G.P. Lelyveld

DETERMINATION OF GINKGOLIDES AND BILOBALIDE IN GINKGO-BILOBA LEAVES AND PHYTOPHARMACEUTICALS

Abstract A method has been developed for the determination of the pharmacologically active terpenoids ginkgolide A, B and C and bilobalide in Ginkgo biloba leaves and phytopharmaceutical preparations containing ginkgo extracts. The leaves (400–800 mg) ar selectively extracted with methanol—water (10:90) and the resulting extract is purified by means of a polyamide and a C 18 solid-phase extraction column After concentration, the terpenoids are determined by high-performance liquid chromatography on a C 18 column with methanol—water (33:67) as eluent and refractive index detection. Benzyl alcohol is used as an internal standard. The recovery of the method is 95 ± 5%. The reproducibility is dependent on the concentration and varies from 2 to 15%. The minimum concentraon that can be determined in leaves is 10 μg of terpenoid/g of dry leaves. With a small modification the method can be used equally well for phytopharmaceuticals. Several ginkgo medicines were investigated and the total concentration of terpenoids was found to vary by a factor 18. The concentration in leaves varied by a factor 40.

Screening of the needles of different yew species and cultivars for paclitaxel and related taxoids

The needles of several yew species and cultivars were analysed by high-pressure liquid chromatography for paclitaxel, 10-deacetylpaclitaxel, cephalomannine, baccatin III, 10-deacetylbaccatin III and brevifoliol. About 750 samples were collected from five different locations in the Netherlands and the UK. The results of this screening show a large variation in taxane content between the different species and cultivars. The content of paclitaxel and 10-deacetylbaccatin III varied from 0 to 500 micrograms/g and 0 to 4800 micrograms/g dried needles, respectively. Brevifoliol was found in a very high concentration in Taxus brevifolia. 10-Deacetylpaclitaxel, cephalomannine and baccatin III were found in concentrations ranging from 0 to 500 micrograms/g dried needles.

Sex-Related Perception of Insect and Plant Volatiles in Lygocoris pabulinus

We recorded electroantennograms of male and female Lygocoris pabulinus antennae to 63 insect and plant volatiles. EAGs were between 100 and 500 μV. Overall, male EAGs were about twice the size of female EAGs. In both sexes, largest EAGs were recorded to (E)-2-hexenyl butanoate and (E)-2-hexen-1-ol. Response profiles were similar in both sexes. However, male antennae were more sensitive to a number of esters, especially the butanoates and pentanoates. Female antennae were more sensitive to nine of the 19 plant volatiles, i.e., to hexan-1-ol, heptan-1-ol, 1-octen-3-ol, 2-heptanone, (R)-carvone, linalool, geraniol, nerol, and methyl salicylate. Sexual differences in responses suggest that males are more sensitive to insect-produced pheromone-type compounds, whereas females are more sensitive to plant compounds for their orientation towards oviposition sites.

Chemotaxonomy of Commercial Buchu Species (Agathosma betulina and A. crenulata)

ABSTRACT The essential oils of Agathosma betulina, A. crenulata and their hybrids were analyzed to determine whether the taxa could be distinguished by their monoterpene chemistry. Pulegone was found to be the key component for identification of the oils. A. betulina is identified by a pulegone content of 2.4% to 4.5%, the hybrids have 7.6% to 27.8% and A. crenulata has 31.6% to 73.2% pulegone. A. betulina and the hybrids have a higher content of 8-mercapto-p-menthan-3-one than 8-acetylthio-p-menthan-3-one while, the reverse is true for A. crenulata. The cis-8-mercapto-p-menthan-3-one content is higher than that of the trans- isomer for A. betulina and die hybrids, but the reverse is true for A. crenulata. Two A. betulina chemotypes were identified. The Diosphenol chemotype is characterized by high ϕ-diosphenol (>10%) and diosphenol (>12%), and low isomenthone ( 31%) and low ϕ-diosphenol (<0.16%) and diosphenol (<0.14%) ...

Investigation of the essential oil of Vietnamese ginger.

Abstract The composition of the hydrodistilled essential oil of dried Vietnamese ginger was determined by means of GC, GC-MS and 13C NMR. The oil yield was

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.

Confirmation of the structure of kessane by NMR spectroscopy.

ABSTRACT In order to prove the correct relative and absolute stereochemistry of the sesquiterpene ether (−)-kessane that was recently synthesized by us, its chromatographic retention, mass and 1H-NMR spectrum and optical rotation were compared with that of natural kessane. Natural kessane was isolated by means of fractionated vacuum distillation and repeated medium-pressure liquid chromatography from the essential oil of Valeriana officinalis. The recorded data confirm that the two compounds are identical. Further, by means of one- and two-dimensional 1H- and 13C-NMR spectroscopy at 600 MHz, it was possible to assign all protons and determine all coupling constants in the 1H-NMR spectrum. The NMR data are in full agreement with the relative stereochemistry proposed in the original work on kessane.

Investigation of Nepalese essential oils. I. The oil of Cinnamomum glaucescens (Sugandha kokila)

ABSTRACT The commercially available essential oil of Cinnamomum glaucescens (fam. Lauraceae) fruits, was investigated by various physico-chemical, chromatographic and spectroscopic methods. Both the total fruit (incl. seed) oil and the pericarp oil obtained by steam- and hydrodistillation of Nepalese fruits were examined. Major components of the total oil were 1,8-cineole (13%), methyl cinnamate (14%), α-terpineol (7%) and many mono- and sesquiterpene hydrocarbons. The pericarp oil consisted mainly of 1,8-cineole (56%) and α-terpineol (10%). Minor amounts of monoterpene hydrocarbons, other monoterpene alcohols and methyl cinnamate were also present.

Preparative isolation of (+)-Beta-eudesmol from Amyris balsamifera.

SummaryOptically pure (+)-beta-eudesmol is a possible starting material for the synthesis of several termite defense compounds. A two step procedure for the isolation of gram quantities of (+)-beta-eudesmol from commercially availableAmyris balsamifera oil (syn. West Indian sandalwood oil), containing 8% beta-eudesmol, was developed. Step one consisted of an efficient vacuum distillation of the total oil. Step two was a medium pressure LC separation with an AgNO3 impregnated silica gel stationary phase. Several other separation procedures failed due to the presence of many closely related sesquiterpene alcohols (75% of the oil).