Diterpene Content Research Articles

Novel Taxane Diterpenes from Taxus sumatrana with the First C‐21 Taxane Ester

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Novel taxane diterpenes from Taxus sumatrana with the first C-21 taxane ester

Phytochemical investigation of the taxane diterpenes content of an acetone extract of the leaves and twigs of Taxus sumatrana (Taxaceae) has resulted in the isolation of five new taxane diterpenes esters, tasumatrols H–L ( 1– 5 ) together with 13 known taxanes ( 11– 23 ). Compound 5 is the first 21-carbon taxane ester to be isolated from a natural source. The structures of these taxanes as well as their derivatives were established on the basis of spectral analyses, especially MS as well as 1-and 2D NMR. Compounds 2 and 4 showed significant activity against human liver carcinoma (Hepa59T/VGH), human large cell carcinoma of the lungs (NCI), human cervical epitheloid carcinoma (Hela), human colon adenocarcinoma (DLD-1) and human medulloblastoma (Med) cell lines.

HPLC quantitation of kaurane diterpenes in Xylopia species

Xylopia frutescens is a tree native to the Brazilian Amazon whose seeds are rich in kaurenoic acid, a diterpene that showed in vitro activity against Trypanosoma cruzi. Aiming to find out alternative sources for kaurenoic acid, the content of some kaurane diterpenes was evaluated in X. aromatica and X. brasiliensis, species occurring in the Cerrado area of Minas Gerais, and also in X. frutescens. A reversed phase HPLC isocratic method was developed and validated to perform the assays. Kaurenoic acid was found to be the most abundant diterpene within the analyzed species, with a 3.16±0.97% content in the seeds of X. frutescens, which also presented the highest amount of xylopic acid (1.09±0.33%). The highest concentration of 16-α-hydroxykauranoic acid (1.96±1.58%) was found in the stems of X. aromatica.

Analysis of labdane-type diterpenes from Cistus creticus (subsp. creticus and subsp. eriocephalus), by GC and GC-MS.

The qualitative and quantitative analysis of labdane-type diterpenes of the hexane extracts and of the essential oils of the leaves, fruits and resin "Ladano", of Cistus creticus subsp. creticus and Cistus creticus subsp. eriocephalus, have been carried out by GC and GC-MS analysis using two capillary chromatographic columns, i.e., HP-5MS and CP-Wax. The methanolic extract of the fruits of C. creticus subsp. creticus was examined and seven labdane diterpenes were isolated and identified by spectroscopic methods. Data on the investigation of labdane diterpenes by GC and GC-MS is limited and most of them have never been analysed by this method. The results obtained by this analysis could be useful for identifying them in crude plant extracts. Manoyl oxides were studied further for the percentage content of their isomers. The hexane extracts of the two subspecies as well as the manoyl oxide isomers isolated from the methanolic extract of the fruits of C. creticus subsp. creticus, were tested for their antimicrobial activity against Gram-positive and Gram-negative bacteria. Global numerical differences of these C. creticus subspecies, based on labdane diterpenes content in the hexane extracts as well as in the essential oils, were established by statistical methods. Phenotypic differences are discussed.

Determination of Free Diterpenes in Green and Roasted Coffees

The three coffee diterpenes cafestol, kahweol, and 16-O-methylcafestol are mostly esterified with fatty acids. Little has been published about the diterpenes occurring in the free form. By means of gel permeation chromatography on Bio Beads S-X3, it is now possible to simultaneously analyze and quantify the small amounts of these compounds by RP-HPLC. In this way, free kahweol was first proved to be an ingredient of Robusta coffee. Various Arabica and Robusta coffees – both green and roasted – were investigated. Free diterpenes were found in green coffees in amounts below 200 mg/kg dry matter. In comparison to the respective total diterpene content determined by the same HPLC method after saponification of the coffee oil, the proportion of free diterpenes ranged from 0.7 to 3.5 %. During the roasting process, the three uncombined diterpenes behaved similarly: free 16-O-methylcafestol, cafestol as well as kahweol were degraded with increasing roasting temperature.

Essential Oil Composition of Leaves and Berries ofVitex agnus-castusL. from Calabria, Southern Italy

The essential oil of leaves and berries of Vitex agnus-castus L. (Verbenaceae) growing wild in Calabria, southern Italy, was analyzed by gas chromatography/mass spectrometry. A total of 38 compounds (including two coeluting pairs) were identified (95.8 and 66.1% in leaf and berry oil, respectively); 6 compounds were tentatively identified and 7 compounds remained unknown. All the unknown and tentatively identified compounds eluted in the final part of the chromatograms and were particularly abundant in the berry oil. The main components of the essential oil were 1,8-cineole, sabinene, α-pinene, β-farnesene, β-caryophyllene and α-terpinenyl acetate. The relative amounts of two main constituents namely sabinene and β-farnesene, versus 1,8-cineole and the whole sesquiterpenic fraction in leaves were more comparable to the data reported in the literature for a Dalmatian V. agnus-castus than to the composition of an African sample. The berry essential oil of the present samples was characterized by a large content of sesquiterpenes, diterpenes and other unknown high-molecular-weight compounds (62.1%) compared to the leaf oil (15.3%) and to the literature data regarding the Dalmatian and African types.

Essential Oil Composition of Leaves and Berries of Vitex agnuscastus L. from Calabria, Southern Italy

The essential oil of leaves and berries of Vitex agnus-castus L. (Verbenaceae) growing wild in Calabria, southern Italy, was analyzed by gas chromatography/mass spectrometry. A total of 38 compounds (including two coeluting pairs) were identified (95.8 and 66.1% in leaf and berry oil, respectively); 6 compounds were tentatively identified and 7 compounds remained unknown. All the unknown and tentatively identified compounds eluted in the final part of the chromatograms and were particularly abundant in the berry oil. The main components of the essential oil were 1,8-cineole, sabinene, α-pinene, β-farnesene, β-caryophyllene and α-terpinenyl acetate. The relative amounts of two main constituents namely sabinene and β-farnesene, versus 1,8-cineole and the whole sesquiterpenic fraction in leaves were more comparable to the data reported in the literature for a Dalmatian V. agnus-castus than to the composition of an African sample. The berry essential oil of the present samples was characterized by a large content of sesquiterpenes, diterpenes and other unknown high-molecular-weight compounds (62.1%) compared to the leaf oil (15.3%) and to the literature data regarding the Dalmatian and African types.

Products with biological activity obtained from in vitro micropropagated Sideritis foetens

A method for the in vitro micropropagation of Sideritis foetens species is described. About one million plants were produced from a single nodal segment in one year. Phytochemical studies of plants indicated that this method increases their diterpene content, although the same type of products as in natural plants are obtained. ent-6α- Acetoxy-3β,8α-dihydroxylabda-13(16),14-diene, ent-6α,8α,18-trihydroxylabda-13(16),14-diene, ent-6α-acetoxy-8α-18- dihydroxy-labda-13(16),14-diene and ent-18-acetoxy-6α,8α-dihydroxylabda-13(16),14-diene were isolated from micropropagated plants. ent-3β,6β-Dihydroxy-13- epi-manoyl oxide and ent-16,18-dihydroxy-6-oxomanoyl oxide (ketomanoyl) were obtained by chemical methods from these natural products. Both products inhibit basal adenylatecyclase activity and activity previously stimulated by forskolin or fluoride, but were without effect on glucagon-enhanced activity.

Inter-Tree Variation of Essential Oil Composition ofThuja occidentalisL.

ABSTRACT Variation in the composition and yield of the essential oils of Michigan grown northern white cedar (Thuja occidentalis L.) is reported. Comparison of oil isolated from the foliage of individual trees revealed significant inter-tree variation in oil composition. The optimal pilot scale distillation time was found to be about 40 minutes. Total oil yield using steam distillation is almost identical among the ten trees analyzed, but ketone content and diterpene percentages vary significantly from tree to tree. Ketone content of T. occidentalis can be used as criteria for tree selection since its percentage varies widely from 58 to 77%. Diterpene content may also prove useful as markers but more work is needed to help quantify the genetic and environmental components of phenotypic variation.

Influence of Genotype and Environment on the Diterpenes in the Wax Layer of Some Flue-cured Tobaccos/Einfluss von Genotyp und Umwelt auf die Diterpene in der Wachsschicht einiger „flue-cured“–Tabake

Abstract The composition of the wax layer of some flue-cured tobaccos that were grown under the same conditions in the U. S. A., Brazil and Germany was examined by means of GC and GC/MS. The total amount of wax layer (referring to fresh weight) is significantly influenced neither by the genotype nor by environmental factors. The content of diterpenes, on the other hand, is controlled both genetically and by environmental factors, as it was possible to show taking a- and b-4,8,13-duvatrien-1,3-diol and 4,8,13-duvatrien-1-ol. The concentration of compounds such as norsolandion and nicotine appears to be affected to a great extent or exclusively by environmental factors.