Three novel 3,4-seco-podocarpane trinorditerpenoids from Aleurites moluccana

Three novel 3,4-seco-podocarpane-type trinorditerpenoids, moluccanic acid (1), moluccanic acid methyl ester (2), and 6,7-dehydromoluccanic acid (3), were isolated from the twigs and leaves of Aleurites moluccana. Their structures were elucidated by spectroscopic methods including 2D NMR analysis. The cytotoxicity of compounds 1-3 was evaluated.     

Four novel lignans from Rodgersia podophylla

Four novel lignans were isolated from the rhizomes of Rodgersia podophylla. It is interesting to note that an unusual 2,4-dihydroxyphenyl moiety was found in these compounds in addition to an acetylenic functionality in compounds 3 and 4.     

Two novel diterpenoids from Isodon rubescens var. lushanensis

Two novel diterpenoids, luanchunins A (1) and B (2), along with their precursor, kamebakaurin (3), had been isolated from the stems and leaves of Isodon rubescens var. lushanensis. Their structures were elucidated on the basis of extensive spectroscopic analyses. Compounds 1 and 2 showed potent cytotoxic activity against HL-60 with IC₅₀ values of 4.81 μM and 3.52 μM, respectively. Plausible pathways for the biosynthesis of 1 and 2 were also postulated.     

Two novel norlignans from Gymnotheca chinensis

Two novel norlignans, gymnothedelignans A and B were isolated from the whole plants of Gymnotheca chinensis. These norlignans possess a rare 2/5 epoxy benzocycloheptanone skeleton. Their structures were established on the basis of 1D and 2D NMR spectral data analysis, and the absolute stereochemistry of gymnothedelignans A and B was further confirmed by single crystal X-ray diffraction analysis.     

Two novel tricyclic diterpenoids from Isodon rubescens var. taihangensis

Two novel tricyclic diterpenoids rubescensins U (1) and V (2) were isolated from the leaves of Isodon rubescens var. taihangensis. They were elucidated as a 8,15-seco-ent-kauranoid and an ent-abietanoid, respectively, by 1D and 2D NMR spectra, and single crystal X-ray analysis. Compound 1 is the first example of an 8,15-seco-ent-kaurane from the plants genus Isodon. A discussion of their biogenesis is described.     

Diapolycopenedioic acid xylosyl ester, a novel glyco-C30-carotenoic acid produced by a new marine bacterium Rubritalea squalenifaciens

A novel acyl glyco-carotenoic acid, diapolycopenedioic acid xylosyl ester, was isolated from a marine bacterium Rubritalea squalenifaciens belonging to subdivision 1 of Verrucomicrobia as the major red pigment by using chromatographic methods. The structure of diapolycopenedioic acid xylosyl ester was determined to be 4-[2-O-(12-methyltridecanoyl)-β-xylopyranosyl] hydrogen 4,4′-diapo-ψ,ψ-carotene-4,4′-dioate by analysis of the MS and NMR data for this acid and for the diacetyl diapolycopenedioic acid xylosyl ester. The diapolycopenedioic acid xylosyl ester showed potent antioxidative activity against a lipid peroxidation model.     

Unusual sesquiterpene glucosides from Amaranthus retroflexus

Implementing the phytochemical study of the weed Amaranthus retroflexus, four new sesquiterpene glucosides were isolated from the methanolic extract of the plant. The structures of these metabolites are determined on the basis of the mass spectrometry, and 1D and 2D NMR spectroscopies (DQ-COSY, TOCSY, HSQC, HSQC-TOCSY, HMBC, and NOESY). Two compounds are characterized by a new aglycone and differed from the site of glucosylation. The other two compounds are dimeric diastereoisomers.All the glucoside sesquiterpenes were tested on the wild species Taraxacum officinale to evaluate the role of this weed in the habitat and on the seed of A. retroflexus to verify the potential autotoxic effect of the plant.     

Structures of new phenylphenalene-related compounds from Eichhornia crassipes (water hyacinth)

Two new compounds identified as methyl derivatives of phenyl naphthalenedicarboxylic acid and phenyl naphthalenecarboxylic acid linked to a phenylphenalene unit were isolated from the extract of Eichhornia crassipes (water hyacinth). The structures have been determined on the basis of spectroscopic analyses, mainly using 2D NMR techniques.     

Two novel polycyclic spiro lignans from Gymnotheca involucrata

Two novel lignans, gymnothespirolignans A (1) and B (2), possessing a rare polycyclic spiro skeleton, were isolated from the endemic plant of Gymnotheca involucrata Pei. Their structures were determined by spectroscopic evidences and the absolute configurations were confirmed by single crystal X-ray diffraction analysis. Compounds 1 and 2 showed promising antiviral activities against RSV with an IC₅₀ value of 31.87 and 17.51 μM, respectively.     

Preconcentration of phthalic acid esters in water samples by Saccharomyces cerevisiae immobilized on silica gel

A sensitive and selective column adsorption method is proposed for the off-line preconcentration and determination of phthalic acid esters (PAEs), namely benzyl-butyl phthalate (BBP), di-n-butyl phthalate (DBP) and di-cyclohexyl phthalate (DCHP). The PAEs was preconcentrated on Saccharomyces cerevisiae immobilized on silica gel and then determined by high performance liquid chromatography (HPLC). Several parameters on the recovery of the analytes were investigated. Recoveries of BBP, DBP and DCHP were 100±2, 98±2 and 98±3%, respectively, at 95% confidence level under optimum conditions. The detection limits (3S/N) of BBP, DBP and DCHP were 3.2, 6.3 and 3.1 μg l⁻¹, respectively. The capacity of the adsorbent was also examined and found to be 1.4 mg g⁻¹ for BBP and DBP, and 3.6 mg g⁻¹ for DCHP. S. cerevisiae immobilized on silica gel is suitable for repeated use without decreasing recovery up to about 25 adsorption-elution cycles. The proposed method was successfully applied to the determination of PAEs in river water with high precision and accuracy.     

Oryzamutaic acid A, a novel yellow pigment from an Oryza sativa mutant with yellow endosperm

Oryzamutaic acid A, a novel yellow pigment, was isolated from the endosperm of an Oryza sativa mutant. The structure and absolute configuration of oryzamutaic acid A were elucidated on the basis of spectroscopic analysis, single-crystal X-ray diffraction analysis, and biogenetic reason. Oryzamutaic acid A might be biogenetically derived from four l-amino acids because it contains three amino acid groups and one amine group.     

A novel acylated quercetin tetraglycoside from oolong tea (Camelia sinensis) extracts

A novel acylated quercetin tetraglycoside, namely quercetin 3-O-(2^G-p-coumaroyl-3^G-O-β-l-arabinosyl-3^R-O-β-d-glucosylrutinoside) was isolated from oolong tea (Camelia sinensis) extracts. Structural analysis of this compound was achieved by NMR, TOF-MS and high-resolution FAB-MS. Triglycosyl flavonols have previously been reported from tea leaves and tea seeds however this is the first report of an aromatic acylated and tetraglycosyl flavonol.     

A pair of new atropisomeric cupressuflavone glucosides isolated from Juniperus communis var. depressa

A pair of new atropisomers, (M)- and (P)-cupressuflavone 4′-O-β-d-glucoside, were isolated from Juniperus communis var. depressa, and their absolute structures and axial configurations were determined using 2D NMR and circular dichroism. These are the first reported stable (M)- and (P)-isomers of cupressuflavone glucosides isolated from natural sources.     

Synthesis of methyl (5Z,8Z,10E,12E,14Z)-eicosapentaenoate

The first total synthesis of methyl (5Z,8Z,10E,12E,14Z)-eicosapentaenoate has been achieved in seven steps and in 16% overall yield. The synthesis confirmed the assigned structure of this polyunsaturated natural product.     

Mildbraedin, a novel kaempferol tetraglycoside from the tropical forest legume Mildbraediodendron excelsum

Aqueous methanol extracts of the leaves of Mildbraediodendron excelsum yielded a novel flavonol glycoside characterized by an O-linked branched tetrasaccharide. The structure of the compound was determined by spectroscopic methods to be kaempferol 3-O-α-l-rhamnopyranosyl(1→3)-α-l-rhamnopyranosyl(1→2)[α-l-rhamnopyranosyl(1→6)]-β-d-galactopyranoside. This previously unrecorded natural product was the major phenolic component of leaf material obtained both from a living specimen of the plant and a historic collection made in the field in 1928.     

Sauroine—a novel Lycopodium alkaloid from Huperzia saururus

A novel Lycopodium alkaloid, sauroine (7,8-dihydroxylycopodine, 1) was isolated from the aerial parts of the medicinal species Huperzia saururus. The structure and relative stereochemistry of 1 were elucidated on the basis of its spectral data.     

Four new dimeric triterpene glucosides from Sanguisorba officinalis

In search for bioactive compounds from the roots of Sanguisorba officinalis L. (Rosaceae), four new dimeric triterpene glucosides, namely sanguidioside A, B, C, and D (1-4) were isolated. Alkaline hydrolysis of 1-2 afforded the corresponding dimeric aglycones (1a and 2a). Meanwhile, a ready intra-molecular transesterification was observed, providing dimeric triterpenes 1b and 2b. Alkaline hydrolysis of the crude dimmeric saponin also provided a new dimeric triterpene, sanguidiogenin (9). The structures of all these compounds are elucidated via spectroscopic and chemical methods, and are further confirmed by the X-ray diffraction analysis of the dimeric aglycone 2a. Compound 3 represents the first dimeric saponin of an oleanolic acid and an ursonic acid derivative, while compound 4 is the first dimeric saponin of oleanolic acid derivatives.     

Sulfur-containing sesquiterpenes from Thapsia villosa

Three new sesquiterpenoids bearing sulfurated ester groups have been isolated from the roots of Thapsia villosa L. Their structures have been elucidated by spectroscopic means. This is the first time that a methylthiopropionic acid ester is isolated from natural sources.     

Platypodiol a novel clerodane diterpene from Baccharis platypoda

There is an urgent need for effective leishmanicidal drugs to replace or supplement those in current use. Our group has been bioprospecting many Brazilian plants looking for potential new ‘hits’ to combat leishmaniasis. We found that Baccharis platypoda was one of the Asteraceae species that displayed leishmanicidal activity. We now describe the isolation of the new clerodane diterpene (1), named platypodiol after its ethanolic leaf extract. Its structure was determined by detailed NMR and ESI-TOF/MS/MS experiments. Considering the few publications about this species, this result has increased the phytochemical knowledge about B. platypoda.     

Lacitemzine, a novel sesquiterpene acid from the Tunisian plant Pulicaria laciniata (Coss. et Kral.) Thell.

The flowers of Pulicaria laciniata (Coss. et Kral.) Thell. (Asteraceae) afforded a new sesquiterpene acid 1, named lacitemzine together with the three known compounds, 4-hydroxy-3-methoxypyridine 2, β-sitosterol-3-O-β-d-glucoside 3 and 1,3,5-trimethoxybenzene 4. The structure of compound 1, 2-(2,6-dimethyl-3,4,5,6,7,8,9,10-octahydro-5,8-oxaazulen-9-yl)acrylic acid, contains a guaiane skeleton and was elucidated by spectroscopic procedures including 2D-NMR and X-ray diffraction.