flavonoids having a phenyl group as the B-ring and the chromone as elimination of the B-ring from the flavonoids were used to test the hypothesis of the previously described B-ring effect. The known fact is that Sculletaria baicarensis (Rutaceae) produced the 2-phenyl flavone. Test compounds and their methylated derivatives were prepared from this material for the structure-activity relationship (SAR) study of insect antifeedant activity. In spite of the 2-phenyl flavonoids, some tested compounds did not show any insect antifeedant activity against the common cutworm, although these inactive flavonoids were deficient in the 6-substituent group on the A-ring of the flavonoid. This 6-position-substituted derivative almost showed strong insect antifeedant activity against common cutworm. Moreover, the tested flavonoids having a hydroxyl group as a substituent on any of the positions tended to increase the activity. These results suggested the importance of the 6-position substitution on the flavonoid; however, hydrophilic substituents decreased the activity. Baicalein (5,6,7-trihydroxyflavone) derivatives did not show any activity despite having the 6-substituent derivative. Although the activity of some chromones increased the activity of the flavone, the bulky B-ring was a disadvantage for the antifeedant activity. It was suggested that the charge on C(3) and C(5) of the flavonoid was important for the biological activity. Additionally, an adequate hydrogen bonding property, which is different from lipophilicity, was an advantage for the activity on the basis of a QSAR analysis.  相似文献   

16.
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17.
The insecticidal activity of hexane extracts from the roots and leaves of Aristolochia malmeana was evaluated against Anticarsia gemmatalis larvae by topical application. Extract from the roots was the most active and caused 50% mortality in larvae at 308.4 microg/microL. From this extract, a clerodane diterpene, (-)-kolavenic acid, and three lignans, (-)-kusunokinin, (-)-hinokinin, and (8 S,8' R,9 S)-cubebin, were isolated by chromatography and partition procedures and then evaluated for their insecticidal activities either individually or in pairs. (-)-Kusunokinin showed higher activity against A. gemmatalis (LD10=9.3, LD50=230.1 microg/microL) than the crude extract, and its activity was dose-dependent, whereas the other constituents did not exhibit any significant activity. Together with (-)-kusunokinin and (-)-hinokinin, (-)-copalic acid, (-)-2-oxokolavenic acid, (-)- ent-6-beta-hydroxy-copalic acid, (8 R,8' R,9 R)- and (8 R,8' R,9 S)-cubebins, (-)-fargesin, and (-)-phillygenin were isolated from the hexane extract of the leaves. The compounds were identified on the basis of spectroscopic analysis.  相似文献   

18.
It is well-known that the target of most mood-defining compounds is an ionotropic gamma-aminobutyric acid receptor (GABA(A) receptor). The potentiation of the response of these inhibitory neurotransmitter receptors induces anxiolytic, sedative, and anesthetic activity in the human brain. To study the effects of whiskey fragrance on the GABA(A) receptor-mediated response, GABA(A) receptors were expressed in Xenopus oocyte by injecting rat whole brain mRNA or cRNA prepared from the cloned cDNA for the alpha(1) and beta(1) subunits of the bovine receptors. Most whiskey components such as phenol, ethoxy, and lactone derivatives potentiated the electrical responses of GABA(A) receptors, especially ethyl phenylpropanoate (EPP), which strongly potentiated the response. When this compound was applied to mice through respiration, the convulsions induced by pentetrazole were delayed, suggesting that EPP was absorbed by the brain, where it could potentiate the GABA(A) receptor responses. The extract of other alcoholic drinks such as wine, sake, brandy, and shochu also potentiated the responses to varying degrees. Although these fragrant components are present in alcoholic drinks at low concentrations (extremely small quantities compared with ethanol), they may also modulate the mood or consciousness of the human through the potentiation of the GABA(A) receptor response after absorption into the brain, because these hydrophobic fragrant compounds are easily absorbed into the brain through the blood-brain barrier and are several thousands times as potent as ethanol in the potentiation of the GABA(A) receptor-mediated response.  相似文献   

19.
The effects of irrigation-induced salinity and sodicity on the size and activity of the soil microbial biomass in vertic soils on a Zimbabwean sugar estate were investigated. Furrow-irrigated fields were selected which had a gradient of salinity and sugarcane yield ranging from good cane growth at the upper ends to dead and dying cane at the lower ends. Soils were sampled under dead and dying cane, poor, satisfactory and good cane growth and from adjacent undisturbed sites under native vegetation. Electrical conductivity (EC) and sodium adsorption ratio (SAR) of saturation paste extracts was measured, as well as the exchangeable sodium percentage (ESP). There was a significant negative exponential relationship between EC and microbial biomass C, the percentage of organic C present as microbial biomass C, indices of microbial activity (arginine ammonification and fluorescein diacetate hydrolysis rates) and the activities of the exocellular enzymes β-glucosidase, alkaline phosphatase and arylsulphatase but the negative relationships with SAR and ESP were best described by linear functions. By contrast, the metabolic quotient increased with increasing salinity and sodicity, exponentially with EC and linearly with SAR and ESP.Potentially mineralizable N, measured by aerobic incubation, was also negatively correlated with EC, SAR and ESP. These results indicate that increasing salinity and sodicity resulted in a progressively smaller, more stressed microbial community which was less metabolically efficient. The exponential relationships with EC demonstrate the highly detrimental effect that small increases in salinity had on the microbial community. It is concluded that agriculture-induced salinity and sodicity not only influences the chemical and physical characteristics of soils but also greatly affects soil microbial and biochemical properties.  相似文献   

20.
Twenty-six Streptomyces spp. were screened for their volatile production capacity on yeast starch agar. The volatile organic compounds (VOCs) were concentrated on a porous polymer throughout an 8-day growth period. VOCs were analyzed by gas chromatography with flame ionization detection and identified or characterized by gas chromatography-mass spectrometry. A total of 120 VOCs were characterized by retention index and mass spectra. Fifty-three compounds were characterized as terpenoid compounds, among which 18 could be identified. Among the VOCs were alkanes, alkenes, alcohols, esters, ketones, sulfur compounds, and isoprenoid compounds. Among the most frequently produced compounds were isoprene, acetone, 1-butanol, 2-methyl-1-propanol, 3-methyl-3-buten-1-ol, 3-methyl-1-butanol, 2-methyl-1-butanol, cyclopentanone, dimethyl disulfide, dimethyl trisulfide, 2-phenylethanol, and geosmin. The relationship between the excretion of geosmin and the production of spores was examined for one isolate. A good correlation between headspace geosmin and the number of spores was observed, suggesting that VOCs could be used to indicate the activity of these microorganisms in heterogeneous substrates.  相似文献   

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