Effect of salt stress in urban conditions on two Acer species with different sensitivity.

BACKGROUND: The benefits of trees in urban areas include the following: an increase in ecosystem health, an increase in human health, the mitigation of the effects of heat and drought at microclimate level, the storage and sequestration of carbon, and a reduction in air pollution and noise. These ecosystem services can be provided only by trees that are in good health. The main cause of salt stress in urban environments is the use of de-icing salts on the streets in winter. Salt stress is a complex process that includes changes in plants on the physiological, histological, cellular and molecular levels, leading to limitations in nutrient uptake, disrupting the ionic balance of trees and resulting in the death of roadside trees. In response to salinity, trees have developed a variety of defence mechanisms that allow them to minimize the effects of stress and maintain homeostasis. METHODOLOGY: The reactions of two species Acer species: A. platanoides and A. campestre, which have different sensitivities to the unfavourable conditions of the urban environments (mainly salt stress), were investigated. The research included two experiments: a field experiment with city trees and a controlled pot experiment with young trees treated with increasing doses of salt. In both experiments, the following were performed: an assessment of the health condition of the trees and the content of macroelements as well as the Cl and Na in leaves and a qualitative and quantitative analysis of polyprenols. RESULTS: A. campestre had a more specific strategy than A. platanoides for dealing with Na and Cl, which resulted in undamaged leaves. Under the same conditions, A. platanoides leaves contained more Cl and Na and were severely damaged. The disruption of the ion balance due to salt stress was lower in A. campestre than in A. platanoides. Compared with A. platanoides, A. campestre synthesized more polyprenols in the field experiment. This ability was acquired during the process of acclimation, because it occurred only in the mature trees in the field experiment and not in the young trees in the pot experiment. CONCLUSIONS: The use of two experimental methods (i.e., the field and pot experiments) allowed for a more complete assessment of tree strategies to mitigate salt stress. A. campestre displayed a more specific strategy than A. platanoides. This strategy was based on several elements. A. campestre limited Cl and Na transport to the leaves, which resulted in a lack of damage to those organs. Under the same conditions, A. platanoides individuals contained more Cl and Na in their leaves and were seriously damaged. A. campestre synthesized larger amounts of polyprenols, which probably have the ability to mitigate salt stress. This ability was acquired during the process of acclimation, because it occurred only in the mature trees in the field experiment and was not observed in the young trees in the pot experiment.

Boost of serum resistance and storage stability in cationic polyprenyl-based lipofection by helper lipids compositions.

Lipofection is a widely used molecular biology technique and one of the most promising non-viral gene therapy strategies. However, one of the main drawbacks of using cationic lipids-based lipoplexes in DNA/RNA delivery is serum-associated inhibition of transfection. We have addressed this issue using PTAI (trimethylpolyprenylammonium iodides)-based lipofection model. To overcome serum-sensitivity we used 100 different formulations based on different PTAI, various helper lipids compositions, lipoplex surface modifications with polyethylene glycol (PEG), and precondensation of DNA with poly-L-lysine (PLL). Multicomponent helper lipids compositions boosted serum resistance and largely improved long-term storage of PTAI-based reagents. This was observed, in particular, for PTAI with longer isoprenoid chains. Additionally, our PTAI-based carriers were efficient for DNA and RNA delivery and safe for human red blood cells (RBC). Moreover, a broad array of the modifications used resulted in an important observation - a diverse susceptibility of various cell types to different compositions was noted. Overall, our results show that helper lipids composition mediates efficient serum-resistant DNA/RNA lipofection. Additionally, multicomponent PTAI-based reagents are promising gene delivery carriers both, at the cellular and organismal level.

Effective usage of cationic derivatives of polyprenols as carriers of DNA vaccines against influenza virus.

BACKGROUND: Cationic derivatives of polyprenols (trimethylpolyprenylammonium iodides - PTAI) with variable chain length between 6 and 15 isoprene units prepared from naturally occurring poly-cis-prenols were tested as DNA vaccine carriers in chickens and mice. This study aimed to investigate if PTAI could be used as an efficient carrier of a DNA vaccine. METHODS: Several vaccine mixtures were prepared by combining different proportions of the vaccine plasmid (carrying cDNA encoding a vaccine antigen, hemagglutinin from H5N1 influenza virus) and various compositions of PTAI. The vaccines were delivered by intramuscular injection to either chickens or mice. The presence of specific antibodies in sera collected from the immunized animals was analyzed by enzyme-linked immunosorbent assay (ELISA) and hemagglutination inhibition (HI) test. RESULTS: The mixtures of PTAI with helper lipids, such as DOPE (1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine), DC-cholesterol [{3ß-[N-(N',N'-dimethylaminoethane)-carbamoyl] cholesterol} hydrochloride] or DOPC (1,2-dioleoyl-sn-glycero-3-phosphatidylcholine) induced strong humoral response to the antigen encoded by the DNA vaccine plasmid. CONCLUSION: The animal immunization results confirmed that PTAI compositions, especially mixtures of PTAI with DOPE and DC-cholesterol, do work as effective carriers of DNA vaccines, comparable to the commercially available lipid transfection reagent.

Modeling of Dolichol Mass Spectra Isotopic Envelopes as a Tool to Monitor Isoprenoid Biosynthesis.

The cooperation of the mevalonate (MVA) and methylerythritol phosphate (MEP) pathways, operating in parallel in plants to generate isoprenoid precursors, has been studied extensively. Elucidation of the isoprenoid metabolic pathways is indispensable for the rational design of plant and microbial systems for the production of industrially valuable terpenoids. Here, we describe a new method, based on numerical modeling of mass spectra of metabolically labeled dolichols (Dols), designed to quantitatively follow the cooperation of MVA and MEP reprogrammed upon osmotic stress (sorbitol treatment) in Arabidopsis (Arabidopsis thaliana). The contribution of the MEP pathway increased significantly (reaching 100%) exclusively for the dominating Dols, while for long-chain Dols, the relative input of the MEP and MVA pathways remained unchanged, suggesting divergent sites of synthesis for dominating and long-chain Dols. The analysis of numerically modeled Dol mass spectra is a novel method to follow modulation of the concomitant activity of isoprenoid-generating pathways in plant cells; additionally, it suggests an exchange of isoprenoid intermediates between plastids and peroxisomes.

Quantitative and qualitative characteristics of cell wall components and prenyl lipids in the leaves of Tilia x euchlora trees growing under salt stress.

The study was focused on assessing the presence of arabinogalactan proteins (AGPs) and pectins within the cell walls as well as prenyl lipids, sodium and chlorine content in leaves of Tilia x euchlora trees. The leaves that were analyzed were collected from trees with and without signs of damage that were all growing in the same salt stress conditions. The reason for undertaking these investigations was the observations over many years that indicated that there are trees that present a healthy appearance and trees that have visible symptoms of decay in the same habitat. Leaf samples were collected from trees growing in the median strip between roadways that have been intensively salted during the winter season for many years. The sodium content was determined using atomic spectrophotometry, chloride using potentiometric titration and poly-isoprenoids using HPLC/UV. AGPs and pectins were determined using immunohistochemistry methods. The immunohistochemical analysis showed that rhamnogalacturonans I (RG-I) and homogalacturonans were differentially distributed in leaves from healthy trees in contrast to leaves from injured trees. In the case of AGPs, the most visible difference was the presence of the JIM16 epitope. Chemical analyses of sodium and chloride showed that in the leaves from injured trees, the level of these ions was higher than in the leaves from healthy trees. Based on chromatographic analysis, four poly-isoprenoid alcohols were identified in the leaves of T. x euchlora. The levels of these lipids were higher in the leaves from healthy trees. The results suggest that the differences that were detected in the apoplast and symplasm may be part of the defensive strategy of T. x euchlora trees to salt stress, which rely on changes in the chemical composition of the cell wall with respect to the pectic and AGP epitopes and an increased synthesis of prenyl lipids.

Efficient and non-toxic gene delivery by anionic lipoplexes based on polyprenyl ammonium salts and their effects on cell physiology.

BACKGROUND: One of the major challenges limiting the development of gene therapy is an absence of efficient and safe gene carriers. Among the nonviral gene delivery methods, lipofection is considered as one of the most promising. In the present study, a set of cationic polyprenyl derivatives [trimethylpolyprenylammonium iodides (PTAI)] with different lengths of polyprenyl chains (from 7, 8 and 11 to 15 isoprene units) was suggested as a component of efficient DNA vehicles. METHODS: Optimization studies were conducted for PTAI in combination with co-lipid dioleoylphosphatidylethanolamine on DU145 human prostate cancer cells using: size and zeta potential measurements, confocal microscopy, the fluorescein diacetate/ethidium bromide test, cell counting, time-lapse monitoring of cell movement, gap junctional intercellular coupling analysis, antimicrobial activity assay and a red blood cell hemolysis test. RESULTS: The results obtained show that the lipofecting activity of PTAI allows effective transfection of plasmid DNA complexed in negatively-charged lipoplexes of 200-500 nm size into cells without significant side effects on cell physiology (viability, proliferation, morphology, migration and gap junctional intercellular coupling). Moreover, PTAI-based vehicles exhibit a potent bactericidal activity against Staphylococcus aureus and Escherichia coli. The developed anionic lipoplexes are safe towards human red blood cell membranes, which are not disrupted in their presence. CONCLUSIONS: The developed carriers constitute a group of promising lipofecting agents of a new type that can be utilized as effective lipofecting agents in vitro and they are also an encouraging basis for in vivo applications.

Prenyl Ammonium Salts--New Carriers for Gene Delivery: A B16-F10 Mouse Melanoma Model.

PURPOSE: Prenyl ammonium iodides (Amino-Prenols, APs), semi-synthetic polyprenol derivatives were studied as prospective novel gene transfer agents. METHODS: AP-7, -8, -11 and -15 (aminoprenols composed of 7, 8, 11 or 15 isoprene units, respectively) were examined for their capacity to form complexes with pDNA, for cytotoxicity and ability to transfect genes to cells. RESULTS: All the carriers were able to complex DNA. The highest, comparable to commercial reagents, transfection efficiency was observed for AP-15. Simultaneously, AP-15 exhibited the lowest negative impact on cell viability and proliferation--considerably lower than that of commercial agents. AP-15/DOPE complexes were also efficient to introduce pDNA to cells, without much effect on cell viability. Transfection with AP-15/DOPE complexes influenced the expression of a very few among 44 tested genes involved in cellular lipid metabolism. Furthermore, complexes containing AP-15 and therapeutic plasmid, encoding the TIMP metallopeptidase inhibitor 2 (TIMP2), introduced the TIMP2 gene with high efficiency to B16-F10 melanoma cells but not to B16-F10 melanoma tumors in C57BL/6 mice, as confirmed by TIMP2 protein level determination. CONCLUSION: Obtained results indicate that APs have a potential as non-viral vectors for cell transfection.

Effects of liposomes with polyisoprenoids, potential drug carriers, on the cardiovascular and excretory system in rats.

BACKGROUND: The unpredictable side effects of a majority currently used drugs are the substantial issue, in which patients and physicians are forced to deal with. Augmenting the therapeutic efficacy of drugs may prove more fruitful than searching for the new ones. Since recent studies show that new cationic derivatives of polyisoprenoid alcohols (APrens) might exhibit augmenting properties, we intend to use them as a component of liposomal drug carriers. In this study we investigate if these compounds do not per se cause untoward effects on the living organism. METHODS: Male Sprague-Dawley rats received for four weeks daily injections (0.5 ml sc) of liposomes built of dioleoyl phosphatidylethanolamine (DOPE), liposomes built of DOPE and APren-7 (ratio 10:1) or water solvent. Weekly, rats were observed in metabolic cages (24h); blood and urine were sampled for analysis; body weight (BW) and systolic blood pressure (SBP) were determined. After chronic experiment, kidneys and heart were harvested for histological and morphometric analysis. RESULTS: The 4-week BW increments were in the range of 97 ± 4 to 102 ± 4%, intergroup differences were not significant. Microalbuminuria was the lowest in the group receiving liposomes with APren-7 (0.22 ± 0.03 mg/day). Water and food intake, plasma and urine parameters were similar in all groups. CONCLUSIONS: Newly designed liposomes containing APren-7 did not affect functions of the excretory and cardiovascular systems, and renal morphology; therefore we find them suitable as a component of liposomal drug carriers.

Effects of various squalene epoxides on coenzyme Q and cholesterol synthesis.

2,3-Oxidosqualene is an intermediate in cholesterol biosynthesis and 2,3:22,23-dioxidosqualene act as the substrate for an alternative pathway that produces 24(S),25-epoxycholesterol which effects cholesterol homeostasis. In light of our previous findings concerning the biological effects of certain epoxidated all-trans-polyisoprenes, the effects of squalene carrying epoxy moieties on the second and third isoprene residues were investigated here. In cultures of HepG2 cells both monoepoxides of squalene and one of their hydrolytic products inhibited cholesterol synthesis and stimulated the synthesis of coenzyme Q (CoQ). Upon prolonged treatment the cholesterol content of these cells and its labeling with [(3)H]mevalonate were reduced, while the amount and labeling of CoQ increased. Injection of the squalene monoepoxides into mice once daily for 6days elevated the level of CoQ in their blood, but did not change the cholesterol level. The same effects were observed upon treatment of apoE-deficient mice and diabetic GK-rats. This treatment increased the hepatic level of CoQ10 in mice, but the amount of CoQ9, which is the major form, was unaffected. The presence of the active compounds in the blood was supported by the finding that cholesterol synthesis in the white blood cells was inhibited. Since the ratio of CoQ9/CoQ10 varies depending on the experimental conditions, the cells were titrated with substrate and inhibitors, leading to the conclusion that the intracellular isopentenyl-PP pool is a regulator of this ratio. Our present findings indicate that oxidosqualenes may be useful for stimulating both the synthesis and level of CoQ both in vitro and in vivo.

Application of supercritical CO2 for extraction of polyisoprenoid alcohols and their esters from plant tissues.

In this study, a method of supercritical fluid extraction (SFE) with carbon dioxide of polyisoprenoids from plant photosynthetic tissues is described. SFE was an effective extraction method for short- and medium-chain compounds with even higher yield than that observed for the "classical extraction" method with organic solvents. Moreover, SFE-derived extracts contained lower amounts of impurities (e.g., chlorophylls) than those obtained by extraction of the same tissue with organic solvents. Elevated temperature and extended extraction time of SFE resulted in a higher rate of extraction of long-chain polyisoprenoids. Ethanol cofeeding did not increase the extraction efficiency of polyisoprenoids; instead, it increased the content of impurities in the lipid extract. Optimization of SFE time and temperature gives the opportunity of prefractionation of complex polyisoprenoid mixtures accumulated in plant tissues. Extracts obtained with application of SFE are very stable and free from organic solvents and can further be used directly in experimental diet supplementation or as starting material for preparation of semisynthetic polyisoprenoid derivatives, e.g., polyisoprenoid phosphates.

Role of polyisoprenoids in tobacco resistance against biotic stresses.

Infection with avirulent pathogens, tobacco mosaic virus (TMV) or Pseudomonas syringae pv. tabaci induced accumulation of polyisoprenoid alcohols, solanesol and a family of polyprenols [from polyprenol composed of 14 isoprene units (Pren-14) to -18, with Pren-16 dominating] in the leaves of resistant tobacco plants Nicotiana tabacum cv. Samsun NN. Upon TMV infection, solanesol content was increased seven- and eight-fold in the inoculated and upper leaves, respectively, while polyprenol content was increased 2.5- and 2-fold in the inoculated and upper leaves, respectively, on the seventh day post-infection. Accumulation of polyisoprenoid alcohols was also stimulated by exogenously applied hydrogen peroxide but not by exogenous salicylic acid (SA). On the contrary, neither inoculation of the leaves of susceptible tobacco plants nor wounding of tobacco leaves caused an increase in polyisoprenoid content. Taken together, these results indicate that polyisoprenoid alcohols might be involved in plant resistance against pathogens. A putative role of accumulated polyisoprenoids in plant response to pathogen attack is discussed. Similarly, the content of plastoquinone (PQ) was increased two-fold in TMV-inoculated and upper leaves of resistant plants. Accumulation of PQ was also stimulated by hydrogen peroxide, bacteria (P. syringae) and SA. The role of PQ in antioxidant defense in cellular membranous compartments is discussed in the context of the enzymatic antioxidant machinery activated in tobacco leaves subjected to viral infection. Elevated activity of several antioxidant enzymes (ascorbate peroxidase, guaiacol peroxidase, glutathione reductase and superoxide dismutase, especially the CuZn superoxide dismutase isoform) and high, but transient elevation of catalase was found in inoculated leaves of resistant tobacco plants but not in susceptible plants.

Stimulation of coenzyme Q synthesis.

Uptake of dietary coenzyme Q (CoQ) into organs is limited but there are some exceptions such as adrenal glands and ovaries. Under deficient conditions an optimal solution could be stimulation of the endogenous synthesis. In rodent exercise, cold exposure and a few substances elevate the CoQ levels to some extent. Investigations of the nuclear receptors PPARalpha, RXRalpha and LXRalpha&beta did not answer the question which nuclear receptor regulates CoQ biosynthesis and at present we cannot design a ligand for upregulation of the synthesis. Upon ultraviolet irradiation of CoQ a number of products are formed which influence the synthesis of the mevalonate pathway lipids. Among them epoxidated derivatives were identified. Upon chemical epoxidation of a series of polyisoprenoids it was found that none of the tested poly-cis polyisoprenols had any effect but some of the all-trans polyisoprenols stimulated CoQ synthesis and in some cases also inhibited cholesterol biosynthesis. Tocotrienol epoxides were proved to be very efficient, those having one epoxide in the side chain doubled or trebled the CoQ synthesis while those with two epoxides additionally also inhibited cholesterol synthesis by 50-90%. The elevation of CoQ synthesis was elicited by increased mRNA levels for biosynthetic enzymes while the inhibition point in the cholesterol synthesis was localized to oxidosqualene cyclase.

Prenyl sulfates as alkylating reagents for mercapto amino acids.

A new methodology for prenylation of thiol compounds has been developed. The approach is based on the use of prenyl sulfates as new reagents for S-prenylation of benzenethiol and cysteamine in aqueous systems. The C(10)-prenols geraniol and nerol that differ in the configuration (E or Z, correspondingly) of the alpha-isoprene unit were efficiently O-sulfated in the presence of a pyridine-SO(3') complex. The obtained geranyl and neryl sulfates were tested as alkylating agents. These compounds were chosen to reveal the influence of the alpha-isoprene unit configuration on their alkylation (prenylation) ability. S-Geranyl cysteine was prepared to demonstrate the applicability of this method for prenylation of peptides containing mercapto amino acids.

Contribution of the mevalonate and methylerythritol phosphate pathways to the biosynthesis of dolichols in plants.

Plant isoprenoids are derived from two biosynthetic pathways, the cytoplasmic mevalonate (MVA) and the plastidial methylerythritol phosphate (MEP) pathway. In this study their respective contributions toward formation of dolichols in Coluria geoides hairy root culture were estimated using in vivo labeling with (13)C-labeled glucose as a general precursor. NMR and mass spectrometry showed that both the MVA and MEP pathways were the sources of isopentenyl diphosphate incorporated into polyisoprenoid chains. The involvement of the MEP pathway was found to be substantial at the initiation stage of dolichol chain synthesis, but it was virtually nil at the terminal steps; statistically, 6-8 isoprene units within the dolichol molecule (i.e. 40-50% of the total) were derived from the MEP pathway. These results were further verified by incorporation of [5-(2)H]mevalonate or [5,5-(2)H(2)]deoxyxylulose into dolichols as well as by the observed decreased accumulation of dolichols upon treatment with mevinolin or fosmidomycin, selective inhibitors of either pathway. The presented data indicate that the synthesis of dolichols in C. geoides roots involves a continuous exchange of intermediates between the MVA and MEP pathways. According to our model, oligoprenyl diphosphate chains of a length not exceeding 13 isoprene units are synthesized in plastids from isopentenyl diphosphate derived from both the MEP and MVA pathways, and then are completed in the cytoplasm with several units derived solely from the MVA pathway. This study also illustrates an innovative application of mass spectrometry for qualitative and quantitative evaluation of the contribution of individual metabolic pathways to the biosynthesis of natural products.

Polyisoprenoid epoxides stimulate the biosynthesis of coenzyme Q and inhibit cholesterol synthesis.

In our search for compounds that up-regulate the biosynthesis of coenzyme Q (CoQ), we discovered that irradiation of CoQ with ultraviolet light results in the formation of a number of compounds that influence the synthesis of mevalonate pathway lipids by HepG2 cells. Among the compounds that potently stimulated CoQ synthesis while inhibiting cholesterol synthesis, derivatives of CoQ containing 1-4 epoxide moieties in their polyisoprenoid side chains were identified. Subsequently, chemical epoxidation of all-trans-polyprenols of different lengths revealed that the shorter farnesol and geranylgeraniol derivatives were without effect, whereas the longer derivatives of solanesol enhanced CoQ and markedly reduced cholesterol biosynthesis. In contrast, none of the modified trans-trans-poly-cis-polyprenols exerted noticeable effects. Tocotrienol epoxides were especially potent in our system; those with one epoxide moiety in the side-chain generally up-regulated CoQ biosynthesis by 200-300%, whereas those with two such moieties also decreased cholesterol synthesis by 50-90%. Prolonged treatment of HepG2 cells with tocotrienol epoxides for 26 days elevated their content of CoQ by 30%. In addition, the levels of mRNA encoding enzymes involved in CoQ biosynthesis were also elevated by the tocotrienol epoxides. The site of inhibition of cholesterol synthesis was shown to be oxidosqualene cyclase. In conclusion, epoxide derivatives of certain all-trans-polyisoprenoids cause pronounced stimulation of CoQ synthesis and, in some cases, simultaneous reduction of cholesterol biosynthesis by HepG2 cells.

Investigation of coenzyme Q biosynthesis in human fibroblast and HepG2 cells.

Coenzyme Q (CoQ) deficiency occurs in genetic disorders, during aging and various diseases. Diagnosis requires skin fibroblasts in tissue culture. [3H]Mevalonate incorporation was appropriate to measure the rate of CoQ synthesis in fibroblasts and hepatoblastoma cells. [14C]p-Hydroxybenzoate had limited permeability, but it could be increased with Fugene and cyclodextrin. Inhibition of decaprenyl-4-hydroxybenzoate transferase results in the accumulation of decaprenyl diphosphate, an indicator of enzyme deficiency. Also, analysis of the corresponding mRNAs in this case is useful. In vitro assays to measure trans-prenyltransferase and decaprenyl-4-hydroxybenzoate transferase activities are not available. Neither measurement of methyltransferases is reliable in human cells. In vitro reconstruction of CoQ synthesis, in opposite to cholesterol synthesis, proved to be unsuccessful. Thus, the biochemical characterization of the CoQ biosynthetic system in human cells is restricted to a few reliable analytical procedures.

The search for polyprenols in dendroflora of Vietnam.

The occurrence of polyprenols in leaves of over 340 species of dendroflora in natural habitats in the regions of Hanoi and Hue in Vietnam was studied. Plant material was collected in the late autumn (October/November) during the end of a vegetation season. Leaves of about 200 plant species did not contain detectable amounts of polyprenols in contrast to few systematic families, e.g. Moraceae, Euphorbiaceae, where polyprenols were highly abundant and their pattern could be used as a chemotaxonomic criterion. Most often dominating polyprenols were prenol-11 and prenol-12. In several angiosperm species prenol-13 and detectable amounts of prenol-14 were also found. The incidence of prenol-13 and -14 was not restricted to a specific taxonomic group since species exhibiting domination of such longer chain polyprenols belonged to various systematic families. In some plants (e.g. Ceiba pentandra) alpha-cis polyprenols were accompanied by alpha-trans counterparts. This report describes several new plant species that may serve as natural sources of long chain polyprenols.

New cationic polyprenyl derivative proposed as a lipofecting agent.

Cationic linear poly-cis-isoprenoid prepared from natural plant polyprenol in a mixture with dioleyl phosphatidylethanolamine was found to be an effective lipofection agent for eukaryotic cells. The transfecting activity is related to the poly-cis structure of the polyprenyl chain.

In vitro plant tissue cultures accumulate polyisoprenoid alcohols.

In vitro cultivated plant cells and tissues were found to synthesize polyisoprenoids. Taxus baccata suspension cell cultures accumulated polyisoprenoids of the same pattern as the parental tissue; methyl jasmonate or chitosan treatment almost doubled their content. All the root cultures studied accumulated dolichols as predominant polyisoprenoids. Roots of Ocimum sanctum grown in vitro accumulated approx. 2.5-fold higher amount of dolichols than the roots of soil-grown plants. Dolichols dominated over polyprenols in all Triticum sp. tissues studied.

Alloprenols: novel alpha-trans-polyprenols of Allophylus caudatus.

A novel type of polyprenols, alloprenols, with an alpha-trans-isoprenoid unit was found in the leaves of Allophylus caudatus (Sapindaceae) besides typical alpha-cis-polyprenols. The polyprenol family (Prenol-11-13, Prenol-12 dominating) was accompanied by traces of dolichols of the same chain-length. Prenol alpha-cis- and alpha-trans-isomers were chromatographically separated and their structure was analyzed by HPLC/ESI-MS, HR-ESI-MS and 1H and 13C NMR spectroscopy. Model compounds, semi-synthetic alpha-isomers of all-trans-Pren-9 and mainly-cis-Pren-11, were obtained using an oxidation-reduction procedure. Comparison of their NMR spectra confirmed the structure of the newly identified polyprenols. The observed pattern of NMR signal shifts may be applied for elucidation of isoprenoid structure.