2H-Pyranone and isocoumarin derivatives isolated from the plant pathogenic fungus Leptosphaena maculans.

Two new 2H-pyranones and two new isocoumarin derivatives, maculanslines A-D (1-4), together with seven known compounds (5-11), were isolated from the plant pathogenic fungus Leptosphaena maculans. Their planar structures and absolute configuration were elucidated by comprehensive spectroscopic techniques including high-resolution electrospray ionization mass spectrum, 1D and 2D nuclear magnetic resonance, as well as electronic circular dichroism. All 11 compounds were tested for their inhibitory activity against α-glucosidase. Compound 1 showed moderate inhibitory activity against α-glucosidase with IC50 of 74.35 µM.

New analytical method for the study of metabolism of swertiamarin in rats after oral administration by UPLC-TOF-MS following DNPH derivatization.

The metabolism of swertiamarin in vivo was studied by LC-MS following 2,4-dinitrophenylhydrazine derivatization. The ionization efficiency of the main metabolite erythrocentaurin was greatly enhanced by the new analytical method developed, and erythrocentaurin was successfully detected for the first time in rat plasma after oral administration of swertiamarin. Methyl 4-formylbenzoate was used as the internal standard to quantify erythrocentaurin in rat plasma in negative mode by UPLC-TOF-MS, and it was found that erythrocentaurin reached the maximum mean plasma concentration of 425.8 ± 127.6 ng/mL at about 2 h after oral administration of swertiamarin at a dose of 200 mg/kg. A metabolic pathway of swertiamarin to erythrocentaurin was proposed. Swertiamarin is first hydrolyzed by bacterial ß-glucusidase to give the aglycone, which is readily converted to erythrocentaurin. The monoterpene compound swertiamarin was found to be metabolized to dihydroisocoumarin and alkaloid compounds in vivo, which may be responsible for the pharmacological effect of swertiamarin. The results may shed light on the clinical efficacy of swertiamarin and the new analytical method may assist in studies for the metabolism of other natural iridoids and secoiridoids in vivo.

Rapid preparative isolation of erythrocentaurin from Enicostemma littorale by medium-pressure liquid chromatography, its estimation by high-pressure thin-layer chromatography, and its α-amylase inhibitory activity.

Erythrocentaurin is a relatively simple natural product present among the members of Gentianaceae. A preparative method for the isolation of erythrocentaurin from the ethyl acetate fraction of Enicostemma littorale using medium-pressure liquid chromatography has been reported. The method consisted of a simple step gradient from 10 to 20% ethyl acetate in n-hexane. Using a 70 × 460 mm Si60 column, this method is capable of processing 20 g of material in <3 h (purity ≈ 97%). The recovery of erythrocentaurin was 87.77%. Estimation of erythrocentaurin in extracts and fractions based on high-pressure thin-layer chromatography was carried out on silica gel 60 F(254) plates with toluene/ethyl acetate/formic acid (80:18:2 v/v/v) as the mobile phase. The densitometric analysis was performed at 230 nm. A well-separated compact band of erythrocentaurin appeared at R(f )0.54 ± 0.04. The analytical method showed good linearity in the concentration range of 200-1500 ng/band with a correlation coefficient of 0.99417. The limits of detection and quantification were found to be ≈60 and ≈180 ng/band, respectively. Erythrocentaurin exhibited a concentration-dependent α-amylase inhibition (IC(50) 1.67 ± 0.28 mg/mL). The outcome of the study should be considered for pharmacokinetic and biotransformation studies involving E. littorale.

Influence of field attack by carrot psyllid (Trioza apicalis Förster) on sensory quality, antioxidant capacity and content of terpenes, falcarindiol and 6-methoxymellein of carrots (Daucus carota L.).

The effect of different degrees of attack by carrot psyllid (Trioza apicalis) on quality parameters of carrots was studied in field experiments for two years. Treatments were different degrees of physical insect protection by floating row cover. An increasing attack level of psyllids showed an enhancement effect on the antioxidant capacity (ORAC), content of falcarindiol, 6-methoxymellein, and terpenes, and scores for bitter taste, chemical flavor, terpene flavor, and toughness. Carrot psyllid attack decreased the yield, total sugar, fructose, glucose, and sensory attributes sweet taste, color hue, color strength, crispiness, and juiciness. Carrot plants at 8-10 weeks of age tolerated attack by psyllids at low levels (2% leaves with curling or discoloration).

LC-MS/MS as a tool for identification of bioactive compounds in marine sponge Spongosorites halichondriodes (Dendy 1905).

The sensitivity, specificity and selectivity of liquid chromatography/mass spectrometry tandem mass spectrometry (LC-MS/MS) make it an essential tool for the characterization and identification of low molecular compounds such as fatty acids, sterols, cholastane derivatives, nucleosides etc. In the current work, the marine sponge Spongosorites halichondriodes (order Halichondrida, Family Halichondriidae); a particularly rich source of cytotoxic compounds is studied for the initial characterization of bioactive compounds. The composition of ethyl acetate and butanol extracts were subjected to LC-MS and LC-MS/MS. Many novel sterol derivatives compounds which were not reported in any marine sponge mainly belonged to the group of C25-C28 saturated and unsaturated esters like 3ß, 4ß, 7α, 12α-tetrahydroxy-5ß-cholan-24-oic acid methyl ester, 7 α, 12 ß-dihydroxy-5 ß-cholan24-oic acid methyl ester, novel isocoumarin citrinolactone A, a triterpenoid glycyrrhetinic acid as well as other unknown compounds in this species such as nucleoside inosine was identified. Other compound investigated was 3ß, 6ß, 7α-trihydroxy-5ß-cholan-24-oic acid methyl ester. All the sterol ester derivatives are reported here for the first time in marine sponge belonging to family Halichondriidae. However, the literature report supports the occurrence of 3ß-hydroxy sterols which is considered as a biomarker for this family.

Chemical characterization of Phoma pomorum isolated from Danish maize.

Strains of the genus Phoma are often isolated from various environmental samples including cereals and maize. In the present study we performed a chemical characterization of strains isolated from Danish samples derived from whole plant material collected at harvest. All strains were isolated using a recently developed isolation medium and identified morphologically as P. pomorum. This species is placed in the Phoma section Peyronellaea and strains of other members in this section were also included in the present study. Sequence analysis of the internal transcribed spacer region (ITS) grouped the Danish P. pomorum strains with representative P. pomorum strains isolated from other sources. The metabolite production on dichloran Rose Bengal yeast extract sucrose agar (DRYES) was analyzed and the strains were clustered using an in-house Chemical Image Analysis (CIA) program. The resulting tree showed three clusters, one containing all P. pomorum strains, one containing all Epicoccum nigrum strains and finally a large cluster containing strains of the remaining species, which could not be differentiated due to insufficient metabolite production. The separation of P. pomorum from the other species resulted mainly from the ability to produce isocoumarins. Several isocoumarins were produced by P. pomorum strains with diaporthinic acid as the predominant analogue, but diaporthin, dichlorodiaporthin, diaporthinol, citreo-isocoumarin, 6-methyl citreo-isocoumarin and citreo-isocoumarinol were also identified. This is the first time that a Phoma species has been reported as a producer of isocoumarins.

E-2-ethylhexenal, E-2-ethyl-2-hexenol, mellein, and 4-hydroxymellein in Camponotus species from Brunei.

E-2-ethyl-2-hexen-1-ol (1), mellein (4), and 4-hydroxymellein (5) were identified as the major volatile compounds in the head and/or thorax of Camponotus quadrisectus. Neither 1 nor 5 have been previously detected in insects. Also identified were small amounts of m-cresol (2) and 6-methyl salicylic acid (3). E-2-ethylhexenal (6) and small amounts of 3 were identified in heads of Camponotus irritibilis from Kuala Belalong, Brunei. Compounds 2-4 occur in other Bornean camponotines with hypertrophied mandibular glands, and 4 is widespread in the tribe. The possibility of semiochemical parsimony (multiple functions) for these mandibular gland compounds is reviewed in the context of existing data on mandibular gland products of other camponotines, reported biological activities of the compounds, and secondary loss of metapleural glands in this ant group.

Simultaneous determination of swertiamarin and its metabolites (5Z)-5-ethylidene-8-hydroxy-3,4,5,6,7,8-hexahydro-1H-pyrano[3,4-c]pyridin-1-one and erythrocentaurin in broth of Aspergillus niger by HPLC.

When cultivated with Aspergillus niger, swertiamarin, an important drug, is rapidly transformed into erythrocentaurin and (5Z)-5-ethylidene-8-hydroxy-3,4,5,6,7,8-hexahydro-1H-pyrano[3,4-c]pyridin-1-one (M(1)), a new compound with high anti-inflammatory activity. A simple and rapid HPLC method for simultaneous determination of swertiamarin and its two metabolites in broth of A. niger is described. The chromatographic separation was achieved on a C(18) ODS column (250 x 4.6 mm i.d.) by gradient elution with 0.04% formic acid in water and 0.04% formic acid in acetonitrile as the gradient mixtures. The flow rate was 1 mL/min, the detection wavelength was 237 nm and the column temperature was kept at 30 degrees C. The retention times of swertiamarin, erythrocentaurin and M(1) were 14.6, 16.8 and 24.8 min, respectively. The mean absolute recoveries of three analysts were over 96%. Quantification limits were 0.02 microg/mL for swertiamarin and 0.05 microg/mL for both of the two metabolites. The method was applied for the quantification of swertiamarin and its two metabolites during the fermentation process and the evaluation of the bioavailabilities in the Caco-2 monolayer.