Diterpenoids and flavonoids from Grindelia discoidea

A new labdane-type diterpenoid acid, discoidic acid, has been isolated from the aerial parts of Grindelia discoidea. Its structure has been deduced as 4β-hydroxymethyllabd-7-en- 15-oic acid on the basis of the spectral data of its methyl ester derivative and comparison of these data with those of the methyl ester derivative of its isomer, 3β-hydroxylabd-7-en- 15-oic acid, also isolated from the same extract. In addition, a dihydroflavonol and two flavonols have been isolated.     

A diterpenoid from Elaeoselinum foetidum

A new diterpene acid has been isolated from the roots of Elaeoselinum foetidum. Its structure was established as ent-7α-senecioxy-15α-hydroxy-atis-16-en-19-oic acid by ¹H NMR and ¹³C NMR spectroscopic studies of its methyl ester derivative and confirmed by correlation with a margotianin derivative.     

Biochimica et biophysica acta,vol. 586 (1979)

3-Hydroxyisobutyric acid has been isolated from the urine of rats loaded with sodium isobutyrate. An optical rotation measurement of the methyl ester derivative shows this compound to be the S(+) stereoisomer. This is the same stereoisomer that has been previously identified in cultures of bacteria incubated with ammonium isobutyrate     

A diterpenoid of the atis-16-ene class from Elaeoselinum foetidum

A new diterpenoid has been isolated from the root of Elaeoselinum foetidum. Its structure was established as ent-15α-senecioxy-atis-16-en-19-oic acid mainly by ¹H NMR ¹³C NMR spectroscopic studies of its methyl ester derivative.     

Mass spectra of acetylated derivatives of sialic acids

The fragmentation pattern in electron-impact mass spectrometry has been established for the peracetylated methyl ester methyl glycoside derivative of N-acetylneuraminic acid. The resulting, data allow the interpretation of the mass spectrum of the corresponding derivative of a new sialic acid isolated from the starfish Distolasterias nipon which is shown to be 8-O-methyl-N-acetylneuraminic acid.     

Acylated sucroses and acylated quinic acids analogs from the flower buds of Prunus mume and their inhibitory effect on melanogenesis

The methanolic extract from the flower buds of Prunus mume, cultivated in Zhejiang Province, China, showed an inhibitory effect on melanogenesis in theophylline-stimulated B16 melanoma 4A5 cells. From the methanolic extract, five acylated sucroses, mumeoses A–E, and three acylated quinic acid analogs, 5-O-(E)-p-coumaroylquinic acid ethyl ester, and mumeic acid-A and its methyl ester, were isolated together with 13 known compounds. The chemical structures of the compounds were elucidated on the basis of chemical and physicochemical evidence. Inhibitory effects of the isolated compounds on melanogenesis in theophylline-stimulated B16 melanoma 4A5 cells were also investigated. Acylated quinic acid analogs substantially inhibited melanogenesis. In particular, 5-O-(E)-feruloylquinic acid methyl ester exhibited a potent inhibitory effect [inhibition (%): 21.5 ± 1.0 (P < 0.01) at 0.1 μM]. Moreover, its biological effect was much stronger than that of the reference compound, arbutin [inhibition (%): 10.6 ± 0.6 (P < 0.01) at 10 μM]. Interestingly, the obtained acylated quinic acid analogs displaying melanogenesis inhibitory activity showed no cytotoxicity [cell viability >97% at 10 μM]. It is concluded that acylated quinic acid analogs are promising therapeutic agents for the treatment of skin disorders.     

Improvement of catalytic activity of Candida rugosa lipase in the presence of calix[4]arene bearing iminodicarboxylic/phosphonic acid complexes modified iron oxide nanoparticles

In the present study, iron oxide magnetite nanoparticles, prepared through a co-precipitation method, were coated with phosphonic acid or iminodicarboxylic acid derivatives of calix[4]arene to modulate their surfaces with different acidic groups. Candida rugosa lipase was then directly immobilized onto the modified nanoparticles through sol–gel encapsulation. The catalytic activities and enantioselectivities of the two encapsulated lipases in the hydrolysis reaction of (R/S)-naproxen methyl ester and (R/S)-2-phenoxypropionic acid methyl ester were assessed. The results showed that the activity and enantioselectivity of the lipase were improved when the lipase was encapsulated in the presence of calixarene-based additives; the encapsulated lipase with the phosphonic acid derivative of calix[4]arene had an excellent rate of enantioselectivity against the (R/S)-naproxen methyl and (R/S)-2-phenoxypropionic acid methyl esters, with E = 350 and 246, respectively, compared to the free enzyme. The encapsulated lipases (Fe-Calix-N(COOH)) and (Fe-Calix–P) showed good loading ability and little loss of enzyme activity, and the stability of the catalyst was very good; they only lost 6–11% of the enzyme’s activity after five batches.     

Phosphocalyculin C as a pyrophosphate protoxin of calyculin C in the marine sponge Discodermia calyx

Calyculin C, a minor derivative of the calyculins, has an additional methyl group on C32 of calyculin A. A recent biosynthetic study of calyculins revealed that an end product of calyculin biosynthesis is the pyrophosphate form, phosphocalyculin A. However, the pyrophosphate counterpart derived from calyculin C had not been reported. We isolated phosphocalyculin C as a minor pyrophosphate derivative, by a detailed investigation of an extract from the sponge Discodermia calyx. The treatment of phosphocalyculin C with the D. calyx cell-free extract significantly enhanced its cytotoxicity, providing molecular evidence for its role as the protoxin of calyculin C.     

Structure of a Peptidal Antibiotic P168 Produced by Paecilomyces lilacinus (Thom) Samson

( + )-α-Kainic acid (1) was synthesized by starting from a building block, N-Boc-3-acetoxyallylglycine ethyl ester (2). The key intermediate, a methyl 4-[(tert-butoxycarbonyl)prenylamino]-5-hydroxy-2-pentenoate derivative (9), was prepared from 2 in eight synthetic steps. After converting 10 into a methyl ester (11), intramolecular ene-carbocyclization of 11 gave a pyrrolidine derivative (12), which was converted to 1 in a moderate yield.     

Phenolic constituents of Iris milesii rhizomes

Analysis of a methanol extract of the rhizomes of Iris milesii resulted in the isolation of a new isoflavone, 5,6,7,4′-tetrahydroxy-8-methoxyisoflavone along with prunetin, sakuranetin, 2:6-dimethoxy-1,4-benzoquinone, tectorigenin, irigenin,4-β(D-glucosyloxy)-ferulic acid methyl ester, quercetin-3-methyl ether, tectoridin, iridin and iristectorin B.     

Hydroperoxide isomers and ketohydroxy product from oxidation of linoleic acid by eggplant lipoxygenase

Hydroperoxides produced by oxidation of linoleic acid with purified eggplant lipoxygenase were separated by TLC and analysed by IR spectroscopy. The methyl hydroxystearates from the enzymatically produced hydroperoxides were analysed by MS and GLC. Both analyses indicated that the eggplant enzyme converted linoleic acid almost exclusively (96%) into the 13-hydroperoxy isomer whereas the 9-hydroperoxy isomer was only a minor product (4%). HPLC of the methyl ester of the isolated hydroperoxides showed three components. Each component was collected, reduced to methyl hydroxystearate and characterized by GLC, MS and IR analysis. The components were identified as 13-hydroperoxy cis-trans isomer (92.8%), 13-hydroperoxy trans-trans isomer (2.6%) and 9-hydroperoxy cis-trans isomer (4.6%). A polar by-product present in the reaction mixture was identified by IR, ¹H NMR, and MS (of the toluene-p-sulphonyl derivative) as 13-hydroxy-12-oxo-octadec-cis-9-enoic acid.     

Unsaturated fatty acid from seed oil of consolida regalis

Icosenoic acid [20:1(11)] was isolated from the seed oil of Consolida regalis. The seeds contain ca 30% of fatty oil which comprise ca 25% 20:1 (11). The structure of the fatty acid methyl ester having been isolated by column chromatography was determined by GC/MS, IR and ¹H NMR and was confirmed by HPLC analysis of the bromophenacyl ester derivative.     

Phenanthrene derivatives from Aristolochia argentina

Aristolochic acid Ia, aristolochic acid I methyl ester and aristolochic acid II methyl ester were identified in the roots of Aristolochia argentina.     

Evaluation of human neutrophil elastase inhibitory effect of iridoid glycosides from Hedyotis diffusa

Five iridoid glycosides were isolated from the MeOH extract of Hedyotis diffusa, and their structures were elucidated as E-6-O-p-methoxycinnamoyl scandoside methyl ester (1), Z-6-O-p-methoxycinnamoyl scandoside methyl ester (2), E-6-O-p-feruloyl scandoside methyl ester (3), E-6-O-p-coumaroyl scandoside methyl ester (4), and Z-6-O-p-coumaroyl scandoside methyl ester (5) by interpretation of their spectroscopic data. All the isolated compounds were evaluated for human neutrophil elastase inhibitory effect, and compound 1 showed potent activity with an IC₅₀ value of 18.0 μM. The molecular docking simulation suggested a structural model for the inhibition of human neutrophil elastase by compound 1.     

Glucuronoyl esterase--novel carbohydrate esterase produced by Schizophyllum commune

The cellulolytic system of the wood-rotting fungus Schizophyllum commune contains an esterase that hydrolyzes methyl ester of 4-O-methyl-d-glucuronic acid. The enzyme, called glucuronoyl esterase, was purified to electrophoretic homogeneity from a cellulose-spent culture fluid. Its substrate specificity was examined on a number of substrates of other carbohydrate esterases such as acetylxylan esterase, feruloyl esterase and pectin methylesterase. The glucuronoyl esterase attacks exclusively the esters of MeGlcA. The methyl ester of free or glycosidically linked MeGlcA was not hydrolysed by other carbohydrate esterases. The results suggest that we have discovered a new type of carbohydrate esterase that might be involved in disruption of ester linkages connecting hemicellulose and lignin in plant cell walls.     

红树林植物瓶花木中的细胞毒活性成分(Ⅱ)

从红树林树植物瓶花木(Scyphiphora hydrophyllacea Gaertn. f.)的乙醇提取物中分离得到5个化合物,通过波谱分析,鉴定其结构分别为:shanzhigenin methyl ester (1)、1-epishanzhigenin methyl ester (2)、山柰酚 (3)、芹菜素 (4)和 5,7,2'-trihydroxy-3,6,8,4',5'-pentamethoxyflavone (5)。以上化合物均为首次从瓶花木中分离得到。细胞毒活性测试结果表明,化合物1和2的混合物对人肝癌细胞(SMMC-7721)的增殖有较强的生长抑制活性。     

Biosynthetic relationship between tetrahydroanthracene and anthraquinone in Aloe saponaria

The incorporation of Me¹⁴COONa into aloesaponol I, laccaic acid D methyl ester and aloesaponarin I was demonstrated. The biosynthetic relation between aloesaponol I and aloesaponarin I was established, but incorporation of aloesaponol I into laccaic acid D methyl ester, or vice versa was not demonstrated and this result was confirmed by an investigation using labelled laccaic acid D methyl (¹⁴CH₃) ester. It was possible to show that aloesaponol I and laccaic acid D methyl ester were biosynthesized in parallel in Aloe saponaria.     

Chemical constituents from Aristolochia tagala and their chemotaxonomic significance

Fifteen compounds were obtained from the extract of the whole herbs of Aristolochia tagala, which were divided into eight aristolactam-type alkaloids (1–6, 14 and 15) and seven aristolochic acid derivatives (7–13). Their structures were identified as aristolactam BII, aristolactam II, sauristolactam, aristolactam I, 7-methoxyaristolactam IV, aristolactam AII, 3-hydroxy-4-methoxy-10-nitrophenanthrene-1-carboxylic acid methyl ester, ariskanin A, ariskanin D, ariskanin E, aristolochic acid C, ariskanin C, ariskanin B, aristolactam-N-β-D-glucoside and cepharanone A N-β-D-glucoside by comparison of their spectral data with those reported previously in the literature. The chemotaxonomic relationships between A. tagala and other species of genus Aristolochia were also discussed. As a result, the isolated compounds closely matched the ones obtained in other species of the genus.     

Ent-kaurane derivatives from the root cortex of yacon and other three Smallanthus species (Heliantheae,Asteraceae)

The metabolites produced by the secretory canals of the root cortex from four Smallanthus species belonging to the yacon group were identified as ent-kaurane-type diterpenes. The dichloromethane root cortex extracts of the four species were treated with diazomethane and analyzed comparatively by GC–MS using a simple and rapid procedure which is very sensitive and reproducible permitting detection of minor components. In all cases, ent-16-kauren-19-oic acid (kaurenoic acid) methyl ester was the main component, differences being observed only in the minor components. The minor components identified were grandiflorenic acid methyl ester, ent-16-kauren-19-al, 16α,17-epoxy-15α-angeloyloxy-kauran-19-oic acid methyl ester and several O-acyl derivatives at C-15 or C-18 of kaurenoic acid. One of the minor components, 18-isobutyroyloxy-ent-kaur-16-en-19-oic acid is a new kaurenoic acid derivative. Grandiflorenic acid and 15-α-angeloyloxy-16,17-α-epoxy-ent-16-kauren-19-oic acid were present only in Smallanthus sonchifolius and Smallanthus siegesbeckius which showed very similar GC traces. The different GC profile of RC diterpenes from Smallanthus connatus and Smallanthus macroscyphus supports the view that they are different taxa. Some chemotaxonomic aspects of the genus Smallanthus and the subtribe Milleriinae are briefly discussed.