Teris A. van Beek

High-performance liquid chromatographic method for the analysis of anthraquinone glycosides and aglycones in madder root (Rubia tinctorum L.).

A HPLC method has been developed for the simultaneous characterisation of anthraquinone glycosides and aglycones in extracts of Rubia tinctorum L. The anthraquinones are separated on an end-capped C18-RP column with a water–acetonitrile gradient as eluent and measured with UV detection at 250 nm. With this method the glycosides lucidin primeveroside and ruberythric acid and the aglycones lucidin, alizarin, purpurin, quinizarin and 2,6-dihydroxyanthraquinone can be analysed. Lucidin which is not commercially available was synthesised starting from resorcinol and phthalic anhydride. The glycosides ruberythric acid and lucidin primeveroside are commercially available as a mixture and were separated by droplet counter-current chromatography in ascending flow with chloroform–methanol–water as eluents prior to their use as standards.

Alkaloids of Tabernaemontana eglandulosa

Abstract From the leaves and twigs of Tabernaemontana eglandulosa 22 alkaloids, of which 12 are new, have been isolated. Besides tacamine (pseudo-vincamine) 7 other alkaloids of this new class of indole alkaloids were identified. A further three alkaloids of the cleavamine type, namely the known ( + )20R-15, 20-dihydro-cleavamine and (-)20S-15, 20-dihydro-cleavamine and one new alkaloid, which was tentatively identified as 14S, 20R-velbanamine, two new alkaloids of the pseudo-aspidospermidine type, namely 20R-l,2-dehydro-pseudo-aspidospermidine and 20S-hydroxy-l,2-dehydro-pseudoaspidospermidine and an alkaloid of a novel iboga type were isolated. More common alkaloids isolated were coronaridine, 11-hydroxycoronaridine, voaphylline, tubotaiwine, ibogamine, norfluorocurarine and probably a mixture of 20R- and 20S-pseudo-vincadifformine. Only quantitative differences in the alkaloid content of the leaves, twigs and stembark were observed.

Identification of the sex pheromone of Scrobipalpula absoluta; determination of double bond positions in triple unsaturated straight chain molecules by means of dimethyl disulphide derivatization

The sex pheromone of Scrobipalpula absoluta (Meyrick) (Lepidoptera: Gelechiidae) was identified as a 92:8 mixture of (3E,8Z,11Z)-3,8,11-tetradecatrienyl acetate (1) and (3E,8Z)-3,8-tetradecadienyl acetate (2) through mass spectrometric investigation of the dimethyl disulphide derivatives of excised sex pheromone glands. It is the first time that this method was used for triple unsaturated straight chain molecules. Compound (2) was identified as a new pheromone component. A synthetic mixture of the two identified compounds proved to be attractive in wind tunnel experiments.

Efficient Purification of Ginkgolic Acids from Ginkgo biloba Leaves by Selective Adsorption on Fe3O4 Magnetic Nanoparticles

Ginkgolic acids (GAs; anacardic acids; 6-alkylsalicylic acids) are both unwanted constituents in standardized Ginkgo biloba (Ginkgo) extracts and desirable constituents for pharmacological assays. Thus, for the quality control of Ginkgo extracts, the availability of pure GAs is important. In this investigation, inexpensive and easily prepared Fe3O4 magnetic nanoparticles (MNPs) in methanol were used to selectively adsorb GAs from crude petroleum ether extracts of Ginkgo leaves in the presence of various lipids including other alkylphenols (cardanols and cardols). The adsorption capacity of the MNPs is high, at 4-5% (w/w). The moiety responsible for the adsorption is the salicylic acid group, which binds strongly to Fe(III). Desorption with acidified methanol gave an extract with a GA content of 73%. This could be further separated by preparative HPLC on a C8 column. In total, eight different GAs were captured by MNPs. The MNP adsorption step can replace more traditional column chromatography and liquid-liquid extraction steps and is superior in terms of solvent consumption, selectivity, labor, and energy consumption. MNPs might become an efficient separation technique for selected high-value phytochemicals that contain a salicylic acid moiety.

A simplified method for the determination of Taxanes in Yew Needles by reversed-phase (C18) high pressure liquid chromatography.

An analytical procedure for the large-scale qualitative and quantitative screening of paclitaxel (Taxol®) and related neural taxanes in yew needles has been developed. The needles were selectively extracted with ethanol:water:acetic acid (80:19:1) and the resulting extract was purified from chlorophyll, 3,5-dimethyoxy phenol, taxine alkaloids and cinnamoyl taxanes, by means of small-scale partition chromatography on Extrulet®. After concentration, the taxanes were determined by high pressure chromatography on a C18 column with acetonitrile;water as eluent and ultra violet detection at 227 and 280 nm. Cinnamic acid was used as an internal standard. Various aspects such as extraction efficiency, recovery, peak purity, detection limits, robustness and reproducibility of the method have been evaluated. The method is very labour efficient with only 20 min of manpower input per sample.

Alkaloids from Pycnarrhena longifolia

Abstract From the root and stem of Pycnarrhena longifolia the following alkaloids were isolated and identified: obaberine, homoaromoline, aromoline, daphnoline, limacine, krukovine, magnoflorine and pycnarrhine. Pycnarrhine is a simple isoquinoline derivative which has not previously been reported as a natural product.

Sample preparation of standardized extracts of Ginkgo biloba by supercritical fluid extraction.

A method of sample preparation of standardized extracts of Ginkgo biloba using supercritical fluid extraction (SFE) is described. Ginkgolides and bilobalide could be selectively extracted with carbon dioxide containing 10% methanol at 335 atm and 45 °C from a methanolic solution of the extract. An in-line filter of silica gel was found to be essential for obtaining clean samples. Trapping was carried out with a solid silica gel trap at 80 °C. After eluting the trap with methyl acetate, the sample could be analysed by gas liquid chromatography or high performance liquid chromatography. Recoveries of the five terpenes relative to a standard solid phase extraction (SPE) procedure varied for two different extracts from 98.6 to 102.3%. Relative standard deviations were better for SFE than for SPE. A further advantage of the SFE over the SPE method is that it is much less laborious. A disadvantage is that it requires an automated supercritical extractor. With a small adaptation, the SFE method could also be used for finished ginkgo drugs in an aqueous alcoholic solution.

Isolation and identification of sex pheromone ofSymmetrischema tangolias (Gyen) (Lepidoptera: Gelechiidae).

The sex pheromone of the South American potato tuber mothSymmetrischema tangolias (syn.:Symmetrischema plaesiosema) was identified as a 2:1 mixture of (E,Z)-3,7-tetradecadien-1-ol acetate and (E)-3-tetradecen-1-ol acetate by means of dual-column GC, EAG, GC-EAD, GC-MS, NMR, and wind-tunnel bioassays. (Z)-5-Tetradecen-1-ol acetate and (Z)-7-tetradecen-1-ol acetate were also identified in the pheromone gland extract. MaleS. tangolias were able to detect these acetates (EAG), but their addition to the two-component sex pheromone did not improve attractiveness. Field trials in Cajamarca and Cusco, Peru, showed that traps baited with the synthetic sex pheromone were able to catch large numbers of maleS. tangolias.

Monogagaine, a Novel Dimeric Indole Alkaloid from Tabernaemontana chippii and Tabernaemontana dichotoma [1]

Abstract From the rootbark of Tabernaemontana chippii and the stembark of T. dichotoma a novel dimeric indole alkaloid was isolated which was named monogagaine. It was assigned structure 1 on the basis of spectral data. It showed antimicrobial activity against Bacillus subtilis.

Structure elucidation of female-specific volatiles released by the parasitoid wasp Trichogramma turkestanica (Hymenoptera: Trichogrammatidae).

Summary Females of the parasitoid wasp Trichogramma turkestanica produce the putative polydeoxypropionates (2E,4E,6S,8S,10S)-4,6,8,10-tetramethyltrideca-2,4-diene and (2E,4E,6S,8S,10S)-4,6,8,10-tetramethyltrideca-2,4-dien-1-ol or their enantiomers as sex specific volatiles. The structures were assigned on the basis of GC–MS investigations using synthetic reference compounds.